Experimental Study On Fire Resistance Of Cellular Composite Beams

Compared with the solid steel members,castellated steel members have greater bending stiffness under the same steel volume,and the web hole is convenient for pipeline to pass through,which is better for building function requirements.Therefore,the castellated steel members are more and more used in the steel structure of large span and multi high-rise buildings.At present,more research on the fire resistance of steel,steel and concrete composite members,but on the castellated components,castellated steel and Research on fire resistance performance of concrete composite structure is relatively small,the cellular composite beam structure experimental study on fire resistance of less.Therefore,the fire resistance of the castellated composite beam is studied in this paper.To reflect the true fire cellular composite components of the stress and failure mechanism,the test method used in this paper to simulate the real fire situation,cellular composite beam and observed the different circumstances of the member end temperature change and test in the test after the morphological change.In this paper,a total of 6 experimental groups,respectively on the protection of fireproof coating solid web composite beam,composite beam,castellated hexagon hole castellated composite beam,and the coating of 25mm thick coating type fireproof coating solid composite beam,composite beam,castellated hexagon hole castellated composite beam for heating under constant load fire resistance test.The span of each combination beam is the same.The size and reinforcement parameters of the concrete floor are the same.The width and thickness of the upper and lower flange of the steel beam,as well as the height and thickness of the web are the same.To meet the needs of test,a reinforced concrete material fire test furnace with supporting structure is built for outdoor use,which is 2 meters high,3 meters long and 1.5 meters wide.It is used to simulate fire environment.The wall of the fire test furnace is 0.25 meters thick,and 50mm thick aluminum silicate refractory cotton is placed inside.The main fuel is larch wood,and ignited by solid alcohol block ignition mode.Ventilation measures are combined natural ventilation with artificial ventilation.The test load is loaded by the number of mass 20Kg blocks,applying the fixed load on the component with uniform distribution mode,composite beam simply supported on the supporting structure of the ignition furnace,after monitoring two ends of the beam and midspan vertical displacement monitoring,cross combination of Liang Gangliang three component temperature,monitoring fire test furnace temperature.By comparing and analyzing the change of temperature and shape of each component,it contributes to the research and development of fire resistance of castellated components.Through experimental study,solid and cellular composite beam specimen in the real fire situation,such as fire protection,the fire resistance really poor,when the highest temperature reached 900 degrees,the specimen deformation increases dramatically,and ultimately overturn,different hole shape for the combination of little effect beam fire resistance;for Castellated composite fire-proof paint of the specimens,the fire performance compared to the solid composite beam specimen attenuation is small,and in the cooling stage,because of the cellular structure open pores contribute to cooling,it is compared to the same size of solid web beam bearing capacity of more rapid recovery performance,fire prevention to improve the coating composite beam fire resistance effect,and after the end of the fire,can be recovered through the bearing capacity before the fire.