450级大U肋正交异性组合桥面板静力力学性能

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

摘要:

为了研究大U肋正交异性组合桥面板的静力力学性能，以U肋开口宽为450mm的正交异性钢桥面作为研究对象，引入超高性能混凝土，设计制作了两个足尺的大U肋正交异性超高性能混凝土组合桥面板，通过静力加载试验测试了大U肋正交异性组合桥面板的承载能力、破坏形态及主要截面上的应变；在此基础上，建立基于UHPC塑性损伤的有限元模型展开参数化分析。试验结果表明：大U肋正交异性组合桥面板的U肋厚度由8mm提升到10mm，屈服荷载与极限承载力提升了24.86%与47.48%，纯弯段混凝土裂缝数量减少，裂缝间距增大，加劲肋厚度的改变对于结构静力性能的影响主要体现在结构的非线性阶段。参数化分析结果表明：改变450级大U肋截面构造尺寸对结构屈曲变形能力有不同程度的影响，顶板厚度的改变对结构极限状态时的安全系数影响较小，提高U肋厚度可以大幅提高结构安全储备。依据试验结果与有限元分析提出了450级大U肋钢-UHPC组合桥面板的屈曲折减系数经验公式，该系数同U肋高厚比与U肋底板宽厚比更为相关。

关键词:正交异性组合桥面板;试验研究;大U肋;超高性能混凝土;有限元模拟

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.

Key words:composite bridge deck;ultra-high performance concrete;experimental study;big U-rib;finite element simulation