超高性能混凝土-混凝土组合简支梁弯曲性能试验

Experimental Study on Bending Performance of Ultra-high Performance Concrete-Normal Concrete Composite Simply Supported Beam

摘要:

进行了3根超高性能混凝土（UHPC）位于受拉区的超高性能混凝土-混凝土组合梁（UHPC-NC组合梁）和1根普通钢筋混凝土梁的弯曲性能试验。对UHPC-NC组合梁的受力过程、跨中截面应变分布、裂缝开展模式和破坏形态等进行了研究分析。试验结果表明，UHPC-NC组合梁在加载过程中基本符合平截面假定，并且在UHPC层中配置适量的纵向钢筋，能大幅度提高组合梁的抗弯承载力。同时，将钢筋和UHPC对试验梁极限承载力的贡献分为4个阶段（初始状态、阶段状态、极限状态和破坏状态）进行计算。最后，对组合梁受拉区UHPC层等效矩形应力系数k进行推导。结果表明，UHPC层对组合梁抗弯承载力的贡献效率随着配筋率的不同而不同。

关键词:超高性能混凝土-混凝土组合梁;超高性能混凝土抗弯贡献度;模型试验;极限抗弯承载力

Abstract:

The flexural tests of three ultra-high performance concrete-normal concrete (UHPC-NC) composite beams that ultra-high performance concrete (UHPC) was located in the tensile zone and one ordinary reinforced concrete beam were carried out. The stress process, the strain distribution in the mid-section, the crack development mode and the failure mode of the UHPC-NC composite beam were studied and analyzed. The test results show that the UHPC-NC composite beam basically conforms to the sectional assumption during the loading process, and the proper amount of longitudinal steel bars in the UHPC layer can greatly improve the flexural resistance of the composite beam. At the same time, the contribution of reinforcement and UHPC to the ultimate bearing capacity of test beam was calculated in four stages (initial state, stage state, ultimate state and failure state). Finally, the equivalent rectangular stress coefficient k of the UHPC layer in the tensile zone of the composite beam was derived. The results show that the contribution efficiency of the UHPC layer to the flexural resistance of the composite beam varies with the ratio of reinforcement.

Key words:ultra-high performance concrete-normal concrete composite beam;ultra-high performance concrete bending contribution;model test;ultimate bending capacity