Load transfer mechanism of exterior beam-column joint with unsymmetrical chamfer

This study aims to understand the load transfer mechanism of exterior beam-column joints (BCJs) with unsymmetrical chamfers for strengthening. It comprises both experimental and numerical studies. Four 2/3-scale specimens were prepared including one without joint shear reinforcements as control, one with joint shear reinforcements and two specimens with chamfers installed. They were subjected to constant axial force and tested to failure under reversed horizontal displacements. Based on the experimental results, performance of BCJs can be improved by installing unsymmetrical chamfers. Secondly, parametric studies were conducted via non-linear finite element analysis. BCJs with different sizes of chamfer or ratios of L-C/L-BC ranging from 0.50 to 1.33 were modelled to study the effect of chamfer size on joint shear strength. Here, L-C is size of chamfer; and L-BC is minimum dimension of beam or column. It is found that the joint shear strength is further improved with increasing size of chamfer. Minimum ratio of L-C/L-BC is recommended as 0.67. Lastly, a load transfer mechanism for exterior joint with chamfer is proposed based on strut and tie concept. It takes into account the benefit of additional compressive strut in chamfer in increasing the joint shear strength.