Experimental and numerical study of T-shaped irregularly concrete-filled steel tube columns under combined axial loads and moments

Abstract

T-shaped irregularly concrete-filled steel tube column (T-ICFSTC) is formed by I-shaped steel, U-shaped steel and infilled concrete. The I-shaped steel and U-shaped steel are welded together to form a multi-cell CFST column. The T-ICFSTCs can be used in the corner of T-shaped intersection location of two walls in the buildings, which can avoid the exposure of the columns and increase the available area of the indoor space. The overall flexural stability performance of the T-ICFSTCs under axial loads and moments may still be an important problem in engineering design. This paper studies the overall flexural stability performance of the T-ICFSTCs under combined axial loads and moments. Firstly, the experiments of two T-ICFSTC specimens under eccentric loading with eccentric distance of 100 mm and opposite eccentric directions were carried out. Subsequently, the refined finite element (FE) models and the simplified finite element (FE) models are established and verified by the experimental results. The simplified FE models use beam elements (B31) and have higher calculation efficiency than the refined FE models, and are adopted for the numerical investigation of the T-ICFSTCs. Finally, based on the simplified FE model verified by the experimental results, the parametric analysis of the overall flexural stability capacity of the T-ICFSTCs under axial loads and unidirectional moments is carried out. The parameters studied include the height of the T-ICFSTCs, several geometric parameters of the cross section and the strength of material. Based on the results of numerical investigations, a preliminary design formula of the overall flexural stability capacity of the T-ICFSTCs under axial loads and unidirectional moments is proposed. This paper provides reference for engineering design of the T-ICFSTCs and the foundation to establish a complete design formula of the T-ICFSTCs under axial loads and unidirectional moments.