Interfacial Bonding And Flexural Performance Of Steel-UHPC Adhesively Bonded Composite Bridge Deck

In order to alleviate or even cure the fatigue cracking and pavement vulnerability of orthotropic steel bridge deck,based on a high temperature resistant epoxy resin adhesive with good mechanical properties developed by the research group of the author,a new type of composite structure,steel-UHPC adhesively bonded composite slab,is proposed in this paper.(1)In order to explore the bending performance of steel-UHPC adhesively bonded composite slab,20 steel-UHPC adhesively bonded composite slabs were designed for static bending test.According to the test results,under the negative bending moment load,the elastic stage of steel-UHPC adhesively bonded composite slab is not only determined by the performance of UHPC itself,but also related to the interface performance of composite slab;the interface performance of composite slab cracks UHPC The crack distribution in the pure bending section of cast-in-place slab is denser,and the higher the reinforcement ratio is,the denser the crack is,while the rarer the crack is in the precast slab.Under the positive moment loading,the elastic limit of specimens with the same parameters is greater than that under the negative moment,and the cracking load is also greater than that under the negative moment.The cracking load is not only related to the interface performance between the composite plate UHPC and the steel plate,but also related to the cracking strength of UHPC itself.In two of the interface treatments,when the composite plate reaches yield,the interface does not break away.(2)In order to study the interface shear resistance of steel-UHPC adhesively bonded composite slab,20 push-out specimens were tested and simulated by finite element method.The results show that there are three kinds of failure modes in the interface of push-out specimens,which are related to the interface adhesion between steel-uhpc.In the cast-in-place test piece,the interface performance of the test piece with 1 epoxy resin adhesive and 3～5mm bauxite is the best.Among YZ series of specimens,No.1 epoxy resin adhesive has the best interface performance.Through calculation,the shear strength of No.1 epoxy resin adhesive can reach 3.42MPa in XJ series and 4.82MPa in YZ series.The finite element simulation results are in good agreement with the test results,and the relative error between the model and the measured ultimate bearing capacity is about 1.5%,which shows that the model can accurately predict the shear bearing capacity,load slip curve and the bonding performance of the adhesive laye.(3)Based on the background of a bridge in China,the test design of steel-UHPC adhesively bonded composite slab is carried out.The calculation results show that the UHPC layer and the adhesive layer in steel-UHPC adhesively bonded composite slab structure have obvious localities.The most unfavorable tensile stress on the top of UHPC layer is 9.05MPa,which is less than the nominal tensile stress of UHPC cracking.The most unfavorable shear stress of the adhesive layer is 2.11 MPa,which is less than the shear strength(4.82MPa)of the epoxy resin adhesive tested in the push out test.The maximum stress amplitude of steel UHPC bonded composite deck is 14.46MPa,which is significantly lower than that of pure steel deck,with a decrease of 83%.The maximum tensile stress drop of steel deck is 86.5%.