提出以抗拉强度高、耐腐蚀的超高性能混凝土（UHPC）为腹板和底板，以钢筋混凝土（RC）为顶板的预应力RC-UHPC组合箱梁，并制作了1根试件。开展抗弯试验，分析试件的裂缝开展规律与破坏模式；采用有限元软件对试验进行模拟，通过将有限元计算结果与试验数据进行对比，验证了有限元方法的计算精度，在此基础上建立了19个有限元分析模型，分析不同参数对开裂弯矩的影响；采用相关规范及既有文献资料，对预应力RC-UHPC组合箱梁的开裂弯矩与裂缝宽度进行计算。结果表明：试件加载至约33.3 %极限荷载时出现第一条裂缝，之后荷载-挠度曲线逐渐趋于平缓；开裂弯矩受预应力筋张拉系数、预应力筋配筋率、UHPC抗拉强度影响较大；采用基于换算截面的开裂弯矩计算方法与DBJ 43/T 325-2017中的裂缝宽度计算方法，分别计算预应力RC-UHPC组合箱梁的开裂弯矩及裂缝宽度，计算值与试验值、有限元计算值吻合较好。

The prestressed RC-UHPC composite box girder with high tensile strength and corrosion-resistant ultra-high performance concrete (UHPC) as the web and bottom plate and reinforced concrete (RC) as the top plate was proposed, and a specimen was fabricated. The flexural test was carried out to analyse the crack development pattern and damage mode of the specimen; the finite element software was used to simulate the test, and the calculation accuracy of the finite element method was verified by comparing the finite element calculation results with the test data, on the basis of which 19 finite element analysis models were established to analyse the influence of various parameters on the cracking moment; relevant codes and existing literature were used to investigate the cracking moment of the prestressed RC-UHPC composite box girder. The results show that: the first crack appeared when the specimen was loaded to about 33.3 %; the cracking moment was influenced by the prestressing bar tension factor, the prestressing bar reinforcement ratio and the tensile strength of UHPC; the cracking moment calculation method based on the conversion section and the crack width calculation formulas in DBJ 43/T 325-2017 were used to calculate the cracking moment and crack width of the prestressed RC-UHPC composite box girder, respectively, and the calculated values agreed well with the test values and the finite element analysis values.

TU997

福建省自然科学基金项目；福建省交通科技计划项目