Experimental Study On Mechanical Properties And Strength Calculation Of Steel Reinforced Concrete Members Under Torsion

Steel reinforced concrete structure is a new type of composite structure,which has good fire resistance,durability and seismic performance,and the member stiffness,bearing capacity and ductility are greatly improved.In practical engineering,it is increasingly widely used;and with the increase of various kinds of special-shaped buildings,corner columns and other components are often in the complex state of compression,bending,shear and torsion,and the effect of torque will have an adverse impact on the bearing capacity,so the bearing capacity of steel reinforced concrete structure under complex state of stress has attracted extensive attention of scholars.In this paper,the torsional behavior and strength calculation of steel reinforced concrete(SRC)columns are studied by means of experiments and theoretical analysis.Three groups of section concrete specimens and one reinforced concrete contrast specimen are designed for this project.The three groups of specimens take the form of section steel as the variable(cross section steel,H section steel,angle steel truss),and the torsion ratio,axial compression ratio,concrete strength grade and hoop spacing as the variables within the group.Monotonic loading tests under the action of composite torque to study their characteristics such as crack development pattern,damage morphology and bearing capacity performance.The torsional behavior was analyzed,including torsion ratetorque curve characteristics,cracking torque,ultimate torque,ductility coefficient,and strain-torque relationship curves of each material composing the steel and concrete column.By analyzing the test results,it can be concluded that in the range of the test parameters of this paper,the increase of axial compression ratio makes the bearing capacity of the member increase while the ductility are reduced.The increase of torsional bending ratio has less effect on the improvement of the load capacity of the member.High strength concrete can also increase its bearing capacity to a certain extent.Compared with ordinary reinforced concrete members,the reinforced concrete with profiled steel has stronger restraint effect on the core concrete,and the torsional performance is significantly improved.It is found that the torsion performance of open web members is better than that of solid web members,and that of biaxial symmetric steel members is better than that of uniaxial symmetric steel members.In general,the composite torsion performance of angle steel truss concrete columns is the best,followed by cross shaped steel concrete columns and H-shaped steel concrete columns.By analyzing the stress mechanism of steel reinforced concrete columns and the contribution of various materials to the bearing capacity,the unified calculation formula of cracking torque and ultimate torque of steel reinforced concrete columns is derived by using variable angle space truss model,superposition method and internal force distribution method.The calculated values are in good agreement with the experimental values,which has practical engineering application value.