Precast segmental column bridges exhibit various construction advantages in comparison to traditional monolithic column bridges.However,the lack of cognitions on seismic behaviors has seriously restricted their applic...Precast segmental column bridges exhibit various construction advantages in comparison to traditional monolithic column bridges.However,the lack of cognitions on seismic behaviors has seriously restricted their applications and developments.In this paper,comprehensive investigations are conducted to analyze the dynamic characteristics of precast segmental column bridges under near-fault,forward-directivity ground motions.First,the finite-element models of two comparable bridges with precast segmental columns and monolithic columns are constructed by using OpenSees software,and the nonlinearities of the bridges are considered.Next,three different earthquake loadings are meticulously set up to handle engineering problems,namely recorded near-and far-field ground motions,parameterized pulses,and pulse and residual components extracted from real records.Finally,based on the models and earthquake sets,extensive explorations are carried out.The results show that near-fault forward-directivity ground motions are more threatening than far-field ones;precast segmental column bridges may suffer more pounding impacts than monolithic bridges;the“narrow band”effect caused by near-fault,forward-directivity ground motions may occur in bridges with shorter periods than pulse periods;and pulse and residual components play different roles in seismic responses.展开更多
The comparative research on the seismic performance of grouted sleeve connected pier(GS)and prestressed precast segmental concrete pier(PC)is mostly carried out by numerical simulation.In this study,the GS pier and th...The comparative research on the seismic performance of grouted sleeve connected pier(GS)and prestressed precast segmental concrete pier(PC)is mostly carried out by numerical simulation.In this study,the GS pier and the PC pier of the new railway project from Hetian to Ruoqiang are taken into consideration.Two kinds of 1/5-scale assembled double-column specimens are made,and the quasi-static tests are carried out.The overall seismic performance of the two spliced piers is studied,and compared in terms of failure mechanism,bearing capacity,ductility,stiffness and energy dissipation capacity.The results show that the failure modes of both GS pier and PC pier are characterized by bending.However,the specific failure location and form are different.The GS pier presents a complete hysteretic curve,large equivalent stiffness and strong energy dissipation capacity.The hysteretic area of the PC pier is small.However,it has good self-reset ability and quasi-static residual displacement.Finite element models are set up using DispBeamColumn fiber elements and ZeroLength elements.The models that are calibrated with the test data can effectively simulate the damage development under monotonic loading.The load−displacement curves are in good agreement with the backbone curves of the test results.展开更多
Considering the desirable behavior of concrete filled steel tube(CFT)columns and the complicated behavior of segmental double-column piers under cyclic loads,three post-tensioned precast segmental CFT double-column pi...Considering the desirable behavior of concrete filled steel tube(CFT)columns and the complicated behavior of segmental double-column piers under cyclic loads,three post-tensioned precast segmental CFT double-column pier specimens were tested to extend their application in moderate and high seismicity areas.The effects of the number of CFT segments and the steel endplates as energy dissipaters on the seismic behavior of the piers were evaluated.The experimental results show that the segmental piers exhibited stable hysteretic behavior with small residual displacements under cyclic loads.All the tested specimens achieved a drift ratio no less than 13%without significant damage and strength deterioration due to the desirable behavior of CFT columns.Since the deformation of segmental columns was mainly concentrated at the column-footing interfaces,the increase of the segment numbers for each column had no obvious effects on the loading capacity but reduced the initial stiffness of the specimens.The use of steel endplates improved the bearing capacity,stiffness and energy dissipation of segmental piers,but weakened their self-centering capacity.Fiber models were also proposed to simulate the hysteretic behavior of the tested specimens,and the influences of segment numbers and prestress levels on seismic behavior were further studied.展开更多
In recent years, precast segmental concrete bridge columns became prevalent because of the benefits of accelerated construction, low environmental impact, high quality and low life cycle costs. The lack of a detailed ...In recent years, precast segmental concrete bridge columns became prevalent because of the benefits of accelerated construction, low environmental impact, high quality and low life cycle costs. The lack of a detailed configuration and appropriate design procedure to ensure a comparable performance with monolithic construction has impeded this structural system from being widely used in areas of high seismicity. In this study, precast segmental bridge column cyclic loading tests were conducted to investigate the performance of unbonded post-tensioned segmental bridge columns. One monolithic and two precast segmental columns were tested. The preeast segmental column exhibited minor damage and small residual displacement after the maximum 7% cyclic drift; energy dissipation （ED） can be enhanced byadding ED bars. The experimental results were modeled by a simplified pushover method （SPOM）, as well as a fiber model （FIBM） finite element method. Forty-five cases of columns with different aspect ratios, axial load ratios and ED bar ratios were analyzed with the SPOM and FIBM, respectively. Using these parametric results, a simplified design method was suggested by regressive analysis. Satisfactory correlation was found between the experimental results and the simplified design method for preeast segmental columns with different design parameters.展开更多
The precast segmental column(PSC)plays a vital role in both the design of new bridges and the rehabilitation of existing ones.Previous studies of PSCs have primarily focused on their individual seismic behavior.Howeve...The precast segmental column(PSC)plays a vital role in both the design of new bridges and the rehabilitation of existing ones.Previous studies of PSCs have primarily focused on their individual seismic behavior.However,research on the seismic performance of entire bridges supported by PSCs,particularly those incorporating soil-structure interaction(SSI),remains limited.Moreover,the amplification of earthquake waves as they propagate along the pile foundation to the surface,coupled with the coherency loss between earthquake motions at varying supports,may further impact the seismic responses of such bridges.This study systematically assesses the seismic performance of a PSC bridge(PSCB)supported by pile foundations considering the effects of SSI and depth-varying multi-support ground motions.Moreover,a benchmark bridge with the traditional monolithic column is also analyzed for comparison.The seismic fragility of bridges is calculated based on nonlinear time history analyses and joint probability density functions for both peak and residual responses.Parameter studies are conducted to reveal the influences of sSI,non-uniform excitation,and depth-varying earthquake loads on seismic performance assessments.This paper offers valuable insights for the reliable analysis of seismic response and fragility and the safety design of PSCB systems.展开更多
Considering the wide application of precast segmental bridge columns(PSBCs)in engineering practice,impact-resistant performance has gained significant attention.However,few studies have focused on PSBCs subjected to h...Considering the wide application of precast segmental bridge columns(PSBCs)in engineering practice,impact-resistant performance has gained significant attention.However,few studies have focused on PSBCs subjected to high-energy impacts caused by heavy truck collisions.Therefore,the behavior of PSBCs under a heavy truck impact was investigated in this study using high-fidelity finite element(FE)models.The detailed FE modeling methods of the PSBCs and heavy trucks were validated against experimental tests.The validated modeling methods were employed to simulate collisions between PSBCs and heavy trucks.The simulation results demonstrated that the engine and cargo caused two major peak impact forces during collision.Subsequently,the impact force,failure mode,displacement,and internal force of the PSBCs under heavy truck impacts were scrutinized.An extensive study was performed to assess the influence of the section size,truck weight,impact velocity,and number of precast segments on the impact responses.The truck weight was found to have a minor effect on the engine impact force.Damage was found to be localized at the bottom of the three segments,with the top remaining primarily undamaged.This parametric study demonstrated that larger cross-sections may be a preferred option to protect PSBCs against the impact of heavy trucks.展开更多
The development of each work is inseparable from the management, the quality of the work and the management level is closely related, especially in some production operations, the safety management work occupies an im...The development of each work is inseparable from the management, the quality of the work and the management level is closely related, especially in some production operations, the safety management work occupies an important position, is an important measure to ensure safe production. In recent years, the TBM tunnel has been more and more widely used, and the related production of precast concrete pipe segments has also gradually developed towards standardization and standardization.Combined on the author's work experience of the author, this paper analyzes the production safety management of precast concrete segments and explores the details of safety management from all angles.展开更多
基金National Natural Science Foundation of China under Grant Nos.U1434205 and 51678490the Major Research Plan of China National Railway Ministry of China under Grant Nos.2015G002-B and P2018G007the National Key R&D Program of China under Grant No.2017YFC1500803。
文摘Precast segmental column bridges exhibit various construction advantages in comparison to traditional monolithic column bridges.However,the lack of cognitions on seismic behaviors has seriously restricted their applications and developments.In this paper,comprehensive investigations are conducted to analyze the dynamic characteristics of precast segmental column bridges under near-fault,forward-directivity ground motions.First,the finite-element models of two comparable bridges with precast segmental columns and monolithic columns are constructed by using OpenSees software,and the nonlinearities of the bridges are considered.Next,three different earthquake loadings are meticulously set up to handle engineering problems,namely recorded near-and far-field ground motions,parameterized pulses,and pulse and residual components extracted from real records.Finally,based on the models and earthquake sets,extensive explorations are carried out.The results show that near-fault forward-directivity ground motions are more threatening than far-field ones;precast segmental column bridges may suffer more pounding impacts than monolithic bridges;the“narrow band”effect caused by near-fault,forward-directivity ground motions may occur in bridges with shorter periods than pulse periods;and pulse and residual components play different roles in seismic responses.
基金Supported by the National Natural Science Foundation （51208268）the Pubiic-Welfare-Technology Research Industry Project of Science Technology Department of Zhejiang （2011 C21078） the Social Development Project of Science Technology Bureau of Ningbo （2011CS0017）.
基金Project(N2018G034)supported by China Railway Corporation。
文摘The comparative research on the seismic performance of grouted sleeve connected pier(GS)and prestressed precast segmental concrete pier(PC)is mostly carried out by numerical simulation.In this study,the GS pier and the PC pier of the new railway project from Hetian to Ruoqiang are taken into consideration.Two kinds of 1/5-scale assembled double-column specimens are made,and the quasi-static tests are carried out.The overall seismic performance of the two spliced piers is studied,and compared in terms of failure mechanism,bearing capacity,ductility,stiffness and energy dissipation capacity.The results show that the failure modes of both GS pier and PC pier are characterized by bending.However,the specific failure location and form are different.The GS pier presents a complete hysteretic curve,large equivalent stiffness and strong energy dissipation capacity.The hysteretic area of the PC pier is small.However,it has good self-reset ability and quasi-static residual displacement.Finite element models are set up using DispBeamColumn fiber elements and ZeroLength elements.The models that are calibrated with the test data can effectively simulate the damage development under monotonic loading.The load−displacement curves are in good agreement with the backbone curves of the test results.
基金National Natural Science Foundation of China under Grant Nos.51978656 and 51478459the Key Research and Development Project of Xuzhou under Grant No.KC22282the Open Fund of Jiangsu Key Laboratory of Environmental Impact and Structural Safety in Civil Engineering,China University of Mining and Technology under Grant No.KFJJ202004。
文摘Considering the desirable behavior of concrete filled steel tube(CFT)columns and the complicated behavior of segmental double-column piers under cyclic loads,three post-tensioned precast segmental CFT double-column pier specimens were tested to extend their application in moderate and high seismicity areas.The effects of the number of CFT segments and the steel endplates as energy dissipaters on the seismic behavior of the piers were evaluated.The experimental results show that the segmental piers exhibited stable hysteretic behavior with small residual displacements under cyclic loads.All the tested specimens achieved a drift ratio no less than 13%without significant damage and strength deterioration due to the desirable behavior of CFT columns.Since the deformation of segmental columns was mainly concentrated at the column-footing interfaces,the increase of the segment numbers for each column had no obvious effects on the loading capacity but reduced the initial stiffness of the specimens.The use of steel endplates improved the bearing capacity,stiffness and energy dissipation of segmental piers,but weakened their self-centering capacity.Fiber models were also proposed to simulate the hysteretic behavior of the tested specimens,and the influences of segment numbers and prestress levels on seismic behavior were further studied.
基金National Natural Science Foundation of China under Grants Nos.51208268 and 51178429K.C.Wong Magna Fund in Ningbo University+1 种基金Transportation Science and Technology Project of Ningbo City under Grant No.201507Natural Science Foundation of Ningbo City under Grant No.2015A610293
文摘In recent years, precast segmental concrete bridge columns became prevalent because of the benefits of accelerated construction, low environmental impact, high quality and low life cycle costs. The lack of a detailed configuration and appropriate design procedure to ensure a comparable performance with monolithic construction has impeded this structural system from being widely used in areas of high seismicity. In this study, precast segmental bridge column cyclic loading tests were conducted to investigate the performance of unbonded post-tensioned segmental bridge columns. One monolithic and two precast segmental columns were tested. The preeast segmental column exhibited minor damage and small residual displacement after the maximum 7% cyclic drift; energy dissipation （ED） can be enhanced byadding ED bars. The experimental results were modeled by a simplified pushover method （SPOM）, as well as a fiber model （FIBM） finite element method. Forty-five cases of columns with different aspect ratios, axial load ratios and ED bar ratios were analyzed with the SPOM and FIBM, respectively. Using these parametric results, a simplified design method was suggested by regressive analysis. Satisfactory correlation was found between the experimental results and the simplified design method for preeast segmental columns with different design parameters.
基金supported by the National Natural Science Foundation of China(Grant Nos.52422809 and 52027811).
文摘The precast segmental column(PSC)plays a vital role in both the design of new bridges and the rehabilitation of existing ones.Previous studies of PSCs have primarily focused on their individual seismic behavior.However,research on the seismic performance of entire bridges supported by PSCs,particularly those incorporating soil-structure interaction(SSI),remains limited.Moreover,the amplification of earthquake waves as they propagate along the pile foundation to the surface,coupled with the coherency loss between earthquake motions at varying supports,may further impact the seismic responses of such bridges.This study systematically assesses the seismic performance of a PSC bridge(PSCB)supported by pile foundations considering the effects of SSI and depth-varying multi-support ground motions.Moreover,a benchmark bridge with the traditional monolithic column is also analyzed for comparison.The seismic fragility of bridges is calculated based on nonlinear time history analyses and joint probability density functions for both peak and residual responses.Parameter studies are conducted to reveal the influences of sSI,non-uniform excitation,and depth-varying earthquake loads on seismic performance assessments.This paper offers valuable insights for the reliable analysis of seismic response and fragility and the safety design of PSCB systems.
基金The authors would like to acknowledge the financial support received from the National Natural Science Foundation of China(Grant Nos.52278188 and 51978258)Natural Science Foundation of the Jiangsu Province(No.BK20211196)+1 种基金Chongqing Natural Science Foundation(CSTB2022NSCQ-MSX0969)the SOAR fellowship from the University of Sydney.
文摘Considering the wide application of precast segmental bridge columns(PSBCs)in engineering practice,impact-resistant performance has gained significant attention.However,few studies have focused on PSBCs subjected to high-energy impacts caused by heavy truck collisions.Therefore,the behavior of PSBCs under a heavy truck impact was investigated in this study using high-fidelity finite element(FE)models.The detailed FE modeling methods of the PSBCs and heavy trucks were validated against experimental tests.The validated modeling methods were employed to simulate collisions between PSBCs and heavy trucks.The simulation results demonstrated that the engine and cargo caused two major peak impact forces during collision.Subsequently,the impact force,failure mode,displacement,and internal force of the PSBCs under heavy truck impacts were scrutinized.An extensive study was performed to assess the influence of the section size,truck weight,impact velocity,and number of precast segments on the impact responses.The truck weight was found to have a minor effect on the engine impact force.Damage was found to be localized at the bottom of the three segments,with the top remaining primarily undamaged.This parametric study demonstrated that larger cross-sections may be a preferred option to protect PSBCs against the impact of heavy trucks.
文摘The development of each work is inseparable from the management, the quality of the work and the management level is closely related, especially in some production operations, the safety management work occupies an important position, is an important measure to ensure safe production. In recent years, the TBM tunnel has been more and more widely used, and the related production of precast concrete pipe segments has also gradually developed towards standardization and standardization.Combined on the author's work experience of the author, this paper analyzes the production safety management of precast concrete segments and explores the details of safety management from all angles.
