Finite Element Analysis of Concrete Encased I-Section Steel Column Exposed to Fire

Abstract

This thesis presents finite element analysis of concrete encased I-section steel column exposed to fire by using 3D finite element (FE) software. The objective of this research was to investigate the Finite element analysis of concrete encased I-section steel column exposed to fire. In this research, two analyses have been employed thermal and mechanical analysis for the same x section of concrete and different steel section of composite columns are conducted by exposing the surface to fire. The first analyses simulate non-linear transient heat transfer analysis from ISO 834 time-temperature curve to the surface of concrete column. The second analysis conducted non-linear stress analysis to simulate the structural behavior of the same column concrete but different steel size subjected to mechanical load and nodal temperature (as nodal temperature time history) has been calculated. The results of this research indicated that composite column as fire exposure time increase the material behavior degrades since the nodal temperature distribution increases when exposure time increase. The stress distribution of the column section has decreased; however, when the steel ratio decreases the fire duration has differently increased. In addition an increase in duration of fire exposure of the column, the compressive strength of concrete has decreased. At elevated temperatures is the composite column totally depending on the thickness of the steel section. Larger steel sections result in an increase in strength and stiffness at ambient temperatures, but more steel results mostly in a smaller concrete cover. As last it is concluded that the thickness of the steel section is the most determining factor in the temperature distribution. It is recommend that this study can lay a basis for Finite Element Analysis of fire effects in other structural elements i.e. the reinforced concrete, steel structure and composite column member as one side, two side and three side fire exposures are studies.