Computational simulation of elliptical concrete-filled steel tubular short columns including new confinement model

Abstract

The confinement mechanism in elliptical concrete-filled steel tubular (CFST) columns differs considerably from that in circular or rectangular CFST columns. It is essential to quantify this confinement effect in elliptical CFST columns in order to accurately predict their structural responses. This paper describes a computational model utilizing the method of fiber analysis for the nonlinear simulation of short CFST elliptical columns that are concentrically loaded. Based on available experimental data, a new model of confinement is developed for determining the lateral stresses on the filled concrete in CFST elliptical columns and included in the fiber-based model. A factor of strength degradation is derived that quantifies the post-peak residual strength of concrete. Comparisons with experimental results are made to assess the accuracy of the computer simulation method developed. Investigations into the performance of CFST elliptical columns with important variables are undertaken by using the computer simulation program. An equation is given that determines the capacities of short elliptical CFST columns recognizing concrete confinement. The applicability of the codified methods for CFST columns of rectangular and circular sections to the design of CFST elliptical columns is investigated. It is found that the computer simulation and design models proposed provide accurate predictions of the structural behavior and strength of short elliptical CFST columns loaded concentrically.