Research On Fire Resistance Of Prefabricated Concrete Composite Beam Subjected To Fire

With the energy-saving emission reduction,the increasing demands for environmental protection,and the rapid rise in labor costs,modernization of construction industry becomes an important way of sustainable development.As one of the forms of building industrialization,The assembled structure has the advantages of energy saving,environmental protection,saving template and shortening the duration,becoming a hotspot of research.,Currently,the research on the prefabricated reinforced concrete composite beam is mainly focused on the static performance and seismic performance.The research on the fire resistance of the prefabricated reinforced concrete composite beam is relatively small,which makes the anti-fire ability and safety of the prefabricated composite beam lack of necessary knowledge.Based on that,this paper studies the fire resistance of prefabricated composite beams,The main research work is as follows:1.According to the relevant literature,arrange the high temperature concrete and steel material properties,to be as realistic as possible,the thermal parameters and stress-strain relationship of concrete and steel used in this paper are selected.2.The temperature field of eight reinforced concrete beams was verified by finite element software ABAQUS,after verifying the rationality of the model,the temperature field model of the prefabricated reinforced composite concrete beams(PRCC)and the reinforced concrete beams are established,and the two are compared and analyzed.3.The mechanical model of the composite beam at room temperature and the composite beam model was verified by finite element software ABAQUS,after verifying the rationality of the model,the thermo-mechanical coupling model of the PRCC beams and the reinforced concrete beams are established.4.According to the results of the finite element software,the friction coefficient on the interface of PRCC beams,slip on the interface of PRCC beams at high temperature and the variation law of stress of concrete in compression zone and longitudinal reinforcement under high temperature,and the two are compared and analyzed.From the results it can be seen that as the temperature of the interface of PRCC beam around 400?,so the friction coefficient of the interface of PRCC beam is taken as 1;Under the same load ratio,the initial stress value of the concrete in the compression zone is larger than that of the reinforced concrete beam,and the change trend is different.The initial stress value increases with the load ratio;Under the same load ratio,the initial stress of the longitudinal reinforcement of the PRCC beam is also larger than that of the reinforced concrete beam.The change trend is similar,and the initial stress value increases with the load ratio;Under the same load ratio,the longitudinal reinforcement stress of the PRCC beam is always larger than that of the reinforced concrete beam,and the phenomenon of "stress advance" occurs.5.According to the results of the finite element software,the influence of related factors including load ratio,concrete strength,stirrup ratio and composite parameter Kh on the fire behavior were analyzed,and the fire resistance limits of the same section PRCC beams and reinforced concrete beams were compared and analyzed.From the results it can be seen that with the increase of load ratio,fire resistance of the beam decreased;increase of concrete strength will lead to the increase of fire resistance of composite beam;Stirrup ratio has no obvious influence on the fire resistance of PRCC beam;If the composite parameter Kh is less than a certain value,the fire resistance of composite beams will be greatly enhanced;There is an optimum ratio of shear span so that the fire resistance of composite beams largest;The effect of fire surface on the fire resistance of composite beams is significant,the lower the fire surface is,the higher the fire resistance is;fire resistance of the PRCC beam is slightly larger than the reinforced concrete beam.