Sectional Strength Design of T-shaped Irregularly Concrete-filled Steel Tube Columns Under Combined Axial Load and Any Directional Moments

Abstract

This paper studies the sectional strength capacity and design method of T-shaped irregularly concrete-filled steel tube columns (T-ICFSTCs) under combined axial load and moment. The T-ICFSTC is formed by I-shaped steel, U-shaped steel and infilled concrete, and the I-shaped and U-shaped steel are welded together. T-ICFSTCs can be used in the corner of walls in residential building to avoid the exposure of columns in its indoor and to increase available area of indoor space. Based on finite element (FE) model verified by the tests, the load-bearing behavior of T-ICFSTCs under axial load and moment is investigated. Since the mono-symmetric T-shaped section exhibits different capacity under different directional bending moments, the sectional strength design curves of T-ICFSTCs subjected to combined N-M action are investigated under unidirectional moment along asymmetric and symmetric axis respectively. Sequently, for biaxial bending action, it is found that the shape of sectional strength design curve of T-ICFSTCs under combined N-Mx-My action are exclusively influenced by axial compressive ratio. A complete set of design methods and formulas for predicting sectional strength capacity of T-ICFSTCs under axial load and any directional moment are respectively established and agree well with FE numerical investigation results. This study could provides fundamentals and reference for sectional strength design of T-ICFSTCs.