Comparison between ACI and AISC for Concrete-Filled Tubular Columns

A wide range of experimental data and associated analytical results are used to examine the applicability of two widely used design codes (i.e., ACI and AISC) for calculating the capacity of concrete-filled steel tubular columns (CFTs). The database consists of the measured results from past studies as well as from three specimens tested by the writers. The test specimens include short and slender CFTs made with normal- and high-strength steel tubes filled with normal- and high-strength concrete. To gauge the success of the code-based methods, the capacities are also computed based on fiber analysis techniques, along with a member level iteration algorithm for analyzing members with significant length. In addition to inherent differences between ACI and AISC, the reported study points to potentially large differences between the capacities as computed from these two methods. However, the capacities from ACI and detailed analytical results are generally closer. Neither design method appears to be appropriate for CFTs made with high-strength steel tubes. A simple method based on full plasticity of the steel tube tends to produce significantly improved results for such cases.