Experimental Research On Seismic Performance Of Damaged Rc Column With Different Reinforced Measures

With the accelerating pace of urbanization in China,the old buildings built in early construction lag behind the increasingly developing urban functional requirements,and the low seismic capacity of the buildings in early construction is the main cause of the serious earthquake disaster in China.In the previous earthquake damage,RC(reinforced concrete)column is the main bearing member of the building structure,but most of it is not completely damaged in the earthquake damage.It still has a certain bearing capacity,and the restoration value is high.Therefore,there is great market demand for reinforcement and reconstruction of existing buildings.As an internationally advanced seismic design method,performance-based seismic design can better evaluate the damage degree of a structure after earthquake.Based on the above reasons and methods,the RC column,which is damaged by low cycle reciprocating loading,is used as the earthquake damage column,and the steel pipe,square steel tube,circular steel tube(bottom gap)and increasing cross section are used to reinforce the column,and the seismic performance after the reinforcement is researched by the low cycle reciprocating loading test.The main research contents are as follows:(1)According to Chinese code,14 RC column specimens are designed with different axial compression ratio,seismic damage level and reinforcement measures.Among them are 2 contrast specimens and 12 pre-damaged specimens.The low cycle loading preloading test of 14 RC column specimens and the low cycle reciprocating loading test after strengthening of 12 pre damaged specimens were carried out respectively.The failure phenomena,ductility,energy dissipation capacity and stiffness degradation of the RC column specimens before and after reinforcement were analyzed.(2)Based on the skeleton curve,the 6 performance states and the corresponding deformation limits of the RC columns before and after reinforcement are divided,and the corresponding macroscopic failure states of the specimens before and after the reinforcement are given,and the relationship between the limit of deformation and the degree of failure is established.The results show that the axial compression ratio has the greatest influence on the performance of the specimen,and the second is the strengthening method,and the effect of the earthquake damage is less.(3)Based on the comparative analysis of the two test results before and after RC column test,the seismic performance of RC column specimen after strengthening is studied.The results show that the seismic performance of RC columns strengthened by seismic damage is improved,and the circular steel tube is better than the square steel tube and the square steel tube is better than the strengthened section.Under high axial compression,the seismic performance of specimens is increased significantly.(4)The relative deformation limits of the 6 performance states before the reinforcement of the RC column are compared.The deformation limits of the performance states of the specimen after the earthquake damage RC column are basically higher than those before the reinforcement and the contrast specimens before the reinforcement.The limit deformation limit of the specimen under the effect of low axial pressure is close to that before and before the reinforcement,and the limit deformation limit of the specimen under the action of the high axial pressure is greatly improved than that before the reinforcement and the contrast specimen before the reinforcement.(5)By comparing and analyzing the two test results before and after reinforcement,the strengthening method of RC column for earthquake damage is optimized,and the design proposal is put forward.