Numerical investigation of branch plate-to-CHS connection under eccentric shear loading

Abstract

Circular Hollow Section (CHS) columns are usually used in high-rise buildings. International design specifications usually overestimate the design of the beam-to-CHS column branch plate connections. This paper numerically investigates the behavior and strength of beam-to-CHS column branch plate connections using a finite element (FE) model. The FE model is verified using different experimental results available in previous literature. A parametric study is carried out on specimens subjected to eccentric shear loading on the branch plate with a constant column length and end conditions. The parameters included the CHS column diameter, wall thickness, branch plate length and the effect of load eccentricity. A notable effect of these parameters is observed on the connection capacity. The mode of failure of the studied specimens ranged from chord plastification for small thicknesses followed by chord face punching to excessive column ovalization at the vicinity of the connection followed by either chord punching or tearing out in the weld. For CHS columns with large thicknesses, punching failure in the column face or premature weld failure is observed. Finally, the results of the parametric study indicated a prominent effect of load eccentricity on the in-plane bending capacity. Therefore, a proposed improvement to the current design guidelines for the strength of CHS column branch plate connection subjected to in-plane bending is presented in this paper.