This study focuses on variations in the hysteretic behavior of buckling-restrained braces(BRBs)configured with or without out-of-plane eccentricity under cyclic loading.Quasi-static experiments and numerical simulatio...This study focuses on variations in the hysteretic behavior of buckling-restrained braces(BRBs)configured with or without out-of-plane eccentricity under cyclic loading.Quasi-static experiments and numerical simulations were carried out on concentrically and eccentrically loaded BRB specimens to investigate the mechanical properties,energy dissipation performance,stress distribution,and high-order deformation pattern.The experimental and numerical results showed that compared to the concentrically loaded BRBs,the stiffness,yield force,cumulated plastic ductility(CPD)coefficient,equivalent viscous damping coefficient and energy dissipation decreased,and the yield displacement and compression strength adjustment factor increased for the eccentrically loaded BRBs.With the existence of the out-of-plane eccentricity,the initial yield position changes from the yield segment to the junction between the yield segment and transition segment under a tensile load,while the initial high-order buckling pattern changes from a first-order C-shape to a secondorder S-shape under a compressive load.展开更多
Performance-based seismic design(PBSD) aims to assess structures at different damage states. Since damage can be directly associated to displacements, seismic design with consideration of displacement seems to be logi...Performance-based seismic design(PBSD) aims to assess structures at different damage states. Since damage can be directly associated to displacements, seismic design with consideration of displacement seems to be logical. In this study, simple formulae to estimate the peak floor displacement patterns of eccentrically braced frames(EBFs) at different performance levels subjected to earthquake ground motions are proposed. These formulae are applicable in a PBSD and especially in direct displacement-based design(DDBD). Parametric study is conducted on a group of 30 EBFs under a set of 15 far field and near field accelerograms which they scaled to different amplitudes to adapt various performance levels. The results of thousands of nonlinear dynamic analyses of EBFs have been post-processed by nonlinear regression analysis in order to recognize the major parameters that influence the peak displacement pattern of these frames. Results show that suggested displacement patterns have relatively good agreement with those acquired by an exact nonlinear dynamic analysis.展开更多
In this paper,the seismic responses and resilience of a novel K-type superelastic shape memory alloy(SMA)self-centring(SC)eccentrically braced frame(EBF)are investigated.The simulation models of the SMA-based SC-EBF a...In this paper,the seismic responses and resilience of a novel K-type superelastic shape memory alloy(SMA)self-centring(SC)eccentrically braced frame(EBF)are investigated.The simulation models of the SMA-based SC-EBF and a corresponding equal-stiffness traditional EBF counterpart are first established based on some existing tests.Then twenty-four near-fault ground motions are used to examine the seismic responses of both EBFs under design basis earthquake(DBE)and maximum considered earthquake(MCE)levels.Structural fragility and loss analyses are subsequently conducted through incremental dynamic analyses(IDA),and the resilience of the two EBFs are eventually estimated.The resilience assessment basically follows the framework proposed by Federal Emergency and Management Agency(FEMA)with the additional consideration of the maximum residual inter-storey drift ratio(MRIDR).The novel SMA-based SC-EBF shows a much better resilience in the study and represents a promising attractive alternative for future applications.展开更多
基金National Natural Science Foundation of China under Grant No.51978184。
文摘This study focuses on variations in the hysteretic behavior of buckling-restrained braces(BRBs)configured with or without out-of-plane eccentricity under cyclic loading.Quasi-static experiments and numerical simulations were carried out on concentrically and eccentrically loaded BRB specimens to investigate the mechanical properties,energy dissipation performance,stress distribution,and high-order deformation pattern.The experimental and numerical results showed that compared to the concentrically loaded BRBs,the stiffness,yield force,cumulated plastic ductility(CPD)coefficient,equivalent viscous damping coefficient and energy dissipation decreased,and the yield displacement and compression strength adjustment factor increased for the eccentrically loaded BRBs.With the existence of the out-of-plane eccentricity,the initial yield position changes from the yield segment to the junction between the yield segment and transition segment under a tensile load,while the initial high-order buckling pattern changes from a first-order C-shape to a secondorder S-shape under a compressive load.
文摘Performance-based seismic design(PBSD) aims to assess structures at different damage states. Since damage can be directly associated to displacements, seismic design with consideration of displacement seems to be logical. In this study, simple formulae to estimate the peak floor displacement patterns of eccentrically braced frames(EBFs) at different performance levels subjected to earthquake ground motions are proposed. These formulae are applicable in a PBSD and especially in direct displacement-based design(DDBD). Parametric study is conducted on a group of 30 EBFs under a set of 15 far field and near field accelerograms which they scaled to different amplitudes to adapt various performance levels. The results of thousands of nonlinear dynamic analyses of EBFs have been post-processed by nonlinear regression analysis in order to recognize the major parameters that influence the peak displacement pattern of these frames. Results show that suggested displacement patterns have relatively good agreement with those acquired by an exact nonlinear dynamic analysis.
基金The authors are grateful for the financial supports from the Research Grants Council of Hong Kong through the GRF Project(No.PolyU 152246/18E)the National Key Research and Development Program of China(No.2019YFB1600700)the Hong Kong Polytechnic University(Nos.ZE2L,ZVX6,and P0035787).The findings and opinions expressed in this paper are solely those of the authors and do not represent the view of the sponsors.
文摘In this paper,the seismic responses and resilience of a novel K-type superelastic shape memory alloy(SMA)self-centring(SC)eccentrically braced frame(EBF)are investigated.The simulation models of the SMA-based SC-EBF and a corresponding equal-stiffness traditional EBF counterpart are first established based on some existing tests.Then twenty-four near-fault ground motions are used to examine the seismic responses of both EBFs under design basis earthquake(DBE)and maximum considered earthquake(MCE)levels.Structural fragility and loss analyses are subsequently conducted through incremental dynamic analyses(IDA),and the resilience of the two EBFs are eventually estimated.The resilience assessment basically follows the framework proposed by Federal Emergency and Management Agency(FEMA)with the additional consideration of the maximum residual inter-storey drift ratio(MRIDR).The novel SMA-based SC-EBF shows a much better resilience in the study and represents a promising attractive alternative for future applications.
