Experimental Study on Mechanical Properties of 450-level Big U-rib Orthotropic Composite Bridge Deck

Abstract:

To study the mechanical properties of orthotropic steel-concrete composite bridge deck with big U-ribs. The orthotropic steel bridge deck with a U-rib opening width of 450mm was chosen as the research object in which ultra-high performance concrete was introduced. Two full-scale big U-rib steel-concrete composite bridge decks are tested to evaluate the static bearing capacity including the strain of concrete and steel bars， the deformation of the structure and the development of cracks. And parametric analysis is carried out based on the finite element model of UHPC plastic damage. The results showed that the thickness of the big U-rib in the bridge deck was increased from 8mm to 10mm， the yield load and ultimate bearing capacity were arisen by 24.86% and 47.48%， the number of concrete cracks in the pure bending section was reduced， and the crack spacing increased. The effect of the thickness of the troughs on the static performance of the structure is mainly reflected in the nonlinear stage. The parametric analysis results showed that when the cross-sectional configuration of the 450-level big U-rib structure were changed， the buckling deformation capacity of the structure were influenced differently. Changing the thickness of the top plate of the structure has less influence on the safety factor in ultimate state， while increasing the thickness of the U-rib could significantly increase the safety factor of the structure. Based on the experimental results and FEA， an empirical formula for the buckling reduction coefficient of 450-level big U-rib steel-UHPC composite bridge deck is proposed， which is more related to the height-thickness ration of U-rib and width-thickness ratio of U-rib bottom plate.