Finite Element Analysis And Reinforcement Design Of 24-meter-span Prestressed Double-T Slab After Fire

Due to the characteristics of good crack resistance,less consumables and light weight,the prestressed concrete double-T slab is widely used in large space and large span structures.Compared with ordinary reinforced concrete members,the cross-sectional size of the prestressed concrete double-T slab is smaller,and it is more likely to cause internal damage when a fire occurs,and the prestressed concrete member prestress level decreases at high temperatures,which affects the performance during normal use.Therefore,the research on the mechanical behavior of double-T slab after the fire and the reinforcement design have important reference meaning for engineering applications.In this paper,the fired single-story factory building panel—24-meter-span prestressed concrete double-T slab was used as the research object.The finite element analysis software ABAQUS was used to conduct heat conduction analysis and thermal-mechanical coupling analysis.The reinforcement scheme of the prestressed double-T slab after a fire was designed.The main contents of this paper include:(1)By testing of the factory building,the maximum fire temperature was determined,and the maximum fire temperature experienced by the prestressed double T plates in different areas was determined;(2)According to the fire temperature distribution,the fire conditions of the prestressed double T plate during the fire were determined.Based on the ISO standard fire curve,the elevated temperature curves of different working conditions were determined,and the thermal performance of concrete and prestressed steel stranded wire were clarified,the heat conduction analysis finite element model of prestressed double-T slab was established.The mechanical properties of the concrete and the prestressed steel stranded wire after a fire were clarified,the thermal-mechanical coupling analysis finite element model of prestressed double-T slab was established.(3)The cross-sectional temperature distribution of the double-T slab and the temperature of the prestressed steel stranded wire under different fire temperatures are obtained by the heat conduction analysis,the change rule of the effective prestressing force of the prestressed steel stranded wire with experienced temperature is determined.The cracking load,failure load,deflection change law and failure characteristics of the prestressed double-T slab after different temperatures were determined by the thermal-mechanical coupling analysis of the prestressed double T slad.(4)Based on the results of finite element analysis,the reliability of the prestressed double-T slab after a fire was evaluated,and the reinforcement scheme of the prestressed double-T slab was designed.