Study On Seismic Performance Of SMA-FRP Rebar Reinforced Concrete Frame Structure Based On Performance-based Seismic Design Method

Steel reinforced concrete frame structures are very liable to corrosion while have tendency to incur permanent plastic deformation under excessive earthquake loading.Recently,fiber reinforced polymer(FRP)reinforcing bars have been used in concrete structures to address corrosion issues.However,due to their insufficient ductility and energy dissipation capacity,they are not considered in structures which require ductility and damping characteristics.To solve the problem of damage accumulation of structures,SMA-FRP reinforced concrete frame which proposed in this study can not only address corrosion issues,but also solve the problem of permanent deformation of structures under seismic loading.As a new smart material,shape memory alloys(SMA)have the unique ability to undergo large deformations while falling back to their original undeformed shape after removing of the load.Thus,the use of SMA in structures can make the structure create negligible residual deformations under earthquake loading while maintain good seismic performance under main shock-aftershock ground motion sequence which will greatly reduce maintenance costs after earthquakes.However,there is only little relevant study in our country,so it is necessary to carry out further research on the seismic performance of SMA-FRP reinforced concrete frame structures.The main contents and conclusions of this paper are as follows:1.In this paper,the performance-based seismic design method is applied to the design of SMA-FRP reinforced concrete frame,reinforced concrete frame and GFRP reinforced concrete frame.According to the results of tensile test of SMA-FRP composite material,the constitutive model of SMA-FRP bars is given by simulation analysis.On this basis,the finite element model of three kinds of frame structures of reinforced concrete,FRP reinforced concrete and SMA-FRP reinforced concrete is established by using OpenSees finite element software.2.Next,they are analyzed under three single ground motion records to obtain maximum inter-story drift(ID)curves,residual inter-story drift curves and dynamic pushover curves using incremental dynamic analysis(IDA)method.The results showed that SMA-FRP reinforced concrete frame show equivalent seismic performance with steel reinforced concrete frame in the base shear force vs displacement relationship and PGA vs inter-story driftrelationship.The residual inter-story dirft after earthquakes are far less than the other two kinds of concrete frame structure.3.Then three main shock-aftershock ground motion records were used to conduce nonlinear time history analysis on SMA-FRP reinforced concrete frame,steel reinforced concrete frame and GFRP reinforced concrete frame to study dynamic response of structures at 4% IDR(inter-story drift ratio)limit state.IDR time history curves,residual IDR and cumulative residual IDR of three structures were gained.The results showed that the steel reinforced concrete frame produced residual IDR both in main shock and aftershocks,structural damage were accumulated.However,SMA-FRP reinforced concrete frame had no permanent deformation and kept good seismic performance all the time.In summary,analysis results showed that SMA-FRP reinforced concrete frame exhibited better seismic performance than steel reinforced concrete frame and GFRP reinforced concrete frame under both single ground motion records and main shock-aftershock ground motion records by comparing and analyzing the results of numerical modeling which can provide a reference for future theoretical research and practical application of SMA-FRP reinforced concrete frame structures.