受损木梁的抗弯加固试验与承载力计算分析

Calculation and Analysis on Load Carrying Capacity of Damaged Timber Beams Strengthened With CFRP

针对雅安地震中大量受损的木结构,统计了木梁的主要损伤情况,研究了受损木梁的抗弯加固试验,分析了裂缝和木结对梁和加固梁在受弯过程中的载荷、位移的影响,建立了加固木梁的极限承载力与梁参数、裂缝形式与分布,以及CFRP(carbon fiber reinforced polymer)加固率影响的理论计算公式。试验结果表明:抗弯加固木梁的整个变形过程符合平截面假定,碳纤维布能有效提高梁极限承载力,提高幅度可达到25.2%;受木结和初始裂缝的影响,随着CFRP加固层数的增加,其承载力提高幅度反而下降;裂缝和木结对木梁极限承载力影响很大,是木梁破坏的主要原因,新裂缝的萌生点位于木节处,木梁破坏的主要位置为木结处。同时,基于最大有效应力建立的木梁承载力计算模型,计算值与试验值符合较好,其误差在8%以内,符合工程计算要求。

On the basis of carrying capacity mechanism and influence factors of timber structures, three timber beams were strengthened with CFRP and studied about the influences of CFRP layers, cracks and knots on their ultimate carrying capacity. The experimental results showed that the ultimate capacity was effectively improved by the CFRP reinforcement to a percentage of 25.2%, while the carrying capacity decreased with the number of reinforcement layers after a peak effect. The cracks and knots were the main damage factors for the timber beams. The new cracks initiated at the knot positions and destroy the beam thereafter. The computed ultimate capacities of the strengthened beams accord well with the tested data with relative errors less than 8%, validating the calculation model for the beams.