Experimental Research And Theoretical Analysis On Torsional Behavior Of Stud Welding Steel Reinforced Concrete Beams

This paper belongs to the key content of Natural Science Foundation of China(NSFC) projects entitled "Study on Design Method and Performance of SRC Members Under Compression, Bending, Shearing and Torsion Action ". Taking steel reinforced concrete(SRC) Members with welded stud under torsion as study objects and positions, lengths, diameters and space of welded stud as variable parameters,9specimens, including8SRC beams and1reinforced concrete(RC) beam, were carried out by self-designed and patented torsion testing device to reveal the mechanical behavior and failure mechanism of stud welding steel reinforced concrete(SSRC) members with different variable parameters, analyze the influence of SSRC members on each variable parameter, obtain strength calculate formula of SSRC members under torsion by theoretical research and propose reasonable constructional measures to increase torsional behavior. Study proves that:The torsion failure process of SSRC beams can be divided into four stages:elastic stage, cracking stage, elastic-plastic stage(including approximate elastic stag, mutations stage and hardening stage), failure stage. Before carked the surrounding concrete of specimens bear most of torque, and the surrounding concrete is gradually invalidated after cracked. Profiled steel frame, reinforcement cage and concrete work together under torsion, the stud increases the concrete confined effect by profiled steel frame effectively and improve torsional behavior of specimens.The failure characteristic of normal SRC specimens under torsion represents the spiral main cracks developing and extending through specimens surface. Besides the the spiral main cracks, meanwhile, a large number of horizontal bonding cracks emerge among the spiral main cracks at specimens surface. The crack distribution of specimens becomes more dense and homogeneous due to the welded stud.Compare with normal SRC member the torsion performance of SRC member with welded stud have significantly improved(the average improvement is24.1%), and the stud welding at different locations, to varying degrees of increase. The ultimate torque of member have been improved about9.0%when welded stud on flange of steel. While welded stud on web of steel, the ultimate torque of member have been increased along25.9%. The ultimate torque of member have been improved about33.0%when welded stud on flange and web of steel. Some construction measures can obviously improve the torsion performance of SRC member under torsion, like welding stud on web of steel and overhanging stud beyond the stirrup etc.By simulation and analysis via the ABAQUS finite element analysis software, the writer extended research the torsion performance of SSRC member under variable parameters. In based on the analysis of a large number of numerical simulation and experimental study, the theoretical formulas of cracking torque and ultimate torque of SSRC beams are proposed. and the computed result matched actual test value.