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 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
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
This paper examines the quasi-static cyclic behavior, lateral strength and equivalent damping capacities of a system of post-tensioned segmental bridge columns tied with large diameter martensitic Shape Memory Alloy ...This paper examines the quasi-static cyclic behavior, lateral strength and equivalent damping capacities of a system of post-tensioned segmental bridge columns tied with large diameter martensitic Shape Memory Alloy （SMA） link-bars. Moment-curvature constitutive relationships are formulated and analysis tools are developed for the PT column, including a modified four-spring model prepared for the SMA bars. The suggested system is exemplified using a column with an aspect ratio of 7.5 and twelve 36.5 mm diameter NiTi martensitic SMA bars. A post-tensioning force of 40% to 60% of the tendon yield strength is applied in order to obtain a self re-centering system, considering the residual stress of the martensitie SMA bars. The cyclic response results show that the lateral strength remains consistently around 10% of the total vertical load and the equivalent viscous damping ratios reach 10%-12% of critical. When large diameter NiTi superelastic SMA bars are incorporated into the column system, the cyclic response varies substantially. The creep behavior of the superelastic SMA bar is accounted for since it affects the re-centering capability of the column. Two examples are presented to emphasize the modeling sensitivities for these special bars and quantify their cyclic behavior effects within the column assembly.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
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 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Research fund of Hanyang University Under Grant No.HY-2010-N
文摘This paper examines the quasi-static cyclic behavior, lateral strength and equivalent damping capacities of a system of post-tensioned segmental bridge columns tied with large diameter martensitic Shape Memory Alloy （SMA） link-bars. Moment-curvature constitutive relationships are formulated and analysis tools are developed for the PT column, including a modified four-spring model prepared for the SMA bars. The suggested system is exemplified using a column with an aspect ratio of 7.5 and twelve 36.5 mm diameter NiTi martensitic SMA bars. A post-tensioning force of 40% to 60% of the tendon yield strength is applied in order to obtain a self re-centering system, considering the residual stress of the martensitie SMA bars. The cyclic response results show that the lateral strength remains consistently around 10% of the total vertical load and the equivalent viscous damping ratios reach 10%-12% of critical. When large diameter NiTi superelastic SMA bars are incorporated into the column system, the cyclic response varies substantially. The creep behavior of the superelastic SMA bar is accounted for since it affects the re-centering capability of the column. Two examples are presented to emphasize the modeling sensitivities for these special bars and quantify their cyclic behavior effects within the column assembly.
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.
