Tensile performance of concrete filled square steel tube exterior-diaphragm #br# connections stiffened with PBL
Zhu Weiqing1,2 Mo Zhipeng1 Liu Yongjian1
1. School of Highway, Changan University, Xian 710064, China; 2. Key Laboratory of Bridge Detection Reinforcement Technology of
the Ministry of Transport, Changan University, Xian 710064, China
Abstract：To obtain the tensile performance and preliminarily validate the seismic behavior of a novel type of concrete filled square steel tube (CFSST) exteriordiaphragm connections stiffened with PBL, tensile experiments on six CFSST connection specimens were carried out, including the ordinary CFSST connections, ordinary CFSST exterior-diaphragm connections, novel CFSST exterior-diaphragm connections stiffened with PBL and CFSST connections stiffened by PBL and with exterior-diaphragm removed. By comparing the failure modes, initial stiffness, yield load and ultimate load, deformation components, strain and stress distribution of branch plates or diaphragm of different specimens, the improvement due to the PBL ribs and the effects of removing the exterior-diaphragm on tensile performamce of novel connection specimens were studied emphatically. It is found that, compared to ordinary CFSST connection and CFSST exterior-diaphragm connection specimens, CFSST exterior-diaphragm connection specimens stiffened with PBL, due to applications of both exteriordiaphragm and PBL ribs, possess much higher initial stiffness, yield load and ultimate load, relieved deformation concentration and much uniform strain and stress distribution in connection region. Hence, the novel type of connection has excellent load transmission capacity of tension in steel beam flanges, so that the connections showld possess excellent seismic behavior due to the failure mode of yielding of beam ends. After removing exterior-diaphragm from the novel CFSST connections stiffened with PBL, however, initial stiffness, yield load and ultimate load, and strain and stress uniformity in branch plates were reduced, and the load transmission capacity was decreased. The research results laid the basis for further researches on calculation method of tensile capacity and seismic behavior of connections.
