This work reviews models and methods for determining the dynamic response of pavements to moving vehicle loads in the framework of continuum-based three dimensional models and linear theories.This review emphasizes th...This work reviews models and methods for determining the dynamic response of pavements to moving vehicle loads in the framework of continuum-based three dimensional models and linear theories.This review emphasizes the most representative models and methods of analysis in the existing literature and illustrates all of them by numerical examples.Thus,13 such examples are presented here in some detail.Both flexible and rigid(concrete)pavement models involving simple and elaborate cases with respect to geometry and material behavior are considered.Thus,homogeneous or layered half-spaces with isotropic or cross-anisotropic and elastic,viscoelastic or poroelastic properties are considered.The vehicles are modeled as simple point or distributed loads or discrete spring-mass-dashpot system moving with constant or variable velocity.The dynamic response of the above pavement-vehicle systems is obtained by analytical/numerical or purely numerical methods of solution.Analytical/numerical methods have mainly to do with Fourier transforms or complex Fourier series with respect to both space and time.Purely numerical methods involve the finite element method(FEM)and the boundary element method(BEM)working in time or frequency domain.Critical discussions on the advantages and disadvantages of the various pavement-vehicle models and their methods of analysis are provided and the effects of the main parameters on the pavement response are determined through parametric studies and presented in the examples.Finally,conclusions are provided and suggestions for future research are made.展开更多
When dealing with the oscillations of fixed-base structures or machines induced by external forces,suppressing the vibrational impact on the adjacent structures and the environment helps to maintain the structural dur...When dealing with the oscillations of fixed-base structures or machines induced by external forces,suppressing the vibrational impact on the adjacent structures and the environment helps to maintain the structural durability and ensure the users′comfort level.This study proposed an inerter-based optimal solution to suppress the vibrational forces and energy transmitted to the supporting ground by utilizing the great potential of the inerter.For the external force,which contains various frequency bands,the stochastic response and an energy balance analysis are conducted to evaluate the force transmissibility,structural displacement,and vibration power flow.Given the benefits of the inerter,a transmitted-force-based optimal design framework is proposed for inerter systems,of which the effectiveness is validated by numerical examples.The obtained results show that inerter systems are capable of providing significant reductions in the structural displacement and the force transmitted to the supporting ground.Particularly,the closed-form power equation indicated that a grounded inerter can suppress the force transmission and vibrational energy,thus leading to a less negative impact on the ground and environment.Revealing the working mechanism and optimal design strategy of the inerter can help solve the force-transmission control problem experienced by some practical structures.展开更多
According to news reports on severe earthquakes since 2008,a total of 51 cases with magnitudes of 6.0 or above were analyzed,and 14 frequently occurring secondary disasters were identified.A disaster chain model was d...According to news reports on severe earthquakes since 2008,a total of 51 cases with magnitudes of 6.0 or above were analyzed,and 14 frequently occurring secondary disasters were identified.A disaster chain model was developed using principles from complex network theory.The vulnerability and risk level of each edge in this model were calculated,and high-risk edges and disaster chains were identified.The analysis reveals that the edge“floods→building collapses”has the highest vulnerability.Implementing measures to mitigate this edge is crucial for delaying the spread of secondary disasters.The highest risk is associated with the edge“building collapses→casualties,”and increased risks are also identified for chains such as“earthquake→building collapses→casualties,”“earthquake→landslides and debris flows→dammed lakes,”and“dammed lakes→floods→building collapses.”Following an earthquake,the prompt implementation of measures is crucial to effectively disrupt these chains and minimize the damage from secondary disasters.展开更多
The finite-depth concrete panels have been widely applied in the protective structures,and its impact resistance and dynamic fracture failures,especially the scabbing/perforation limits,under high velocity projectile ...The finite-depth concrete panels have been widely applied in the protective structures,and its impact resistance and dynamic fracture failures,especially the scabbing/perforation limits,under high velocity projectile impact,are mainly concerned by protective engineers,which are numerically studied based on an improved dynamic concrete model in this study.Firstly,based on the framework of the KCC(Karagozian&Case concrete)model,a dynamic concrete model is proposed which considers an independent tensile damage model and a continued transition between dynamic tensile and compressive properties.Secondly,the strength surface,equation of state and damage parameters of the proposed model are comprehensively calibrated by a triaxial compressive test with high confinement pressure,the rationality of which is further verified based on the single element tests,e.g.,uniaxial and triaxial compression as well as uniaxial,biaxial and triaxial tension.Thirdly,a series of projectile high velocity impact tests on thin and thick concrete panels are simulated,which indicates that the projectile residual velocity and dynamic fracture failures are reproduced satisfactorily,while the KCC model underestimates both the spalling and scabbing dimensions severely.Finally,based on the validated concrete model and finite element analyses approach,the validations of the existing five empirical formulae are evaluated,in terms of the depth of penetration(DOP)and scabbing/perforation limits of concrete panel.Both the Army corps of engineers(ACE)and modified National Defense Research Committee(NDRC)formulae are recommended in the design of the protective structure to avoid scabbing failure.展开更多
Nowadays,the development of novel metallic materials for rock support have attracted research interests since they can significantly improve the deformation and energy absorption capacities of rock bolts.Although prev...Nowadays,the development of novel metallic materials for rock support have attracted research interests since they can significantly improve the deformation and energy absorption capacities of rock bolts.Although previous studies proved the importance and mechanical advantages of utilizing high-strength and high-toughness(HSHT)steels in rock support,there is no systematic analysis to reveal the essential energy absorption parameter and the guidelines for further development of metallic rock support materials.This paper analyzes the energy absorption characteristics of novel HSHT steels(negative Poisson’s ratio(NPR)and twinning-induced plasticity(TWIP)steels)in comparison with conventional rock support materials.A physically based crystal plasticity(CP)model was set up and calibrated to study the effect of strain hardening rate(SHR).Meanwhile,the roles of underlying physical mechanisms,i.e.the dislocation density and twin volume fraction,were studied.The results show that the improvement of energy absorption density(EAD)is essential for further development of rock support materials,besides the increase of energy absorption rate(EAR)for previous development of conventional rock support materials.The increase of EAD requires increases of both strength and deformation capacity of materials.For HSHT steels,the decrease of SHR has a positive effect on the improvement of EAD.In addition,the increase of EAD is followed by the increase of twin volume fraction and the decrease of plastic Poisson’s ratio which can promote deformation plasticity of materials.Meanwhile,the increase of EAR is correlated with the accumulation of dislocation density,which can increase the strength of materials.This paper provides the theoretical basis and guidelines for developing rock support materials in deep underground engineering and other related fields.展开更多
This paper reviews the applications of the multi degree-of-freedom(MDOF)equivalent linear system in seismic analysis and design of planar steel and reinforced concrete framed structures.An equivalent MDOF linear struc...This paper reviews the applications of the multi degree-of-freedom(MDOF)equivalent linear system in seismic analysis and design of planar steel and reinforced concrete framed structures.An equivalent MDOF linear structure,analogous to the original MDOF nonlinear structure,is constructed,which has the same mass and elastic stiffness as the original structure and modal damping ratios that account for the effects of geometrical and material nonlinearities.The equivalence implies a balance between the viscous damping work of the equivalent linear structure and that of the nonlinearities in the original nonlinear structure.This work balance is established with the aid of a transfer function in the frequency domain.Thus,equivalent modal damping ratios can be explicitly determined in terms of the period and deformation levels of the structure as well as the soil types.Use of these equivalent modal damping ratios can help address a variety of seismic analysis and design problems associated with planar steel and reinforced concrete framed structures in a rational and accurate manner.These include force-based seismic design with the aid of acceleration response spectra characterized by high amounts of damping,improved direct displacement-based seismic design and the development of advanced seismic intensity measures.The equivalent modal damping ratios are also utilized in the context of linear modal analysis for the definition and construction of the MDOF response spectrum.Furthermore,the equivalent modal damping ratios are employed in a seismic retrofit method for steel-framed structures with viscous dampers.Finally,it is demonstrated that modal behavior(or strength reduction)factors can be easily constructed based on these modal damping ratios for a more rational and accurate force-based seismic design,including the determination of inelastic displacement profiles.展开更多
This paper reviews works on the dynamic analysis of flexible and rigid pavements under moving vehicles on the basis of continuum-based plane strain models and linear theories.The purpose of this review is to provide i...This paper reviews works on the dynamic analysis of flexible and rigid pavements under moving vehicles on the basis of continuum-based plane strain models and linear theories.The purpose of this review is to provide in-formation about the existing works on the subject,critically discuss them and make suggestions for further research.The reviewed papers are presented on the basis of the various models for pavement-vehicle systems and the various methods for dynamically analyzing these systems.Flexible pavements are modeled by a homogeneous or layered half-plane with isotropic or anisotropic and linear elastic,viscoelastic or poroelastic material behavior.Rigid pavements are modeled by a beam or plate on a homogeneous or layered half-plane with material properties like the ones for flexible pavements.The vehicles are modeled as concentrated or distributed over a finite area loads moving with constant or time dependent speed.The above pavement-vehicle models are dynamically analyzed by analytical,analytical/numerical or purely numerical methods working in the time or frequency domain.Representative examples are presented to illustrate the models and methods of analysis,demonstrate their merits and assess the effects of the various parameters on pavement response.The paper closes with con-clusions and suggestions for further research in the area.The significance of this research effort has to do with the presentation of the existing literature on the subject in a critical and easy to understand way with the aid of representative examples and the identification of new research areas.展开更多
In order to explore a kind of high-strength,earthquake-resistant,eco-nomical and suitable connection,4 groups of cross-laminated timber wall-to-floor and wall-to-wall bolted connections were tested under monotonic and...In order to explore a kind of high-strength,earthquake-resistant,eco-nomical and suitable connection,4 groups of cross-laminated timber wall-to-floor and wall-to-wall bolted connections were tested under monotonic and cyclic load-ing.The defommation characteristics and failure modes of the cross-laminated tim-ber wall-to-floor and wall-to-wall bolted connections were exploited.Load-slip curves,bearing capacity,yielding point,stiffness and ductility of each group of specimens were analyzed.The test results indicate that the loading process of cross-laminated timber bolted connections under tension can be categorized as five stages,namely the elastic stage,the slip stage,the embedding stage,the yield-ing stage and the ultimate stage.The ultimate tensile capacity of cross-laminated timber bolted wall-to-floor connections is 2.67 times that of the wall-to-wall bolted connections.Compared with cross-laminated timber self-tapping screwed connections,the ultimate tensile capacity of the cross-laminated timber wall-to-floor bolted connections is 2.70 times that of the self-tapping screwed connec-tions,and the ultimate tensile capacity of the cross-laminated timber wall-to-wall bolted connections is 3.83 times that of the self-tapping screwed connections.The crosslaminated timber bolted connections have larger yielding displacement and wider plastic range,and they are more energy dissipative and more ductile.Furthermore,the cost of the cross-laminated timber wall-to-floor bolted connec-tions is 46%that of the self-tapping screwed connections,while the cost of cross-laminated wall-to-wall bolted connections is 53%that of the self-screwed connections.展开更多
A 9 m high,near full scale three-storey configurable steel frame compositefloor building incorporating frictionbased connections is to be tested using two linked bi-directional shake tables at the International joint re...A 9 m high,near full scale three-storey configurable steel frame compositefloor building incorporating frictionbased connections is to be tested using two linked bi-directional shake tables at the International joint research Laboratory of Earthquake Engineering(ILEE)facilities,Shanghai,China,as part of the RObust BUilding SysTem(ROBUST)project.A total of nine structural configurations are designed and detailed.To have a better understanding of the expected system behaviour,as well as effects of other structural and non-structural elements(NSEs)on the overall system response,experimental testing at component level has been conducted prior to the shake table testing.This paper presents an introduction to the ROBUST project,followed by a numerical study on one of the nine configurations of the structure,having Moment Resisting Steel Frame(MRSF)in the longitudinal direction and Concentrically Braced Frame(CBF)in the transverse direction.Hysteretic properties employed in the numerical models are validated against component test results.The predictions of the building’s seismic response under selected base excitations are presented indicating the likely low damage performance of the structure.展开更多
Following a magnitude M 7.9 earthquake that struck near Mandalay,Myanmar in March 2025,this study investigates the seismic damage inflicted upon the city’s municipal water supply system.The analysis focuses on the fa...Following a magnitude M 7.9 earthquake that struck near Mandalay,Myanmar in March 2025,this study investigates the seismic damage inflicted upon the city’s municipal water supply system.The analysis focuses on the failure characteristics of water facilities and pipelines,examines cross-system cascading effects,and proposes corresponding recovery strategies.The main findings are as follows:(1)The damage to water plant facilities,concentrated in ancillary structures and connections due to insufficient seismic measures,demonstrated significant intensity-dependence.Increased seismic intensity not only aggravated structural damage but also compromised core treatment processes,leading to deteriorated water quality.(2)Within the same seismic intensity zone,high-density polyethylene(HDPE)pipes exhibited a significantly lower damage occurrence rate than ductile iron(DI)pipes,highlighting the material’s substantial influence on seismic performance.Moreover,a strong positive correlation was observed between the overall pipeline network damage and the seismic intensity.The average damage rate in IntensityⅨzones was 6.84 times that of IntensityⅧzones.(3)A cascading failure,initiated by a power outage,led to water supply disruption,loss of emergency response capability,and elevated secondary risks.This strongly coupled cross-system effect resulted in significant spatiotemporal propagation of disaster impacts.(4)The post-earthquake recovery adopted a phased strategy that prioritized critical facilities.Actions involved rapidly restoring the core supply zone with temporary points,reinstating the water plant’s power supply,and deploying targeted technologies for efficient pipeline repair.The outcomes of this study are expected to provide critical support and a valuable reference for developing earthquake-resilient urban water supply systems.展开更多
In recent years,extensive research has focused on applying machine learning(ML)techniques to predict the properties of engineered cementitious composites(ECCs).ECCs exhibit crucial characteristics such as compressive ...In recent years,extensive research has focused on applying machine learning(ML)techniques to predict the properties of engineered cementitious composites(ECCs).ECCs exhibit crucial characteristics such as compressive strength(CS),tensile strength(TS),and tensile strain(TSt).Accurate forecasting of these critical properties can reduce material waste,lower construction expenses,and expedite project timelines for engineers and designers.This study investigates mixture design components and corresponding strengths of ECCs based on only polyethylene fiber drawing from existing literatures.Artificial neural network(ANN)models are developed to predict CS,TS,and TSt using a dataset of 339 experimental results with twelve input variables.The ANN models,implemented in MATLAB,consider various hidden layers and neurons to optimize accuracy and validation metrics demonstrate the model’s high accuracy.Sensitivity analysis explores individual parameter impacts.Drawing inspiration from this study,it would be advantageous to enhance the predictive modeling toolkit by leveraging the progress made in existing technologies,thereby driving the green and low-carbon development of civil engineering.This approach not only improves the efficiency and sustainability of construction practices but also aligns with global environmental goals by reducing the carbon footprint associated with civil engineering projects.展开更多
To realize seismic-resilient reinforced concrete(RC)moment-resisting frame structures,a novel selfcentering RC column with a rubber layer placed at the bottom(SRRC column)is proposed herein.For the column,the longitud...To realize seismic-resilient reinforced concrete(RC)moment-resisting frame structures,a novel selfcentering RC column with a rubber layer placed at the bottom(SRRC column)is proposed herein.For the column,the longitudinal reinforcement dissipates seismic energy,the rubber layer allows the rocking of the column,and the unbonded prestressed tendon enables self-centering capacity.A refined finite element model of the SRRC column is developed,the effectiveness of which is validated based on experimental results.Results show that the SRRC column exhibits stable energy dissipation capacity and no strength degradation;additionally,it can significantly reduce permanent residual deformation and mitigate damage to concrete.Extensive parametric studies pertaining to SRRC columns have been conducted to investigate the critical factors affecting their seismic performance.展开更多
This study integrates previous experimental data and employs machine learning(ML)methods,including Random Forest(RF),Support Vector Machine(SVM),Artificial Neural Network(ANN),and eXtreme Gradient Boosting(XGBoost),to...This study integrates previous experimental data and employs machine learning(ML)methods,including Random Forest(RF),Support Vector Machine(SVM),Artificial Neural Network(ANN),and eXtreme Gradient Boosting(XGBoost),to predict the compressive strength(CS)and tensile strength(TS)of engineered cementitious composites(ECC).XGBoost emerged as the superior model among the four ML models,providing an interpretable and highly accurate predictive framework.To optimize the model performance,hyperparameter tuning using a fivefold cross-validation approach with the data divided into 80%training and 20%testing subsets.The Shapley Additive Explanations(SHAP)algorithm was also employed to reveal the impact of important features,such as the water/binder ratio,fly ash content,and water reducer dosage,on the model’s predictions and their interrelationships.The XGBoost demonstrates the most exemplary performance,as reflected in the R^(2)values of 0.92 and 0.97 for CS and TS testing,respectively.The SHAP analysis provided insights into the impact of individual features on CS and TS,shedding light on how specific characteristics influence the predictive accuracy of these properties.This highly accurate prediction model uncovers insights into correlated features,aids in creating new mix designs of ECC,and supports global efforts toward a low-carbon future in the construction industry by reducing carbon emissions.展开更多
An approach to control the profiles of interstory drift ratios along the height of building structures via topology optimization is proposed herein.The theoretical foundation of the proposed approach involves solving ...An approach to control the profiles of interstory drift ratios along the height of building structures via topology optimization is proposed herein.The theoretical foundation of the proposed approach involves solving a min-max optimization problem to suppress the maximum interstory drift ratio among all stories.Two formulations are suggested:one inherits the bound formulation and the other utilizes a p-norm function to aggregate all individual interstory drift ratios.The proposed methodology can shape the interstory drift ratio profiles into inverted triangular or quadratic patterns because it realizes profile control using a group of shape weight coefficients.The proposed formulations are validated via a series of numerical examples.The disparity between the two formulations is clear.The optimization results show the optimal structural features for controlling the interstory drift ratios under different requirements.展开更多
文摘This work reviews models and methods for determining the dynamic response of pavements to moving vehicle loads in the framework of continuum-based three dimensional models and linear theories.This review emphasizes the most representative models and methods of analysis in the existing literature and illustrates all of them by numerical examples.Thus,13 such examples are presented here in some detail.Both flexible and rigid(concrete)pavement models involving simple and elaborate cases with respect to geometry and material behavior are considered.Thus,homogeneous or layered half-spaces with isotropic or cross-anisotropic and elastic,viscoelastic or poroelastic properties are considered.The vehicles are modeled as simple point or distributed loads or discrete spring-mass-dashpot system moving with constant or variable velocity.The dynamic response of the above pavement-vehicle systems is obtained by analytical/numerical or purely numerical methods of solution.Analytical/numerical methods have mainly to do with Fourier transforms or complex Fourier series with respect to both space and time.Purely numerical methods involve the finite element method(FEM)and the boundary element method(BEM)working in time or frequency domain.Critical discussions on the advantages and disadvantages of the various pavement-vehicle models and their methods of analysis are provided and the effects of the main parameters on the pavement response are determined through parametric studies and presented in the examples.Finally,conclusions are provided and suggestions for future research are made.
基金Scientific Research Fund of Institute of Engineering Mechanics,China Earthquake Administration under Grant Nos.2019EEVL03,2019D14 and 2020EEEVL0401National Natural Science Foundation of China under Grant No.51978525National Key R&D Program of China 2021YFE0112200。
文摘When dealing with the oscillations of fixed-base structures or machines induced by external forces,suppressing the vibrational impact on the adjacent structures and the environment helps to maintain the structural durability and ensure the users′comfort level.This study proposed an inerter-based optimal solution to suppress the vibrational forces and energy transmitted to the supporting ground by utilizing the great potential of the inerter.For the external force,which contains various frequency bands,the stochastic response and an energy balance analysis are conducted to evaluate the force transmissibility,structural displacement,and vibration power flow.Given the benefits of the inerter,a transmitted-force-based optimal design framework is proposed for inerter systems,of which the effectiveness is validated by numerical examples.The obtained results show that inerter systems are capable of providing significant reductions in the structural displacement and the force transmitted to the supporting ground.Particularly,the closed-form power equation indicated that a grounded inerter can suppress the force transmission and vibrational energy,thus leading to a less negative impact on the ground and environment.Revealing the working mechanism and optimal design strategy of the inerter can help solve the force-transmission control problem experienced by some practical structures.
基金National Key Research and Development Program of China(No.2022YFC3803000).
文摘According to news reports on severe earthquakes since 2008,a total of 51 cases with magnitudes of 6.0 or above were analyzed,and 14 frequently occurring secondary disasters were identified.A disaster chain model was developed using principles from complex network theory.The vulnerability and risk level of each edge in this model were calculated,and high-risk edges and disaster chains were identified.The analysis reveals that the edge“floods→building collapses”has the highest vulnerability.Implementing measures to mitigate this edge is crucial for delaying the spread of secondary disasters.The highest risk is associated with the edge“building collapses→casualties,”and increased risks are also identified for chains such as“earthquake→building collapses→casualties,”“earthquake→landslides and debris flows→dammed lakes,”and“dammed lakes→floods→building collapses.”Following an earthquake,the prompt implementation of measures is crucial to effectively disrupt these chains and minimize the damage from secondary disasters.
基金supported by the National Natural Science Foundation of China(Grant No.52208500)。
文摘The finite-depth concrete panels have been widely applied in the protective structures,and its impact resistance and dynamic fracture failures,especially the scabbing/perforation limits,under high velocity projectile impact,are mainly concerned by protective engineers,which are numerically studied based on an improved dynamic concrete model in this study.Firstly,based on the framework of the KCC(Karagozian&Case concrete)model,a dynamic concrete model is proposed which considers an independent tensile damage model and a continued transition between dynamic tensile and compressive properties.Secondly,the strength surface,equation of state and damage parameters of the proposed model are comprehensively calibrated by a triaxial compressive test with high confinement pressure,the rationality of which is further verified based on the single element tests,e.g.,uniaxial and triaxial compression as well as uniaxial,biaxial and triaxial tension.Thirdly,a series of projectile high velocity impact tests on thin and thick concrete panels are simulated,which indicates that the projectile residual velocity and dynamic fracture failures are reproduced satisfactorily,while the KCC model underestimates both the spalling and scabbing dimensions severely.Finally,based on the validated concrete model and finite element analyses approach,the validations of the existing five empirical formulae are evaluated,in terms of the depth of penetration(DOP)and scabbing/perforation limits of concrete panel.Both the Army corps of engineers(ACE)and modified National Defense Research Committee(NDRC)formulae are recommended in the design of the protective structure to avoid scabbing failure.
基金supported by the National Natural Science Foundation of China(Grant Nos.52204115 and 41941018)the Foundation of Research Institute for Deep Underground Science and Engineering(Grant No.XD2021022).
文摘Nowadays,the development of novel metallic materials for rock support have attracted research interests since they can significantly improve the deformation and energy absorption capacities of rock bolts.Although previous studies proved the importance and mechanical advantages of utilizing high-strength and high-toughness(HSHT)steels in rock support,there is no systematic analysis to reveal the essential energy absorption parameter and the guidelines for further development of metallic rock support materials.This paper analyzes the energy absorption characteristics of novel HSHT steels(negative Poisson’s ratio(NPR)and twinning-induced plasticity(TWIP)steels)in comparison with conventional rock support materials.A physically based crystal plasticity(CP)model was set up and calibrated to study the effect of strain hardening rate(SHR).Meanwhile,the roles of underlying physical mechanisms,i.e.the dislocation density and twin volume fraction,were studied.The results show that the improvement of energy absorption density(EAD)is essential for further development of rock support materials,besides the increase of energy absorption rate(EAR)for previous development of conventional rock support materials.The increase of EAD requires increases of both strength and deformation capacity of materials.For HSHT steels,the decrease of SHR has a positive effect on the improvement of EAD.In addition,the increase of EAD is followed by the increase of twin volume fraction and the decrease of plastic Poisson’s ratio which can promote deformation plasticity of materials.Meanwhile,the increase of EAR is correlated with the accumulation of dislocation density,which can increase the strength of materials.This paper provides the theoretical basis and guidelines for developing rock support materials in deep underground engineering and other related fields.
文摘This paper reviews the applications of the multi degree-of-freedom(MDOF)equivalent linear system in seismic analysis and design of planar steel and reinforced concrete framed structures.An equivalent MDOF linear structure,analogous to the original MDOF nonlinear structure,is constructed,which has the same mass and elastic stiffness as the original structure and modal damping ratios that account for the effects of geometrical and material nonlinearities.The equivalence implies a balance between the viscous damping work of the equivalent linear structure and that of the nonlinearities in the original nonlinear structure.This work balance is established with the aid of a transfer function in the frequency domain.Thus,equivalent modal damping ratios can be explicitly determined in terms of the period and deformation levels of the structure as well as the soil types.Use of these equivalent modal damping ratios can help address a variety of seismic analysis and design problems associated with planar steel and reinforced concrete framed structures in a rational and accurate manner.These include force-based seismic design with the aid of acceleration response spectra characterized by high amounts of damping,improved direct displacement-based seismic design and the development of advanced seismic intensity measures.The equivalent modal damping ratios are also utilized in the context of linear modal analysis for the definition and construction of the MDOF response spectrum.Furthermore,the equivalent modal damping ratios are employed in a seismic retrofit method for steel-framed structures with viscous dampers.Finally,it is demonstrated that modal behavior(or strength reduction)factors can be easily constructed based on these modal damping ratios for a more rational and accurate force-based seismic design,including the determination of inelastic displacement profiles.
文摘This paper reviews works on the dynamic analysis of flexible and rigid pavements under moving vehicles on the basis of continuum-based plane strain models and linear theories.The purpose of this review is to provide in-formation about the existing works on the subject,critically discuss them and make suggestions for further research.The reviewed papers are presented on the basis of the various models for pavement-vehicle systems and the various methods for dynamically analyzing these systems.Flexible pavements are modeled by a homogeneous or layered half-plane with isotropic or anisotropic and linear elastic,viscoelastic or poroelastic material behavior.Rigid pavements are modeled by a beam or plate on a homogeneous or layered half-plane with material properties like the ones for flexible pavements.The vehicles are modeled as concentrated or distributed over a finite area loads moving with constant or time dependent speed.The above pavement-vehicle models are dynamically analyzed by analytical,analytical/numerical or purely numerical methods working in the time or frequency domain.Representative examples are presented to illustrate the models and methods of analysis,demonstrate their merits and assess the effects of the various parameters on pavement response.The paper closes with con-clusions and suggestions for further research in the area.The significance of this research effort has to do with the presentation of the existing literature on the subject in a critical and easy to understand way with the aid of representative examples and the identification of new research areas.
基金This study is funded by the Fundamental Research Funds for the Central Universities(Program No.22120180315).
文摘In order to explore a kind of high-strength,earthquake-resistant,eco-nomical and suitable connection,4 groups of cross-laminated timber wall-to-floor and wall-to-wall bolted connections were tested under monotonic and cyclic load-ing.The defommation characteristics and failure modes of the cross-laminated tim-ber wall-to-floor and wall-to-wall bolted connections were exploited.Load-slip curves,bearing capacity,yielding point,stiffness and ductility of each group of specimens were analyzed.The test results indicate that the loading process of cross-laminated timber bolted connections under tension can be categorized as five stages,namely the elastic stage,the slip stage,the embedding stage,the yield-ing stage and the ultimate stage.The ultimate tensile capacity of cross-laminated timber bolted wall-to-floor connections is 2.67 times that of the wall-to-wall bolted connections.Compared with cross-laminated timber self-tapping screwed connections,the ultimate tensile capacity of the cross-laminated timber wall-to-floor bolted connections is 2.70 times that of the self-tapping screwed connec-tions,and the ultimate tensile capacity of the cross-laminated timber wall-to-wall bolted connections is 3.83 times that of the self-tapping screwed connections.The crosslaminated timber bolted connections have larger yielding displacement and wider plastic range,and they are more energy dissipative and more ductile.Furthermore,the cost of the cross-laminated timber wall-to-floor bolted connec-tions is 46%that of the self-tapping screwed connections,while the cost of cross-laminated wall-to-wall bolted connections is 53%that of the self-screwed connections.
基金support from New Zealand Ministry of Business,Innovation and Employment(MBIE)through an Endeavour Fund for the Research Programme(Sustainable Earthquake Resilient Buildings for a Better Future-PROP-83779-ENDRP-AUT)is greatly appreciated.
文摘A 9 m high,near full scale three-storey configurable steel frame compositefloor building incorporating frictionbased connections is to be tested using two linked bi-directional shake tables at the International joint research Laboratory of Earthquake Engineering(ILEE)facilities,Shanghai,China,as part of the RObust BUilding SysTem(ROBUST)project.A total of nine structural configurations are designed and detailed.To have a better understanding of the expected system behaviour,as well as effects of other structural and non-structural elements(NSEs)on the overall system response,experimental testing at component level has been conducted prior to the shake table testing.This paper presents an introduction to the ROBUST project,followed by a numerical study on one of the nine configurations of the structure,having Moment Resisting Steel Frame(MRSF)in the longitudinal direction and Concentrically Braced Frame(CBF)in the transverse direction.Hysteretic properties employed in the numerical models are validated against component test results.The predictions of the building’s seismic response under selected base excitations are presented indicating the likely low damage performance of the structure.
基金National Key Research and Development Program of China under Grant No.2023YFC3805201Scientific Research Fund of Institute of Engineering Mechanics,China Earthquake Administration under Grant Nos.2024B29 and 2024B25。
文摘Following a magnitude M 7.9 earthquake that struck near Mandalay,Myanmar in March 2025,this study investigates the seismic damage inflicted upon the city’s municipal water supply system.The analysis focuses on the failure characteristics of water facilities and pipelines,examines cross-system cascading effects,and proposes corresponding recovery strategies.The main findings are as follows:(1)The damage to water plant facilities,concentrated in ancillary structures and connections due to insufficient seismic measures,demonstrated significant intensity-dependence.Increased seismic intensity not only aggravated structural damage but also compromised core treatment processes,leading to deteriorated water quality.(2)Within the same seismic intensity zone,high-density polyethylene(HDPE)pipes exhibited a significantly lower damage occurrence rate than ductile iron(DI)pipes,highlighting the material’s substantial influence on seismic performance.Moreover,a strong positive correlation was observed between the overall pipeline network damage and the seismic intensity.The average damage rate in IntensityⅨzones was 6.84 times that of IntensityⅧzones.(3)A cascading failure,initiated by a power outage,led to water supply disruption,loss of emergency response capability,and elevated secondary risks.This strongly coupled cross-system effect resulted in significant spatiotemporal propagation of disaster impacts.(4)The post-earthquake recovery adopted a phased strategy that prioritized critical facilities.Actions involved rapidly restoring the core supply zone with temporary points,reinstating the water plant’s power supply,and deploying targeted technologies for efficient pipeline repair.The outcomes of this study are expected to provide critical support and a valuable reference for developing earthquake-resilient urban water supply systems.
文摘In recent years,extensive research has focused on applying machine learning(ML)techniques to predict the properties of engineered cementitious composites(ECCs).ECCs exhibit crucial characteristics such as compressive strength(CS),tensile strength(TS),and tensile strain(TSt).Accurate forecasting of these critical properties can reduce material waste,lower construction expenses,and expedite project timelines for engineers and designers.This study investigates mixture design components and corresponding strengths of ECCs based on only polyethylene fiber drawing from existing literatures.Artificial neural network(ANN)models are developed to predict CS,TS,and TSt using a dataset of 339 experimental results with twelve input variables.The ANN models,implemented in MATLAB,consider various hidden layers and neurons to optimize accuracy and validation metrics demonstrate the model’s high accuracy.Sensitivity analysis explores individual parameter impacts.Drawing inspiration from this study,it would be advantageous to enhance the predictive modeling toolkit by leveraging the progress made in existing technologies,thereby driving the green and low-carbon development of civil engineering.This approach not only improves the efficiency and sustainability of construction practices but also aligns with global environmental goals by reducing the carbon footprint associated with civil engineering projects.
基金the National Key R&D Program of China(No.2022YFC3803003)the Fundamental Research Funds for the Central Universities.
文摘To realize seismic-resilient reinforced concrete(RC)moment-resisting frame structures,a novel selfcentering RC column with a rubber layer placed at the bottom(SRRC column)is proposed herein.For the column,the longitudinal reinforcement dissipates seismic energy,the rubber layer allows the rocking of the column,and the unbonded prestressed tendon enables self-centering capacity.A refined finite element model of the SRRC column is developed,the effectiveness of which is validated based on experimental results.Results show that the SRRC column exhibits stable energy dissipation capacity and no strength degradation;additionally,it can significantly reduce permanent residual deformation and mitigate damage to concrete.Extensive parametric studies pertaining to SRRC columns have been conducted to investigate the critical factors affecting their seismic performance.
文摘This study integrates previous experimental data and employs machine learning(ML)methods,including Random Forest(RF),Support Vector Machine(SVM),Artificial Neural Network(ANN),and eXtreme Gradient Boosting(XGBoost),to predict the compressive strength(CS)and tensile strength(TS)of engineered cementitious composites(ECC).XGBoost emerged as the superior model among the four ML models,providing an interpretable and highly accurate predictive framework.To optimize the model performance,hyperparameter tuning using a fivefold cross-validation approach with the data divided into 80%training and 20%testing subsets.The Shapley Additive Explanations(SHAP)algorithm was also employed to reveal the impact of important features,such as the water/binder ratio,fly ash content,and water reducer dosage,on the model’s predictions and their interrelationships.The XGBoost demonstrates the most exemplary performance,as reflected in the R^(2)values of 0.92 and 0.97 for CS and TS testing,respectively.The SHAP analysis provided insights into the impact of individual features on CS and TS,shedding light on how specific characteristics influence the predictive accuracy of these properties.This highly accurate prediction model uncovers insights into correlated features,aids in creating new mix designs of ECC,and supports global efforts toward a low-carbon future in the construction industry by reducing carbon emissions.
基金supported by the National Natural Science Foundation of China(Grant No.51638012)。
文摘An approach to control the profiles of interstory drift ratios along the height of building structures via topology optimization is proposed herein.The theoretical foundation of the proposed approach involves solving a min-max optimization problem to suppress the maximum interstory drift ratio among all stories.Two formulations are suggested:one inherits the bound formulation and the other utilizes a p-norm function to aggregate all individual interstory drift ratios.The proposed methodology can shape the interstory drift ratio profiles into inverted triangular or quadratic patterns because it realizes profile control using a group of shape weight coefficients.The proposed formulations are validated via a series of numerical examples.The disparity between the two formulations is clear.The optimization results show the optimal structural features for controlling the interstory drift ratios under different requirements.
