Experimental Research And Elastoplastic Time-history Analysis Of The Seismic Performance Of RC Structure With Specially Shaped Columns

In recent years reinforced concrete (RC) frame structure with specially shaped columns (SSC) has received quite extensive application because of its good architectural functions. At home experimental researches have been conducted on the seismic behavior of SSC members, beam-column joints and the monolithic structure of SSC, with lots of achievements being made. However, few researches have been done on the seismic performance of the SSC structure in seismic regions with earthquake intensity of degree 8. To promote the practical application of RC structures with SSC in earthquake intensity of degree 8, this paper studies the seismic performances of such structures through experiment and theoretical analysis.Based on shaking table tests, pseudo-static tests of three 1/3 scaled model of two-bay and three-story RC frames for studying their seismic performance are carried out to comprehensively study the hysteretic curves, skeleton curves, displacement ductility, stiffness degradation, strength deterioration, failure patterns and process, shear-resistant strength of joints, etc. The research shows that: (1) the failure process of these three specimens is all from the beams to the columns, so this pattern meets the requirement of seismic design; (2) the failure patterns of members are a result of bending or bending under compression, not a result of shear or bonded damage. Some joints have been damaged in the experiment; therefore, enough attention should be given to the seismic design of joints; (3) the displacement ductility of the frame with SSC is qualified; (4) the adoption of the frame with wide SSC at the bottom story can enhance the seismic performance to some extent.Based on shaking table test, the paper analyses the elastoplastic time-history of the structure with SSC, using Nonlinear Dynamic Analysis of Structures in 2 Dimensions based on model of bar systems. The analytical results accord well with the results of shaking table tests. The analysis indicates that the displacement of the structure, whether under slight earthquake or under sever earthquake, satisfies the requirements of the codes. The calculated results also show that the RC frame with SSC has good ductility, capacity of energy dissipation, failure patterns and process, and therefore, has good seismic behavior.In order to study the seismic performance on RC frame with SSC, the nonlinear finite element analysis based on concrete solid element by FEA software ANSYS has been done to simulate the experiment. The curve indicates the analytical results generally agree with the experimental ones. Finally, some suggestions for engineering designs are put forward based on the above study.