作者机构：
School of Civil and Environmental Engineering, Changsha University of Science & Technology, Changsha 410114, China;Key Laboratory of Safety Control of Bridge Engineering of Ministry of Education, Changsha University of Science & Technology, Changsha 410114, China;[Chao-Huang Cai] College of Architecture and Civil Engineering, Beijing University of Technology, Beijing 100124, China;[Zhao-Hui Lu] Key Laboratory of Urban Security and Disaster Engineering of Ministry of Education, Beijing University of Technology, Beijing 100124, China;[Yu Leng] School of Civil and Environmental Engineering, Changsha University of Science & Technology, Changsha 410114, China<&wdkj&>Key Laboratory of Safety Control of Bridge Engineering of Ministry of Education, Changsha University of Science & Technology, Changsha 410114, China
通讯机构：
[Chao-Huang Cai] C;College of Architecture and Civil Engineering, Beijing University of Technology, Beijing 100124, China
摘要：
Failure probability of a structure is dominated by the importance domain whose extent is much smaller than the whole random variable space. Once the importance domain is identified, the failure probability can be evaluated efficiently through compressing the sampling space into the importance domain. Recently, ring simulation has attempted to identify the importance interval in one dimension (i.e., the radius). To obtain a complete importance domain in all dimensions, a new simulation method, called “partial ring simulation”, is proposed for the efficient estimation of the failure probability. In the proposed method, the importance domain, consisting of importance radius and importance direction, is adaptively identified by a stepwise strategy utilizing the information from prior steps. For generating samples located in the importance domain, a Markov chain Monte Carlo sampling is then constructed. The effectiveness of the proposed method is validated by four examples involving parallel, series, and nonlinear limit state functions, small failure probabilities, and high-dimensional problems. The results indicate that the proposed method greatly improves the computational efficiency of ring simulation.
Failure probability of a structure is dominated by the importance domain whose extent is much smaller than the whole random variable space. Once the importance domain is identified, the failure probability can be evaluated efficiently through compressing the sampling space into the importance domain. Recently, ring simulation has attempted to identify the importance interval in one dimension (i.e., the radius). To obtain a complete importance domain in all dimensions, a new simulation method, called “partial ring simulation”, is proposed for the efficient estimation of the failure probability. In the proposed method, the importance domain, consisting of importance radius and importance direction, is adaptively identified by a stepwise strategy utilizing the information from prior steps. For generating samples located in the importance domain, a Markov chain Monte Carlo sampling is then constructed. The effectiveness of the proposed method is validated by four examples involving parallel, series, and nonlinear limit state functions, small failure probabilities, and high-dimensional problems. The results indicate that the proposed method greatly improves the computational efficiency of ring simulation.
作者：
Tao Li*;Yongfei Lin;Ling Zeng;Xiaowei Tang;Gang Yang;...
期刊：
Soil Dynamics and Earthquake Engineering,2026年200:109721 ISSN：0267-7261
通讯作者：
Tao Li
作者机构：
Key Laboratory of Safety Control of Bridge Engineering, Ministry of Education, Changsha University of Science & Technology, Changsha, China;[Ling Zeng] School of Civil and Environmental Engineering, Changsha University of Science & Technology, Changsha, China;[Xiaowei Tang; Gang Yang] State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology, Dalian, China;[Shun Liu] China Institute of Water Resources and Hydropower Research, Beijing, China;[Tao Li; Yongfei Lin] Key Laboratory of Safety Control of Bridge Engineering, Ministry of Education, Changsha University of Science & Technology, Changsha, China<&wdkj&>School of Civil and Environmental Engineering, Changsha University of Science & Technology, Changsha, China
通讯机构：
[Tao Li] K;Key Laboratory of Safety Control of Bridge Engineering, Ministry of Education, Changsha University of Science & Technology, Changsha, China<&wdkj&>School of Civil and Environmental Engineering, Changsha University of Science & Technology, Changsha, China
摘要：
Static liquefaction will occur in saturated sand-clay mixtures under static loading. Understanding the mechanical behavior of sand-clay mixtures is crucial for evaluating its safety and stability. Through a series of isotropically consolidated undrained triaxial compression tests (CU), the effect of clay content (CC) on static shear strength of sand-clay mixtures were studied under constant sand skeleton void ratio (e s ). Test results demonstrate that static liquefaction happened for specimens with CC = 0 % (pure sand), 3 %, 5 %, 7 %, and 10 % under different confining pressures. By contrast, no static liquefaction occurred for specimens with CC = 12 % and 15 %. When CC = 0 %∼15 %, the peak deviator stress (q peak ) and mean effective stress at the steady state (p ss ') of corresponding specimens raise 305.6 %, 94.4 % and 97.6 % as well as 114.1 %, 987.9 % and 266.2 % under three different confining pressures, respectively. In addition, the microscopic characteristics of sand-clay mixtures with various clay contents were observed. It can be found that when CC ≤ 10 %, the clay particles primarily filled in the inter-sand voids, distributed on the surfaces of sand particles and located at the sand-sand contact points. And these clay particles can lubricate and bond sand particles, which can promote the liquefaction of mixed soil. The bonding effect of clay on sand is further enhanced when CC = 12 % and 15 %, and clay play an inhibitory role in the liquefaction of sand. Finally, a calculation equation of clay participation coefficient was proposed in current study, which can consider the effect of content, particle size and plasticity index of clay on the mechanical properties of sand-clay mixtures. The equation demonstrates excellent fitting results for both steady state data and cyclic stress ratio data in the present study and relevant literature.
Static liquefaction will occur in saturated sand-clay mixtures under static loading. Understanding the mechanical behavior of sand-clay mixtures is crucial for evaluating its safety and stability. Through a series of isotropically consolidated undrained triaxial compression tests (CU), the effect of clay content (CC) on static shear strength of sand-clay mixtures were studied under constant sand skeleton void ratio (e s ). Test results demonstrate that static liquefaction happened for specimens with CC = 0 % (pure sand), 3 %, 5 %, 7 %, and 10 % under different confining pressures. By contrast, no static liquefaction occurred for specimens with CC = 12 % and 15 %. When CC = 0 %∼15 %, the peak deviator stress (q peak ) and mean effective stress at the steady state (p ss ') of corresponding specimens raise 305.6 %, 94.4 % and 97.6 % as well as 114.1 %, 987.9 % and 266.2 % under three different confining pressures, respectively. In addition, the microscopic characteristics of sand-clay mixtures with various clay contents were observed. It can be found that when CC ≤ 10 %, the clay particles primarily filled in the inter-sand voids, distributed on the surfaces of sand particles and located at the sand-sand contact points. And these clay particles can lubricate and bond sand particles, which can promote the liquefaction of mixed soil. The bonding effect of clay on sand is further enhanced when CC = 12 % and 15 %, and clay play an inhibitory role in the liquefaction of sand. Finally, a calculation equation of clay participation coefficient was proposed in current study, which can consider the effect of content, particle size and plasticity index of clay on the mechanical properties of sand-clay mixtures. The equation demonstrates excellent fitting results for both steady state data and cyclic stress ratio data in the present study and relevant literature.
关键词：
Bridge damage localization;Vibration;Finite element model;Transfer learning;Time-frequency analysis
摘要：
The complex structural systems of large bridges pose challenges for damage identification using traditional mechanical or data-driven methods. A key limitation of supervised machine learning methods is the lack of effective samples representing structural damage conditions. A novel domain adaptation transfer learning (TL) method, SE-TL-ResNet34 model, is proposed for structural damage identification, enabling the balanced training and reducing overfitting. First, convolutional neural networks (CNNs) were utilized to extract modal damage features from the time–frequency images derived from structural acceleration signals. Second, time–frequency features from finite element models (FEM) and monitoring data were integrated using TL. Finally, the pre-trained CNN was fine-tuned to classify multiple types of structural damage. The effectiveness and accuracy of the proposed method were validated using test data from both FEM and an experimental cable-stayed bridge specimen. Results indicate that the proposed domain adaptation TL approach outperforms traditional supervised learning methods in damage identification accuracy.
The complex structural systems of large bridges pose challenges for damage identification using traditional mechanical or data-driven methods. A key limitation of supervised machine learning methods is the lack of effective samples representing structural damage conditions. A novel domain adaptation transfer learning (TL) method, SE-TL-ResNet34 model, is proposed for structural damage identification, enabling the balanced training and reducing overfitting. First, convolutional neural networks (CNNs) were utilized to extract modal damage features from the time–frequency images derived from structural acceleration signals. Second, time–frequency features from finite element models (FEM) and monitoring data were integrated using TL. Finally, the pre-trained CNN was fine-tuned to classify multiple types of structural damage. The effectiveness and accuracy of the proposed method were validated using test data from both FEM and an experimental cable-stayed bridge specimen. Results indicate that the proposed domain adaptation TL approach outperforms traditional supervised learning methods in damage identification accuracy.
摘要：
The uncertainty of distribution parameters significantly impacts the outcomes of structural reliability analysis. Considering these uncertainties, the failure probability becomes uncertain and the estimation of its distribution often encounters burdensome computational effort. In this paper, to avoid repeated sampling of input random vector and performance function calls, an efficient quantitative estimation method for determining the distribution and quantiles of failure probability is developed through fixing the sampling distribution of input random vector. The fixed sampling distribution is innovatively designed to cover the majority of important failure domains across varying distribution parameter values, after investigating the propagation relation of uncertainty between distribution parameters and design point. Using only one sample set of input vector and iterating the weights associated with the uncertain distribution parameters, the distribution of failure probability can be obtained. In the proposed method, the repeated reliability analysis is avoided and the computational effort approximates that of a single reliability analysis. The efficiency and accuracy of the method are verified by four examples involving unimodal/bimodal distribution, low/high reliability, low/high variability, and nonlinear/high-dimensional performance functions.
The uncertainty of distribution parameters significantly impacts the outcomes of structural reliability analysis. Considering these uncertainties, the failure probability becomes uncertain and the estimation of its distribution often encounters burdensome computational effort. In this paper, to avoid repeated sampling of input random vector and performance function calls, an efficient quantitative estimation method for determining the distribution and quantiles of failure probability is developed through fixing the sampling distribution of input random vector. The fixed sampling distribution is innovatively designed to cover the majority of important failure domains across varying distribution parameter values, after investigating the propagation relation of uncertainty between distribution parameters and design point. Using only one sample set of input vector and iterating the weights associated with the uncertain distribution parameters, the distribution of failure probability can be obtained. In the proposed method, the repeated reliability analysis is avoided and the computational effort approximates that of a single reliability analysis. The efficiency and accuracy of the method are verified by four examples involving unimodal/bimodal distribution, low/high reliability, low/high variability, and nonlinear/high-dimensional performance functions.
摘要：
A new method was proposed for predicting residual stress in light alloys using truncated conical indentation. In this method, a truncated conical indenter with a cone angle of 120°, insensitive to edge-chamfer and friction effects, was used to test the residual stress of light alloys. Selecting the ratio of indentation work between stressed and unstressed specimens as an analytical parameter, a dimensionless truncated conical indentation (TCI) model related to the ratio of indentation work between stressed and unstressed, material properties, and normalized residual stress was established via dimensional analysis and numerical calculations. The TCI model could predict equi-biaxial residual stress and uniaxial residual stress, and its accuracy was verified in a wide range of light alloys with varying residual stress by numerical simulation. The stability of the TCI model is verified numerically by introducing errors in material parameters. Truncated conical indentation tests were conducted on cruciform specimens and rectangular specimens respectively made of three aluminum alloys. The results exhibited the residual stress predicted by proposed method agrees well with the applied stress, and the relative errors between them were within ±10 % in most cases.
A new method was proposed for predicting residual stress in light alloys using truncated conical indentation. In this method, a truncated conical indenter with a cone angle of 120°, insensitive to edge-chamfer and friction effects, was used to test the residual stress of light alloys. Selecting the ratio of indentation work between stressed and unstressed specimens as an analytical parameter, a dimensionless truncated conical indentation (TCI) model related to the ratio of indentation work between stressed and unstressed, material properties, and normalized residual stress was established via dimensional analysis and numerical calculations. The TCI model could predict equi-biaxial residual stress and uniaxial residual stress, and its accuracy was verified in a wide range of light alloys with varying residual stress by numerical simulation. The stability of the TCI model is verified numerically by introducing errors in material parameters. Truncated conical indentation tests were conducted on cruciform specimens and rectangular specimens respectively made of three aluminum alloys. The results exhibited the residual stress predicted by proposed method agrees well with the applied stress, and the relative errors between them were within ±10 % in most cases.
摘要：
Our study employs panel data from 272 Chinese prefecture-level cities (2003-2020), leveraging the "Civilized City" selection campaign as a quasi-natural experiment. Using a Spatial Durbin Difference-in-Differences model, we systematically analyze the policy's impact on local environmental governance performance and its spatial spillover effects, with rigorous robustness checks. Results reveal a significant positive spatial correlation in China's environmental governance performance, indicating interdependence among cities rather than isolated decision-making. The "Civilized City" initiative not only improves local environmental governance but also generates spillover benefits for neighboring regions, thereby enhancing coordinated regional sustainability. Finally, we propose policy recommendations grounded in empirical findings and China's governance context.
摘要：
Several reinforced concrete (RC) structures requiring strengthening already have cracks of different width, some of them of shear nature. However, there is an extra lack of knowledge on the effectiveness of using fiber-reinforced polymer (FRP) composites for shear strengthening of pre-cracked RC structure. To bring knowledge in this domain, RC T-cross section beams with maximum pre- induced shear crack widths of 0, 0.5 and 1.0 mm were strengthened in shear using near-surface-mounted (NSM) technique with passive and prestressed carbon fiber-reinforced polymer (CFRP) laminates. The effects of maximum width of the pre-cracks, passive or prestressed CFRP laminates, and CFRP shear strengthening ratio on the beam’s load carrying capacity, deflection performance, stiffness degradation and CFRP strain were analyzed. The ability of prestressed CFRP to restrain the pre-cracks in the beams while they are subjected to the sustained pre-load was also investigated. The test results showed that prestressed CFRP reduced the pre-crack width of RC beams under sustained pre-load by 12.4–50.4 %. The pre-cracking, despite to have decreased the beam’s stiffness, had minimal influence on the growth rate of the maximum shear crack width, and the decrease of the beam’s load carrying capacity was limited to 3.0 % and 14.5 % for a pre-crack width of 0.5 and 1.0 mm, respectively. Applying prestress to CFRP laminates and decreasing CFRP spacing were effective in reducing the maximum shear crack width, enhancing the load carrying capacity and improving stiffness of strengthened beams. A formulation for calculating the contribution of prestressed NSM CFRP for the shear capacity of RC beams was proposed and its good predictive performance is demonstrated.
Several reinforced concrete (RC) structures requiring strengthening already have cracks of different width, some of them of shear nature. However, there is an extra lack of knowledge on the effectiveness of using fiber-reinforced polymer (FRP) composites for shear strengthening of pre-cracked RC structure. To bring knowledge in this domain, RC T-cross section beams with maximum pre- induced shear crack widths of 0, 0.5 and 1.0 mm were strengthened in shear using near-surface-mounted (NSM) technique with passive and prestressed carbon fiber-reinforced polymer (CFRP) laminates. The effects of maximum width of the pre-cracks, passive or prestressed CFRP laminates, and CFRP shear strengthening ratio on the beam’s load carrying capacity, deflection performance, stiffness degradation and CFRP strain were analyzed. The ability of prestressed CFRP to restrain the pre-cracks in the beams while they are subjected to the sustained pre-load was also investigated. The test results showed that prestressed CFRP reduced the pre-crack width of RC beams under sustained pre-load by 12.4–50.4 %. The pre-cracking, despite to have decreased the beam’s stiffness, had minimal influence on the growth rate of the maximum shear crack width, and the decrease of the beam’s load carrying capacity was limited to 3.0 % and 14.5 % for a pre-crack width of 0.5 and 1.0 mm, respectively. Applying prestress to CFRP laminates and decreasing CFRP spacing were effective in reducing the maximum shear crack width, enhancing the load carrying capacity and improving stiffness of strengthened beams. A formulation for calculating the contribution of prestressed NSM CFRP for the shear capacity of RC beams was proposed and its good predictive performance is demonstrated.
摘要：
The solid propellant is a particle-reinforced material with significant tension-compression asymmetry. Based on the constant-speed tensile test, constant-speed compression test, and cross-sectional SEM scanning test, this study investigated the differences in the mechanical properties of the HTPB propellant under tensile and compressive loading and the underlying mechanisms. The results show that the tensile strength of HTPB propellant is much smaller than compressive strength. According to the SEM test results of the failure surface, the tensile mechanical properties of the propellant are mainly affected by matrix, and the influence of particles on the mechanical properties is more obvious during the compression process. According to test data, a tension-compression integrated nonlinear constitutive model was constructed, and its application in simulation calculation was realized. The results show that the theoretical, simulation calculation and test results are in good agreement. At 15% strain, the maximum error between the theoretical results and the experimental curve is 9.1% and 4.8% respectively in the process of tension and compression. Therefore, the model can accurately describe the stress-strain relationship of HTPB propellant under different strain rates of tensile and compression. This model can provide theoretical support for accurately evaluating the structural integrity of SRMs.
通讯机构：
[Hu, P ] C;Changsha Univ Sci & Technol, Sch Civil Engn, Changsha 410114, Hunan, Peoples R China.
摘要：
Numerical investigations are conducted to evaluate the effectiveness of bypass channels in suppressing the aerodynamic coefficients of a stationary circular cylinder. The aerodynamic coefficients, which vary with the geometric shape, thickness, entrance location, and exit location of bypass channels, are given attention. Compared with the bare cylinder, the flow from bypass channels can weaken the cross-communication between the bilateral shear layers of the cylinder and suppress the alternating vortex shedding in the wake. Under the optimal parameters, the root mean square lift coefficient ( C l rms ) of a stationary cylinder can be reduced by more than 83.7% with a 60.1% reduction in the mean drag coefficient ( C d mean ). Then, the vortex-induced vibrations (VIVs) of a single-degree-of-freedom spring-mounted cylinder are investigated under the optimal parameters. The results show that bypass channels are able to alter the vortex shedding pattern in the wake, disrupting the periodicity of lift fluctuations. Eventually, the maximal VIV amplitude of the cylinder with bypass channels can be reduced by 94.87%.
摘要：
This study examines the prestress transmission behavior in near-surface-mounted (NSM) carbon fiber-reinforced polymer (CFRP)-strengthened reinforced concrete structures, with particular emphasis on the effects of temperature. Experimental tests were conducted to evaluate the tensile and shear properties of epoxy adhesives under a range of curing temperatures (20-100 degrees C) and ambient service temperatures (0-80 degrees C). The results reveal an inverse exponential relationship between curing time and temperature. Notably, adhesive strength declines significantly above 60 degrees C and the adhesive loses functionality at 80 degrees C. Building on these findings, an analytical model was developed to predict prestress transfer length, CFRP strain distribution, and interfacial shear stress. The model incorporates effective bond stiffness and a prestress reduction coefficient to account for varying prestress levels (10-50%). Parametric analyses identify the CFRP elastic modulus, cross-sectional geometry, adhesive thickness, and degree of curing as critical factors influencing prestress transmission. The model's predictions were validated against experimental data, demonstrating its reliability. Overall, this work provides a theoretical foundation for optimizing the design of NSM CFRP-strengthened structures under complex thermal conditions.
摘要：
Orthotropic steel decks (OSDs) are welded structures prone to weld defects, increasing the risk of fatigue fracture. It is crucial to clarify the fatigue evolution mechanism of weld defects throughout the entire lifecycle. In this study, the fatigue propagation behavior of weld defects is investigated from the hidden stage to final fracture. Firstly, a full-scale segmental OSD model with prefabricated defects was utilized to investigated fatigue propagation behavior of surface cracks. Secondly, stress intensity factors (SIFs) of welding defects throughout the entire process were simulated using a refined finite element model. Finally, the crack shape evolution and fatigue life were analyzed at different fatigue stages. The research identifies three stages in the fatigue evolution of hidden defects: the hidden defect stage, the initiation stage of surface crack, and the propagation stage of surface crack. Regardless of the initial aspect ratios, hidden defects evolve into a circular, while surface defects evolve into a flattened semi-ellipse. Compared to the propagation life of surface cracks, the hiding life of cracks account for a significantly larger proportion of the total life, and this proportion increases with both the initial aspect ratio and the hidden depth of the defects.
Orthotropic steel decks (OSDs) are welded structures prone to weld defects, increasing the risk of fatigue fracture. It is crucial to clarify the fatigue evolution mechanism of weld defects throughout the entire lifecycle. In this study, the fatigue propagation behavior of weld defects is investigated from the hidden stage to final fracture. Firstly, a full-scale segmental OSD model with prefabricated defects was utilized to investigated fatigue propagation behavior of surface cracks. Secondly, stress intensity factors (SIFs) of welding defects throughout the entire process were simulated using a refined finite element model. Finally, the crack shape evolution and fatigue life were analyzed at different fatigue stages. The research identifies three stages in the fatigue evolution of hidden defects: the hidden defect stage, the initiation stage of surface crack, and the propagation stage of surface crack. Regardless of the initial aspect ratios, hidden defects evolve into a circular, while surface defects evolve into a flattened semi-ellipse. Compared to the propagation life of surface cracks, the hiding life of cracks account for a significantly larger proportion of the total life, and this proportion increases with both the initial aspect ratio and the hidden depth of the defects.
摘要：
Weld residual stress (WRS) is a major contributor to fatigue cracking at the U-rib-to-deck (RD) joints of orthotropic steel bridge decks (OSBD). To investigate the generation, and distribution mechanism of WRS and its impact on the ultimate bearing capacity, an FEA model of the RD joint was developed by using a thermo-mechanical coupling calculation approach. Then, the differences in WRS of RD joints with different weld forms were compared. Furthermore, a simulation method considering WRS for the ultimate bearing capacity of OSBD and a theoretical formula for its calculation were developed. Finally, the impact of different weld types on the RD joint's ultimate bearing capacity was compared. The results revealed that the maximum WRS values at the weld center were 410 MPa, which highlights the need for particular attention to fatigue failure at this location. For the application of different weld forms in RD joints, it is recommended to prioritize concave welds for structures with high fatigue requirements, while convex welds are more suitable for non-critical areas with low fatigue requirements, and select right-angle welds in regions of moderate fatigue requirements. The ultimate bearing capacity considering WRS showed a 5 % improvement in accuracy compared to that without WRS. The ultimate bearing capacity of the RD joint can be calculated by using the theoretical formula proposed in this article. Additionally, the weld type has a negligible consequence on the ultimate bearing capacity of OSBD.
Weld residual stress (WRS) is a major contributor to fatigue cracking at the U-rib-to-deck (RD) joints of orthotropic steel bridge decks (OSBD). To investigate the generation, and distribution mechanism of WRS and its impact on the ultimate bearing capacity, an FEA model of the RD joint was developed by using a thermo-mechanical coupling calculation approach. Then, the differences in WRS of RD joints with different weld forms were compared. Furthermore, a simulation method considering WRS for the ultimate bearing capacity of OSBD and a theoretical formula for its calculation were developed. Finally, the impact of different weld types on the RD joint's ultimate bearing capacity was compared. The results revealed that the maximum WRS values at the weld center were 410 MPa, which highlights the need for particular attention to fatigue failure at this location. For the application of different weld forms in RD joints, it is recommended to prioritize concave welds for structures with high fatigue requirements, while convex welds are more suitable for non-critical areas with low fatigue requirements, and select right-angle welds in regions of moderate fatigue requirements. The ultimate bearing capacity considering WRS showed a 5 % improvement in accuracy compared to that without WRS. The ultimate bearing capacity of the RD joint can be calculated by using the theoretical formula proposed in this article. Additionally, the weld type has a negligible consequence on the ultimate bearing capacity of OSBD.
摘要：
Understanding the dynamic response and failure mechanisms of rock slopes during earthquakes is crucial in sustainable geohazard prevention and mitigation engineering. The initiation of landslides involves complex interactions between seismic wave propagation, dynamic rock mass behavior, and crack network evolution, and these interactions are heavily influenced by the slope geometry, lithology, and structural parameters of the slope. However, systematic studies remain limited due to experimental challenges and the inherent variability of landslide scenarios. This study employs Discrete Element Method (DEM) modeling to comprehensively investigate how geological structure parameters control the dynamic amplification and deformation characteristic of typical bedding/anti-dip layered slopes consist of parallel distributed rock masses and joint faces, with calibrated mechanical properties. A soft-bond model (SBM) is utilized to accurately simulate the quasi-brittle rock behavior. Numerical results reveal distinct dynamic responses between bedding and anti-dip slopes, where local amplification zones (LAZs) act as seismic energy concentrators, while potential sliding zones (PSZs) exhibit hindering effects. Parametric analyses of strata dip angles and thicknesses identify a critical dip range where slope stability drastically decreases, highlighting high-risk configurations for earthquake-induced landslides. By linking the slope failure mechanism to seismic risk reduction strategies, this work provides practical guidelines for sustainable slope design and landslide mitigation in tectonically active regions.
摘要：
Nonlinear flutter has attracted wide attention due to the bottleneck caused by linear flutter theory on flutter-resistant design of super-long-span bridges. The longer the span, the more closely spaced the natural modes, which may cause competition among flutter-modes in a nonlinear flutter, but it is rarely reported so far. To this end, this study experimentally investigates the 3D nonlinear flutter characteristics of a long-span suspension bridge with closely spaced natural modes based on full-bridge aeroelastic model wind tunnel tests. Since there are two unstable flutter-modes within the interested post-critical regime and thus various complex but interesting flutter-modes competition processes were observed, such as continuous modes competition where the vibration amplitude evolution exhibits various different types of “sawtooth” shapes during stable vibration stages. Meanwhile, the complex nonlinear bifurcation behaviors caused by modes competition were also observed. The evolutionary characteristics of flutter-modes competition are analyzed in detail and relevant mechanisms are discussed. As the wind speed increases, the flutter of the studied bridge mainly undergoes a transition from being dominated by the symmetric mode to being dominated by the antisymmetric mode, accompanied by a continuous modes competition zone in between as a transitional zone. The results show that the continuous modes competition will result in a decrease in the maximum amplitude RMS of the full-span, which is beneficial for the structure. But it may also lead to a transient increase in the maximum amplitude of the full-span due to the coupling vibration shape formed by the two significant flutter-modes, which may be bad for the structure.
Nonlinear flutter has attracted wide attention due to the bottleneck caused by linear flutter theory on flutter-resistant design of super-long-span bridges. The longer the span, the more closely spaced the natural modes, which may cause competition among flutter-modes in a nonlinear flutter, but it is rarely reported so far. To this end, this study experimentally investigates the 3D nonlinear flutter characteristics of a long-span suspension bridge with closely spaced natural modes based on full-bridge aeroelastic model wind tunnel tests. Since there are two unstable flutter-modes within the interested post-critical regime and thus various complex but interesting flutter-modes competition processes were observed, such as continuous modes competition where the vibration amplitude evolution exhibits various different types of “sawtooth” shapes during stable vibration stages. Meanwhile, the complex nonlinear bifurcation behaviors caused by modes competition were also observed. The evolutionary characteristics of flutter-modes competition are analyzed in detail and relevant mechanisms are discussed. As the wind speed increases, the flutter of the studied bridge mainly undergoes a transition from being dominated by the symmetric mode to being dominated by the antisymmetric mode, accompanied by a continuous modes competition zone in between as a transitional zone. The results show that the continuous modes competition will result in a decrease in the maximum amplitude RMS of the full-span, which is beneficial for the structure. But it may also lead to a transient increase in the maximum amplitude of the full-span due to the coupling vibration shape formed by the two significant flutter-modes, which may be bad for the structure.
关键词：
single-column pier curved girder bridge;overturning resistance of bridges;the secondary effects of overturning;vehicle-bridge interaction;reinforcement measures
摘要：
The overturning resistance of curved single-column pier bridges has garnered increasing attention with the rise in infrastructure demands. However, aspects such as the secondary effects of overturning and the dynamic interactions between vehicles and bridges have not been fully explored. Hence, a refined finite element model incorporating Vehicle-Bridge Interaction (VBI) dynamics has been applied to a highway ramp bridge in this study, aiming to elucidate how VBI-induced vibrations contribute to bridge overturning and to develop effective reinforcement strategies for enhanced stability under eccentric loads. The analysis suggests that the rotation of the main girder, influenced by eccentric overload, is a significant factor in the overturning process. The initial overturning stability coefficient was found to be 0.948, pointing to potential areas for improvement. By implementing targeted reinforcement measures, specifically the addition of cover beams, the stability coefficient was improved to 2.626. The study provides insights into VBI-induced overturning in curved single-column pier bridges, offering a reinforcement strategy aimed at enhancing stability under eccentric loads.
摘要：
To study the flexural performance of damaged reinforced concrete beams reinforced with carbon fiber nets (CFNs), seven beams were designed for a flexural test. The physical parameters, such as damage phenomena, characteristic load, deflection variation, concrete strain, reinforcement strain, and CFRP mesh strain, were analyzed using different forms of U-hoops and the preload amplitude as variables. The results show that the magnitude of the preload and the different U-hoop forms affect the ultimate load capacity, crack distribution, and deflection of the beams. Compared with the unreinforced beams, the yield load, ultimate load, and cracking load of the reinforced beams were significantly increased; CFNs reinforcement could significantly improve the flexural load-carrying capacity of the beams. Under the same preload amplitude, the X-shaped diagonal U-hoop has better diagonal crack suppression capability than the vertical U-hoop. Under secondary stress conditions, CFNs reinforcement inhibits the appearance and development of cracks and increases the flexural load capacity, which can effectively alleviate the stiffness degradation caused by the preload. The simulation of the test results using the ANSYS (v2023 R1) 2016 platform produced good agreement, with an error of about 10%, which verifies the feasibility of using the finite element method to simulate the test beam.
摘要：
With the increase of the density of subway line in big cities, it is common for newly built shield tunnels to cross beneath the existing pile foundations at short distances. When the disturbance generated during the construction of the shield tunnels is transmitted to the bearing stratum of the existing pile tip, a punching shear failure may occur in the bearing stratum. To study the evolution process and final form of the punching shear failure of the bearing stratum, a scaled model test based on the Particle Image Velocimetry (PIV) technology is designed. By using PIV technology to analyze deformation images of the bearing stratum, the failure range and shape of the bearing stratum between the pile tip and tunnel induced by excavation are obtained. Using the failure shape of the bearing stratum provided by the model test, a theoretical failure mechanism based on the spatial discretization technique is constructed. The limit analysis theorem is employed here to calculate the theoretical solution of the punching shear failure surface of the bearing stratum. The good agreement of the failure range for the bearing stratum between the model test and theoretical result indicates that the model test presented here is effective.
With the increase of the density of subway line in big cities, it is common for newly built shield tunnels to cross beneath the existing pile foundations at short distances. When the disturbance generated during the construction of the shield tunnels is transmitted to the bearing stratum of the existing pile tip, a punching shear failure may occur in the bearing stratum. To study the evolution process and final form of the punching shear failure of the bearing stratum, a scaled model test based on the Particle Image Velocimetry (PIV) technology is designed. By using PIV technology to analyze deformation images of the bearing stratum, the failure range and shape of the bearing stratum between the pile tip and tunnel induced by excavation are obtained. Using the failure shape of the bearing stratum provided by the model test, a theoretical failure mechanism based on the spatial discretization technique is constructed. The limit analysis theorem is employed here to calculate the theoretical solution of the punching shear failure surface of the bearing stratum. The good agreement of the failure range for the bearing stratum between the model test and theoretical result indicates that the model test presented here is effective.
作者：
Zhang, Liang;Jiang, Hao;Zhang, Sheng;Bei, Zhenghao;Huang, Ning
期刊：
Measurement,2025年253:117561 ISSN：0263-2241
通讯作者：
Jiang, H
作者机构：
[Zhang, Liang; Huang, Ning; Zhang, Sheng] Hunan City Univ, Coll Civil Engn, 518 Yingbin East Rd, Yiyang 413000, Hunan, Peoples R China.;[Bei, Zhenghao; Jiang, Hao] Changsha Univ Sci & Technol, Sch Civil Engn, 960 Wanjiali South RD, Changsha 410114, Hunan, Peoples R China.
通讯机构：
[Jiang, H ] C;Changsha Univ Sci & Technol, Sch Civil Engn, 960 Wanjiali South RD, Changsha 410114, Hunan, Peoples R China.
关键词：
Tunnel lining detection;Cavity filler;Forward simulation;Generalized S -transform;Wavelet packet analysis
摘要：
Tunnel lining cavities and other defects can cause cracks in tunnel structures and damage to concrete, seriously affecting the safety of driving in tunnels. Due to varying geological conditions, the materials filling different cavity areas in tunnels differ. By formulating corresponding repair measures for different fillers in cavity areas, many unnecessary losses can be avoided. Therefore, this paper proposes a method based on multi-parameter information for identifying and extracting the characteristics of different fillers in tunnel cavity areas through forward simulation using gprMax software and field test analysis. Ground penetrating radar (GPR) is used to detect cavities of different shapes filled with various media, focusing on cavity signals while reducing interference from I-beams, and reconstructing radar signals through migration. Statistical parameters are introduced for analysis, and techniques such as Fast Fourier Transform, generalized S-transform, and wavelet packet transform are employed to extract features from the processed radar signals. The characteristics of the filling medium in the cavity area are extracted from three aspects: frequency, time–frequency, and energy. This method can provide a reference for interpreting the GPR data of tunnel lining cavity filling media in actual engineering applications.
Tunnel lining cavities and other defects can cause cracks in tunnel structures and damage to concrete, seriously affecting the safety of driving in tunnels. Due to varying geological conditions, the materials filling different cavity areas in tunnels differ. By formulating corresponding repair measures for different fillers in cavity areas, many unnecessary losses can be avoided. Therefore, this paper proposes a method based on multi-parameter information for identifying and extracting the characteristics of different fillers in tunnel cavity areas through forward simulation using gprMax software and field test analysis. Ground penetrating radar (GPR) is used to detect cavities of different shapes filled with various media, focusing on cavity signals while reducing interference from I-beams, and reconstructing radar signals through migration. Statistical parameters are introduced for analysis, and techniques such as Fast Fourier Transform, generalized S-transform, and wavelet packet transform are employed to extract features from the processed radar signals. The characteristics of the filling medium in the cavity area are extracted from three aspects: frequency, time–frequency, and energy. This method can provide a reference for interpreting the GPR data of tunnel lining cavity filling media in actual engineering applications.
摘要：
A damage assessment method for bridge suspender wires subjected to random variable loads is proposed using a subcycle corrosion fatigue crack growth (CFCG) model. The CFCG analysis is conducted by tracking crack tip opening displacement (CTOD) and crack tip plastic zone size in the time-series loading history. The coupling mechanism between corrosion pit growth and CFCG on a time scale is developed based on the rate competition principle. Following this, a corrosion fatigue life prediction model is established by integrating corrosion fatigue damage size including pit depth and crack length. The accuracy and efficiency of the proposed method are verified by experimental and finite element method (FEM) results. A case study is then conducted on the application of corrosion fatigue life prediction of suspender wires using in-situ monitoring data. The results show that the calculation results of the proposed model are in good agreement with experimental and FEM results, with the maximum life prediction error less than 9%. The proposed model can effectively address the problems of model distortion and low computational efficiency caused by cyclic load sequences reconstruction, and provide theoretical support for the damage assessment of bridge suspenders in service.
A damage assessment method for bridge suspender wires subjected to random variable loads is proposed using a subcycle corrosion fatigue crack growth (CFCG) model. The CFCG analysis is conducted by tracking crack tip opening displacement (CTOD) and crack tip plastic zone size in the time-series loading history. The coupling mechanism between corrosion pit growth and CFCG on a time scale is developed based on the rate competition principle. Following this, a corrosion fatigue life prediction model is established by integrating corrosion fatigue damage size including pit depth and crack length. The accuracy and efficiency of the proposed method are verified by experimental and finite element method (FEM) results. A case study is then conducted on the application of corrosion fatigue life prediction of suspender wires using in-situ monitoring data. The results show that the calculation results of the proposed model are in good agreement with experimental and FEM results, with the maximum life prediction error less than 9%. The proposed model can effectively address the problems of model distortion and low computational efficiency caused by cyclic load sequences reconstruction, and provide theoretical support for the damage assessment of bridge suspenders in service.
关键词：
Pile foundation;Karst cave;Active and passive loading;Model experiment;Numerical simulation
摘要：
This study, part of a preliminary safety evaluation for a real project, investigates the responses of karst-penetrating piles under active and passive loading, compared to non-cave cases. A series of reduced-scale model experiments and numerical simulations were conducted with a 1:35 similarity ratio, considering the effects of cave number and height on dimensionless pile responses. The results revealed that the decrease in axial force within and near the caves is due to the vertical resistance generated by the bulged pile segment, the pile-rock interface, and the cave bottom against the bulged pile segment. The deflection and bending moment profiles of karst-penetrating piles, which are significantly affected by pile head constraints, resemble those in non-cave cases, but with increased magnitudes as cave number and height rise. Additionally, reduced pile-rock contact shortens the effective pile length, preventing the shallow soil layer from providing sufficient lateral resistance. Consequently, deeper soil layers must mobilize their resistance to maintain lateral equilibrium. The effects of caves on pile responses depend on their position relative to the critical pile length of 4/ α . Finally, pile head settlement and deflection exhibit a nearly linear positive relationship with both cave number and height. To simplify future predictions, several fitting formulas are proposed to link pile responses with and without karst caves. These formulas enable convenient prediction of the responses of karst-penetrating piles by scaling non-cave responses, reducing the need for extensive testing across various undetected cave scenarios.
This study, part of a preliminary safety evaluation for a real project, investigates the responses of karst-penetrating piles under active and passive loading, compared to non-cave cases. A series of reduced-scale model experiments and numerical simulations were conducted with a 1:35 similarity ratio, considering the effects of cave number and height on dimensionless pile responses. The results revealed that the decrease in axial force within and near the caves is due to the vertical resistance generated by the bulged pile segment, the pile-rock interface, and the cave bottom against the bulged pile segment. The deflection and bending moment profiles of karst-penetrating piles, which are significantly affected by pile head constraints, resemble those in non-cave cases, but with increased magnitudes as cave number and height rise. Additionally, reduced pile-rock contact shortens the effective pile length, preventing the shallow soil layer from providing sufficient lateral resistance. Consequently, deeper soil layers must mobilize their resistance to maintain lateral equilibrium. The effects of caves on pile responses depend on their position relative to the critical pile length of 4/ α . Finally, pile head settlement and deflection exhibit a nearly linear positive relationship with both cave number and height. To simplify future predictions, several fitting formulas are proposed to link pile responses with and without karst caves. These formulas enable convenient prediction of the responses of karst-penetrating piles by scaling non-cave responses, reducing the need for extensive testing across various undetected cave scenarios.
