CFRP加固梁U型锚固效果的数值分析

Finite Element Analysis of the Effects of U-wrap Anchorages on RC Beams Strengthened with CFRP Sheets

CFRP与混凝土层间剥离是纤维加固钢筋混凝土梁中最常见的破坏形式,在CFRP端部或沿全梁设置横向U型锚固是目前工程中使用最广泛的防止过早剥离破坏的方法。采用数值计算方法,对比了无U型锚固,端部设置U型锚固以及沿全梁施加U型锚固3种情况下,加固梁的承载力、变形、粘结层的滑移量以及CFRP应变分布,分析研究U型锚固在CFRP加固钢筋混凝土梁中的作用。由计算分析结果可知,U型锚固可有效提高加固梁的承载力和刚度,防止过早剥离破坏的发生。在钢筋屈服后,沿全梁设置U型锚固比端部设置U型锚固能够更有效防止发生剥离破坏,但同时也引起CFRP应变分布不均匀,当CFRP被拉断破坏时,沿全梁锚固时加固梁的极限承载力低于端部锚固情形。

Premature debonding between CFRP and concrete commonly occurs in RC beams strengthened with CFRP sheets .U‐w rap anchorages installed at the ends of CFRP sheets or along the entire beams are currently well accepted for preventing the debonding failure in engineering practice . Three schemes of CFRP strengthening beams without U‐w raps ,with U‐w raps at CFRP ends and along the entire beam are numerically studied .The loading capacities and deflections of the beams ,bond‐slips in the interfaces and strains of CFRP sheets in the three cases are compared under different loading levels .The result shows that the strength and stiffness of the strengthened beams are effectively improved with the clamping of U‐wraps .After the yield of steel reinforcement ,U‐wrap anchorages along entire beam are more effective for preventing the debonding failure than those at CFRP ends and lead to the uneven strains of CFRP sheets as well At the ultimate state ,CFRP can rupture locally at the places of high strain concentrations leading to decrease in the loading capacity compared to the beam anchored at two ends of CFRP .