Study On Deck Pavement Of Steel-concrete Composite Bridge Based On Temperature-load Coupling

Due to the difference in the expansion coefficient of steel and concrete,when the solar radiation or the outside temperature changes,the temperature change rate of the steel structure part is very fast,and the concrete layer is lagging behind,and the temperature difference between the two will cause complex temperature effects.Under the coupling effect of this unfavorable temperature effect and vehicle load,the bridge deck paving usually produces ruts,fatigue cracking and other problems in the early stage of operation,so it is necessary to carry out research on the mechanical characteristics of the bridge deck paving under temperatureload coupling for steel-concrete composite girder bridges.Firstly,in order to explore the mechanical characteristics of the steel-concrete composite bridge deck pavement structure under temperature-load coupling in the high-altitude area of Mountainous Region of Yunnan Province,the causes of the rutting disease of the bridge deck pavement of the steel-concrete composite bridge were analyzed through field investigation,and the temperature-load coupling method was proposed for the characteristics of the steel-concrete composite bridge;based on finite element software,a three-dimensional finite element model of a steel-concrete composite girder suspension bridge was established,and the mechanical response of the bridge under constant load,vehicle load and temperature was analyzed and verified the reliability of the finite element simulation results.Secondly,based on the simulation model of the pavement temperature field of the bridge deck,the temperature field of the pavement structure of the steel-concrete composite bridge deck and the change law of the temperature stress affected by the ambient temperature are analyzed.The results show that in the period of 0:00 ～ 6:00,the temperature of the bridge deck pavement is in a stable stage,and the temperature of the pavement layer is basically the same as the ambient temperature;in the period of 6:00 ～ 14:00,the temperature of the bridge deck pavement structure is in the heating stage,and the temperature of the top surface of the pavement layer is high;during the period of 14:00 ～ 24:00,the temperature of the bridge deck pavement structure is in the cooling stage,and the temperature of the bottom surface of the pavement layer is higher.For different paving structures,the maximum tensile stress is between0.8MPa ～ 1.0MPa,while the maximum compressive stress is between 0.5MPa ～ 0.6MPa;the temperature stress of the pavement layer under high temperature conditions in summer is dominated by compressive stress,the compressive stress on the top surface of the pavement layer is greater than 0.8MPa,and the temperature stress of the lower layer of the pavement is less affected by the ambient temperature,and it is basically stable at 0.3MPa ～ 0.4 MPa.Finally,based on the coupling model of bridge deck pavement temperature-load,the sensitivity factors of the pavement layer and the mechanical response characteristics are analyzed.The results show that increasing the thickness of the upper and lower layers of the bridge deck of the steel-concrete composite bridge can significantly reduce the tensile stress and interlayer shear stress of the road surface;the modulus of the upper layer of the pavement increases,and the tensile stress of the paving surface increases,and the reduction of the modulus of the lower layer can significantly reduce the interlayer shear stress;under the most unfavorable temperature-load coupling,the mechanical response of the pavement structure of the steel-concrete composite bridge deck gradually decreases along the depth of the pavement layer,and there are certain differences between different paving structures;The tensile stress and interlayer shear stress of the pavement layer in the area of the loaded steel stringer are 15.5%and 12.0% higher than that of the non-loaded steel stringer area,and the longitudinal fatigue cracking problem of the pavement layer along the flange of the steel stringer should be focused on.Under the action of 500,000 times of axial load,the permanent deformation generated by the four pavement structures is less than 3.5mm,and for the permanent deformation verification of the bridge deck pavement,the estimated value is similar to the measured value,and the maximum deviation is 13.5%,which has good consistency.In this paper,the mechanical simulation analysis of the steel-concrete composite bridge deck pavement under temperature-load coupling is proposed,which reveals the change of stress response characteristics of the steel-concrete composite bridge deck,and a useful analysis method and theoretical reference for the optimization of deck paving construction of steelconcrete composite girder bridges is provided.