Analysis and behavior of high-strength rectangular CFT columns

Abstract

The current AISC Specification (AISC 360-16) specifies the material strength limits for concrete-filled steel tube (CFT) columns. According to AISC 360-16, the steel yield stress (Fy) for CFT columns should not exceed 525 MPa, and the concrete compressive strength (f’c) should not exceed 70 MPa. CFT columns are classified as high strength if either Fy or f’c exceeds these specified limits, and are classified as conventional strength if both Fy and f’c are less than or equal to the limits. Due to lack of adequate research and comprehensive design equations, AISC 360-16 does not endorse the use of high-strength materials for CFT columns. This paper makes a contribution towards addressing this gap using a two-step approach. The first step consists of compiling an experimental database of high-strength rectangular CFT column tests in the literature and evaluating the possibility of extending the current AISC 360-16 design equations to high-strength rectangular CFT columns. The second step consists of developing and benchmarking detailed 3D nonlinear finite element models for predicting the behavior of high-strength CFT columns from the database. The benchmarked models are being used to perform comprehensive parametric studies to address gaps in the database and propose design equations for high-strength rectangular CFT members, which will be part of a future paper.