This paper presents an experimental and numerical study to investigate the hysteretic performance of a new type of isolator consisting of shape memory alloy springs and friction bearing called an SMA spring-friction b...This paper presents an experimental and numerical study to investigate the hysteretic performance of a new type of isolator consisting of shape memory alloy springs and friction bearing called an SMA spring-friction bearing （SFB）. The SFB is a sliding-type isolator with SMA devices used for the seismic protection of engineering structures. The principle of operation of the isolation bearing is introduced. In order to explore the possibility of applying SMA elements in passive seismic control devices, large diameter superelastic tension/compression NiTi SMA helical springs used in the SFB isolator were developed. Mechanical experiments of the SMA helical spring were carried out to understand its superelastic characteristics. After that, a series of quasi-static tests on a single SFB isolator prototype were conducted to measure its force-displacement relationships for different loading conditions and study the corresponding variation law of its mechanical performance. The experimental results demonstrate that the SFB exhibits full hysteretic curves, excellent energy dissipation capacity, and moderate recentering ability. Finally, a theoretical model capable of emulating the hysteretic behavior of the SMA-based isolator was then established and implemented in MATLAB software. The comparison of the numerical results with the experimental results shows the efficacy of the proposed model for simulating the response of the SFB.展开更多
As a novel coupling beam for coupled shear wall structures,the bending-type frictional steel truss coupling beam(BFTCB)concentrates the deformation and energy dissipation in friction dampers at the bottom chord,allowi...As a novel coupling beam for coupled shear wall structures,the bending-type frictional steel truss coupling beam(BFTCB)concentrates the deformation and energy dissipation in friction dampers at the bottom chord,allowing the main body to remain elastic during earthquakes.As the preparatory work for resilient structure design based on the BFTCB,this work concentrates on developing the hysteretic model for BFTCB.Firstly,the BFTCB stiffness-strength decoupling mechanism was introduced,i.e.,the shear strength is provided by friction dampers while webs control its initial stiffness.Secondly,a hysteretic model that reflects the BFTCB two-stage sliding characteristic was proposed.The model consists of a trilinear backbone curve and the unloading and reverse loading rules.The model has eight control parameters,of which two core parameters(initial stiffness and limiting shear strength)are derived from the BFTCB stiffness-strength decoupling mechanism,whereas the remaining parameters are obtained by theoretical analysis and empirical calibration.The hysteretic model was then compared with the test curves and demonstrated good accuracy.Finally,a series of FE prototypes of BFTCB with different design stiffnesses and strengths was adopted to verify the hysteretic model.The results showed that the proposed model fitted well with the FE prototypes,indicating its applicability to BFTCB with varying core design parameters.Therefore,the hysteretic model can be adopted for BFTCB to support the resilient shear wall structure design.展开更多
To study the seismic performance of double-skin steelconcrete composite box（ DSCB） piers, a total of 11 DSCB pier specimens were tested under bidirectional cyclic loading. The effects of the loading pattern, the ste...To study the seismic performance of double-skin steelconcrete composite box（ DSCB） piers, a total of 11 DSCB pier specimens were tested under bidirectional cyclic loading. The effects of the loading pattern, the steel plate thickness, the axial load ratio, the slenderness ratio and the aspect ratio were taken into consideration. The damage evolution process and failure modes of the tested specimens are presented in detail. Test results are also discussed in terms of the hysteretic curve, skeleton curve, ductility and energy dissipation capacity of DSCB pier specimens. It can be concluded that the hysteretic performance of DSCB piers in one direction is affected and weakened by the cyclic loading in the other direction. DSCB piers under bidirectional cyclic loading exhibit good performance in terms of load carrying capacity, ductility, and energy dissipation capacity. Overall, DSCB piers can meet the basic aseismic requirements. The research results can be taken as a reference for using DSCB piers as high piers in bridges in strong earthquakeprone areas.展开更多
Previous quasi-static cyclic tests of shear walls,which routinely used an incremental lateral displacement test protocol with a constant axial load,failed to reflect the character of moment-shear force interaction of ...Previous quasi-static cyclic tests of shear walls,which routinely used an incremental lateral displacement test protocol with a constant axial load,failed to reflect the character of moment-shear force interaction of prototype buildings.To study the effect of the moment-shear force interaction on the seismic performance of shear walls,three identical 2-story shear wall specimens with different loading patterns were constructed at 1/2 scale,to represent the lower portion of an 11-story high-rise building,and were tested under reversed cyclic loads.The axial force,shear force and bending moment were simultaneously applied to simulate the effects of gravity loads and earthquake excitations on the prototype.The axial force and bending moment delivered from the upper structure were applied to the top of the specimens by two vertical actuators,and the shear force was applied to the specimens by two horizontal actuators.A mixed force-displacement control test program was adopted to ensure that the bending moment and the lateral shear were increased proportionally.The experimental results show that the moment-shear force interaction had a significant effect on the failure pattern,hysteretic characteristics,ductility and energy dissipation of the specimens.It is recommended that moment-shear force interaction should be considered in the loading condition of RC shear wall substructures cyclic tests.展开更多
基金Beijing Natural Science Foundation under Grant No.8132024Science and Technology Development Project of Beijing Municipal Commission of Education under Grant No.KM201510016004
文摘This paper presents an experimental and numerical study to investigate the hysteretic performance of a new type of isolator consisting of shape memory alloy springs and friction bearing called an SMA spring-friction bearing （SFB）. The SFB is a sliding-type isolator with SMA devices used for the seismic protection of engineering structures. The principle of operation of the isolation bearing is introduced. In order to explore the possibility of applying SMA elements in passive seismic control devices, large diameter superelastic tension/compression NiTi SMA helical springs used in the SFB isolator were developed. Mechanical experiments of the SMA helical spring were carried out to understand its superelastic characteristics. After that, a series of quasi-static tests on a single SFB isolator prototype were conducted to measure its force-displacement relationships for different loading conditions and study the corresponding variation law of its mechanical performance. The experimental results demonstrate that the SFB exhibits full hysteretic curves, excellent energy dissipation capacity, and moderate recentering ability. Finally, a theoretical model capable of emulating the hysteretic behavior of the SMA-based isolator was then established and implemented in MATLAB software. The comparison of the numerical results with the experimental results shows the efficacy of the proposed model for simulating the response of the SFB.
基金supported by the Scientific Research Fund of MultiFunctional Shaking Tables Laboratory of Beijing University of Civil Engineering and Architecture(2022MFSTL06)Science&Technology Foundation of Liaoning Province,China:General Program(2021-MS131).
文摘As a novel coupling beam for coupled shear wall structures,the bending-type frictional steel truss coupling beam(BFTCB)concentrates the deformation and energy dissipation in friction dampers at the bottom chord,allowing the main body to remain elastic during earthquakes.As the preparatory work for resilient structure design based on the BFTCB,this work concentrates on developing the hysteretic model for BFTCB.Firstly,the BFTCB stiffness-strength decoupling mechanism was introduced,i.e.,the shear strength is provided by friction dampers while webs control its initial stiffness.Secondly,a hysteretic model that reflects the BFTCB two-stage sliding characteristic was proposed.The model consists of a trilinear backbone curve and the unloading and reverse loading rules.The model has eight control parameters,of which two core parameters(initial stiffness and limiting shear strength)are derived from the BFTCB stiffness-strength decoupling mechanism,whereas the remaining parameters are obtained by theoretical analysis and empirical calibration.The hysteretic model was then compared with the test curves and demonstrated good accuracy.Finally,a series of FE prototypes of BFTCB with different design stiffnesses and strengths was adopted to verify the hysteretic model.The results showed that the proposed model fitted well with the FE prototypes,indicating its applicability to BFTCB with varying core design parameters.Therefore,the hysteretic model can be adopted for BFTCB to support the resilient shear wall structure design.
基金The National Natural Science Foundation of China(No.5117810151378112)the Doctoral Fund of Ministry of Education(No.20110092110011)
文摘To study the seismic performance of double-skin steelconcrete composite box（ DSCB） piers, a total of 11 DSCB pier specimens were tested under bidirectional cyclic loading. The effects of the loading pattern, the steel plate thickness, the axial load ratio, the slenderness ratio and the aspect ratio were taken into consideration. The damage evolution process and failure modes of the tested specimens are presented in detail. Test results are also discussed in terms of the hysteretic curve, skeleton curve, ductility and energy dissipation capacity of DSCB pier specimens. It can be concluded that the hysteretic performance of DSCB piers in one direction is affected and weakened by the cyclic loading in the other direction. DSCB piers under bidirectional cyclic loading exhibit good performance in terms of load carrying capacity, ductility, and energy dissipation capacity. Overall, DSCB piers can meet the basic aseismic requirements. The research results can be taken as a reference for using DSCB piers as high piers in bridges in strong earthquakeprone areas.
基金Scientific Research Fund of Institute of Engineering Mechanics,China Earthquake Administration under Grant No.2019B05the Heilongjiang Provincial Natural Science Foundation of China under Grant No.LH2019E098,the National Natural Science Foundation of China under Grant Nos.51878631 and 51678544the National Key Research and Development Program of China under Grant Nos.2017YFC1500605 and 2018YFC1504602-01。
文摘Previous quasi-static cyclic tests of shear walls,which routinely used an incremental lateral displacement test protocol with a constant axial load,failed to reflect the character of moment-shear force interaction of prototype buildings.To study the effect of the moment-shear force interaction on the seismic performance of shear walls,three identical 2-story shear wall specimens with different loading patterns were constructed at 1/2 scale,to represent the lower portion of an 11-story high-rise building,and were tested under reversed cyclic loads.The axial force,shear force and bending moment were simultaneously applied to simulate the effects of gravity loads and earthquake excitations on the prototype.The axial force and bending moment delivered from the upper structure were applied to the top of the specimens by two vertical actuators,and the shear force was applied to the specimens by two horizontal actuators.A mixed force-displacement control test program was adopted to ensure that the bending moment and the lateral shear were increased proportionally.The experimental results show that the moment-shear force interaction had a significant effect on the failure pattern,hysteretic characteristics,ductility and energy dissipation of the specimens.It is recommended that moment-shear force interaction should be considered in the loading condition of RC shear wall substructures cyclic tests.
