钢-UHPC组合梁负弯矩区受力性能试验

为解决钢-混组合梁负弯矩区桥面板的开裂问题，以桥面连续钢-混组合梁为研究对象，负弯矩区桥面板采用超高性能混凝土（Ultra-High-Performance Concrete，UHPC）代替传统普通混凝土，对其抗裂性能展开研究，并设计3根不同负弯矩区接口形式的钢-UHPC组合梁，采用一种独特的转角加载方式进行全过程静力加载试验，获得转角、临界开裂荷载、应变等关键试验数据；基于Abaqus的混凝土塑性损伤模型建立试验梁的非线性有限元模型，并对试验过程进行模拟。研究结果表明：钢-混组合梁负弯矩区采用UHPC，能明显提高负弯矩区的开裂性能、有效解决了负弯矩区桥面板的开裂问题；建议了合理的负弯矩区接口形式及负弯矩区UHPC纵向铺设长度取0.1L；采用黏结滑移理论，提出了简易的UHPC裂缝宽度计算公式。

Experiment on Negative Bending Behavior of Steel-UHPC Composite Beams

To solve the cracking problem of bridge deck in steel-concrete composite beams under negative moment, ultrahigh-performance concrete (UHPC) was used instead of normal concrete under negative bending for investigating the cracking behavior. Three steel-UHPC composite beams with different joint forms in the negative moment region were tested using a unique rotation angle loading method. The experimental key data, including the rotation angle, critical cracking load, and strain, were obtained. A nonlinear finite element model of the test beam was established based on the plastic damage model of concrete of Abaqus, and the entire test process was simulated. The results show that the cracking behavior is visibly enhanced using UHPC, thereby effectively solving the cracking problem of bridge deck. A reasonable joint form is presented based on the theoretical analysis and test results. The appropriate proportion of the UHPC longitudinal laying in the negative moment region is proposed to be 0.1L. A simplified formula for calculating the UHPC crack width was developed based on the bond-slip theory.