高应变强化超高性能混凝土T形梁抗弯承载力

Calculation Method for Flexural Capacity of High Strain Hardening UHPC T-Beams

摘要:

为探究配筋高应变强化T形超高性能混凝土（UHPC）梁的抗弯承载力计算方法，对5根梁试件进行了三分点加荷纯弯试验，试件变化参数为配筋率和配筋强度.绘制了钢筋与高应变强化UHPC的荷载挠度曲线，将T形梁破坏过程分成3个阶段：弹性阶段、裂缝发展阶段、持荷至破坏阶段.与普通混凝土梁不同的是，在高应变强化UHPC梁体达到极限承载力时，受拉区UHPC对抗弯承载力有贡献作用；同时，受压区UHPC应力应变依然为线性关系.在考虑受拉区UHPC开裂后抗拉强度的基础上，提出了受拉区UHPC等效矩形应力系数，在平截面假定基础上推导出了配筋高应变强化T形UHPC梁抗弯承载力计算公式，并与国外提出的计算方法进行对比，分析各计算方法的准确性.结果表明，所提出方法的计算值与试验值有较高的吻合度，可为配筋高应变强化T形UHPC梁理论分析和设计提供参考.

Abstract:

In order study the calculation method for flexural capacity of high strainhardening ultrahigh performance concrete (UHPC) Tbeams, a fourpoint loading experiment of five girder specimens was conducted and the loaddeflection curve of reinforcement and high strain strengthening UHPC was drawn. The Tbeam failure process was divided into the elastic stage, the fracture development stage, and the loadtofailure stage. Different from common concrete, when the force of high strainhardening UHPC beam reach the ultimate load carrying capacity, the relationship between stress and strain of UHPC of compressive region is still linear. Meanwhile, since the contribution of UHPC tensile strength of tensile region to flexural capacity, after UHPC cracking, should be considered, an equivalent rectangular stress coefficient β of UHPC of tensile region is proposed. The calculation method for flexural capacity of reinforced UHPC Tbeams is deduced, based on the flat section assumption. This method is compared with the foreign calculation method and the accuracy of each method is analyzed. The results show that the calculated value of the proposed method fits the test value well, providing reference for theory analysis and structural design of reinforced UHPC T-beams.