外贴CFRP增强钢筋混凝土梁许用剥离应变研究

Allowable debonding strain limitation of externally CFRP-strenghtened RC beam

为进一步明确碳纤维增强材料（CFRP）加固钢筋混凝土（RC）受弯构件的破坏模式,判断相关规范提出的CFRP许用剥离应变计算公式的正确性,设计并开展钢筋混凝土梁外贴CFRP加固试验,采用2点对称简支加载,探究加固试件的破坏模式和CFRP初始剥离时的应变。结果表明：加固试件的基本破坏模式为CFRP剥离破坏;一些规范规定的许用剥离应变与试验值的比值在0.28-5.12之间,多数规范的许用剥离应变远大于实测值,按规范计算的许用剥离应变的变异系数均大于46%;CFRP的剥离不仅与混凝土强度、CFRP用量和弹性模量有关,还与剪跨比、箍筋配筋率和纵筋配筋率等因素有关。

In order to further clarify the failure modes of RC flexural members strengthened with CFRP,and determine the accuracy of the formula for determining CFRP allowable debonding strain proposed by relevant codes,experimental tests were carried out to investigate the failure mode and tensile strain in CFRP laminates at initial debonding of CFRP-strenghtened RC beams which were simply supported and loaded under two points symmetrical loading. The results show that the main failure mode of the strenghtened beams is CFRP laminates debodning; the allowable debonding strains are 0.28-5.12 times of the tested tensile strains at initial debonding with a coefficient of variation more than 46%,and most of the code models highly overestimate the allowable debonding strain; the debonding of CFRP laminates of flexural strenghtened RC beam is related not only to the concrete strength,the amount of FRP laminates,and the modulus of elasticity,but also to the factors such as shear-span ratio,stirrup reinforcement ratio and longitudinal reinforcement ratio.