The Calculation For Equivalent Fire Load Of Axially Loaded Concrete Columns Based On The Temperature-Time Curve Obtained Through FDS

The building fire is very dangerous because of high frequency and serious loss. Moreand more people pay attention to anti-fire performance of reinforced concrete members orstructures with highly application. The results show that, environmental temperature isconfined by many factors, and the structure calculation of resistance to fire sometimes haslarge difference under the condition of applying IS0834standard warming up curveuniformly and it can’t truly reflect structure response of resistance. In this paper, we canobtain the actual temperature curve by using the FDS to simulate the indoor fire, as theboundary conditions of temperature field finite element analysis of structures. Anotherway about concrete structure fire resistance design is introduced---equivalent fire load.Itis a new design method with consideration of the unity of the high temperature andearthquake/snow/wind acted on structural.Firstly, using the FDS to simulate fire development of single room, get theenvironment temperature curve. With actual temperature curve as the third kind boundarycondition and finite element analysis software ANSYS, calculate the component sectiontemperature field distribution, to provide the basis of simplified calculation of equivalentfire load; By using the foregoing theory and numerical analysis, put forward specificequivalent fire load of the simplified calculation method of further modification of theexisting formula, all subject to the pillar of example analysis show that the simplifiedformula is reasonable.The main conclusions are as follows: the indoor temperature of the each point is inthe rising over time with the fire development. location, open state, fire source positionand size have an impact on the temperature rising the curve of actual, the structure fireresistance design standards are used in heating curves as the ambient temperature is notscience, either is not accurate. The component temperature distribution within the crosssection under fire directly affects simplified calculation results.We can get the temperaturedistribution in cross section at different time by ANSYS thermal analysis. The calculation results indicated that concrete is hot inert materials. Along with the advancement of time,Isothermal within the same value is toward inside continuously. According to demand,different temperatures at different time of the isothermal results can be extracted. Based onthe existing equivalent fire load, simplified calculation of more accurate method isproposed. Replaced500℃boundary, this paper put forward the two steps simplifiedmodel, in order to gain more accuracy. Calculation results show that the simplified methodcan about effectively improve the accuracy of10%for pillar all around fire.