Experimental and numerical studies on seismic behavior of new cross square hollow column-truss beam connections

Abstract

Five cyclic tests on the specimens were conducted to investigate seismic behavior of new cross square hollow column-truss beam connections. The variables are beam, column section size and axial force ratio. The paper reports on the failure modes, hysteretic curves, ultimate load carrying capacity, ductility, energy dissipation capacity, and stiffness degradation of the specimens. Two types of failure modes, i.e., column failure and beam failure mode, were found from the tests. The specimens experiencing the column failure mode exhibit poor seismic performance due to the overall instability induced by the occurrence of the plastic hinge of the column. While, the specimens displaying the beam failure mode exhibit well seismic behavior owing to the redistribution of the plastic stresses among the members of the truss beam. Noteworthy, the failure mode will change from column failure to beam failure when the column thickness increases and the axial force ratio decreases. Additionally, in the beam failure mode, the increase of the column thickness can improve the connection’s bearing and energy dissipation capacity, while the impact of the axial force ratio can be ignored. Based on the test results, the limit value of axial force ratio corresponding to the boundary failure mode under different column thicknesses is determined by using the nonlinear numerical model.