Experimental Study On Seismic Performance And Bearing Capacity Calculation Of Steel Reinforced Concrete Structure Under Composite Torsion

In civil engineering structures,there are many cases of torsion of components,but there are not individually subjected to torque,and most of them are in a state of compound torsion.Therefore,with the continuous intensive research of steel reinforced concrete structure,the increasing number of applications and the increasing demand for seismic resistance,it is particularly important to study damage evolution law,failure process of steel reinforced concrete members and the complex stress behavior under earthquake action.The formula for calculating the torsion capacity is of great significance to insure the safety of the structure.In order to analyse the seismic performance of SRC columns,this paper carried out the test on 18 SRC columns and 2 RC columns under cyclic loading.The influences of steel form,axial compression ratio,torsion-bending ratio,concrete strength,stirrup ratio,reinforcement ratio,presence of stud and the joint form of the stirrup were taken into consideration.The whole process of stressing,final failure modes of the specimen and the influences of vary parameters to the seismic index of the SRC columns were analyzed.The test result indicates that compared to H-beam specimens,cross-sectional steel concrete columns have better seismic capacity and ease the cumulative damage.Increasing the axial compression ratio can slowly improve the peak load capacity and decrease the ductility,but the degree of cumulative damage suffers less impact from the axial compression ratio.Increasing the torsion ratio can improve the peak load capacity and the ductility,but the degree of cumulative damage also increases.Increasing concrete strength has a limited increase in the peak load capacity of the specimen,while the reduction in internal damage indicators is small.Boosting stirrup ratio significantly increases the peak load capacity of H-beam specimens and improves energy dissipation and ductility,significant improvement in stiffness degradation and cumulative damage.Increasing reinforcement ratio effectively improves the seismic capacity of the specimen,the stiffness of the specimen degrades slowly and the cumulative damage index of the specimen is slightly reduced.Welding pins and welding hoops increase the peak load capacity of the specimens with a slight reduction in ductility,and the stiffness degradation is not significant and the cumulative damage is eased.Meanwhile,based on the experimental analysis and the derivation of the cracking torque formula of reinforced concrete composite torsion,the formula for calculating the cracking torque of steel reinforced concrete composite torsion member is established.This paper divides the members into the section steel force part and the reinforced concrete force part by the principle of superposition,and distributes the axial force,bending moment,shear force and torsion reasonably.The calculation method of torsional bearing capacity of steel reinforced concrete compression-bending-shear-torsion members is proposed by means of variable angle space truss model.