Built-up Closed Cold-Formed Steel Columns with Restrained Thermal Elongation Subjected to Fire

Abstract

Built-up cold-formed steel sections are widely used in building construction as primary structural elements. However, so far, the research on built-up cold-formed steel structural elements under fire situation is still scarce. Using the commercially available profiles, namely lipped channel (C) and plain channel (U), built-up closed cold-formed steel columns (R) were built and tested under fire conditions with restraint to thermal elongation. A numerical model was developed and calibrated based on the experimental tests in order to accurately reproduce the behavior of coldformed steel columns with restrained thermal elongation. It was found that the critical temperatures may be significantly influenced by the level of thermal restraint provided by the surrounding structure to the cold-formed steel column in fire