Research On Fire Resistance Of Prefabricated Steel Reinforced Concrete Beams

At present,China's architectural field is gradually moving towards industrialization.Prefabricated assembly building is an important carrier for the diversified development of industrial buildings.The development of prefabricated buildings can effectively control budget costs,construction duration,improve quality,and improve the safety of on-site construction.The coefficient reduces the generation of waste and the waste of energy to achieve the sustainable development of the building.The study of prefabricated steel reinforced concrete beams(hereinafter abbreviated as PSRC beams)focuses on the flexural bearing capacity of beams under normal temperature.There is no report on the fire resistance of PSRC beams under fire and high temperature.Due to the structure of PSRC beams and cast-in-situ SRC beams Different,especially the interface between cast-in-place part and prefabricated part has the risk of destruction at high temperature,so it is necessary to study its fire resistance performance.The main work is as follows:Based on that,this paper studies the fire resistance of prefabricated composite beams,The main research work is as follows:(1)Based on the research and analysis of thermal parameters and mechanical properties of concrete and steel under high temperature at home and abroad,the model of the concrete and the thermodynamic parameters and the thermodynamic constitutive relation in the simulation are selected.(2)Using finite element software ABAQUS to establish three-dimensional temperature field calculation model of PSRC beam,calculation model of bending capacity at normal temperature and theoretical calculation model of fire resistance at high temperature,and use the existing experimental data to verify the validity and rationality of the model.authenticating.(3)Using ABAQUS thermo-mechanical coupling model for PSRC beam and cast-in-place SRC beam,the fire-resistance limit of PSRC beam and cast-in-situ SRC beam at high temperature is compared.It is known that the fire resistance of cast-in-place SRC beam is slightly better than PSRC beam,and analyze the stress variation of concrete and steel in compression zone of PSRC beam under high temperature.(4)Due to the influence of temperature on the prefabricated part and cast-in-place concrete superimposed surfaces,this paper analyzes the superposition plane of PSRC beam under high temperature by taking different friction coefficients between superposed surfaces.The effect of friction coefficient on the fire resistance of PSRC beams wasstudied.In addition,the variation law of the slippage of the overlap surface and the distribution law of the slip on the PSRC beam under different frictional coefficients of the overlapped surface are discussed.(5)Computation and analysis of the parameters that affect the fire-resistance limit of PSRC beams.The results show that the load ratio,the section size of the steel section,and the number of fire surfaces are the main factors affecting the fire-resistance limit of prefabricated steel reinforced concrete beams.With the increase of load ratio,the fire-resistance limit of the beam obviously declines.When the aspect ratio of the internal H-section steel is kept constant,increasing the section size of the section steel is beneficial to improve the fire-resistant limit of the steel-concrete beam.The more the number of fire surfaces,the smaller the fire resistance limit of PSRC beams;the strength of cast-in-place concrete,the yield strength of steel bars,the yield strength of steel bars,the position of loads,and the span of beams are secondary factors that affect the ultimate load of steel reinforced concrete beams.The research in this paper can be used as a reference for the fire-resistant design of PSRC girder with simply supported ends.