Experimental Study On Temperature Field And Thermal Damage Of Concrete Beam At Elevated Temperature

With the rapid development of social economy and urbanization process speeding up,kinds of building fires occur frequently, poses great risk to people’s life and property safety.Reinforced concrete is the main load-bearing structure material of high-rise building structure,so the research of its fire performance has also become a hot topic in the study of building fire.Fire damage for concrete structures is mainly concentrated in the high temperaturemechanical properties of the material, the internal temperature field of structures and thestress and deformation with high temperatures and time variation. Because of the firetemperature variability and the complexity of concrete structure analysis after the fire damage,the study of such problems has continued.In this paper, some research work, such as, the fire temperature field and the mechanicalproperties of concrete elements have been done:(1) For the research of temperature distribution in the section of reinforced concrete beamunder different high temperatures, the experiment measured the temperature-time curve ofdifferent section point under three heating modes by the means of three surface heating test onthe three reinforced concrete beams, using the self-made high temperature electric heatingfurnace and temperature acquisition system. Through the comparative analysis of the test data,the laws of internal heat transfer and temperature field distribution of the beam element atelevated temperature were summed up,which provide reference to the analysis of mechanicalproperties of the structure under high temperature.(2) The calculation methods of concrete temperature field theory and thermal parametershas been analyzed, using the finite element analysis software ABAQUS, with actualtemperature in the furnace condition as boundary condition, the theoretical calculation resultsof the beam section temperature field has been obtained, and it’s coincide better with theexperimental data.(3) By concrete compressive strength and splitting tensile strength test, the comparativeanalysis of the strength data for different temperatures, holding time and cooling method under for the test block has been done, the high temperature strength of concrete damage lawhas been obtained.(4) Using the strength reduction factor which were obtained from literature material aboutconcrete and steel after high temperature, on the basis of the experimental data measured oftemperature field, the remaining carrying capacity of the beam after high temperature hasbeen calculated by equivalent cross-section reduction method, the bearing capacity changerules of reinforced concrete beam after high temperature has been achieved.