Moment-connection between I-beam and built-up square column by a diagonal through plate

Abstract Built-up box-columns are commonly used in rigid orthogonal moment resisting frames; however, the installation and welding of necessary horizontal continuity plates inside the columns are both labour-consuming and costly tasks. Accordingly, a new beam-to-box-column connection, called a diagonal through-plate connection, is presented in this paper to provide a new load path different from that of conventional connections and to facilitate the construction process of the connection. As the stiffness, strength and ductility of square box columns are almost similar around any axis, this connection is composed of vertical plates that pass through the diagonal axes of a square box-column and are welded to the box corners. In this paper, a detailed analysis and design procedure are presented for the proposed connection. In addition, the behaviour of the designed specimens was examined both experimentally and numerically. The cyclic response of the relatively identical test specimens showed that the connection withstands more than a 0.06-rad story drift with permissible strength degradation as well as that the connection can be qualified as a connection of special moment resisting frames within the limited sizes under investigation. Test observations and verified finite element results revealed that the column plates contribute effectively to the stiffness and strength of the connection panel zone; however, the panel zone remains relatively elastic throughout the test. A comprehensive parametric study was conducted using the finite element method to provide more detailed insight into the connection behaviour, including the load transferring mechanism and panel zone behaviour.