粘铝合金板加固RC梁抗弯性能试验及正截面承载力

Flexural Behavior Test and Normal Section Bearing Capacity of RC Beam Strengthened with Aluminum Alloy Plate

为了探讨铝合金板厚度与端部U形铝合金箍板构造对RC梁破坏机理及抗弯性能的影响,对16根铝合金板加固RC梁进行了4点弯曲静力加载试验。在试验梁底铝合金板的表面以及试验梁跨中截面的顶面、侧面粘贴应变片,在试验梁底跨中、梁顶两端支座布置百分表。为了推导铝合金板加固RC梁的正截面承载力计算式,基于试验得到的破坏机理,通过引入6个基本假定,分析了5种不同破坏模式的相对受压区高度。建立了各破坏模式下铝合金板加固RC梁的正截面承载力计算式,并将其与引入文献中的试验结果进行了对比分析。结果表明:试件破坏形态包括适筋破坏、端部铝合金板与结构胶剥离、端部铝合金板与梁剥离及中部铝合金板剥离4种情况;当端部设置U形铝合金箍板时,可有效抑制端部铝合金板发生剥离,使钢筋与铝合金板的材料性能得到充分发挥,试件承载力与延性明显提升;当铝合金板厚度分别为2~6 mm时,试件承载力随铝合金板厚度的增加而提高;端部设置U形铝合金箍板可有效防止端部铝合金板发生剥离,但试件仍可能会出现中部铝合金板剥离现象;当试件出现适筋破坏特征时,试件抗弯承载力的计算值与试验值比值均在1以下。本研究所提计算式具有明显的规律性和适用性,可为工程实际设计提供参考。

In order to investigate the effects of the thickness of aluminum alloy plate and the U-shaped aluminum alloy hoop plate structure on the failure mechanism and flexural performance of RC beams,16 RC beams strengthened with aluminum alloy plates are tested under 4-point bending static loading.The strain gauges are pasted on the surface of the aluminum alloy plate at the bottom of the test beam and on the top and side of the mid-span section of the test beam,and the dial indicators are arranged at the middle of the bottom span and at the both ends of the top of beam.In order to derive the calculation formula of normal section bearing capacity of RC beams strengthened with aluminum alloy plates,based on the failure mechanism obtained from the tests,the heights of relative compression zone of 5 different failure modes are analyzed by introducing 6 basic assumptions.The formulas for calculating the bearing capacity of RC beams strengthened with aluminum alloy plates with various failure modes are established and compared with the experimental results in the literature.The result shows that(1)the failure modes of the specimens include 4 conditions:suitable reinforcement failure,end aluminum alloy plate and structural adhesive peeling,end aluminum alloy plate and beam peeling,and middle aluminum alloy plate peeling;(2)when the U-shaped aluminum alloy hoop plate is set at the end,the end aluminum alloy plate can be effectively inhibited from peeling,and the material properties of the steel bar and aluminum alloy plate are fully played;(3)when the thickness of the aluminum alloy plate is 2-6 mm,the bearing capacity of the specimen increases with the increase of the thickness of the aluminum alloy plate;(4)setting the U-shaped aluminum alloy ferrule plate at the end can effectively prevent the aluminum alloy plate at the end from spalling,but the aluminum alloy plate at the middle of the specimen may still spalling;(5)the ratio of the calculated value to the test value is less than 1 when the failure characteristics of the bars appear.The presented formula has obvious regularity and applicability,which can provide reference for practical engineering design.