Experimental and numerical investigations on collar plate and doubler plate reinforced SHS T-joints under axial compression

This paper presents the experimental and numerical investigations on collar plate and doubler plate reinforced square hollow section (SHS) T-joints under axial compression. A total of eleven SHS T-joints with different brace to chord width ratio (beta) was tested, in which four specimens were reinforced with collar plate, four specimens were reinforced with doubler plate and three specimens were unreinforced for comparison. The joint strengths, failure modes, load-deformation curves and load-strain distribution curves of all specimens are reported. The effects of brace to chord width ratio (beta), reinforcement type and reinforced plate thickness on the structural behaviour of SHS T-joints under axial compression were evaluated. It is shown from the comparison that the reinforced plates including both collar plate and doubler plate significantly increase the load carrying capacity of SHS T-joints under axial compression. The joint strength and initial stiffness benefit from the increase of the beta ratio, but the ductility is deteriorated. Furthermore, the joint strength, initial stiffness and ductility of collar plate reinforced SHS T-joints under axial compression are improved with the increase of the collar plate thickness. Whereas, the increase of the doubler plate thickness has detrimental effect on the joint strength and ductility of doubler plate reinforced SHS T-joints under axial compression. The corresponding finite element analysis (FEA) was also performed and calibrated against the test results. The new design equations were proposed based on the test and numerical results for collar plate and doubler plate reinforced SHS T-joints, which were verified to be more accurate.