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 numerical technique has to be verified by experimental results before being used extensively. In this paper, the ultimate capacity of doubler plate-reinforced tubular joints is studied. To establish a reference point, a doubler plate-reinforced tubular T-joint was fabricated, instrumented, and tested to failure under axial compression brace loading. The structural behaviors were observed and analyzed. It was found that the ultimate capacity was greatly improved by the inclusion of the doubler plate. The experimental load-displacement curves were compared with the finite-element predictions and good agreement was obtained. The finite-element techniques were then verified and could be used to study the ultimate capacity. A behavioral study was then conducted by applying various types of brace loading and varying different geometric parameters, one at a time.