Static performance of doubler plate reinforced tubular T/Y-joints subjected to brace tension

In the present study, data extracted from the finite element analysis of 210 models, which were verified against the data available from eight experimental tests, were used to investigate the geometrical effect on the ultimate strength, initial stiffness, and failure modes in doubler plate reinforced tubular T/Y under axially tensile load. Results indicated that the doubler plate can significantly increase the initial stiffness, ultimate capacity, and considerably improve failure modes. Also, the reinforcing effect of the doubler plate thickness and doubler plate length on the ultimate capacity becomes more remarkable when one of these parameters is big. Despite this significant difference between the static capacity of unreinforced and doubler plate reinforced T- and Y-joints subjected to brace tension, studies on these types of reinforced joints have been confined to very few T-joint tests. Moreover, no design formula is available to compute the ultimate capacity of doubler plate reinforced T/Y-joints. For these reasons, geometrically parametric investigation was followed by a set of nonlinear regression analyses to propose an ultimate capacity parametric formula for the static analyses of doubler plate reinforced tubular T/Y-joints under axially tensile load.