ABSTRACT
This paper examines the cyclic performance of CHS joints used in steel tubular structures. Quasi-static experimental study into the response of eight T-joint specimens is described. Four of them are subjected to cyclic axial load, and the other four are subjected to cyclic in-plane bending. The general test arrangement, specimen details, and most relevant results (failure modes and load-relative deformation hysteretic curves) are presented. Some indexes to assess the seismic performance of tubular joints, including strength, ductility and energy dissipation, are synthetically analyzed and compared. Test results show that failure modes of axially loaded joints mainly contain weld cracking in tension and chord plastification in compression. But for joints under cyclic in-plane bending, punching shear may become a regular failure mode accompanied by ductile fracture of the welds. Hysteretic curves behave stably in general. Ultimate strengths of joints are also compared with equation values for monotonic loading from various design codes. Results indicate existing codes can be used to check the ultimate capacity of tubular T-joints under cyclic loading to a certain extent. It is also found that there is a significant distinction in the energy dissipation mechanism for tubular joints under different loading conditions. Additionally, it is deserved to note that weld cracking sometimes happened under lower cyclic load level compared with design resistance specified by the codes.
