Fire Behavior and Modeling of Short RC Columns in Pure Axial Compression: Role of Volume, Configuration, and Spacing of Lateral Reinforcement

Abstract

This paper studies the role of volume, spacing, and configuration of lateral reinforcement on the axial load resisting capacity of reinforced concrete (RC) columns at elevated temperatures. Short RC columns were tested under combined thermal and compressive loading conditions. Columns with different confinement reinforcement volumes, two different lateral reinforcement configurations, and three different lateral reinforcement spacing values were tested as a part of this study. The test results indicate that lateral reinforcement passing through the core of the column is more effective than rectangular lateral reinforcement placed at the perimeter in improving the fire performance of RC columns. Two different numerical approaches, namely, finite element-based approach in combination with a concrete plasticity model and fiber-based sectional analysis approach along with concrete confinement models available in the literature were used to simulate the axial compression behavior of RC columns at elevated temperatures. It was established that some of the popular confinement models developed for ambient temperature conditions could also be used to model the confinement effect at elevated temperatures. Further, a parametric study was conducted to study the role of lateral reinforcement on a broader set of column parameters. It was established that the confinement effect is generally more pronounced at elevated temperatures than at room temperature.