Collapse Analysis Of Steel Structure Under Elevated Temperatures

Abstract

Initial local damage spreading from one component to the other componentcausing the failure of the entire structure or disproportionately is defined as progressive collapse. Disproportionate collapse results from small damage or minor action triggering the collapse of a relatively whole part of the structure. The present study investigates a three dimensional, four storey rectangular shaped moment resisting steel frame structure subjected to fire loads. The investigated parameter comprise of the application of elevated temperatures in each consecutive storeys. The main objective of this study is to understand the responses due to staticlinear loading in the structure caused by different column removal scenarios. Linear static progressive collapse analysis is carried out using the finite element software-SAP 2000 and the results obtained in terms of Demand Capacity Ratio (DCR) for the selected columns which are checked for permissible limits as mentioned in General Services Administration (GSA) guidelines. The comparisons are drawn before and after the effect of fire. Based on the DCR values obtained the collapse of the structure is predicted. The force redistribution and influence on the axial forces due to column loss are also studied. The effect of fire has significant change in DCR values which indicates the redistribution of moments at different levels.