Nonlinear Analysis On Interface Of Ovelay-UHPC Lightweight Composite Bridge Decks

In order to solve the two major problems of steel structure fatigue damage and pavement damage commonly occurring in long-span steel bridges,the author’s team proposed a new type of composite bridge deck structure system,namely steel deck +UHPC(Ultra-high performance Concrete)+ surface Layer combination bridge deck system.Based on the characteristics of UHPC high toughness,the composite bridge deck is in a non-linear stress stage in normal use,and the overall thickness of the bridge deck system is relatively thin,the surface stress distribution law and the applicability of the existing linear analysis method to the new composite bridge deck Need to be further explored.To this end,this paper established a non-linear finite element model of steel-UHPC-surface composite slabs to carry out research,and mainly completed the following research work:a nonlinear finite element model of the steel-UHPC-TPO composite plate is established based on experiments to explore the stress characteristics of the composite plate and the stress distribution between the TPO and UHPC layers of the wear layer.;Based on the validated nonlinear finite element model,the wear layer thickness,initial modulus and interlayer contact state are analyzed.The calculation results of the interlayer stress between the linear and nonlinear models are compared and analyzed.The following results are obtained: through nonlinear The finite element model observes that the linear elastic phase of the composite slab under bending load ends earlier than the experimental observation value.The elastic ultimate load calculated by the finite element model is 5.96 k N,and the test observes the first crack in the 2# and 3#specimens.The load values are 8.9k N and 11.4k N respectively;the factor analysis results show that when the friction coefficient between the TPO and UHPC layers is4.0,it is the closest to the actual situation.Completely continuous contact status or overload will cause the maximum shear stress and tensile stress in the TPO layer Increase,with the increase of TPO thickness or under high temperature conditions,the maximum shear stress and tensile stress in the TPO layer will decrease.Increasing the thickness of the TPO layer under economical and applicable conditions can effectively reduce the risk of longitudinal cracks in the surface layer;it is recommended to make80% continuous The friction coefficient of 1.6 is taken as the calculated friction coefficient closer to the actual contact condition.The contact state and thickness of the layers have no obvious influence on the shear stress distribution in the SMA layer.High temperature will significantly reduce the shear stress in the SMA layer compared to normal temperature.For the two composite plate structures,overloading has an adverse effect on the force between the surface layer and the UHPC layer;the calculation results of the interlayer shear stress and the normal stress in the incomplete continuous condition are lower than those of the fully continuous condition model;the thickness affects the interlayer shear stress and normal stress The calculated values have obvious effects;under high temperature conditions,the interlayer shear stress and normal stress of the two surface materials are significantly reduced.There is little difference in the calculated stress between the linear model and the nonlinear model of the combined bridge deck using TPO as the surface layer,and both are lower than the experimental strength value to meet the safety requirements.The linear model can be used in the actual engineering design and calculation to meet the engineering accuracy requirements.ball.The linear model calculation of the combined bridge deck using SMA as the surface layer is more secure,and the actual engineering calculation using the linear model can meet the requirements.