The Study On Torsional Stiffness Of Steel Reinforced Concrete Members In Axial Compression And Torsion

Steel reinforced concrete structures which consisting of reinforced concrete,longitudinal bar and stirrup in the center of the section is a new type of composite structures.It gives full play to the steel and concrete material properties.With the advantages of large stiffness,high carrying capacity and good seismic performance,it is widely used in national engineering construction.At present,the research results of anti-torsion of steel reinforced concrete members at home and abroad are all very limited.The research on torsion resistance of steel reinforced concrete members starts relatively late in China.China's relevant standards,like ‘Technical specification of steel reinforced concrete struuctures'(YB9082-2006)and ‘Technical specification for steel reinforced concrete composite structures'(JGJ138-2001)make no mention of the calculation method and formula of steel reinforced concrete members under torsion.And in building structure,the component is mostly in the condition of torsion.So carrying out the research of torsional behavior and the method of calculation is very urgent.The research on steel reinforced concrete component was made through the following aspects in this paper:(1)In this paper,a hollow box-shaped steel reinforced concrete specimen which was choosen from the test of National Central University of Taiwan was simulated by the finite element software ABAQUS.Comparing the torque-twist ratio curves,crack torque and ultimate torque of finite element simulation with the experimental results,the finite element simulation results show a good agreement with the experimental results.(2)In this paper,the stress,strain and deformation of SRC members with different axial compression ratios were analyzed.(3)In this paper,by comparing the torque-twist ratio curve of each member,the effect of various parameters(axial compression ratio,strength grade of concrete,steel configuration,ratio of reinforcement,steel ratio)on torsion stiffness of six steel reinforced concrete members and one reinforced concrete member in axial compression and torsion were analyzed.(4)The torsional stiffness of steel reinforced concrete members can be simplified to three stages:elastic stage before cracking,after cracking to steel reinforced concretemembers yield,after yielding to limit state.Based on the torsion stiffness calculating theory and method of reinforced concrete members and steel reinforce composite beams,as well as according to the results of finite element analysis and considering the correction coefficient of steel stiffness before cracking and under limit state and the effect of axial compression ratio on the stiffness of reinforced concrete before cracking,the calculation formula of torsional stiffness of three stages were established.By comparing the simulation values with the calculation values,the accuracy of the formula is verified initially.