Seismic Performance And Damage Analysis Of Reactive Powder Concrete Filled Square Steel Tubular Column

Most of the damage to buildings caused by earthquake is not done overnight.The damage of buildings caused by earthquake is the result of the cumulative fatigue damage value generated inside the buildings exceeding the critical value of structural damage resistance.Therefore,accurate calculation of fatigue damage inside the structure can accurately and effectively judge the damage degree inside the structure after the earthquake,and investigate whether the structure can continue to use.This work has provided a guarantee for the safety of people’s lives and property,which is of great significance to reduce earthquake losses.Reactive Powder Concrete(RPC)has the advantages of high strength,good toughness and excellent durability,but has the disadvantages of high brittleness and easy cracking.However,the restraint effect of steel pipe on RPC can effectively improve these shortcomings.Therefore,the RPC structure of steel pipe formed by filling RPC inside the steel pipe can not only overcome the shortcomings of RPC brittleness and easy cracking,but also effectively prevent premature local buckling failure of steel pipe.At present,most of the researches on RPC structure of steel pipe focus on basic mechanical properties,hysteresis properties and other aspects,and there are few researches on damage performance of RPC structure of steel pipe under earthquake at home and abroad.Therefore,this paper established RPC column model of square steel tube,and analyzed the effects of axial compression ratio,slenderness ratio and steel content on its seismic performance.On this basis,the restoring force model and earthquake damage model of square steel tube RPC column were established,and the damage degree of RPC column caused by earthquake was determined by the damage model.The specific research contents are as follows:(1)On the basis of low-cycle reciprocating load test of square steel tube RPC column conducted in the same project,128 square steel tube RPC column models,3 test control models and 125 square steel tube RPC column models taking into account axial compression ratio,slenderness ratio and steel content were established by using ABAQUS.The experimental results of RPC column with square steel tube are in good agreement with the finite element calculation results of the control model.(2)125 square RPC column models were grouped according to axial compression ratio,slenderness ratio and steel content.It was found that the axial compression ratio had little effect on the elastic stage of RPC column,but the ultimate bearing capacity of RPC column was negatively correlated with axial compression ratio in strengthening and declining stages.Slenderness ratio and steel content have great influence on the bearing capacity of RPC column.According to the skeleton curve model and hysteresis rule of square steel tube RPC column,the restoring force model was established,and the correctness of the restoring force model was verified by test data.(3)Based on the finite element calculation results of 125 square steel tube RPC columns,referring to the Park damage model and the effective energy hypothesis of FuGuo,a damage model consisting of deformation and effective accumulated hysteresis energy dissipation was established in this paper.The damage parameters α=0.851 and β=-0.508 were obtained by nonlinear fitting.Experimental data were used to verify the damage model,and the values of the damage variables were all close to 1,indicating that the damage model could well reflect the earthquake damage state of RPC column of square steel tube.