Research On The Fire Resistance Performance Of SRC Column-RC Beam Frame Under Beam Failure Mode

The composite structure has the advantages of high rigidity,good ductility,superior seismic and fire resistance,and flexible form.In recent years,it has been widely used in super high-rise structures.At present,some relevant research work has been carried out at home and abroad on the fire resistance of single members of steel reinforced concrete columns(SRC columns)and reinforced concrete beams(RC beams)under fire.However,there are few researches on the fire resistance performance of SRC column-RC beam integral frame structure under high temperature,especially for the catenary effect of RC beam in SRC column-RC beam frame structure under high fire temperature.Therefore,it is necessary to study the fire resistance performance of the SRC column-RC beam integral frame structure to ensure the safety of this type of structure under fire.In this paper,the failure process,failure mechanism,fire resistance limit,main influencing parameters and catenary effect of the SRC column-RC beam integral frame structure are studied.The main work and conclusions are as follows:(1)The ABAQUS finite element analysis software is used to establish the temperature field calculation and analysis model of the SRC column-RC beam frame structure under high temperature and the thermo-mechanical coupling calculation model,and the validity and rationality of the model are verified by the existing test data.(2)Analyze the development law of the temperature field of the SRC column-RC beam frame structure under the high temperature of fire,as well as the failure process,failure mode and failure mechanism of the frame under the beam failure mode.The beam failure mode SRC column-RC beam frame structure deformation law is analyzed,and the beam failure mode SRC column-RC beam frame structure stress change law of concrete,steel bar and section steel under high temperature is analyzed.(3)The main parameters that affect the fire resistance limit of SRC column-RC beam frame structure under the beam failure mode are analyzed.The research shows that the beam load ratio and concrete material strength have significant effects on the fire resistance performance of the frame under fire.With the increase of the fire load ratio of the beam,the fire resistance performance of the frame has a significant tendency to decrease;while keeping other parameters unchanged,increasing the concrete compressive strength of the frame will lead to an increase in the level of internal force of the beam,and the fire resistance limit will be greatly improved.decline.The column load ratio,frame span,and reinforcement ratio have little effect on the fire resistance of SRC column-RC beam frame under the beam failure mode.(4)By adding linear springs at the beam ends and setting appropriate frame lateral stiffness,the catenary effect of the SRC column-RC beam frame structure under the beam failure mode under fire is simulated,and the catenary effect and damage of the frame beam are analyzed.Mechanism and deformation laws.The effects of beam fire load ratio,column fire load ratio,beam-column concrete strength,beam reinforcement ratio,frame span on the fire resistance limit of the restrained frame and the catenary effect of restrained frame RC beams are analyzed.