| The steel-concrete composite girder bridge combines the advantages of steel and concrete materials,and is full of innovative space.Composite girder bridge ensures the cooperation of steel girder and concrete deck through shear connectors,and applies prestressing force to avoid concrete cracking in negative moment zone.However,the construction technology of composite girder bridge is complex,there are many hidden projects,and improper construction quality control easily leads to different degrees of diseases during the service period of the bridge,affecting the service life of the bridge.However,there is no specific construction quality inspection standard for steelconcrete composite girder bridge at present.In view of the above problems,this paper investigates the relevant codes at home and abroad,summarizes and analyses the construction quality inspection standards of steel-concrete composite beam bridges that have been clearly stipulated in the codes,determines the construction quality inspection parameters that are not mentioned or specified in the codes,and studies the vertical deviation of shear connectors and the initial construction by means of refined numerical analysis and field measured data analysis of bridges.The influence of initial imperfections on the performance of interface connection of composite structures,the influence of construction errors on the stress of concrete in negative moment zone when prestressing by preloading method or fulcrum displacement method,and the constant range of static load test verification coefficients of steel-concrete composite girder bridges are studied.The main contents include:(1)Investigation and analysis of construction quality inspection code for steel-concrete composite girder bridgesBased on the investigation and analysis of relevant codes at home and abroad,from raw materials to construction process,the construction quality inspection parameters of steel-concrete composite beam bridge are systematically sorted out,and the construction quality inspection parameters not specified in the codes,such as the vertical degree of shear connectors and the allowable deviation of initial construction defects,are determined.The preloading method is adopted.Or the construction allowable deviation when the prestressing force is applied by the fulcrum displacement method,and the constant range of the check coefficient of static load test,etc.(2)Analysis of effect of verticality deviation and initial defects of shear connectors on interface connection performance of composite structuresBased on the refined numerical model,the influence of the vertical deviation and initial defect of the bolt on its shear performance is analyzed.The results show that the shear capacity and stiffness increase with the increase of the inclined angle when the inclined direction of the bolt is opposite to the loading direction;when the inclined direction is the same as the loading direction,the shear capacity and stiffness decrease with the increase of the inclined angle,and when the inclined angle of the bolt is less than 7 degrees,the shear capacity and the reduction rate of the shear stiffness are less than 5%.It is suggested that the allowable deviation of the verticality of bolts should be set at 7 degrees.When the defect degree of the stud is less than 10% or the distance from the root is greater than or equal to the diameter of the stud,the influence of the defect on the bearing capacity of the stud is small.It is suggested that the defect of the bolt which is more than 10% or less than the diameter of the bolt from the root should be prevented in the construction process.(3)Analysis of key parameters for quality inspection of prestressing construction in negative moment zone of steel-concrete composite girder bridgesThrough numerical calculation and theoretical analysis,the influence of construction errors on the stress of concrete in negative moment zone is studied when prestressing is applied by Preloading Method and fulcrum displacement method.The results show that the pre-loading value and the displacement of fulcrum are linear with the pre-compressive stress of concrete.That is,when the relative error between the pre-loading value or the displacement of fulcrum and the design value is less than 5%,the deviation between the stress of concrete slab and the design value is less than 5%.It is suggested that the relative error between pre-loading value and fulcrum displacement value and design value should not exceed 5%.(4)Study on constant value range of check coefficient in static load test of steel-concrete composite girder bridgesBased on the static load test data of several steel-concrete composite girder bridges,it is found that the stress check coefficients are concentrated in the range of 0.2-1.0 and the deflection check coefficients are concentrated in the range of 0.4-1.0.Considering that the relative slip of steel concrete in steel-concrete composite girder bridges will reduce the bearing capacity and stiffness of composite girder,it is suggested that the constant range of stress and deflection check coefficients of steel-concrete composite girder bridges be appropriately broadened compared with steel bridges and concrete bridges.(5)Establishment of construction quality evaluation system for steel-concrete composite girder bridgesUsing analytic hierarchy process,the construction quality evaluation system of steel-concrete composite beam bridge is divided into three parts,including quality inspection of raw materials,quality inspection of construction process and quality acceptance of completed bridge.Combining with the existing specifications and the study of key parameters of new construction quality inspection,the whole process construction quality evaluation system for steel-concrete composite beam bridge is finally established. |
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