预制NSC梁现浇UHPC铰缝弯剪性能试验与分析

Bending and Shear Performance of Prefabricated NSC Beam with UHPC Key Joints

超高性能混凝土(UHPC)具有优异力学性能以及与预制混凝土粘接强度高,将其作为装配式空心板梁桥铰缝材料,可以避免铰缝病害的发生。先对空心板梁桥进行整体受力分析,根据分析计算得到的最大弯剪比,设计3组共6根铰缝梁模型进行弯剪试验常规型NSC铰缝梁(N-N)、常规型UHPC铰缝梁(N-U)和加强型UHPC铰缝梁(E-U),研究铰缝梁的主要开裂形态、承载能力和荷载-挠度响应。其试验结果表明:N-U试件、E-U试件开裂荷载较N-N试件开裂荷载分别高出477%、794%;N-U承载力较N-N试件提高近215.1%,E-U承载力较N-N试件提高近543.4%;E-U试件变形刚度较大,N-U试件次之,N-N试件最弱;加强型UHPC铰缝应用于空心板梁桥具有良好的工程意义。

Due to the excellent mechanical properties of UHPC and its high bonding strength with prefabricated concrete,it can be used as key joint material of adjacent prestressed box-girder bridges to avoid the occurrence of key joint diseases.In this paper,the overall force analysis of adjacent prestressed box-girder bridges is firstly carried out.According to the maximum bent-shear ratio calculated by analysis,three sets(6 in total)of joint beam models were designed for bending and shear test(normal type NSC key joint beam(N-N),the normal type UHPC key joint beam(N-U),the enhanced type UHPC key joint beam(E-U)).The main cracking morphology,bearing capacity and load-deflection response of joint beam are studied.The test results show that the cracking load of N-U specimen and E-U specimen is 477%and 794%higher than that of N-N specimen respectively.The bearing capacity of N-U was nearly 215.1%higher than that of N-N specimens,and the bearing capacity of E-U was nearly 543.4%higher than that of N-N specimens.The deformation stiffness of the E-U specimen was relatively large,followed by the N-U specimen,and the N-N specimen was the weakest.The application of enhanced UHPC key joints in adjacent prestressed box-girder bridges has good engineering significance.