Study On The Prestress Loss Of Fire Process And Post-disaster Evaluation Method Of PC Girder Bridge

With the social and economic development develops rapidly, the basic construction ofroad and bridge has entered a new stage of development, but in recent years, the bridgefrom fire accident to happen from time to time, most bridges are pre-stressed concretebridge, under high temperature, the thermal parameters and thermodynamic parameters ofconcrete and pre-stressed iron resulting in varying degrees of impact, cause serious threat tostructural of bridge, even the risk of bridge collapse exisited. So, it is necessary to study thefire resistance of pre-stressed bridge on the condition of high temperature fire and timely,scientific to be hurt structure damage assessment, puts forward reasonable strengtheningplan to restore the safety and function of the structure, in order to applt the social andeconomic development needs.Collected the law on concrete and prestressed reinforced mechanical performanceparameters and thermal parameters with temperature variation finishing at home and abroad.Through Contrastive Analysis, given the thermal parameters applicable to this articleprestressed concrete structure temperature field analysis, and applies to prestressed concretestructure deformation analysis of the mechanical performance parameters.Use the results of the above analysis, put forward the effective prestress loss formulaof prestressed concrete beam in fire. Use general-purpose finite element analysis softwareconducted the whole process analysis of the prestressed concrete rectangular beam underthe load, prestressed, and high temperature, concrete strength response in different fire time,summarizes the deformation law of the structure under the fire environment;Based on theprestressed concrete box girder under load, prestressed, and high temperature combinedeffect, analysis the whole process of effective prestress response in different firetime,summarizes the deformation law of the structural deformation under the fireenvironment. Based on the strength of concrete damage and effective prestress loss to PCbeam deformation contribution, obtained the weight ratio of the concrete strength andeffective prestress contribution to structural deformation.The evaluate of prestressed concrete beams post fire was expounded and detailed content was discussed. The injury diagnostic procedures of prestressed concrete beambridge post fire were put forward. Based on the horizontal incremental detectionmethod,Integrated the ultrasonic-rebound combined method for testing post fire effectiveprestress concrete strength damage situation.Given the post fire concrete strength damagegrade criteria of assessment and the prestressed steel effective prestress loss grade criteria ofassessment, and given the prestressed concrete beam bridge post fire damage combinedcriteria of assessment.By the Bridge fire engineering example demonstrate the results of this study. Theresult of this paper for practical prestressed concrete bridge fire accident analysis,assessment and reinforcement application has certain reference value.