Simulation Study On Fire Resistance Of Prestressed Concrete Double-T Slab In Fabricated Parking Building

Prestressed concrete double-T slab has the advantages of large span,superior structural performance,good overall performance and flexible section form.However,the mechanical properties of the prefabricated parking building constructed with double-T slab roof system are very complex under fire.When the prefabricated parking building is in fire,the development of the fire is quite different from that of the ordinary building,which is often more complex.In this article,the mechanical properties of prestressed concrete double-T slab under high temperature are analyzed and studied.Firstly,taking the parking building suffering from fire as the research object,the fire field of the parking building is simulated by PyroSim,and the temperature time relationship curve of the parking building is obtained.The result of the fire field simulation is applied to the finite element analysis software ABAQUS,and the temperature field of the prestressed concrete double-T slab in the FDS temperature rise curve and ISO834 temperature rise curve is obtained The thermal mechanical coupling analysis of the components is carried out by using the internal temperature field of the double-T slab,and the changes of the stress and deflection of the concrete and prestressed reinforcement in the process of fire are obtained.The results of finite element analysis are compared with those of ISO834 standard under the action of fire,which provides the basis for reinforcement design after fire.FDS simulation results show that the maximum temperature of ytpb2424 double-T slab with narrow rib beam spacing is about 60? higher than that of ytpb2430 double-T slab when the width of double-T slab is changed;when the position of fire source is changed,the maximum temperature of fire field at the slab end is about 100? higher than that in the slab;when the fire source is at the slab end,the temperature distribution in the fire field is mainly concentrated in the fire source The two sides of the double-T slab rib beam directly above form a longitudinal distribution along the double-T slab.According to ABAQUS simulation calculation,the maximum temperature of temperature field in the double-T slab under FDS temperature rise curve and ISO standard temperature rise curve reaches 750 ? and 940 ?respectively after 1 hour of fire;the deflection values of members are 380 mm and 518 mm respectively,and the stress values of steel strand fall to 42% and 35% of normal temperature respectively,and the maximum stress of concrete and prestressed steel strand is mainly concentrated at the support.The simulation results show that when the location of the fire source is located at the end of the double-T slab,the maximum temperature and the duration of the high temperature are significantly improved.At the same time,the high temperature is mainly concentrated on both sides of the rib beam of the double-T slab directly above the fire source.This phenomenon becomes more pronounced with the narrower rib-to-beam spacing of the slab.In the case of aFDS temperature-time curve fire,the deflection value of the double-T slab has not reached the fire resistance limit,while the deflection value of the double-T slab under the ISO834 curve has reached the fire resistance limit,and the single T slab is judged by the ISO834 standard heating curve has certain limitations.In this paper,the stress analysis of concrete and prestressed steel strands under high temperature of double-T slab can provide a basis for the fire resistance design and later strengthening of double-T slab.