Research On Mechanical Properties Of Corrugated Steel Plate-UHPC Composite Bridge Deck Under Positive Bending Moment

As an innovating orthotropic bridge deck,the corrugated steel plate-UHPC composite bridge deck was proposed to further reduce the number of welds in geometric irregularities and reduce the fatigue risk from the source.Using bending undulating corrugated steel plate instead of traditional roof-U-rib welding structure in order to eliminate the fatigue details of the weld seam between the roof and the longitudinal rib and eliminate the fatigue problem of the part completely,the UHPC structural layer with ultra-high performance concrete is set on the top of the corrugated steel plate,which is loaded simultaneously to ensure the bearing capacity of the structure and the stiffness of the bridge deck;and the composite pin with excellent shear resistance is introduced as the connector to ensure the coordinated force between them.Since there still be little research on the new proposed structure,in this paper,the mechanical characteristics of the new deck under positive bending moment are studied and analyzed.The main work and conclusions are as follows:(1)A three-dimensional finite element model of corrugated steel plate-UHPC composite deck is established,and the calculated results are in good agreement with the experimental data.Based on the finite element model,the stress change,strain distribution,crack development and damage evolution of UHPC from the whole to the local components under bending moment are further obtained as a powerful supplement to the experiment.(2)By simplifying the combined pin into a spring,the finite element spring model is established,which reduces the calculation cost to a certain extent.The results of spring model are in good agreement with the experimental results.On this basis,the factors affecting the positive moment bearing capacity of composite plates are analyzed.The composite slabs with different shear spans show the characteristics of high bearing capacity and small slip.Even if the shear spans are small and the longitudinal shear force is large,the bending failure of the mid-span section is still the control part of the structure,which further shows the excellent bearing capacity of the composite pins.Increasing the thickness of UHPC layer can improve the stiffness of the structure section and increase the bearing capacity.Meanwhile,the nominal shear stress at the interface increases and the interface slip increases.The continuous arrangement of pins is the key to the good mechanical properties of composite slabs.When the number of connectors decreases and the interface slip can not be effectively restrained,the mechanical properties of composite slabs will be significantly weakened.The setting of steel mesh has little effect on the bearing capacity,overall stiffness and interface slip of composite slabs.(3)According to the experimental and computational results of composite slabs,the theoretical analysis of the bearing capacity of the corrugated roof-UHPC composite bridge deck is carried out,and the practical formulas for calculating the deflection,cracking moment and ultimate bearing capacity of the elastic stage are given and verified respectively.The above research results can provide reference for engineering application and further research of corrugated roof-UHPC composite bridge deck.