FINITE ELEMENT ANALYSIS OF COMPOSITE COLUMNS SUBJECTED TO FIRE

Abstract

The potential hazard of fire is one of the major concerning issues after the recent events of 9/11 and others. A lot of studies and research work is being carried out presently, to ensure the safety of buildings. But, there is no accurate method to estimate the fire endurance/resistance for a building due to the variability of fire characteristics, material properties of construction material, and other characteristics of a building. One can only provide guidelines and can adopt from the lessons learnt in the past to ensure better quality to make the buildings more fire proof, so that they can withstand high temperatures and stresses for a longer time, before collapse mechanism occurs. From a long time, live laboratory tests have been conducted to study the performance of assemblies by subjecting them to appropriate time-temperature histories that are derived from standardized fire curves. In recent times, due to the advances in technology, computer models have been developed, that aid towards the simulations of assemblies and other components of a building that are subjected to a fire event. This approach helps in attaining reasonable results, thereby providing an alternative to the prescriptive and performance-based approaches. For proper and accurate simulation process, the use of software is a must along with the support of technical resources. This project deals with the behaviour of composite column at ambient and elevated temperatures. The behaviour is highly non linear due to the composite material action and also due to the material properties at high temperatures. To exactly know how the column behaves at elevated temperatures, step by step analysis is carried out on steel sections and composite sections at ambient temperature. Finite element software Ansys 11 (Academic Research) was used for the ambient temperature analysis as well as to study the non-uniform temperature distributions and the coupled thermal-structural analysis in case of a I-section column partially encased with concrete.