Study On Temperature Stresses Between UHPO-TPO Layers Of Ultra-high Performance Lightweight Combined Bridge Deck

In order to solve two difficult problems of fatigue cracking of steel bridge surface and early damage of pavement layer,the ultra high performance lightweight composite bridge deck system was put forward,UHPC(Ultra-High Performance Concrete)was laid on the steel bridge surface,and the surface layer was 10 mm TPO(Thin Polymer Overlay).In order to master the variation law of the temperature stress of the light combined deck and avoid the stress damage between the TPO-UHPC layers,this paper studies the temperature stress between the UHPC-TPO layers of the super high performance lightweight composite bridge deck,and the following work has been completed.The thermodynamic parameters of the pavement material were studied and tested.The coefficient of thermal expansion of the TPO material was measured by the strain gauge method.The TPO elastic modulus was measured by the ultrasonic method and corrected by the static elastic modulus.The experimental results show that the TPO strain has a linear positive correlation with the temperature,and the TPO coefficient of thermal expansion is much larger than that of the cement-based material;the TPO elastic modulus decreases with the increase of the temperature.The ABAQUS finite element software was used to establish the finite element model of the Runyang Yangtze River Bridge,and the inter-layer temperature stress of the composite paving structure was studied.The parameter sensitivity analysis was performed on the main factors affecting the temperature stress between TPO-UHPC layers,and the influence of thermal expansion coefficient ratio,TPO thickness,and construction temperature on the temperature stress between layers was investigated.The results of finite element analysis show that the TPO-UHPC layer stress distribution has a significant boundary effect.The temperature stress between the layers is close to zero away from the edge of the pavement layer and increases rapidly near the edge of the slab.Under uniform temperature changes,the interlaminar shear stress and the normal tensile stress decrease with the ratio of the expansion coefficient and the thickness of the TPO layer.The interlaminar shear stress dominates the pavement system compared to the normal tensile stress.In the environment of high temperature and low temperature,the influence of construction temperature on TPO-UHPC interlayer stress is opposite.Selecting the appropriate TPO thickness andconstruction temperature can reduce the temperature stress amplitude.The analysis of the individual vehicle load and vehicle-temperature coupling of the paving structure shows that the shear stress between the layers decreases with increasing temperature,and the normal tensile stress increases with increasing temperature.Under the vehicle-temperature coupling effect,both the interlaminar shear stress and the normal tensile stress between layers decrease with increasing temperature.The stress level and temperature stress level under vehicle-temperature coupling are very close to each other,only slightly increased,and the stress peaks are distributed at the pavement layer boundary position,which is consistent with the temperature stress distribution,and near the wheel position,the coupling stress and the vehicle load.The stress levels are very close.