Publications

Due to the increasing number of fire accidents that are able to leave behind great losses and complete collapse of structures, structural fire safety has become a major consideration in the design of high rise buildings. The aim of this research is to evaluate how certain factors can influence the critical time (fire resistance) of concrete encased dual Ishaped steel columns under fire loads using ABAQUS. The parameters that were considered are: the applied load level, stiffness of surrounding structure to column, section dimensions, concrete cover, and axial distance from concrete surface to longitudinal bars. In order to achieve the posted objective, numerical investigation using ABAQUS software was used. The analysis method considered is an alternative of Heat Transfer Method. This approximate method is based on dividing the section into layers at the location of experimentally recorded temperature-time histories and then linking load amplitude to its corresponding layer. In the study, twelve models were generated which belong to three types of sections subjected to high and low load levels, as well as, high and low surrounding stiffness. It was found that decreasing the load level and increasing the concrete cover have a big influence in increasing the critical time of the column. The effect of increasing the stiffness of the surrounding on reducing the critical time is insignificant and can be eliminated by designers. However, the effect of slenderness (section dimensions) on the restraining axial force requires further investigation. Keywords :Built-up sections, dual I shaped column sections, composites, critical time, fire resistance rate, simulation.