A NUMERICAL STUDY ON THE EFFECT OF CONCRETE INFILL AND INTUMESCENT COATING TO FIRE-RESISTANT BEHAVIOUR OF STUB ELLIPTICAL STEEL HOLLOW SECTIONS UNDER AXIAL COMPRESSION

摘要

This paper presents a numerical study on the effect of concrete infill and intumescent coating to the fire resistant behaviour of stub elliptical concrete filled steel tubular (CFST) columns under standard fire. The selected elliptical steel hollow sections in this research cover the common used elliptical sections in current construction market; from 200 × 100 mm to 500 × 250 mm with wall thicknesses varying from 5 to 12.5 mm. Temperature distribution, critical temperature and fire exposing time of selected stub elliptical columns with concrete infill and other intumescent coating fire protection options under axial compression were extracted from numerical simulations using commercial FE package ABAQUS. Based on the comparison and analysis of the obtained results, the effect of concrete core and external intumescent coating to the thermal and structural fire-resistant behaviour of stub elliptical columns are discussed. Simple formulae are proposed to assess the critical steel temperature and maximum axial compressive load of stub elliptical CFST columns in standard fire.