High Temperature Deformation Analysis Of Prestressed Concrete Box Girder

At present, China’s roads and bridges foundation construction develops rapidly,especially in the central and western regions, the highway bridges in the proportion is higher,and usually is a box section of prestressed concrete beam bridge. Accompanied by a variety ofbridge disaster, which bridge fire can cause of the bridge structure safety posed a seriousthreat, even the existence of the risk of leading to the bridge collapse. So it is necessary tomake the fire resistant performance research for the prestressed concrete box girder bridgeunder high temperature. Because of the high cost of the fire test, scale model have scaleproblems, and can’t simulate the complex boundary conditions, this article uses the finiteelement program ANSYS for prestressed concrete box section beam simulation analysis. Themain contents are as follows:①Collected the concrete and prestressed steel thermal parameters with temperaturechange rule research results in the domestic and foreign, conducting a comparative analysis todetermine the suitable value or formula for temperature field analysis of prestressed girderbridge. Classificated the results of the research on various mechanical properties of concreteand prestressed steel bars under and after high temperature in domestic and foreign.Comparative analysis, and determine a suitable thermodynamic parameters for prestressedbox girder bridge displacement field analysis, which mainly refers to the constitutive relation.②Based on the basic principle of thermodynamics, formulated the basic methods andsteps of the finite element solution. By using the transient analysis mathods on the box girderspan section, a fire temperature field nonlinear analysis have been done,and obtained the firetemperature distribution on box girder section at standard temperature curve. In addition,analysis the impact of temperature distribution, include the time of fire, cross-sectionaldimensions and fire positions.③Using thermal-structure indirect coupling method, make a nonlinear analysis on theprestressed concrete simply supported box beam bridge displacement field at hightemperature. And by time of fire, fire location, flange length, outer loads, prestressing degree,prestressed reinforcement ratio, the protective layer thickness, section size, span length andthe strength grade of concrete and so on influencing factors are calculated and analyzed,obtained their influence law of the box beam deflection. In addition, compared the mid-spandeflection difference with the simple support and three span continuous beam under differentfire position.