Numerical Simulation Analysis On Fire Resistance Of Steel Structure Substation

In recent years,with the number of substations increasing year by year,The number of large oil-filled equipment such as transformers and combustible cables has increased exponentially,leading to a significant increase in the risk of fire in substations,which poses a serious threat to the safety of substation main structure,especially steel substations in fire.Steel substations are more often protected by spraying fireproof coatings and cladding fireproof panels.The temperature distribution,displacement response and fire resistance limit time of the steel structure differ while the fire protection method is different;most of the equipment rooms of indoor substations are high and large space buildings,and the thermal-mechanical response characteristics in case of fire are different from those of general indoor fires.This thesis intends to numerically simulate the fire resistance performance of the main structure of an indoortype steel substation,and study its temperature distribution and fire resistance performance under different working conditions,in order to provide reference for the fire protection of steel substations.In this thesis,the fire simulation software FDS is first used to simulate a fire in an indoor substation building,and establishing different fire scenarios by altering the rate of heat release from the fire source and the location of the fire source,and analyzing the temperature distribution of different fire scenarios.Secondly,the values of the parameters related to the fire resistance analysis of the steel are determined.The sequentially thermal-mechanical coupling method described is used to simulate the fire resistance of substation steel structures using ABAQUS software,and structural temperature distribution,displacement response and fire resistance limit time of different fire scenarios were compared and analyzed.Finally,different fire protection measures and different fire scenarios are set as different working conditions,and temperature distribution and fire resistance of substation steel structure under different thickness of fire protection layer and different working conditions were studied.The main findings of this thesis include:(1)The rate of heat release from the fire source and the location of the fire source have significant effects on the distribution and size of the temperature field of the fire.The rate of heat release from the fire source mainly affects the fire temperature magnitude and has less effect on the fire temperature distribution.The location of the fire source mainly affects the fire temperature distribution and has less effect on the temperature maximum near the fire source.(2)After the fire resistance test of the structure according to the load bearing method of the code,it was found that the thickness of the fire protection layer that meets the fire resistance requirements is on the safe side,but the structural damage forms under the FDS simulated fire and under the ISO 834 standard heating curve are different.(3)The heating curve of the simulated fire using FDS is locally higher than the ISO 834 standard heating curve,which may lead to premature structural damage.(4)As the thickness of the fire protection layer increases,the temperature reduction rate of the component gradually decreases.When the fire protection layer is too thick,it is not economical to increase the thickness of the protection layer again in order to improve the fire resistance of the structure.(5)The fireproof coating and fireproof board have different effects on the temperature distribution and the displacement response of the structure in fire.The application of fireproof coating does not change the heat transfer path,has less effect on the temperature distribution of the components in fire,and reduces and delays the displacement response of the structure in fire.The cladding of fireproof board can changes the heat transfer path,which may lead to a larger temperature difference in the cross-section of the component and a larger bending deformation of the component.