UHPC桥面板力学性能与承载力计算方法

Mechanical Properties and Bearing Capacity Calculation Method of UHPC Bridge Deck

为研究某超千米混合式组合梁斜拉桥超高性能混凝土(Ultra-High Performance Concrete,UHPC)桥面板的静力抗弯力学性能,本文设计制备了抗压强度大于160 MPa.弹性模量大于45 GPa的UHPC材料,并开展了两片足尺UHPC桥面板静载抗弯试验,桥面板长宽高为3.8 m×1.0 m×0.17 m.通过分析UHPC桥面板抗弯受力状态和破坏机理,提出了UHPC桥面板受力计算图式,建立了UHPC桥面板的开裂弯矩和考虑UHPC受拉软化段应力下降的承载力计算公式.结果表明:UHPC桥面板具有优异的抗弯力学性能,开裂弯矩均值达到77.4 kN·m,受拉纵筋屈服时的弯矩均值为237.1 kN·m,板件破坏模式以底部受拉纵筋屈服为主要特征;理论公式计算值与试验值吻合较好.研究工作为UHPC桥面板在千米级斜拉桥主梁中的应用提供了理论分析和试验依据.

To study the static bending mechanical properties of UHPC(Ultra-High Performance Concrete,UHPC)bridge deck of a super-kilometer hybrid composite beam cable-stayed bridge,UHPC materials with compressive strength greater than 160 MPa and elastic modulus greater than 45 GPa were designed and prepared in this paper,and two full-size UHPC bridge decks with length,width and height of 3.8 m×1.0 m×0.17 m were tested under static load.By analyzing the bending stress state and failure mechanism of UHPC bridge decks,the stress calculation diagram of UHPC bridge deck was proposed,and the cracking moment of UHPC bridge decks and the bearing capacity calculation formula considering the stress reduction of UHPC in the tensile softening section were established.The results show that the UHPC bridge decks have excellent flexural mechanical properties.The average cracking moment reaches 77.4 kN•m,and the average bending moment corresponding to the yield of the tensile longitudinal reinforcement is 237.1 kN•m.The failure mode of the plate is mainly characterized by the yield of the tensile longitudinal reinforcement at the bottom.The calculated values of the theoretical formula are in good agreement with the experimental values.This research work provides a theoretical and experimental basis for the application of UHPC bridge decks in the main girder of kilometer-level cable-stayed bridges.