Ultimate capacity of doubler plate-reinforced tubular joints

To ensure structural integrity after modification and/or retrofitting, the behavior of strengthened tubular joints needs to be understood. The finite- element method is a useful tool for studying the problem. However, this num erical technique has to be verified by experimental results before being us ed extensively. In this paper, the ultimate capacity of doubler plate-reinf orced tubular joints is studied. To establish a reference point, a doubler plate-reinforced tubular T-joint was fabricated, instrumented, and tested t o failure under axial compression brace loading. The structural behaviors w ere observed and analyzed. It was found that the ultimate capacity was grea tly improved by the inclusion of the doubler plate. The experimental load-d isplacement curves were compared with the finite-element predictions and go od agreement was obtained. The finite-element techniques were then verified and could be used to study the ultimate capacity. A behavioral study was t hen conducted by applying various types of brace loading and varying differ ent geometric parameters, one at a time.