Experimental study and theoretical analysis on the ultimate strength of high-strength-steel tubular K-Joints

In order to investigate the failure mode and mechanism of K-joints fabricated using high-strength steel and to develop a formula that can predict their ultimate strength, full-scale tubular K-joints with tube-gusset plate connections of Q690 high-strength steel are fabricated and tested under static loads. Based on the tubular energy theory and virtual work principle and using the ring-generator separation model, a formula for predicting the ultimate strength of high-strength steel K-joints is developed. In order to verify the correctness of the formula, using the finite element model, a sensitivity analysis is performed on the factors that affect the ultimate strength of the joints. The results indicate that the stress in the main post and the thickness and diameter of the main post significantly affect the ultimate strength of the K-joints. Moreover, the results predicted by the proposed formula correlate well with the experimental and numerical results. Hence, the proposed formula can be used for practical engineering design.