Research on Flexural Performance of Reinforced Concrete Beams Strengthened with High-Strength Polyurethane Composites
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摘要: 为研究高强聚氨酯复合材料(HSPUC)加固混凝土梁抗弯性能,开展了2根采用不同梁底加固范围的HSPUC加固混凝土梁和1根对比混凝土梁的静力破坏试验,分析了试验梁破坏形态、承载能力、裂缝特征、变形及应变发展规律和界面滑移性能。采用ABAQUS有限元软件建立了HSPUC加固混凝土梁抗弯性能精细化数值模型,分析了加固层抗折强度和加固层厚度对抗弯性能影响。研究结果表明:采用梁底非通长HSPUC加固试验梁和采用梁底通长HSPUC加固试验梁分别发生了加固端保护层剥离破坏和塑性弯曲破坏,极限承载力较未加固试验梁分别提高了30.4%、79.4%; HSPUC加固法充分发挥了HSPUC材料的高强力学性能,延缓了裂缝的发展,有效抑制了混凝土梁因裂缝扩展而引起的刚度下降,对混凝土梁抗弯刚度和极限承载力的提高作用显著;各加固梁试验过程中HSPUC层与混凝土梁间具有可靠的黏结强度和良好的协同工作性能;数值模型计算荷载–跨中挠度曲线与试验曲线吻合良好,可用于HSPUC加固混凝土梁受弯全过程计算分析。Abstract: In order to study the flexural performance of reinforced concrete beams strengthened with high-strength polyurethane composites (HSPUC), the static failure tests of two reinforced concrete beams strengthened by HSPUC reinforcement layer with different strengthening areas at the bottom of the beams and one comparative reinforced concrete beam were carried out, and the failure modes, bearing capacity, crack characteristics, deformation and strain development laws, and interface slip of the test beams were investigated. A refined numerical model was constructed through the finite element program ABAQUS to simulate the flexural performance of reinforced concrete beams strengthened with HSPUC, and the effects of flexural strength and thickness of reinforcement layer on the flexural performance were analyzed. The results showed that the test beams strengthened by HSPUC in non-full length range and full length range of the bottom of the beam experienced debonding failure of the protective layer at the beam end and plastic flexural failure, respectively. Their ultimate bearing capacity increased by 30.4% and 79.4% compared to the unreinforced test beam, respectively. The HSPUC reinforcement method made full use of the high-strength mechanical properties of HSPUC, which could delay the occurrence and development of cracks and therefore effectively inhibit the stiffness decrease caused by crack propagation, significantly improving the flexural stiffness and ultimate bearing capacity of reinforced concrete beams. The reliable bonding strength and good cooperative working performance between the HSPUS layer and the reinforced concrete beam were observed. The mid-span load-deflection curves calculated by the numerical model were in good agreement with the experimental curves, so the numerical model can be used to calculate and analyze the entire flexural process of reinforced concrete beams strengthened with HSPUC.
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