Heat Transfer Analysis In Steel Structures

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. The performance-based approach is very time consuming and also involves high costs. 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. This project deals with the study of heat transfer mechanism that takes place in steel structures in case of a fire event. For proper and accurate simulation process, the use of software is a must along with the support of technical resources. Due to high thermal conductivity of steel the heat gets transferred rather fast in the steel section which creates non-uniform temperature distributions because of variable thermal properties, like thermal conductivity and specific heat. 3-D finite element software TAS (Thermal Analysis Software) was used to study the non-uniform temperature distributions in case of a W 12x27 beam protected with vermiculite coating. The results were compared with the studies done by Professor Bletzacker, which involved the furnace testing of a W 12x27 beam by subjecting it to ASTM E-119 curve time-temperature history. In addition to this, the sensitivity of results was evaluated based on the variation of thermal properties for concrete, vermiculite, and gypsum board. Different beam models for W12x27 section protected with vermiculite and gypsum board coatings were simulated to justify their performance based on temperature rise within the assembly. Also, simulations were performed for analyzing the behavior of the beam when subjected to different fire curves like ASTM E-119 and ENV. Analytical analysis was also carried out using the method of Lumped mass parameter method to provide a comparison of results from different models. Finally, conclusions and recommendations were made to ensure further development and understanding in the field of Structural and Fire Protection Engineering