Research On Fire Resistance Performance Of Prestressed Concrete Box Girder Bridge

With the fast development of our economy and transportation construction, traffic accidents is growing rapidly and transportation infrastructure risk also increases. As one of the risks, fire cause more and more damage to the bridge. The fire to bridge hinder the normal traffic, and even cause bridge collapse, more serious economic losses and social losses. Due to the high cost and constraints, the fire resistance test of bridge is difficult. Using finite element method, this paper adopted prestressed concrete box girder bridge widely used in bridge engineering for fire resistance performance studying. The main research contents are as follows:(1) The research productions and rules on thermal properties of prestressed reinforcement and concrete under high temperature is referenced both at home and abroad. Suitable thermal properties of materials is confirmed as the basis of studying the temperature field of box girder section.(2) By the transient analysis method, research the temperature field of box girder section in the way of nonlinear analysis, in the case of the standard heating conditions.The effect factors of temperature field, such as the time by fire, cover thickness, cross-sectional size and surfaces exposed to fire, is analyzed.(3) Based on research productions on mechanical properties of prestressed reinforcement and concrete before and after high temperature inside and outside of country, appropriate mechanical properties of materials is confirmed as the basis of studying the fire response of prestressed concrete box girder bridge.Based on the finite element calculation of temperature stress, methods and procedures are provided for the fire response of prestressed concrete box girder bridge.(4) Using the thermal-structural coupled analysis method, research the fire response of simply supported prestressed concrete box girder bridge under different cover thickness, getting the prestressed reinforcement temperature and deflection varying with the time by fire and the differences of load-deflection relationship before and after fire. Research continuous prestressed concrete box girder bridge, getting section stress and support reaction in the case of the most disadvantageous position by fire.