AL Hunaity, SA, Far, H & Saleh, A 2022, 'Vibration behaviour of cold-formed steel and particleboard composite flooring systems', Steel and Composite Structures, vol. 43, no. 3, pp. 403-417.
View/Download from: Publisher's site
View description>>
Recently, there has been an increasing demand for buildings that allow rapid assembly of construction elements, have ample open space areas and are flexible in their final intended use. Accordingly, researchers have developed new competitive structures in terms of cost and efficiency, such as cold-formed steel and timber composite floors, to satisfy these requirements. Cold-formed steel and timber composite floors are light floors with relatively high stiffness, which allow for longer spans. As a result, they inherently have lower fundamental natural frequency and lower damping. Therefore, they are likely to undergo unwanted vibrations under the action of human activities such as walking. It is also quite expensive and complex to implement vibration control measures on problematic floors. In this study, a finite element model of a composite floor reported in the literature was developed and validated against four-point bending test results. The validated FE model was then utilised to examine the vibration behaviour of the investigated composite floor. Predictions obtained from the numerical model were compared against predictions from analytical formulas reported in the literature. Finally, the influence of various parameters on the vibration behaviour of the composite floor was studied and discussed.
Alibeikloo, M, Khabbaz, H & Fatahi, B 2022, 'Random Field Reliability Analysis for Time-Dependent Behaviour of Soft Soils Considering Spatial Variability of Elastic Visco-Plastic Parameters', Reliability Engineering & System Safety, vol. 219, pp. 108254-108254.
View/Download from: Publisher's site
View description>>
Low embankment strategy is one of the effective methods to control time-dependent settlement of soft soils in infrastructure construction projects. Spatial variability of soil characteristics is a crucial factor, affecting the reliability of predictions of the long-term settlement in soft soils. In this paper, the time-dependent behaviour of soft soils is analysed incorporating spatial variability of elastic visco-plastic model parameters. Standard Gaussian random fields for correlated elastic-plastic model parameter (λ/V) and the initial creep coefficient (ψ0/V) are generated adopting Karhunen-Loeve expansion method based on the spectral decomposition of correlation function into eigenvalues and eigenfunctions. Then the generated random fields are incorporated in the proposed non-linear elastic visco-plastic (EVP) creep model. The impacts of spatially variable elastic visco-plastic model parameters (i.e. ψ0/V and λ/V) on long-term settlement predictions are evaluated through random field analysis (RF) with different spatial correlation lengths, and results are then compared to a single random variable (SRV) analysis. The probability of failure (PF) is calculated adopting RF and SRV analysis to determine the critical spatial correlation length, resulted in a maximum probability of failure. This study can be employed by design engineers to determine the critical spatial correlation length for safe design in the absence of adequate data to determine the exact spatial correlation length. The results also confirm that SRV analysis is not always the most conservative analysis in predicting time-dependent settlement of soft soils; and it is essential to perform RF analysis considering the spatial correlation length to reduce the risk and increase the reliability of the design to be applied in construction.
Angeloski, A, Price, JR, Ennis, C, Smith, K, McDonagh, AM, Dowd, A, Thomas, P, Cortie, M, Appadoo, D & Bhadbhade, M 2022, 'Thermosalience Revealed on the Atomic Scale: Rapid Synchrotron Techniques Uncover Molecular Motion Preceding Crystal Jumping', Crystal Growth & Design, vol. 22, no. 3, pp. 1951-1959.
View/Download from: Publisher's site
View description>>
The solid-state phase transformation in nickel(II) bis(diisopropyldithiocarbonate) is analyzed using a combination of high-speed in situ single-crystal diffraction, terahertz spectroscopy, optical microscopy, thermal analysis, and density functional theory. We show that the monoclinic P21/c structure of this compound undergoes a displacive phase change at about 3 °C. The monoclinic angles and unit cell volumes change reversibly between 110.3°/2265 Å3 and 103.8°/2168 Å3. An analysis of atomic positions using high-resolution in situ synchrotron X-ray diffraction data revealed details of the atomic displacements that show a change in order that precedes and accompanies the change in structure. The structural changes are rapid and are manifested as reversible macroscale crystal movement and jumping (thermosalience) and represent the first case of thermosalience in dithiocarbamate complexes.
Basack, S, Nimbalkar, S, Karakouzian, M, Bharadwaj, S, Xie, Z & Krause, N 2022, 'Field Installation Effects of Stone Columns on Load Settlement Characteristics of Reinforced Soft Ground', International Journal of Geomechanics, vol. 22, no. 4.
View/Download from: Publisher's site
Chen, D, Wu, C, Li, J & Liao, K 2022, 'A numerical study of gas explosion with progressive venting in a utility tunnel', Process Safety and Environmental Protection, vol. 162, pp. 1124-1138.
View/Download from: Publisher's site
View description>>
A numerical model of a progressive vented gas explosion is presented. A CFD tool in combination with correlation analysis and an artificial neural network (ANN) were utilized to establish and refine the numerical model. The experimental results of 44 fixed vented gas explosions and one progressive vented gas explosion with moving obstacles were used to validate the numerical accuracy. The results indicated that the method to estimate the activation pressure of the pressure relief panels for a fixed vented gas explosion achieved a lower overpressure prediction compared to that for a progressive vented gas explosion. The progressive venting procedure was modelled by two-layer pressure relief panels with the upper layer having activation pressures with a linear ascent trend. The vents on the tunnel had an insignificant impact on the explosion load after being lifted over the tunnel top, and their falling process was unnecessary to be modelled. A non-negligible impact of the obstacles inside the tunnel on the flow field upon being pushed away from their initial positions was demonstrated. By employing an ANN, the critical parameters in the numerical model were determined, which were used to accurately replicate the experimental results. The findings clarified a revenue for the modeling of a progressive vented gas explosion as well as some shortcomings of the CFD tool.
Chen, Q, Guo, D, Ke, W, Xu, C & Nimbalkar, S 2022, 'Novel Open Trench Techniques in Mitigating Ground-Borne Vibrations due to Traffic under a Wide Range of Ground Conditions', International Journal of Geomechanics, vol. 22, no. 6.
View/Download from: Publisher's site
Chi, K, Li, J & Wu, C 2022, 'Behavior of Reinforced Ultra-High Performance Concrete Slabs Under Impact Loading After Exposure to Elevated Temperatures', International Journal of Computational Methods.
View/Download from: Publisher's site
View description>>
Steel fiber-reinforced ultra-high performance concrete (UHPC) material is prone to explosive spalling under elevated temperatures. With the addition of polypropylene (PP) fiber, thermal spalling of UHPC can be mitigated and its fire resistance can be improved. This research investigates the impact resistance of steel and PP fiber-reinforced UHPC slabs after exposure to elevated temperatures, and the structural behavior and damage were compared against normal strength concrete (NSC) slabs. Karagozian & Case concrete (KCC) model was adopted to simulate both NSC and UHPC materials. With consideration of thermal hazards, the material damage, equation of state and strain rate sensitivity were adapted. The validity of this numerical model was evaluated against available experimental results. The numerical model was used to investigate the impact resistance of the reinforced UHPC slabs after exposure to fire hazards. The effect of fire exposure time, impact velocity and impact mass on the resistance of the reinforced NSC and UHPC slabs were analyzed. The simulation results revealed that punching shear failure areas in the NSC slabs were 2.5 times, 3.4 times, 3.0 times and 1.2 times larger than the UHPC slabs after exposure to international standardization ISO-834 standard fire for 1[Formula: see text]h, 2[Formula: see text]h, 3[Formula: see text]h and 4[Formula: see text]h, respectively. After exposure to the standard fire ISO-834 for 2 h, the punching shear failure on the bottom side of NSC increased 90.9% with the increase in falling height from 1[Formula: see text]m to 7[Formula: see text]m, while for the UHPC slabs, the increment was around 67.9%. After exposure to the standard fire ISO-834 for 2[Formula: see text]h, the punching shear damage of the NSC slabs increased by 72.9% with the punch weight increased from 100[Formula: see text]kg to 700[Formula: see text]kg, whereas the damage in the UHPC slabs increased by 53.8%.
Dong, L, Yang, Y, Liu, Z, Ren, Q, Li, J, Zhang, Y & Wu, C 2022, 'Microstructure and mechanical behaviour of 3D printed ultra-high performance concrete after elevated temperatures', Additive Manufacturing, vol. 58, pp. 103032-103032.
View/Download from: Publisher's site
View description>>
This study investigated the characteristics of 3D printed ultra-high performance concrete (3DP-UHPC) after elevated temperatures. The effects of the bonding strip, steel fibre, specimen preparation method, loading direction and temperature on the fire resistance of 3DP-UHPC were analysed. The variations in microstructure and mineral composition of 3DP-UHPC after different temperatures were examined using scanning electron microscopy (SEM) and energy spectrum analyser (EDS). The strength degradation mechanism of 3DP-UHPC after the elevated temperatures was revealed in terms of the macro and micro levels. Meanwhile, the compressive strength of 3DP-UHPC after the elevated temperatures was measured, and its corresponding compressive constitutive model was proposed. The experimental results indicated that 3DP-UHPC had certain fire resistance, and the addition of steel fibre and the preparation method improved its fire resistance. The expansion of the crack at the junction of the steel fibre and matrix, as well as the oxidation and decarburization of steel fibre, affected the compressive strength of 3DP-UHPC after 400 ℃. During heating, water vapour escaped from the weak interface of the bonding strip endowed 3DP-UHPC with slightly better elevated-temperature burst resistance as compared to mould-casting ultra-high performance concrete (MC-UHPC). The compressive strength of 3DP-UHPC was the highest after 300 ℃ for the target temperatures set in this study, but the temperature had little effect on the strength difference between each direction of 3DP-UHPC. The compressive constitutive model of 3DP-UHPC after the elevated temperatures was developed, facilitating its engineering application in the field of fire safety.
Dong, W, Li, W, Guo, Y, Qu, F, Wang, K & Sheng, D 2022, 'Piezoresistive performance of hydrophobic cement-based sensors under moisture and chloride-rich environments', Cement and Concrete Composites, vol. 126, pp. 104379-104379.
View/Download from: Publisher's site
View description>>
Silicone hydrophobic powder (SHP) and crystalline waterproofing admixture (CWA) were used to improve the impermeability of carbon black (CB)/cement-based sensors. The mechanical, electrical and piezoresistive properties, waterproofing and chloride resistance of CB/cementitious composites were investigated in this study. The piezoresistivity before or after different durations of immersion in freshwater and 3% sodium chloride solution and the stability in freshwater and marine environment were studied and compared. The results show that compressive strength increased with the additions of CWA and SHP, while the tensile strength slightly decreased with CWA, due to the formation of crystalline. Moreover, cementitious composites with SHP exhibited the best water impermeability, while the counterpart containing CWA presented the optimal chloride resistance. Although cementitious composites with SHP exhibited the highest electrical resistivity, the most stable piezoresistivity occurred after 90 days of immersion in freshwater. On the other hand, cementitious composites incorporating CWA presented the lowest electrical resistivity, but the piezoresistivity continually decreased with the immersion duration. Because of the free ions, piezoresistivity increased as a result of the immersion in sodium chloride solution. The related results will provide an insight into the piezoresistivity of hydrophobic cement-based sensors under moisture and chloride environments for future structural health monitoring.
Dong, W, Li, W, Guo, Y, Wang, K & Sheng, D 2022, 'Mechanical properties and piezoresistive performances of intrinsic graphene nanoplate/cement-based sensors subjected to impact load', Construction and Building Materials, vol. 327, pp. 126978-126978.
View/Download from: Publisher's site
View description>>
The electrical, mechanical properties, and piezoresistive performances of intrinsic graphene nanoplate (GNP)/cementitious composites were investigated after subjected to impact load in this paper. The stabilized electrical resistivity before/after exposure to impact load and real-time electrical response under dynamic load were simultaneously studied. The cement hydration and microstructures of (GNP)/cementitious composites were characterized by thermal gravity analysis (TGA) and scanning electron microscope. The nearly identical hydration degree of 1.0% GNP filled cement mortar (1GNPCM) and mortar with 2% GNP (2GNPCM) indicates the physical interactions between the GNP and cement matrix. The excellent intrinsic physical properties of GNP played an important role in the enhancements of GNP/cementitious composites. After exposed to impact, the stabilized electrical resistivity, mechanical performance, and piezoresistivity of 1GNPCM were greatly changed, whereas the counterpart of 2GNPCM was well-maintained and nearly unaffected. Therefore, the severe microstructural deteriorations in 1GNPCM could be responsible for the variations, which damaged the conductive passages. The almost unchanged mechanical, electrical and piezoresistive properties enable 2GNPCM as a promising cement-based senor to provide stable piezoresistivity even after exposure to impact load. The related outcomes provide an insight into the development of impact-resistant cement-based sensors and promote the applications of cement-based sensors under extreme loading conditions.
Dong, W, Li, W, Sun, Z, Ibrahim, I & Sheng, D 2022, 'Intrinsic graphene/cement-based sensors with piezoresistivity and superhydrophobicity capacities for smart concrete infrastructure', Automation in Construction, vol. 133, pp. 103983-103983.
View/Download from: Publisher's site
Dong, W, Li, W, Wang, K, Shah, SP & Sheng, D 2022, 'Multifunctional cementitious composites with integrated self-sensing and self-healing capacities using carbon black and slaked lime', Ceramics International, vol. 48, no. 14, pp. 19851-19863.
View/Download from: Publisher's site
View description>>
This study aims to develop multifunctionality of cementitious composites with the integrated self-sensing and self-healing capacities by incorporating conductive carbon black (CB) with CB-encapsulated slaked lime (SL). The microsized SL particles were premixed with a half of designed content of nanosized CB particles. When CB agglomerations coat around the SL surfaces, SL does not hydrate until the CB coating is removed. Another half of designed weight of CB is uniformly dispersed using ultrasonication with superplasticizer and added to obtain piezoresistivity. The results show that the stress sensing capacity of CB-SL-cementitious composite performs well with the compressive stress. Autogenous healing performances presented significantly can improve the self-healing capacity with the increase of SL. Furthermore, the healing efficiency is affected by the crack width and dispersion of SL, and the smaller cracks with SL are more easily healed. The size of CB agglomerations decreases with the added SL, and the main product of self-healing is calcium carbonate.
Du, T, Li, C, Wang, X, Ma, L, Qu, F, Wang, B, Peng, J & Li, W 2022, 'Effects of pipe diameter, curing age and exposure temperature on chloride diffusion of concrete with embedded PVC pipe', Journal of Building Engineering, vol. 57, pp. 104957-104957.
View/Download from: Publisher's site
View description>>
Concrete structures are often embedded with pipe opening for the installation of pipelines which tends to weaken the integrity and durability. The effects of pipe diameter, curing age, and exposure temperature, on the chloride ion resistance of concrete with embedded PVC pipe (CEPP) were investigated in this paper. The testing parameters include compressive strength, electric flux density, chloride ion diffusion coefficient, chloride ion penetration depth, and chloride ion content. The results showed that electric flux density and chloride ion diffusion coefficient of CEPP increased with the diameter of PVC pipes following a second-degree parabola and a linear relation respectively, while the chloride ion diffusion coefficient decreased with the prolonging curing age. The chloride ion resistance and compressive strength of CEPP were decreased with the increase of pipe diameters, because the weak areas formed in the transition interfaces between the PVC pipes and concrete matrices and expanded with increased diameter. The chloride ion penetration depth and chloride ion content were relatively higher in the testing points near the PVC pipes than the ones far away from the PVC pipes. In addition, the rate of chloride ion penetration of CEPP could be accelerated by the higher exposure temperatures, leading to severer chloride ion penetration of CEPP. Finally, a novel modified Fick's second law diffusion model considering the effects of pipe diameters and curing age was proposed to predict the chloride ion resistance of CEPP.
El‐Hawat, O, Fatahi, B & Taciroglu, E 2022, 'Novel post‐tensioned rocking piles for enhancing the seismic resilience of bridges', Earthquake Engineering & Structural Dynamics, vol. 51, no. 2, pp. 393-417.
View/Download from: Publisher's site
View description>>
AbstractThe rocking pile foundation system is a relatively new design concept that can be implemented in bridges to improve their seismic performance. This type of foundation prevents plastic damage at the bridge piers and the foundation system, which are difficult to repair and can lead to collapse. However, lack of adequate energy dissipation in this type of foundation can result in large deck displacements and subsequent catastrophic failures of the bridge. The present study proposes a novel foundation system that integrates post‐tensioned piles with the rocking foundation to simultaneously prevent plastic hinging at the piers and reduce the deck displacements during severe earthquakes. The effectiveness of the proposed foundation system is investigated and compared against the rocking pile and conventional fixed‐base foundation systems using identical bridge configurations. Three‐dimensional finite element models of these bridges were developed to capture possible nonlinear behavior of the bridge as well as soil‐structure interaction effects. Six strong earthquakes with both horizontal components were selected and scaled to the appropriate seismic hazard level with a return period of 2475 years. Static pushover and nonlinear time‐history analyses were then performed to compare the dynamic response of the bridges, including deck displacements, pier and pile inertial forces, and other nonlinear behavior experienced by the structure. The results reveal that by integrating the post‐tensioned piles with the rocking foundation, the deck displacements were reduced to an acceptable limit without subjecting the bridge to any damage. In contrast, the bridge with the fixed base foundation experienced extensive damage at the piers, and the bridge with the rocking foundation experienced substantial deck displacements that ultimately led to unseating, resulting in the collapse of both bridges. It was therefore concluded that the p...
Farooq, MA & Nimbalkar, S 2022, 'Novel sustainable base material for concrete slab track', Construction and Building Materials, vol. 366.
View/Download from: Publisher's site
Fathipour, H, Payan, M, Jamshidi Chenari, R & Fatahi, B 2022, 'General failure envelope of eccentrically and obliquely loaded strip footings resting on an inherently anisotropic granular medium', Computers and Geotechnics, vol. 146, pp. 104734-104734.
View/Download from: Publisher's site
Ganbat, N, Altaee, A, Zhou, JL, Lockwood, T, Al-Juboori, RA, Hamdi, FM, Karbassiyazdi, E, Samal, AK, Hawari, A & Khabbaz, H 2022, 'Investigation of the effect of surfactant on the electrokinetic treatment of PFOA contaminated soil', Environmental Technology & Innovation, vol. 28, pp. 102938-102938.
View/Download from: Publisher's site
Guo, Y, Li, W, Dong, W, Luo, Z, Qu, F, Yang, F & Wang, K 2022, 'Self-sensing performance of cement-based sensor with carbon black and polypropylene fibre subjected to different loading conditions', Journal of Building Engineering, vol. 59, pp. 105003-105003.
View/Download from: Publisher's site
View description>>
Different dosages of carbon black (CB) were used to manufacture the cost-effective and highly sensitive polypropylene (PP) fibre cement-based sensors in this paper. The distribution of conductive phases and static electrical resistivity were firstly investigated through microscopic characterization and static resistivity, respectively. Then the self-sensing performance of the CB/PP fibre cementitious composites in response to different loading conditions was comprehensively assessed by cyclic compression, notched bending, and splitting tensile conditions. The results indicate that the improvement of PP fibres on conductivity and self-sensing performance is heavily dependent on the coating efficiency of CB nanoparticles on the surfaces of PP fibres. In particular, the cement-based sensors with excellent CB coating efficiency demonstrate the most promising pre-crack flexural sensing capacity. Additionally, the strain hardening characteristics and damage sensing ability for the intrinsic cement-based sensors were explored by splitting tension together with digital image correlation tracking. Apart from a strong linear correlation between fractional change of resistivity and tensile strain during the strain hardening stage, the distinct sensing characteristics between the strain hardening stage and softening stage can give the diagnosis of damage stage (strain hardening stage or softening stage) and crack width (microcracking or macrocracking). Therefore, the intrinsic CB/PP fibre cementitious composites as robust cement-based sensors can provide a great potential to sense strain and deformation as well as detect crack and damage for concrete infrastructure subjected to various loading conditions.
Guo, Y, Li, W, Dong, W, Wang, K, He, X, Vessalas, K & Sheng, D 2022, 'Self-sensing cement-based sensors with superhydrophobic and self-cleaning capacities after silane-based surficial treatments', Case Studies in Construction Materials, vol. 17, pp. e01311-e01311.
View/Download from: Publisher's site
View description>>
A novel cement-based sensors was developed with integrated self-sensing superhydrophobicity, and self-cleaning functions in this paper. The synthesis was carried out by penetrating precast graphene nanoplate/cement-based sensors with silane/isopropanol solutions. The silane-treated cement-based sensors showed satisfactory stress/strain sensing performance with an average gauge factor of 141.8, and exhibited excellent hydrophobic behaviour with the highest water contact angle of 163° on the intact surface. The contact angle decreased to 148° and 142°, for the surface with scratches and for the inner part of sensors, respectively. The reduction was due to the spalling and less amount of silane particles within the scratches and the harder entry of silane to the inner part of sensor. The self-cleaning properties of silane-treated cement-based sensor were evaluated by the visual observation of removing efficiency of hydrophilic carbon black dust and lipophilic sauces after water rinsing. It was found that the silane-treated cement-based sensor showed excellent self-cleaning performance using hydrophilic carbon dust. Despite the removing efficiency decreased for the lipophilic sauces, the silane-treated cement-based sensors maintained much less stain than that of untreated ones on the surface. The related results will promote the synthesis and practical applications of multifunctional cement-based sensors for the application of intrisic structural health monitoring.
Hao, J, Zhu, X, Yu, Y, Zhang, C & Li, J 2022, 'Damage localization and quantification of a truss bridge using PCA and convolutional neural network', Smart Structures and Systems, vol. 30, no. 6, pp. 673-686.
View/Download from: Publisher's site
View description>>
Deep learning algorithms for Structural Health Monitoring (SHM) have been extracting the interest of researchers and engineers. These algorithms commonly used loss functions and evaluation indices like the mean square error (MSE) which were not originally designed for SHM problems. An updated loss function which was specifically constructed for deep-learning-based structural damage detection problems has been proposed in this study. By tuning the coefficients of the loss function, the weights for damage localization and quantification can be adapted to the real situation and the deep learning network can avoid unnecessary iterations on damage localization and focus on the damage severity identification. To prove efficiency of the proposed method, structural damage detection using convolutional neural networks (CNNs) was conducted on a truss bridge model. Results showed that the validation curve with the updated loss function converged faster than the traditional MSE. Data augmentation was conducted to improve the anti-noise ability of the proposed method. For reducing the training time, the normalized modal strain energy change (NMSEC) was extracted, and the principal component analysis (PCA) was adopted for dimension reduction. The results showed that the training time was reduced by 90% and the damage identification accuracy could also have a slight increase. Furthermore, the effect of different modes and elements on the training dataset was also analyzed. The proposed method could greatly improve the performance for structural damage detection on both the training time and detection accuracy.
Hao, Y, Xiao, D, Hao, H, Li, J & Li, J 2022, 'Experimental study of reinforced concrete beams reinforced with hybrid spiral-hooked end steel fibres under static and impact loads', Advances in Structural Engineering, vol. 25, no. 15, pp. 3019-3030.
View/Download from: Publisher's site
View description>>
Discrete short steel fibres were proposed to be mixed with concrete for arresting cracks and enhancing the post-cracking resistance. It has been proven in previous tests that spiral steel fibres possessed markedly higher bonding to concrete matrix, leading to significantly improved performance of steel fibre reinforced concrete (SFRC) in terms of crack controllability, impact resistance, deformability and energy absorption capability. However, at the initial stage of cracking, SFRC reinforced with spiral fibres has relatively lower resistance to crack opening as compared to that reinforced with other types of steel fibres because of spiral shape stretching. To overcome this shortcoming, in the present study, short hooked-end steel fibres that exhibit high pull-out resistance at the crack initiation stage were mixed with spiral steel fibres in the normal-strength concrete matrix. A total volume fraction of 1% of hybrid steel fibres was mixed to cast SFRC specimens. With various mix ratios between spiral and hooked-end fibres considered, five batches of SFRC specimens were tested. Uniaxial compressive tests and four-point bending tests were carried out to compare the mechanical properties of SFRC materials with hybrid fibres while three-point bending tests on SFRC structural beams under static, drop-weight impact and post-impact static loading tests were conducted to investigate the structural performances. An equal dosage of hooked-end and spiral fibres was found to outperform other blend proportions to provide synergetic reinforcement to concrete matrix in terms of post-cracking resistance, energy absorption capacity and post-impact performance.
Hasan, H 2022, 'NUMERICAL SIMULATION OF PERVIOUS CONCRETE PILE IN LOOSE AND SILTY SAND AFTER TREATING WITH MICROBIALLY INDUCED CALCITE PRECIPITATION', International Journal of GEOMATE, vol. 22, no. 90, pp. 32-39.
View/Download from: Publisher's site
View description>>
It is essential to provide a stable foundation system for construction projects to reduce the geotechnical risk of failure due to static or dynamic loads. Pile foundations are recommended to increase bearing capacity and decrease the dynamic oscillations of soils. Recently, soil stabilization using microbially induced calcite precipitation (MICP) was widely used to increase shear strength parameters and reduce the hydraulic conductivity of sand. In this study, the technique of using MICP was reviewed based on previous studies and analyzed using Plaxis 3D to evaluate the enhancement of a single pervious concrete pile under static, free vibration and earthquake stages of loose and silty sand. In the static stage, under the applying load to reach prescribed displacement of 76 mm, the results of loose sand demonstrate that the static load capacity was increased from 470 kN of untreated loose sand to 582, 598 and 612 kN after treating by MICP along the shaft and tip of a concrete pile with 0.5,0.75 and 1 m, respectively. In the earthquake stage, the result of treated loose sand such as vertical and lateral displacement was insignificant compared with untreated loose sand. The Plaxis 3D models have clarified the benefit of using MICP with the pile foundation model.
He, X, Wang, F, Li, W & Sheng, D 2022, 'Deep learning for efficient stochastic analysis with spatial variability', Acta Geotechnica, vol. 17, no. 4, pp. 1031-1051.
View/Download from: Publisher's site
View description>>
Using machine-learning models as surrogate models is a popular technique to increase the computational efficiency of stochastic analysis. In this technique, a smaller number of numerical simulations are conducted for a case, and obtained results are used to train machine-learning surrogate models specific for this case. This study presents a new framework using deep learning, where models are trained with a big dataset covering any soil properties, spatial variabilities, or load conditions encountered in practice. These models are very accurate for new data without re-training. So, the small number of numerical simulations and training process are not needed anymore, which further increases efficiency. The prediction of bearing capacity of shallow strip footings is taken as an example. We start with a simple scenario, and progressively consider more complex scenarios until the full problem is considered. More than 12,000 data are used in training. It is shown that one-hidden-layer fully connected networks can give reasonable results for simple problems, but they are ineffective for complex problems, where deep neural networks show a competitive edge, and a deep-learning model achieves a very high accuracy (the root-mean-square relative error is 3.1% for unseen data). In testing examples, this model is proven very accurate if the parameters of specific cases are well in the defined limits. Otherwise, the capability of deep-learning models can be extended by simply generating more data outside the current limits and re-training the models.
Hu, JY, Zhang, SS, Chen, E & Li, WG 2022, 'A review on corrosion detection and protection of existing reinforced concrete (RC) structures', Construction and Building Materials, vol. 325, pp. 126718-126718.
View/Download from: Publisher's site
View description>>
Performance deterioration of existing reinforced concrete (RC) structures due to corrosion of inside steel reinforcement has been a worldwide issue for long, in particular for RC structures in aggressive environments. Although extensive research on steel corrosion has been carried out over past decades, it is still a challenging problem in civil engineering. Starting from a brief introduction on corrosion mechanism of steel in concrete, this paper presents a comprehensive review on corrosion detection techniques and protection methods for existing RC structures where corrosion has already occurred. Direct detection methods based on electrochemical and physical principles related to the steel corrosion process, and indirect methods based on measurement of corrosion-induced damages in reinforced concrete are critically reviewed, with the basic working mechanism and state of the art of each method given. According to protecting mechanism, corrosion protection methods are categorized into “prevention solutions” and “therapy solutions”, with the former including high-performance fiber-reinforced cementitious composite (HPFRCC) overlay, anti-corrosion coating and corrosion inhibitor while the latter including cathodic protection (CP) and electrochemical chloride extraction (ECE). Among them, HPFRCC overlay is regarded as effective in corrosion prevention due to its high durability although it is mainly used for strengthening because of its excellent mechanical properties, while carbon fiber reinforced polymer (CFRP) can be acted as both strengthening material and anode in CP and ECE. The dual functions of these materials make them very promising in protecting corrosion-damaged RC structures. The paper aims to not only provide useful information to researchers working on detection and protection of steel corrosion, but also shed lights on the advanced strengthening strategies for corrosion-damaged structures.
Huang, L, Liu, Z, Wu, C, Liang, J & Pei, Q 2022, 'A three-dimensional indirect boundary integral equation method for the scattering of seismic waves in a poroelastic layered half-space', Engineering Analysis with Boundary Elements, vol. 135, pp. 167-181.
View/Download from: Publisher's site
Joshua Tapas, M, Thomas, P, Vessalas, K & Sirivivatnanon, V 2022, 'Mechanisms of Alkali-Silica Reaction Mitigation in AMBT Conditions: Comparative Study of Traditional Supplementary Cementitious Materials', Journal of Materials in Civil Engineering, vol. 34, no. 3.
View/Download from: Publisher's site
View description>>
This study investigates the mechanisms of alkali-silica reaction (ASR) mitigation by supplementary cementitious materials (SCMs) under accelerated mortar bar test (AMBT) conditions. The study compares the effect of traditional SCMs (fly ash, slag, metakaolin, and silica fume) on ASR expansion, calcium silicate hydrate (C-S-H) composition, and portlandite consumption as well as on the availability of silicon and aluminum in solution. Results show that at typical SCM replacement levels for effective ASR mitigation (15% metakaolin, 25% fly ash, and 65% slag), the Si/Ca and Al/Si ratios of C-S-H are increased to comparable values, suggesting that at these dosages the SCMs contribute almost equivalent amounts of silicon and aluminum in solution. Studies of blended cement + SCM pastes show that the order of pozzolanicity is as follows: silica fume > metakaolin > fly ash > slag, which is consistent with the order of efficacy of SCMs in mitigating ASR expansion and the measured concentrations of silicon in solution. Solubility studies of the SCMs showed formation of sodium aluminum silicate hydrate (N-A-S-H) in fly ash and metakaolin and formation of calcium aluminum silicate hydrate (C-A-S-H) in slag after 28 days of exposure to AMBT conditions. This highlights the role of alkali activation of SCMs in ASR mitigation under AMBT conditions.
Karki, D, Al-Hunaity, S, Far, H & Saleh, A 2022, 'Composite connections between CFS beams and plywood panels for flooring systems: Testing and analysis', Structures, vol. 40, pp. 771-785.
View/Download from: Publisher's site
Le, A, Nimbalkar, S, Zobeiry, N & Malek, S 2022, 'An efficient multi-scale approach for viscoelastic analysis of woven composites under bending', Composite Structures, vol. 292, pp. 115698-115698.
View/Download from: Publisher's site
Leng, D, Zhu, Z, Liu, G & Li, Y 2022, 'Neuro fuzzy logic control of magnetorheological elastomer isolation system for vibration mitigation of offshore jacket platforms', Ocean Engineering, vol. 253, pp. 111293-111293.
View/Download from: Publisher's site
Li, J, Wang, W, Wu, C, Liu, Z & Wu, P 2022, 'Impact response of ultra-high performance fiber-reinforced concrete filled square double-skin steel tubular columns', Steel and Composite Structures, vol. 42, no. 3, pp. 325-351.
View/Download from: Publisher's site
View description>>
This paper studies the lateral impact behavior of ultra-high performance fiber-reinforced concrete (UHPFRC) filled double-skin steel tubular (UHPFRCFDST) columns. The impact force, midspan deflection, and strain histories were recorded. Based on the test results, the influences of drop height, axial load, concrete type, and steel tube wall thickness on the impact resistance of UHPFRCFDST members were analyzed. LS-DYNA software was used to establish a finite element (FE) model of UHPFRC filled steel tubular members. The failure modes and histories of impact force and midspan deflection of specimens were obtained. The simulation results were compared to the test results, which demonstrated the accuracy of the finite element analysis (FEA) model. Finally, the effects of the steel tube thickness, impact energy, type of concrete and impact indenter shape, and void ratio on the lateral impact performances of the UHPFRCFDST columns were analyzed.
Li, W, Dong, W, Guo, Y, Wang, K & Shah, SP 2022, 'Advances in multifunctional cementitious composites with conductive carbon nanomaterials for smart infrastructure', Cement and Concrete Composites, vol. 128, pp. 104454-104454.
View/Download from: Publisher's site
View description>>
Conductive carbon nanomaterials have been extensively developed for smart cementitious composites to gain multifunctionalities (e.g. self-sensing, self-healing, self-heating, and electromagnetic interference shielding). This paper critically reviewed dispersion and percolation of 0 dimension (0D), 1 dimension (1D) and 2 dimensions (2D) carbon materials used in cementitious composites and their effects on the electrical and piezoresistive performances. The different dispersion methods summarized are from mechanical dispersion, ultrasonic and high shearing, chemical modification, mineral additives, to carbon materials at multiple dimensions and hybrid dispersion methods. The electrical resistivity and piezoresistivity of cementitious composites with single carbon material or hybrid carbon materials are comprehensively analysed and compared in terms of efficiency and self-sensing mechanism. Furthermore, the existing theoretical modelling studies have been reviewed, indicating that many factors related to the electrical and piezoresistive behaviours, such as water content and nanocomposite agglomeration, have not been considered yet. Although some previous studies demonstrated the potential of applying conductive cementitious composites for self-sensing or heating pavements, further explorations still should be conducted on sustainable and economical manufacturing. Subsequently, the challenges and perspectives of the self-sensing stability, data acquisition system and sensor configuration are proposed with potential solutions for future smart infrastructure.
Li, W, Konsta-Gdoutos, M, Shi, X, Sobolev, K & Shah, SP 2022, 'Editorial: Intelligent Concrete, New Functionalities and Nanotechnology', Frontiers in Materials, vol. 9.
View/Download from: Publisher's site
Li, W, Qu, F, Dong, W, Mishra, G & Shah, SP 2022, 'A comprehensive review on self-sensing graphene/cementitious composites: A pathway toward next-generation smart concrete', Construction and Building Materials, vol. 331, pp. 127284-127284.
View/Download from: Publisher's site
View description>>
Two-dimension graphene-based nanomaterials (GBNs), such as multi-layers graphene (GNPs) and graphene oxide (GOs) have been extensively applied to enhance the mechanical properties, durability, and self-sensing performance of construction materials. Although there are some reviews on the mechanical properties and durability of graphene-based cementitious composites (GBCCs), very few papers have comprehensively covered the nano-, micro- and meso-scale properties, components, structures, and self-sensing properties, and the applications of the GBCCs. In this review, the characteristics of various GBNs with different dimensions were firstly illustrated and compared, and the enhancement methods for dispersion of 2D GBNs before mixed with cementitious materials were also comprehensively compared and discussed. When GBNs were mixed with cement, the nano- and micro-scale characteristics of GBCCs with respect to the hydration, phase transformations, microstructures, and pore characteristics were also systematically discussed. Macroscale performances of GBCCs, such as rheology, flowability, mechanical strength were analyzed, and the durability performances (e.g. chemical and fire attack, shrinkage and transport properties) of GBCCs were evaluated correspondingly. On the other hand, the self-sensing properties (e.g. electrical resistivity, piezoresistivity, and electromagnetic properties) of GBCCs were assessed for potential practical applications for structural health monitoring (SHM). Furthermore, some case studies and applications of GBCCs as advanced cement-based sensors for SHM were also evaluated. Finally, the application challenges and perspectives of adopting 2D GBNs for smart and sustainable concrete structures were proposed and discussed correspondingly. The conclusions of this review will promote future researchers and civil engineers in the concrete-related industry with the aim to developing sustainable and functional graphene-based concrete for the n...
Li, Y & Whitacre, BE 2022, 'Economic Growth and Adult Obesity Rates in Rural America', REVIEW OF REGIONAL STUDIES, vol. 52, no. 3, pp. 387-410.
Liu, A, Lin, S, Wang, J & Kong, X 2022, 'A Succinct Method for Non-Line-of-Sight Mitigation for Ultra-Wideband Indoor Positioning System', Sensors, vol. 22, no. 21, pp. 8247-8247.
View/Download from: Publisher's site
View description>>
Ultra-wideband (UWB) is a promising indoor position technology with centimetre-level positioning accuracy in line-of-sight (LOS) situations. However, walls and other obstacles are common in an indoor environment, which can introduce non-line-of-sight (NLOS) and deteriorate UWB positioning accuracy to the meter level. This paper proposed a succinct method to identify NLOS induced by walls and mitigate the error for improved UWB positioning with NLOS. First, NLOS is detected by a sliding window method, which can identify approximately 90% of NLOS cases in a harsh indoor environment. Then, a delay model is designed to mitigate the error of the UWB signal propagating through a wall. Finally, all the distance measurements, including LOS and NLOS, are used to calculate the mobile UWB tag position with ordinary least squares (OLS) or weighted least squares (WLS). Experiment results show that with correct NLOS indentation and delay model, the proposed method can achieve positioning accuracy in NLOS environments close to the level of LOS. Compared with OLS, WLS can further optimise the positioning results. Correct NLOS indentation, accurate delay model and proper weights in the WLS are the keys to accurate UWB positioning in NLOS environments.
Liu, J, Li, J, Fang, J, Liu, K, Su, Y & Wu, C 2022, 'Investigation of ultra-high performance concrete slabs under contact explosions with a calibrated K&C model', Engineering Structures, vol. 255, pp. 113958-113958.
View/Download from: Publisher's site
View description>>
Karagozian and Case (K&C) concrete model is extensively adopted in the numerical simulations of ultra-high performance concrete (UHPC) structural members subjected to impulsive loads such as impact and blast. In this study, a calibration of the K&C concrete model was conducted for UHPC in terms of three strength surfaces, equation of state, shear dilatancy, damage evolution and strain rate effect to offer simple and general guidelines on the determination of key model parameters for this new class of concrete. With the calibrated concrete model, a single element method was adopted to verify its accuracy through a comparison to the results from the static tests of the uniaxial compression, direct tension and triaxial compression. Furthermore, the numerical simulations of contact explosion tests on the UHPC slabs with the incorporation of the strain rate effect were performed and the numerical results exhibited good predictions regarding the failure mode, crater and scabbing damage as compared to the test results. More importantly, this proposed numerical model and simulation methodology are reasonable to be generally used for structural members constructed of UHPC materials under contact explosions when lacking sufficient static and dynamic test data. Using the calibrated and validated K&C concrete model, parametric studies were conducted to derive a new empirical equation for predicting the local damage mode of UHPC slabs under contact explosions.
Liu, J, Li, J, Fang, J, Su, Y & Wu, C 2022, 'Ultra-high performance concrete targets against high velocity projectile impact – a-state-of-the-art review', International Journal of Impact Engineering, vol. 160, pp. 104080-104080.
View/Download from: Publisher's site
View description>>
Known for its high mechanical strength and ductility, ultra-high performance concrete (UHPC) emerges as a promising material in civil and military constructions to resist hazardous loads such as high velocity projectile impact (HVPI). Due to its unique material properties, structures built with UHPC perform differently to its counterparts made of conventional concrete under HVPI, and thus the empirical and semi-empirical resistant functions for conventional concrete against HVPI require careful evaluation before application to UHPC structures. This study presents a comprehensive review of the research advances in thick UHPC targets to resist HVPI for projectiles at normal incidence. First, the static and dynamic material properties of UHPC are briefly introduced in comparison to conventional concrete. Second, based on physical tests, key aspects in UHPC design to resist HVPI are reviewed, which include fibre reinforcement, high strength coarse aggregate, alternative binder system as well as structural reinforcement and designs. Third, in a view of the development in material constitutive models under complex dynamic loads and computational techniques, numerical simulations of UHPC under HVPI are reviewed and discussed. Further, empirical and semi-empirical formulae to predict the depth of penetration (DOP) on conventional concrete are collected and evaluated on their suitability for UHPC.
Liu, J, Liu, C, Qu, K, Li, J & Wu, C 2022, 'Calibration of Holmquist Johnson Cook (HJC) model for projectile penetration of geopolymer-based ultra-high performance concrete (G-UHPC)', Structures, vol. 43, pp. 149-163.
View/Download from: Publisher's site
View description>>
Holmquist Johnson Cook (HJC) model has been extensively adopted to simulate the projectile penetration of concrete targets. In this study, based on the available experimental data of uniaxial compression, triaxial compression, split Hopkinson pressure bar (SHPB) and Hugoniot tests, HJC model parameters in terms of the strength surface, strain rate effect, damage evolution and equation of state (EOS) were systematically calibrated for a newly fabricated ultra-high performance concrete termed as geopolymer-based ultra-high performance concrete (G-UHPC). Using the HJC model with calibrated model parameters, numerical simulations of projectile penetration into plain and fibre reinforced G-UHPC targets were performed in a commercial finite element program LS-DYNA. The numerical results for the depth of penetration (DOP) exhibited fair agreement with the test data. The numerical projectile velocity and displacement evolutions were also validated through comparing to the semi-analytical model. These observations demonstrated the applicability and validity of the calibrated HJC model to estimate DOP of G-UHPC targets subjected to projectile impact. With the calibrated and validated HJC model, parametric studies were further conducted to explore the effect of uniaxial compressive strength of G-UHPC, projectile impact velocity, mass, diameter and nose shape on the final DOP values. Based on the numerical results from the parametric studies, an empirical equation concerning the aforementioned variables was proposed, which could help design G-UHPC protective barriers against projectile penetration.
Liu, J, Liu, C, Xu, S, Li, J, Fang, J, Su, Y & Wu, C 2022, 'G-UHPC slabs strengthened with high toughness and lightweight energy absorption materials under contact explosions', Journal of Building Engineering, vol. 50, pp. 104138-104138.
View/Download from: Publisher's site
View description>>
This study investigates the dynamic characteristics of geopolymer-based ultra-high performance concrete (G-UHPC) slabs strengthened with high toughness and lightweight energy absorption materials under the 1 kg TNT contact explosions. A total of four slabs were tested, including plain G-UHPC slab (G-UHPC-P), 20-layer basalt textile reinforced G-UHPC slab (G-UHPC-BFM), 20-layer steel wire mesh reinforced G-UHPC slab (G-UHPC-SWM) and 1.5 vol-% steel fibre reinforced G-UHPC slab with polyurethane coating (G-UHPC–SF–PU). The test results revealed that the steel wire mesh reinforcement was more effective in resisting contact explosions than the basalt textile reinforcement for G-UHPC. The polyurethane coating on the rear face of the slab exhibited its high tensile strength and deformability to absorb the blast-induced energy so as to enhance the anti-explosion performance of the slab, and additionally prevented the splash of slab fragments upon contact explosions to minimise secondary hazards. Based on the multi-material arbitrary Lagrangian-Eulerian (ALE) algorithm, local damage of G-UHPC-SWM and G-UHPC–SF–PU induced by contact explosions was reproduced using the explicit finite element software LS-DYNA. Fair agreement between the numerical and test results demonstrated that the numerical model could simulate the response of G-UHPC-SWM and G-UHPC–SF–PU with reasonable accuracy. Extensive numerical studies by varying polyurethane strain rate, coating thickness and the bonding between the polyurethane coating and the slab were further performed to analyse their effect on the maximum bulge depth of the polyurethane coating subjected to contact explosions.
Liu, K, Wu, C, Li, X, Tao, M, Li, J, Liu, J & Xu, S 2022, 'Fire damaged ultra-high performance concrete (UHPC) under coupled axial static and impact loading', Cement and Concrete Composites, vol. 126, pp. 104340-104340.
View/Download from: Publisher's site
View description>>
The load bearing structural components such as columns could experience axial static loads during the service life. High temperature induced by fire would have a significant detrimental impact on the mechanical properties of concrete materials. The structure could be severely damaged as the column was simultaneously loaded by other impact loads. In this study, the behavior of fire damaged ultra-high performance concrete (UHPC) with a compressive strength of 128.3 MPa under coupled axial static and impact loading was studied. UHPC specimens were heated to the target temperatures (250, 500 and 750 °C) in an electric furnace and then naturally cooled down to room temperature. The results demonstrated that the P-wave velocity and compressive strength of the heated-cooled treatment UHPC degraded significantly as the target temperature exceeded 250 °C. The impact tests were then conducted on the heated-cooled treatment UHPC specimens with axial static compression. The experimental results indicated that the axial static compression could enhance the dynamic mechanical properties such as compressive strength and elastic modulus in the elastic phase and weaken the dynamic mechanical properties in the plastic phase. In addition, the dynamic increase factor (DIF) of UHPC exhibited an increase with the temperature. The UHPC specimen could withstand a temperature of 250 °C, but lost most of its strength at temperatures of 500 and 750 °C. Thus, the axially loaded static force accelerated the failure of the specimen after being heated to above 250 °C.
Lu, Z-H, Wang, J, Tang, Z, Zhao, Y-G & Li, W 2022, 'A novel cohesive zone model for predicting the interface bonding behaviours of the ballastless track of high-speed railway', Structures, vol. 41, pp. 1-14.
View/Download from: Publisher's site
View description>>
The interface damage is one of the main concerns for high-speed railway ballastless track structures during its whole service life, as it would affect the reliability of track structures or even cause the high-speed train accident. In this paper, various existing cohesive zone models (CZMs) were identified and compared regarding the performance in modeling the interface behaviors of ballastless track structures. The results show that the existing CZMs cannot accurately represent the nonlinear relationship of the ascending and descending sections in the interface traction-separation curve concurrently. Therefore, a new CZM was proposed in this study, and the feasibility of the proposed model was examined by the experimental results. It indicates that the proposed model can reasonably describe the nonlinear behaviors of the ascending and descending sections in the traction-separation curve by introducing exponential coefficients. The proposed CZM also exhibits higher accuracy in predicting the normal and tangential cracking behaviors of the interlayer interface of the ballastless track structures in comparison with the existing models, with the coefficients of determination (R2) in the fitting results all above 0.85. As a result, this model can be used for the analysis of the interface behaviours of ballastless track structures.
Luo, Z, Li, W, Wang, K, Shah, SP & Sheng, D 2022, 'Nano/micromechanical characterisation and image analysis on the properties and heterogeneity of ITZs in geopolymer concrete', Cement and Concrete Research, vol. 152, pp. 106677-106677.
View/Download from: Publisher's site
View description>>
Heterogeneity of interfacial transition zones (ITZs) is a key factor for the properties and failure mechanism of geopolymer concrete. The nano/microscale properties and heterogeneity of the ITZs (the top, bottom and lateral interfaces) prepared by encompassing polished aggregates in the modelled fly ash-based geopolymer concrete were statistically investigated in this study. The nanoindentation and nanoscratch results show that the nano/micromechanical properties of the gel-related phases of ITZs at the top and bottom boundaries are higher than the corresponding ones at the lateral boundaries and bulk paste. The mechanism of the better properties of ITZs at the top and bottom boundaries is unveiled based on quantitative image analysis of the amount, diameter and proportion distribution of fly ash particles. A strategy of controlling heterogeneity of ITZs and using polished aggregates, rapid scratch and statistical analysis is proposed to investigate more complicated ITZs within acceptable testing duration.
Mehrabi, N & Khabbaz, H 2022, 'A trustful transition zone for high-speed rail using stone columns', Australian Journal of Civil Engineering, vol. 20, no. 1, pp. 56-66.
View/Download from: Publisher's site
View description>>
The high-speed railway projects have encountered several geotechnical challenges. One of the most important challenges is the differential settlement control in transition zones. Cement-treated soil is a common method to prevent the differential settlement at transition zones. An alternative method uses stone columns for controlling the differential settlement in approaching embankment of bridges. In this study, numerical modelling using PLAXIS 2D is selected for the assessment of stone columns in the reduction of total and differential settlements. One of the overpass bridges of the track constructed for the Tehran–Isfahan railway, the first high-speed railway in the country, is chosen as the case study. Three models are created based on the properties of the selected case study. The first one is a typical approaching embankment. The second one is the bridge abutment section, and the last one is a typical reinforced approaching embankment with stone columns.
Nguyen, HAD & Ha, QP 2022, 'Wireless Sensor Network Dependable Monitoring for Urban Air Quality', IEEE Access, vol. 10, no. 99, pp. 40051-40062.
View/Download from: Publisher's site
Nguyen, QD, Afroz, S, Zhang, Y, Kim, T, Li, W & Castel, A 2022, 'Autogenous and total shrinkage of limestone calcined clay cement (LC3) concretes', Construction and Building Materials, vol. 314, pp. 125720-125720.
View/Download from: Publisher's site
View description>>
In this study, the developments of autogenous and total shrinkage of limestone calcined clay cement (LC3) concretes were investigated. Three concrete grades including 25 MPa, 32 MPa and 45 MPa of both LC3 and general purpose cement (GPC) concretes were considered. Compressive strength and tensile strength were measured until curing of 28 days. In addition, pore size distribution of cementitious pastes was evaluated by using nitrogen adsorption. Several models were used to assess their applicability for LC3 concretes in predicting mechanical properties and shrinkage development. The LC3 concretes showed higher autogenous shrinkage at a later age up to 100 days due to continuous refinement of the pore structure whilst the development of total shrinkage was similar between LC3 and OPC concretes. All models underestimated LC3 concrete autogenous shrinkage and the Bazant B4 model provided the best prediction of total shrinkage development.
Nguyen, TN, Sanchez, LFM, Li, J, Fournier, B & Sirivivatnanon, V 2022, 'Correlating alkali-silica reaction (ASR) induced expansion from short-term laboratory testings to long-term field performance: A semi-empirical model', Cement and Concrete Composites, vol. 134, pp. 104817-104817.
View/Download from: Publisher's site
View description>>
Correlating short-term expansion of concrete specimens in the laboratory and long-term expansion of concrete in the field is crucial to evaluate the reliability of laboratory test methods and essential for the prognosis of alkali-silica reaction (ASR) in concrete infrastructures. In this study, a novel semi-empirical approach is proposed for forecasting ASR-induced expansion of unrestrained concrete in the field using laboratory measurements data. In addition to the use of short-term laboratory expansion data, the model accounts for the effects of alkali leaching, alkali contribution from aggregates, and environmental conditions (i.e., temperature and relative humidity). A comprehensive database from the literature was gathered for the development and calibration of the proposed model. Finally, the model was used for various concrete blocks incorporating different reactive aggregates and exposed to three outdoor conditions in Canada and the USA. Model outcomes show that it is highly promising for forecasting the induced expansion of concrete in the field from the accelerated laboratory tests data. Analysing the modelling results also highlights the importance of alkali leaching and environmental conditions on the correlation between laboratory and field performance.
Omar, KR, Fatahi, B & Nguyen, LD 2022, 'Impacts of Pre-contamination Moisture Content on Mechanical Properties of High-Plasticity Clay Contaminated with Used Engine Oil', Journal of Testing and Evaluation, vol. 50, no. 6, pp. 3001-3027.
View/Download from: Publisher's site
View description>>
Abstract The oil contamination of soils and the remediation techniques to enhance the engineering properties of the ground have been an emerging challenge in the geoenvironmental field. While several studies were conducted to examine the behavior of the contaminated granular soils, little is known about the mechanical properties of the oil-contaminated clays. This paper investigates the impacts of the in situ pre-contamination moisture content (PMC) on the behavior of fine-grained soil contaminated with various levels of used engine oil. Extensive laboratory experiments were performed on sandy clay with different initial moisture conditions and various amounts of used engine oil varying from 0 to 16 %. The experimental results, including the Atterberg limits, linear shrinkage (LS), unconfined compressive strength, shear strength, and small-strain shear modulus in conjunction with microstructural image analysis, were reported and discussed. It is observed that when oil content was increased, both LS and plastic limit (PL) increased while the liquid limit decreased in the contaminated soil. Moreover, the inclusion of engine oil contributed to the reduction in the plasticity index, which was also impacted by the PMC of the soil. An increment in the PL was correlated with a significant decrease in shear strength, shear modulus, and other associated parameters such as friction angle and cohesion. In agreement with the results, a broader range of elasticity and improved stability at the microstructure level was associated with a lower pre-contamination water content (PMC). Overall, this paper shows that knowledge of site moisture levels before contamination is essential to evaluate the implications of contamination by used engine oil.
Ottenhaus, L-M, Li, Z & Crews, K 2022, 'Half hole and full hole dowel embedment Strength: A review of international developments and recommendations for Australian softwoods', Construction and Building Materials, vol. 344, pp. 128130-128130.
View/Download from: Publisher's site
Peellage, WH, Fatahi, B & Rasekh, H 2022, 'Experimental investigation for vibration characteristics of jointed rocks using cyclic triaxial tests', Soil Dynamics and Earthquake Engineering, vol. 160, pp. 107377-107377.
View/Download from: Publisher's site
Punetha, P & Nimbalkar, S 2022, 'Geotechnical rheological modeling of ballasted railway tracks considering the effect of principal stress rotation', Canadian Geotechnical Journal, vol. 59, no. 10, pp. 1793-1818.
View/Download from: Publisher's site
View description>>
The rotation of principal stress direction experienced by the soil elements in a railway track substructure during a train passage influences the magnitude of accumulated settlement. However, the existing methods to evaluate the track response under repeated train loads disregard the influence of principal stress rotation (PSR). This article presents a novel approach for assessing the behavior of ballasted railway tracks incorporating the contribution of PSR on track deformation. The proposed technique employs a geotechnical rheological model to evaluate the track behavior, in which the material plasticity is captured through plastic slider elements. The influence of PSR is accounted for by extending an existing constitutive relationship for the slider elements for the substructure layers, which is successfully validated against experimental data reported in the literature. The results reveal that PSR causes significant cumulative deformation in the substructure layers, and disregarding it in the analysis leads to inaccurate predictions. The proposed approach is then applied to an open track-bridge transition with heterogeneous support conditions, in which the differential settlement is found to be largely influenced by PSR. The findings from this study highlight the importance of including the effect of PSR in predictive models for a reliable evaluation of track performance.
Punetha, P & Nimbalkar, S 2022, 'Performance improvement of ballasted railway tracks using three-dimensional cellular geoinclusions', Geotextiles and Geomembranes, vol. 50, no. 6, pp. 1061-1082.
View/Download from: Publisher's site
Qian, H, Li, J, Pan, Y, Zong, Z & Wu, C 2022, 'Numerical derivation of P-I diagrams for shallow buried RC box structures', Tunnelling and Underground Space Technology, vol. 124, pp. 104454-104454.
View/Download from: Publisher's site
View description>>
To perform quick damage assessment and preliminary blast resistant design, the present study develops Pressure-Impulse (P-I) diagrams for the shallow-buried box structures based on high fidelity numerical modelling. Shock wave propagation in the soil and its interaction with the roof slab and vertical wall are considered in the blast load modelling, both flexure and shear damage of the roof slab under surface blast loads are considered in the P-I diagram. Parametric studies are carried out to investigate the effects of roof span, wall thickness, concrete strength, flexure and shear reinforcement ratio on the P-I diagram. Based on the numerical results, analytical formulae to predict the P-I diagrams for buried box structures are derived. The applicability of the improved P-I diagrams approaches in practical evaluation is illustrated through case studies.
Qu, F, Li, W, Guo, Y, Zhang, S, Zhou, JL & Wang, K 2022, 'Chloride-binding capacity of cement-GGBFS-nanosilica composites under seawater chloride-rich environment', Construction and Building Materials, vol. 342, pp. 127890-127890.
View/Download from: Publisher's site
View description>>
The effects of granulated blast furnace slag (GGBFS) and nano-silica (NS) on the chloride-binding capacity of cement paste after 6-month exposure to seawater chloride-rich solutions were investigated in this paper. The pH, chloride-binding ratio (CBR), leaching behavior, and phase transformation were investigated by various experimental and analysis methods. Thermodynamic modeling was also used to study the phase assemblages for the Portland cement-GGBFS-NS composites exposed to the NaCl and MgCl2 solutions. It was found that for all cementitious composites, more chlorides were bounded in samples exposed to the salt solutions with sodium ions than that with magnesium ions. Proper additions of GGBFS and NS can enhance the chloride-binding capacity of cementitious composites. The results confirm that the addition of GGBFS can improve the chemical chloride-binding capacity because of the increased amount of chloroaluminate. The increased amount of hydrated gels in the cementitious composites with GGBFS also improved the physical chloride-binding capacity. The addition of NS increased the physical chloride-binding capacity due to the more formation of C-S-H/C-A-S-H gels, while the excessive addition of NS left less aluminum phase available for the formation of chloroaluminate, thus further decreased the chemical chloride-binding capacity. Magnesium ions in solutions increased the amount of chloride in the diffuse layer of C-S-H gels and hydrotalcite. The related results provide novel insight into the influences of GGBFS and NS on the chloride-binding capacity of cementitious composites under chloride-rich environments.
Rao, P, Ouyang, P, Wu, J, Li, P, Nimbalkar, S & Chen, Q 2022, 'Seismic Stability of Heterogeneous Slopes with Tensile Strength Cutoff Using Discrete-Kinematic Mechanism and a Pseudostatic Approach', International Journal of Geomechanics, vol. 22, no. 12.
View/Download from: Publisher's site
Rao, P, Xiang, Y, Ouyang, P, Nimbalkar, S & Chen, Q 2022, 'Finite Element Analysis of Electro-Thermal Coupling of Sandstone Under Lightning Currents', Geotechnical and Geological Engineering, vol. 40, no. 5, pp. 2593-2604.
View/Download from: Publisher's site
Rao, P-P, Ouyang, P-H, Nimbalkar, S, Chen, Q-S, Wu, Z-L & Cui, J-F 2022, 'Analytical modelling of the mechanical damage of soil induced by lightning strikes capturing electro-thermal, thermo-osmotic, and electro-osmotic effects', Journal of Mountain Science, vol. 19, no. 7, pp. 2027-2043.
View/Download from: Publisher's site
Rasouli, H & Fatahi, B 2022, 'Liquefaction and post-liquefaction resistance of sand reinforced with recycled geofibre', Geotextiles and Geomembranes, vol. 50, no. 1, pp. 69-81.
View/Download from: Publisher's site
View description>>
The present study provides an insight into the effect of recycled carpet fibre on the mechanical response of clean sand as backfill material subjected to monotonic loading and cyclic loading as well as post-liquefaction resistance of both unreinforced and carpet fibre reinforced soils. To achieve these goals, a series of multi-stage soil element tests under cyclic loading event resulting in liquefaction followed by undrained monotonic shearing without excess pore water pressure dissipation as well as a series of monotonic undrained shear test is conducted. All the specimens are isotropically consolidated under a constant effective confining stress of 100 kPa by considering the effect of cyclic stress ratio and carpet fibre content ranging from 0.25% to 0.75%. The obtained results revealed the efficiency of carpet fibre inclusion in increasing the secant shear modulus and ductility of clean sand under monotonic shearing without previous loading history. The impact of carpet fibre inclusion on the trend of cyclic excess pore water pressure generation and cyclic stiffness degradation was minimal. However, adding carpet fibre significantly improved both liquefaction and post-liquefaction resistances of clean sand. The liquefaction resistance of clean sand, at a constant 15 loading cycles, improved by 26.3% when the soil was reinforced with 0.75% recycled carpet fibre. In addition, the initial shear modulus of the liquefied specimen significantly increased by adding recycled carpet fibre.
Rasouli, H, Fatahi, B & Nimbalkar, S 2022, 'Re-liquefaction resistance of lightly cemented sands', Canadian Geotechnical Journal, vol. 59, no. 12, pp. 2085-2101.
View/Download from: Publisher's site
View description>>
The re-liquefaction resistance of cemented sands under multiple liquefaction events such as pre-shock, main-shock, and after-shock earthquakes is a complex phenomenon because the response may alter due to bond breakage. A series of multistage liquefaction–re-consolidation soil element tests under undrained stress-controlled cyclic loading condition using cyclic triaxial were carried out to assess the liquefaction and re-liquefaction resistance of cemented sands with varying degrees of cementation. Lightly cemented specimens were reconstituted using Sydney sand and high early strength Portland cement with cement content ranging from 0.25% to 1% and unconfined compression strength from 15 to 80 kPa. The results showed that the re-liquefaction resistance of cemented sands with different amounts of cement decreased after the first liquefaction event and then increased for succeeding liquefaction events. While the trend of residual excess pore water pressure ratio and cyclic stiffness degradation index of untreated sand under successive liquefaction events remained consistent, the corresponding responses for cemented sands altered for the second to the fifth liquefaction events. In fact, the residual excess pore water pressure ratio and cyclic stiffness of cemented sand increased and degraded faster during the early cycles of loading for the second to fifth liquefaction events.
Reja, VK, Varghese, K & Ha, QP 2022, 'Computer vision-based construction progress monitoring', Automation in Construction, vol. 138, pp. 104245-104245.
View/Download from: Publisher's site
View description>>
Automating the process of construction progress monitoring through computer vision can enable effective control of projects. Systematic classification of available methods and technologies is necessary to structure this complex, multi-stage process. Using the PRISMA framework, relevant studies in the area were identified. The various concepts, tools, technologies, and algorithms reported by these studies were iteratively categorised, developing an integrated process framework for Computer-Vision-Based Construction Progress Monitoring (CV-CPM). This framework comprises: data acquisition and 3D-reconstruction, as-built modelling, and progress assessment. Each stage is discussed in detail, positioning key studies, and concurrently comparing the methods used therein. The four levels of progress monitoring are defined and found to strongly influence all stages of the framework. The need for benchmarking CV-CPM pipelines and components are discussed, and potential research questions within each stage are identified. The relevance of CV-CPM to support emerging areas such as Digital Twin is also discussed.
Senanayake, S, Pradhan, B, Huete, A & Brennan, J 2022, 'Spatial modeling of soil erosion hazards and crop diversity change with rainfall variation in the Central Highlands of Sri Lanka', Science of The Total Environment, vol. 806, no. Pt 2, pp. 150405-150405.
View/Download from: Publisher's site
View description>>
The spatial variation of soil erosion is essential for farming system management and resilience development, specifically in the high climate hazard vulnerable tropical countries like Sri Lanka. This study aimed to investigate climate and human-induced soil erosion through spatial modeling. Remote sensing was used for spatial modeling to detect soil erosion, crop diversity, and rainfall variation. The study employed a time-series analysis of several variables such as rainfall, land-use land-cover (LULC) and crop diversity to detect the spatial variability of soil erosion in farming systems. Rain-use efficiency (RUE) and residual trend analysis (RESTREND) combined with a regression approach were applied to partition the soil erosion due to human and climate-induced land degradation. Results showed that soil erosion has increased from 9.08 Mg/ha/yr to 11.08 Mg/ha/yr from 2000 to 2019 in the Central Highlands of Sri Lanka. The average annual rainfall has increased in the western part of the Central Highlands, and soil erosion hazards such as landslides incidence also increased during this period. However, crop diversity has been decreasing in farming systems, namely wet zone low country (WL1a) and wet zone mid-country (WM1a), in the western part of the Central Highlands. The RUE and RESTREND analyses reveal climate-induced soil erosion is responsible for land degradation in these farming systems and is a threat to sustainable food production in the farming systems of the Central Highlands.
Shafaghat, A & Khabbaz, H 2022, 'Recent advances and past discoveries on tapered pile foundations: a review', Geomechanics and Geoengineering, vol. 17, no. 2, pp. 455-484.
View/Download from: Publisher's site
View description>>
© 2020, © 2020 Informa UK Limited, trading as Taylor & Francis Group. The growing tendency to study the behaviour of tapered piles in the last two decades has made it necessary to gain a deeper insight into this specific kind of deep foundation. Tapered piles have been investigated through analytical, experimental, and numerical studies. These piles have revealed different behaviour under various loading conditions. Hence, reviewing and assessing these efforts to comprehend their response can be of great significance. In this paper firstly, it is attempted to go over experimental studies, conducted on tapered piles. Then, the proposed mathematical and numerical solutions, employed to calculate the bearing capacity of single tapered piles, are compared to have a better vision of how these piles behave. In the third section, the optimum tapering angles of tapered piles in loose, medium, and dense sand are discussed. All the efforts are investigated technically to find the advantages, disadvantages, and the research gaps for this specific kind of piles. In addition, another section entitled the directions and ideas for future research on tapered piles is provided comprising the most recent achievements in this area. Moreover, the implementation of tapered piles in a significant project as a case study is discussed.
Shafaghat, A, Khabbaz, H & Fatahi, B 2022, 'Axial and Lateral Efficiency of Tapered Pile Groups in Sand Using Mathematical and Three-Dimensional Numerical Analyses', Journal of Performance of Constructed Facilities, vol. 36, no. 1.
View/Download from: Publisher's site
View description>>
This study presents a new mathematical equation for calculating the pile group efficiency in cohesionless soil under combined axial and lateral loading conditions, considering the tapering angle effect. Based on the mathematical definition of the pile group efficiency, analytical correlations are developed. The tapering effect is considered by developing a new geometry coefficient for efficiency associated with the shaft vertical bearing component of tapered piles. In addition, a simplified mathematical equation is developed for predicting the group interaction factor as a function of pile spacing, number of piles in the group, diameter of the cylindrical reference pile, tapering angle, and pile slenderness ratio. On the other hand, an array of three-dimensional numerical analyses is performed for modeling same-volume single bored piles and pile groups with various arrangements to capture the accuracy of the proposed mathematical equation. The hardening soil constitutive model is adopted for the modeling of piles in loose sand. Subsequently, the load-displacement diagrams of single piles, as well as pile groups, are obtained. The bearing capacities of straight-sided and tapered bored piles are then calculated and compared using a definite settlement criterion. By computing the various bearing-capacity components, group efficiencies can be attained from both numerical and mathematical analyses. The results indicate an acceptable agreement between both analyses. Finally, the developed equation can predict the pile group efficiency incorporating the tapering angle and other influencing parameters as a novel and simple relationship under simultaneous axial and lateral loading conditions.
Shao, R, Wu, C & Li, J 2022, 'A comprehensive review on dry concrete: Application, raw material, preparation, mechanical, smart and durability performance', Journal of Building Engineering, vol. 55, pp. 104676-104676.
View/Download from: Publisher's site
View description>>
Dry concrete, which can be understood literally, is defined as the fresh mixture of concrete having no flowability with a very small slump value. It is a hardened mixture mixed with essentially the same raw materials (cement, aggregate and supplementary cementitious material) but lower water content as compared to conventional concrete. Performance and properties of dry concrete are closely related to the raw materials dosage, preparation technique, curing regimes and curing. At present, the applications of dry concrete products have been expanded to many engineering areas which benefit from their prominent advantages such as fast hardening, high early strength, along with low material and production cost. This paper reviews two most representative dry concrete mixtures, namely roller-compacted concrete (RCC) and dry-cast concrete (DCC), in terms of raw material, preparation method, static/dynamic mechanical behaviour, smart and durability performance, and application. Among them, the static and dynamic mechanical properties, including static strength behaviour and elastic modulus, as well as dynamic responses under seismic and impact loads, are reviewed in detail. In addition, the freeze-thaw resistance, carbonation resistance, permeability, abrasion resistance, fatigue characteristic and volume change which involved in durability investigation of both RCC and DCC are successively elaborated and analysed. Finally, some suggestions and ideas on the further researches of dry concrete are also presented.
Shao, R, Wu, C, Li, J & Liu, Z 2022, 'Development of sustainable steel fibre-reinforced dry ultra-high performance concrete (DUHPC)', Journal of Cleaner Production, vol. 337, pp. 130507-130507.
View/Download from: Publisher's site
View description>>
Dry concrete technology has been extensively utilized in many engineering fields thanks to its remarkable high early strength, fast construction speed and low production cost. However, its shortcomings such as low flexural tensile strength, poor toughness, and susceptible to crack under stress and temperature also render the safety and service life of concrete structures unable to be effectively ensured. Dry ultra-high performance concrete (DUHPC), a promising building material, has improved mechanical and durability performance, and contributes to economical construction by reducing the cross-section size and improving structural long-term serviceability. In this study, the mechanical performance (such as compressive and indirect tensile behaviour) of fibre-reinforced DUHPC (FR-DUHPC) was experimentally investigated after a benchmark mix proportioning was determined via orthogonal tests. Different steel fibre volume contents (0.5–2.0%) and curing regimes including normal-temperature water curing, moist/steam curing and hot-water bath curing were used to explore their impacts on the mechanical properties of DUHPC. In total, 648 FR-DUHPC samples were fabricated and tested for determining their unit weight, compressive, flexural and split tensile strengths. The samples’ failure modes after bending and split tensile tests were analyzed. The results indicated that the fibre addition exhibited a notable positive effect on the mechanical properties of DUHPC, especially for the enhancement of the flexural and split tensile strengths, along with the improvement of post-cracking behaviour. An evident increase in early strength was found via using moist/steam and hot-water bath curing regime, but the former negatively impacted the development of the long-term strength. 50 °C moist/steam curing temperature was suggested for consolidating the pre-cast DUHPC units based on the microstructure analysis conducted, and the volume content of 1.5% was considered to be the...
Shao, R, Wu, C, Li, J & Liu, Z 2022, 'Investigation on the mechanical characteristics of multiscale mono/hybrid steel fibre-reinforced dry UHPC', Cement and Concrete Composites, vol. 133, pp. 104681-104681.
View/Download from: Publisher's site
View description>>
Dry ultra-high performance concrete (DUHPC) is a promising building material with better mechanical and durability properties, developed on the basis of retaining the advantages of traditional dry concrete, such as fast hardening speed, high early age strength and rapid demoulding. In the current study, the impacts of multiscale mono and hybrid steel fibre reinforcements on the static mechanical behaviour of DUHPC were further studied based on the benchmark mix ratio and optimal curing regime obtained from the previous study. The experiments carried out included the quasi-static uniaxial compression, four-point bending and split-tensile tests. The mono fibre reinforcement (0.5–2.0 vol. %) comprised of straight steel fibres with the same diameter but different lengths (6, 10 and 13 mm), while the hybrid fibre reinforcement was composed of different combinations of foregoing fibres at a fixed content (1.5 vol. %), which could be further divided into double and ternary hybridization. Test results revealed that compared to control samples without fibre reinforcement, the single addition of any steel fibres improved the static mechanical behaviour of DUHPC, particularly for flexural and split-tensile performance. In the case of fibre hybridization, the replacement of longer fibres with more addition of short (6 mm) ones evidently reduced the flexural toughness and energy absorption capacity of DUHPC upon cracking, whereas the mixtures with hybrid medium (10 mm) and long (13 mm) fibres as well as with hybrid short, medium and long fibres showed better compressive toughness and energy absorption capability. The proposed multivariate regression linear, nonlinear and most of the mixed models could well estimate the compressive, flexural and split-tensile strength values of mono steel fibre-reinforced DUHPC at a given range of fibre length, volume content and curing age. The updated best-fit models containing compressive strength as an additional independent vari...
Sharari, N, Fatahi, B, Hokmabadi, A & Xu, R 2022, 'Seismic resilience of extra-large LNG tank built on liquefiable soil deposit capturing soil-pile-structure interaction', Bulletin of Earthquake Engineering, vol. 20, no. 7, pp. 3385-3441.
View/Download from: Publisher's site
View description>>
AbstractAssessment of seismic resilience of critical infrastructure such as liquefied natural gas (LNG) storage tanks, is essential to ensure availability and security of services during and after occurrence of large earthquakes. In many projects, it is preferred to build energy storage facilities in coastal areas for the ease of sea transportation, where weak soils such as soft clay and loose sand with liquefaction potential may be present. In this study, three-dimensional finite element model is implemented to examine the seismic response of a 160,000 m3full containment LNG tank supported by 289 reinforced concrete piles constructed on liquefiable soil overlaying the soft clay deposit. The seismic soil-structure interaction analysis was conducted through direct method in the time domain subjected to the 1999 Chi-Chi and the 1968 Hachinohe earthquakes, scaled to Safe Shutdown Earthquake hazard level for design of LNG tanks. The analyses considered different thicknesses of the liquified soil deposit varying from zero (no liquefaction) to 15 m measured from the ground surface. The key design parameters inspected for the LNG tank include the acceleration profile for both inner and outer tanks, the axial, hoop and shear forces as well as the von Mises stresses in the inner tank wall containing the LNG, in addition to the pile response in terms of lateral displacements, shear forces and bending moments. The results show that the seismic forces generated in the superstructure decreased with increasing the liquefied soil depth. In particular, the von Mises stresses in the inner steel tank exceeded the yield stress for non-liquefied soil deposit, and the elastic–plastic buckling was initiated in the upper section of the tank where plastic deformations were detected as a result of excessive von Mises stresses. However, when soil liquefaction occurred, although von Mises stresses in the inner tank shell remai...
Sharari, N, Fatahi, B, Hokmabadi, AS & Xu, R 2022, 'Impacts of Pile Foundation Arrangement on Seismic Response of LNG Tanks Considering Soil–Foundation–Structure Interaction', Journal of Performance of Constructed Facilities, vol. 36, no. 1.
View/Download from: Publisher's site
Sun, Z, Chen, Y, Zheng, J, Jiang, S, Dong, W, Li, X, Li, Y & E, S 2022, 'Temperature‐Dependent Electromagnetic Microwave Absorbing Characteristics of Stretchable Polyurethane Composite Foams with Ultrawide Bandwidth', Advanced Engineering Materials, vol. 24, no. 7, pp. 2101489-2101489.
View/Download from: Publisher's site
View description>>
With the rapid development of current electronic equipment, electromagnetic microwave absorption (EMA) materials with higher design requirements under special circumstances have attracted great attention. Herein, a flexible polyurethane composite foam assisted by coral‐like CNT@Fe3O4/graphene nanocomposites is fabricated by a facile solvothermal and moisture self‐foaming method. The composite foam with 15 wt% nanofillers exhibits an outstanding temperature cycle stability with gradually improved EMA performance at elevated temperature and excellent resilience stability with a tensile strength of 4.81 MPa. An enhanced minimum reflection loss (RLmin) of −59.44 dB at 10.38 GHz with a thickness of 2.28 mm is achieved, while the ultrawide absorption bandwidth of 6.09 GHz nearly covers the full X‐band. This benefits from interface impedance matching, dielectric and magnetic dual losses, and multiple reflections depending on the interior open microcellular structures. It is expected to become a promising thermally tunable microwave absorber in harsh environments.
Tang, Z, Li, W, Peng, Q, Tam, VWY & Wang, K 2022, 'Study on the failure mechanism of geopolymeric recycled concrete using digital image correlation method', Journal of Sustainable Cement-Based Materials, vol. 11, no. 2, pp. 113-126.
View/Download from: Publisher's site
View description>>
In this study, an experimental investigation was conducted to understand the failure mechanism of geopolymeric recycled aggregate concrete (GRAC) under compression. GRAC specimens with different recycled aggregate (RA) replacement ratios were prepared and tested. A digital image correlation (DIC) system was used to monitor the displacement field and strain distribution over the surface of the specimen. The results revealed that RA replacement adversely affected the mechanical properties of geopolymeric concrete, including compressive strength, elastic modulus, and splitting tensile strength. For all the specimens, cracks mainly initiated near the interfacial transition zones, and usually nucleated around natural aggregate (NA) rather than RA. As observed from the final crack patterns, it was more frequent for the RA that cracks passed through the aggregate particles, in comparison with the NA. The location of strain concentration region detected by the DIC method was closely consistent with that of the formed macro cracks.
Tao, G, Ouyang, Q, Lei, D, Chen, Q, Nimbalkar, S, Bai, L & Zhu, Z 2022, 'NMR-Based Measurement of AWRC and Prediction of Shear Strength of Unsaturated Soils', International Journal of Geomechanics, vol. 22, no. 9.
View/Download from: Publisher's site
Tao, M, Lu, D, Shi, Y & Wu, C 2022, 'Utilization and life cycle assessment of low activity solid waste as cementitious materials: A case study of titanium slag and granulated blast furnace slag', Science of The Total Environment, vol. 849, pp. 157797-157797.
View/Download from: Publisher's site
Tian, Z, Li, Y, Li, S, Vute, S & Ji, J 2022, 'Influence of particle morphology and concentration on the piezoresistivity of cement-based sensors with magneto-aligned nickel fillers', Measurement, vol. 187, pp. 110194-110194.
View/Download from: Publisher's site
View description>>
Cement-based sensors with magneto-aligned nickel fillers have the proven capability to significantly enhance piezoresistivity compared with the sensors with randomized fillers. In this paper, the influence of particle morphology and concentration of nickel particles on the piezoresistive and mechanical properties of cement-based sensors, treated with and without magnetic field intervention, are investigated experimentally. Five categories of nickel particles with different average diameters are type N50 (50 nm), N500 (0.5 μm), F(1 μm × 20 μm flake), T (5 μm) and U (25 μm). The obtained results indicate that the application of magnetic field enhances most of the piezoresistive performance and yields best piezoresistivity for the samples with type T nickel powder. Anisotropic piezoresistivity can be achieved under a very low filler content (0.1 vol%) in N50 nano-scale nickel powder and cement composite, followed by the N500 and T nickel particles in 5 vol% content. Small particles with lower content have similar piezoresistive performance to the samples with large particles and higher concentration. One half of the samples can achieve high giant gauge factor (GF) of over 500, two-thirds of which are aligned by magnetic field with anisotropic piezoresistive property. Samples with 5 vol% type T nickel content has the highest GF value, followed by the sample with 5 vol% type F nickel flakes and 10 vol% type U nickel powder. It is also found that mechanical strength decreases with the increase of particle concentration.
Van Nguyen, L, Phung, MD & Ha, QP 2022, 'Game Theory-Based Optimal Cooperative Path Planning for Multiple UAVs', IEEE Access, vol. 10, pp. 108034-108045.
View/Download from: Publisher's site
Van, CN, Tran Thanh, H, Nguyen, TN & Li, J 2022, 'Numerical investigation of the influence of casting techniques on fiber orientation distribution in ECC', Frontiers of Structural and Civil Engineering, vol. 16, no. 11, pp. 1424-1435.
View/Download from: Publisher's site
View description>>
AbstractEngineered cementitious composites (ECC), also known as bendable concrete, were developed based on engineering the interactions between fibers and cementitious matrix. The orientation of fibers, in this regard, is one of the major factors influencing the ductile behavior of this material. In this study, fiber orientation distributions in ECC beams influenced by different casting techniques are evaluated via numerical modeling of the casting process. Two casting directions and two casting positions of the funnel outlet with beam specimens are modeled using a particle-based smoothed particle hydrodynamics (SPH) method. In this SPH approach, fresh mortar and fiber are discretized by separated mortar and fiber particles, which smoothly interact in the computational domain of SPH. The movement of fiber particles is monitored during the casting simulation. Then, the fiber orientations at different sections of specimens are determined after the fresh ECC stops flowing in the formwork. The simulation results show a significant impact of the casting direction on fiber orientation distributions along the longitudinal wall of beams, which eventually influence the flexural strength of beams. In addition, casting positions show negligible influences on the orientation distribution of fibers in the short ECC beam, except under the pouring position.
Wang, D, Wang, X, Yang, Q, Zhang, Y & Wu, C 2022, 'Dynamic response analysis of a large commercial aircraft hitting the AP1000 containment vessel', Zhendong yu Chongji/Journal of Vibration and Shock, vol. 41, no. 10.
View/Download from: Publisher's site
View description>>
Since the event of '9•11', 2001, the protection of nuclear power plants against the impact of large commercial aircraft has been a hot issue in the field of nuclear safety. Using ANSYS/LS-DYNA software, the refinement finite element models of a Boeing 737 MAX 8 and a AP1000 containment vessel were established. The accuracy and validity of the finite element modelling of the plane hitting were validated by using the Riera method. Five different initial impact velocities (100 m/s, 150 m/s, 200 m/s, 250 m/s and 300 m/s) and five different impact heights (39 m, 30 m, 47 m, 54 m and 65 m) in the plane hitting process were taken into account in the numerical simulation. The time history of the impact force and kinetic energy of the aircraft, the dynamic response of the steel containment, the equivalent stress distribution and the local damage of the aircraft were studied and analyzed. The research results show that the engine's contribution to the aircraft impact force is about 3-4 times of that of the front of the fuselage; the peak impact force on the steel tube body in the equivalent beam segment is larger, than that on other segments, the largest one is up to 171% of the latter (at the rate of 300 m/s); the junction part of the containment cylinder body to the dome is the most dangerous position, where the penetrated sizes are greater than those at other locations, the largest penetrated size in ring direction is 29.68 m, and that in vertical direction is 17.86 m. The dome in all conditions are not damaged. The equivalent steel beam segment can withstand the aircraft impact very well. When the impact velocity of the aircraft is greater than 150 m/s, the influence range of the equivalent steel plate stress in the impact area of the containment vessel decreases with the increase of initial impact velocity, and the distribution range of the equivalent steel plate stress in the impact area of the equivalent beam segment is larger than that of the non-equivale...
Wang, L, Tang, S, Chen, TE, Li, W & Gunasekara, C 2022, 'Sustainable High-Performance Hydraulic Concrete', Sustainability, vol. 14, no. 2, pp. 695-695.
View/Download from: Publisher's site
View description>>
Concrete has always been indispensable as a material for the engineering and construction of hydraulic structures (e [...]
Wang, L, Wu, C, Fan, L & Wang, M 2022, 'Effective velocity of reflected wave in rock mass with different wave impedances of normal incidence of stress wave', International Journal for Numerical and Analytical Methods in Geomechanics, vol. 46, no. 9, pp. 1607-1619.
View/Download from: Publisher's site
View description>>
AbstractThe effective velocity of the reflected wave in rock mass is of significance to the detection of crustal structure and the geophysical seismic exploration. In this paper, the modified characteristic method was introduced to solve P‐wave reflection in rock mass with different wave impedances on two sides of the joint. Effective velocity was defined to characterize the propagation velocity of the reflected wave in jointed rock mass. The effects of incident frequency, joint stiffness and wave impedance ratio on the effective velocity were discussed. The results show that when the stress wave propagation in 'hard‐to‐soft' rock mass, the effective velocity increases firstly and then decreases as the incident frequency and the joint stiffness increase, while the effective velocity always decreases as the wave impedance ratio increases; when the stress wave propagation in 'soft‐to‐hard' rock mass, the effective velocity decreases as the incident frequency increases, increases as the joint stiffness increases and decreases as the wave impedance ratio increases. The wave impedance ratio has an important influence on the effective velocity. The effective velocity without considering wave impedance ratio is smaller than that of stress wave propagation in 'soft‐to‐hard' rock mass, but larger than that of stress wave propagation in 'hard‐to‐soft' rock mass.
Wang, X, Li, W, Luo, Z, Wang, K & Shah, SP 2022, 'A critical review on phase change materials (PCM) for sustainable and energy efficient building: Design, characteristic, performance and application', Energy and Buildings, vol. 260, pp. 111923-111923.
View/Download from: Publisher's site
View description>>
Building construction deserves many attentions due to its huge energy consumption, while Phase Change Materials (PCMs) provide positive solutions for improving energy efficiency and enhancing the thermal properties of construction materials. However, PCMs also present some negative impacts, such as weakening mechanical properties and increasing costs, chemical instability and so on. In this paper, the main characteristics of PCMs, design and incorporating methods, effects on energy consumption and construction reliability are comprehensively reviewed and discussed. Although many materials have the capacity of phase change, some organic PCMs are more suitable due to the higher latent heat and favourable phase change point in buildings, when eutectic PCMs present greater potential to become the optimal one but much effort is required for investigations. Current design methods and application in construction materials can meet the essential requirements, but the effectiveness is inadequate, including low efficiency of phase changing, leading to low energy storage. Subsequently, some promising research direction and critical areas for optimization are also proposed accordingly in this paper. Future development of PCMs, including novel PCM and efficient incorporation, real applications and functions in buildings are proposed. Additionally, multifunctional construction materials combining PCM deserve much attention and possess promising prospect for energy saving in sustainable and energy efficient building construction.
Wu, C, Xia, Y & Bi, K 2022, 'Guest editorial', Advances in Structural Engineering, vol. 25, no. 7, pp. 1371-1372.
View/Download from: Publisher's site
Wu, P, Wu, C, Liu, Z, Xu, S, Li, J & Li, J 2022, 'Triaxial strength and failure criterion of ultra-high performance concrete', Advances in Structural Engineering, vol. 25, no. 9, pp. 1893-1906.
View/Download from: Publisher's site
View description>>
Over the past few decades, ultra-high performance concrete (UHPC) has been widely studied and applied because of its outstanding mechanical properties. A large number of studies have been conducted on the uniaxial static and dynamic performance of UHPC materials, however, limited investigations exist on the triaxial compression properties of UHPC. In this study, 98 cylindrical samples of UHPC with different steel fiber volumetric ratios (0.0%–1.5%) were tested to investigate the triaxial behavior of UHPC under different confining pressures (0 MPa–40 MPa). The confining pressure and steel fiber contents have clear impact on the triaxial strength, failure mode, crack width, and the angle between the oblique crack and the axial direction. The triaxial compressive strength and compressive toughness of UHPC subjected to various confining pressures are obtained from the tests and discussed in the study. Based on the testing data, the triaxial compression failure criterion of UHPC is established according to the unified strength theory. Finally, the simplified empirical equations for the full stress-strain curves of UHPC specimens subjected to uniaxial and multiaxial loads are derived, and good agreement with the experimental results is achieved.
Xu, S, Yang, Y, Wu, C & Liu, K 2022, 'Electromagnetic wave absorption performance of UHPC incorporated with carbon black and carbon fiber', Archives of Civil and Mechanical Engineering, vol. 22, no. 2.
View/Download from: Publisher's site
View description>>
This study focuses on the electromagnetic wave absorption performance (EWAP) of ultra-high-performance concrete (UHPC) incorporated with carbon black (CB) and carbon fiber (CF) in 2–18 GHz frequency range (required for the radar wave absorbing materials). The reflectivity of the traditional UHPC was investigated and compared to the cement-based composites reported in the literatures, so as to illustrate the advantages of novel UHPCs with respect to EWAP. Afterwards, the effect of CB and CF on the compressive strength, complex permittivity and reflectivity of the novel UHPCs was investigated. The microstructure of the novel UHPCs was also explored via scanning electron microscopy to illustrate the mechanism of performance enhancement on incorporating CB and CF. The results indicated that EWAP of the traditional UHPC was similar or inferior (at specific frequencies) to the literature reported cement-based composites. However, EWAP of the novel UHPCs was significantly improved after reinforcing with CB or CF. A positive effect of CB and CF was also observed on the compressive strength of the developed UHPCs. This study provides avenues for the use of UHPCs in protecting structures for absorbing the electromagnetic waves and safeguarding these structures against extreme loads, including blast and penetration.
Xu, T, Yang, G, Li, Y & Lai, T 2022, 'Influence of inerter‐based damper installations on control efficiency of building structures', Structural Control and Health Monitoring, vol. 29, no. 5.
View/Download from: Publisher's site
Xu, Z, Khabbaz, H, Fatahi, B & Wu, D 2022, 'Real-time determination of sandy soil stiffness during vibratory compaction incorporating machine learning method for intelligent compaction', Journal of Rock Mechanics and Geotechnical Engineering, vol. 14, no. 5, pp. 1609-1625.
View/Download from: Publisher's site
View description>>
An emerging real-time ground compaction and quality control, known as intelligent compaction (IC), has been applied for efficiently optimising the full-area compaction. Although IC technology can provide real-time assessment of uniformity of the compacted area, accurate determination of the soil stiffness required for quality control and design remains challenging. In this paper, a novel and advanced numerical model simulating the interaction of vibratory drum and soil beneath is developed. The model is capable of evaluating the nonlinear behaviour of underlying soil subjected to dynamic loading by capturing the variations of damping with the cyclic shear strains and degradation of soil modulus. The interaction of the drum and the soil is simulated via the finite element method to develop a comprehensive dataset capturing the dynamic responses of the drum and the soil. Indeed, more than a thousand three-dimensional (3D) numerical models covering various soil characteristics, roller weights, vibration amplitudes and frequencies were adopted. The developed dataset is then used to train the inverse solver using an innovative machine learning approach, i.e. the extended support vector regression, to simulate the stiffness of the compacted soil by adopting drum acceleration records. Furthermore, the impacts of the amplitude and frequency of the vibration on the level of underlying soil compaction are discussed. The proposed machine learning approach is promising for real-time extraction of actual soil stiffness during compaction. Results of the study can be employed by practising engineers to interpret roller drum acceleration data to estimate the level of compaction and ground stiffness during compaction.
Xu, Z, Li, J, Qian, H & Wu, C 2022, 'Blast resistance of hybrid steel and polypropylene fibre reinforced ultra-high performance concrete after exposure to elevated temperatures', Composite Structures, vol. 294, pp. 115771-115771.
View/Download from: Publisher's site
View description>>
In this study, the blast resistance of fibre reinforced ultra-high performance concrete (UHPC) components after exposure to elevated temperatures was investigated. With a hybrid steel and polypropylene (PP) fibre reinforcement, this fire resistant UHPC maintained approximately 60% of its original compressive strength after exposed to 800 °C temperature. Uniaxial and triaxial material behaviour after exposure to high temperatures was studied experimentally and then incorporated into a plasticity concrete model, i.e. Karagozian & Case Concrete (KCC model) model for the blast induced structural response analysis. Material strength and failure surfaces, volumetric change with pressure, strain rate effect and material damage parameters were updated with consideration of fire hazards. The simulated UHPC uniaxial stress–strain curves after exposure to 200, 400, 600 and 800 °C elevated temperatures, together with the simulated post-fire blast tests results on UHPC members were compared with available experimental results. The reasonable agreement between the tests and simulation results validated the proposed model in both material and structural scopes. The numerical model was further applied to predict the blast response of reinforced UHPC components after exposed to thermal hazards.
Yang, T, Xu, S, Liu, Z, Li, J, Wu, P, Yang, Y & Wu, C 2022, 'Experimental and numerical investigation of bond behavior between geopolymer based ultra-high-performance concrete and steel bars', Construction and Building Materials, vol. 345, pp. 128220-128220.
View/Download from: Publisher's site
View description>>
In this study, a total of twenty groups of specimens were tested to investigate bond behavior between the geopolymer based ultra-high-performance concrete (G-UHPC) and steel bars. The failure modes and bond stress-slip relationships were analyzed and discussed in detail. Subsequently, a detailed 3D numerical model was developed and validated against the experimental findings. The validated numerical model was then employed to perform parametric studies to evaluate the effects of steel strength, bond length, and protective layer thickness on the bond behavior between G-UHPC and the steel bar. It was revealed that the bond strength between the steel bar and G-UHPC was enhanced upon increasing the steel bar strength and protective layer thickness, along with reducing the steel bar diameter. The bond slip decreased with an increase in the steel fiber length and volume fraction. Further, the protective layer thickness exhibited an insignificant effect on the linear ascending stage of the bond stress-slip relationships, but positively impacted the maximum bond strength of the specimen. Finally, a bond stress-slip constitutive model was proposed to precisely predict the bond behavior between G-UHPC and the steel bars.
Yang, Y, Wu, C, Liu, Z & Zhang, H 2022, '3D-printing ultra-high performance fiber-reinforced concrete under triaxial confining loads', Additive Manufacturing, vol. 50, pp. 102568-102568.
View/Download from: Publisher's site
View description>>
3D-printing concrete structural members may experience complex stress states, while external reinforcement (wrapping steel tube or fiber-reinforced polymer) may be one of the effective ways to improve performance. Therefore, triaxial mechanical properties of 3D-printing concrete should be explored. This study presents an experimental investigation of the triaxial behavior of 3D-printing ultra-high performance fiber-reinforced concrete (3DP-UHPFRC) loaded in the Z-direction. Mold-casting ultra-high performance fiber reinforced concrete (MC-UHPFRC) was used as the reference specimen. Based on the test data, the failure mode and mechanical properties of the 3D-printing specimens were analyzed, and the failure criteria were explored. The experimental results showed that 3DP-UHPFRC possessed triaxial failure modes, mechanical properties, and failure criteria as MC-UHPFRC. All 3DP-UHPFRC specimens exhibited oblique shear cracks under triaxial compression. The fitting effect of Mohr-Coulomb failure criterion on 3D-printing specimens without steel fiber is poor (R2 is less than 0.9), which is due to the linear relationship of Mohr-Coulomb failure criterion and the obvious nonlinear increase in strength of 3D-printing specimens without steel fiber with the confining pressure, whereas the Power-law and Willam-Warnke failure criteria were good for all 3D-printing specimens. A modified model was established for predicting the stress-strain curves of 3DP-UHPFRC under triaxial confining pressure.
Yang, Y, Wu, C, Liu, Z, Li, J, Yang, T & Jiang, X 2022, 'Characteristics of 3D-printing ultra-high performance fibre-reinforced concrete under impact loading', International Journal of Impact Engineering, vol. 164, pp. 104205-104205.
View/Download from: Publisher's site
View description>>
3D-printing concrete exhibits anisotropy under static loads, owing to its unique additive manufacturing process, while its dynamic performance study is still insufficient. In particular, the dynamic properties of 3D-printing ultra-high performance fibre reinforced concrete (3DP-UHPFRC) have not been studied yet. Therefore, this study explores the characteristics of 3DP-UHPFRC under impact loads using the SHPB tests. Three impact velocities of 3.886, 6.026, and 8.538 m/s were studied in the tests. The impact process was recorded by a high-speed camera. The dynamic mechanical characteristics of 3D-printing ultra-high performance concrete (3DP-UHPC) without fibre, 3DP-UHPFRC and reference specimens were investigated in terms of fibre type, fibre content, preparation method, loading direction, and impact velocity. The characteristics of strain rate, dynamic compressive stress, dynamic increase factor (DIF), energy absorption capacity and failure process were evaluated. The findings of this study indicated that the degree of failure of 3DP-UHPC was similar in all directions, while the degree of failure of 3DP-UHPFRC in all directions was different. The degree of failure in the X-direction was the worst, followed in decreasing order by the degrees of failure in the Y- and Z-directions. At the same impact velocity, the elastic modulus and strain rate effect of the 3D-printing specimens exhibited anisotropic characteristics, owing to the different elastic modulus of the 3D-printing specimens in each direction. Furthermore, the specimens were more susceptible to deformation in the X-direction than that in the Y- and Z-directions. As the impact velocity was increased, the dynamic peak stresses for 3DP-UHPFRC were isotropic at the same impact velocity, owing to the strain rate effect. Finally, the DIF of the 3D-printing specimens was observed to be anisotropic, and in the X-direction the specimens exhibited the most significant strain rate sensitivity.
Yang, Y, Wu, C, Liu, Z, Wang, H & Ren, Q 2022, 'Mechanical anisotropy of ultra-high performance fibre-reinforced concrete for 3D printing', Cement and Concrete Composites, vol. 125, pp. 104310-104310.
View/Download from: Publisher's site
Yu, Y, Liang, S, Samali, B, Nguyen, TN, Zhai, C, Li, J & Xie, X 2022, 'Torsional capacity evaluation of RC beams using an improved bird swarm algorithm optimised 2D convolutional neural network', Engineering Structures, vol. 273, pp. 115066-115066.
View/Download from: Publisher's site
Yuan, P, Xu, S, Liu, J, Su, Y, Li, J, Qu, K, Liu, C & Wu, C 2022, 'Correction to: Experimental investigation of G-HPC-based sandwich walls incorporated with metallic tube core under contact explosion', Archives of Civil and Mechanical Engineering, vol. 22, no. 4.
View/Download from: Publisher's site
Yuan, P, Xu, S, Liu, J, Su, Y, Li, J, Qu, K, Liu, C & Wu, C 2022, 'Experimental investigation of G-HPC-based sandwich walls incorporated with metallic tube core under contact explosion', Archives of Civil and Mechanical Engineering, vol. 22, no. 4.
View/Download from: Publisher's site
View description>>
A novel geopolymer-based high-performance concrete (G-HPC) sandwich wall consisting of two G-HPC layers separated by a metallic tube core possessing high strength and lightweight structure was developed in this study. The contact blast tests with 1 kg TNT were subsequently conducted to explore the blast resistance of the developed sandwich walls. For this purpose, three sandwich walls and a C40 reinforced concrete (RC) slab were employed. The superior blast resistance of the sandwich walls was verified based on the experimental results as compared to the RC slab. The sandwich wall with a circular steel tube core exhibited a superior blast resistance than the wall with a circular aluminum alloy tube core, whereas the sandwich wall with a rectangular steel tube core revealed the best performance. The blast resistance and damage mechanism of the sandwich walls were subsequently analyzed. The accuracy of the available empirical formulas was also examined for predicting the damage in the sandwich walls under contact explosion conditions.
Zhang, SS, Ke, Y, Chen, E, Biscaia, H & Li, WG 2022, 'Effect of load distribution on the behaviour of RC beams strengthened in flexure with near-surface mounted (NSM) FRP', Composite Structures, vol. 279, pp. 114782-114782.
View/Download from: Publisher's site
View description>>
Debonding failures of FRP have been frequently observed in laboratory tests of reinforced concrete (RC) beams flexurally-strengthened with near-surface mounted (NSM) fibre-reinforced polymer (FRP). A number of numerical and theoretical studies have been carried out to predict debonding failures in NSM FRP-strengthened beams, and several strength models have also been proposed. The existing studies, however, were all based on the scenario of a simply supported beam tested under one or two-point loading, while the influence of load distribution has not yet been investigated. This paper presents the first ever study into the effect of load distribution on the behaviour of NSM FRP-strengthened RC beams. A series of large-scale RC beams flexurally-strengthened with NSM FRP strips were first tested under different load uniformities; then a finite element (FE) model, which can give close predictions to the behaviour of such strengthened beams, was developed; finally, the proposed FE model was utilized to investigate the influence of bond length of NSM FRP on the load uniformity effect. It was found that the load uniformity has a significant effect on the beam behaviour, and the degree of this effect varies with the bond length of NSM FRP.
Zhang, X & Far, H 2022, 'Effects of dynamic soil-structure interaction on seismic behaviour of high-rise buildings', Bulletin of Earthquake Engineering, vol. 20, no. 7, pp. 3443-3467.
View/Download from: Publisher's site
Zhang, X, Li, Z-X, Shi, Y, Wu, C & Li, J 2022, 'Fragility analysis for performance-based blast design of FRP-strengthened RC columns using artificial neural network', Journal of Building Engineering, vol. 52, pp. 104364-104364.
View/Download from: Publisher's site
View description>>
In this paper, fragility analysis for performance-based blast design of FRP-strengthened RC columns is carried out. The blast intensity levels, performance levels and performance objectives of the RC columns are defined. A simplified probabilistic risk assessment framework incorporating the performance-based design concept and fragility analysis is established. Since fragility analysis is the most important but time-consuming process of probabilistic assessment risk, an artificial neural network (ANN) based fragility analysis framework is proposed to improve its computational efficiency. Based on the rapid fragility analysis method, fragility curves of several typical RC columns with or without FRP strengthening are calculated to analyze their damage probabilities. This study provides avenues for engineers to estimate the failure probabilities of RC columns with or without FRP strengthening under blast loads and make decisions quickly.
Zhao, H, Hu, Y, Tang, Z, Wang, K, Li, Y & Li, W 2022, 'Deterioration of concrete under coupled aggressive actions associated with load, temperature and chemical attacks: A comprehensive review', Construction and Building Materials, vol. 322, pp. 126466-126466.
View/Download from: Publisher's site
View description>>
Concrete infrastructure subjected to mechanical load or surrounding aggressive environments experiences gradual deterioration of performance. Although many studies have conducted on durability of concrete under single aggressive condition, the related research results have already been well-summarized. The concrete deterioration under coupled actions is severer and more complicated than that under single aggressive conditions. However, few studies have reviewed the studies on this topic. This paper comprehensively reviews the research outcomes of the performance of concrete under various coupled aggressive actions, such as high temperature and impact load, freeze–thaw and fatigue loading, alkali-silica reaction and compression, sulfate attack and dry-wet cycling, chloride penetration and carbonation, as well as acid corrosion and high temperature exposure, and so on. The testing methods, interaction of two aggressive conditions, and strengthening measures have been discussed and summarized correspondingly. The results indicate that the performance degradation under the coupled mechanical load and aggressive environments are much severer compared to the single aggressive environment. The properties of concrete are significantly affected by the severity of coupled aggressive actions, and can be improved at the early-age stage. The experimental methods also have higher impact on the performance of concrete due to different mechanisms, but the difference between under and after high temperature exposures is relatively lower. Finally, some enhancement methods proposed in this review, such as adding fly ash, silica fume, slag, fibers or air-entraining agents, are effective in improving the durability of concrete under coupled aggressive environments.
