Effect Of Spalling On Fire Resistance Of Axially Loaded Reinforced Concrete Column

With the development of economy and increasing of population density,the occurrence of fire increased year by year.At present,there is few research relating to high temperature spalling,the fire resistance of reinforced concrete structure under the high temperature spalling performance research is particularly urgent.Considering decreasing of effective section area dued to spalling,using ABAQUS to build nonlinear finite element calculation model under high temperature.By studying the effect of spalling on fire resistance of axial compression column and comparing influence to fire resistance of concrete column with different curing age,in the same temperature rising conditionconcrete strength and load location.The research contents and results show as follow:1)Based on temperature field model of concrete column,influence of different spalling degree to column temperature field was analyzed.The result shows that the section temperature of different columns shows upward trend as the spalling degree increasing.Enlarge the thickness of concrete protective layer can provide good protection under high temperature.With the same size,temperature of high strength concrete is higher than common concrete because of different thermal parameters.2)Analyzing ultimate fire resistance of common concrete and high strength concrete with different curing ages.The result shows that ultimate fire resistance improved along the thickness of concrete protective layer increasing.3)Analyzing the influence on concrete fire resistance with different load location,it is found out that The fire resistance of eccentric compression column performed better than axial compression column.The ultimate fire resistance was decreased with high temperature and vertical load,some measures should be taken to improved fire resistance performance of concrete column,such as enlarging the thickness of protective layer,adding anti-spalling material in concrete,improving strength level of reinforcement,extending curing age of specimens and so on.