FRP加固钢筋混凝土梁的抗剪计算方法

随着利用FRP加固混凝土结构研究的深入和应用的拓展,FRP加固钢筋混凝土梁抗剪性能的研究已取得了丰硕的成果。以往对抗剪承载力的分析大多是基于有效应变即对极限应变进行有效折减的方法,而最近的研究则引入了裂缝处FRP应变分布不均匀系数。在此基础上,本文综合考虑了FRP发挥的最大应变、沿裂缝应变分布的不均性以及斜裂缝倾角对有效应变的影响,提出了等效有效应变的概念,使计算趋于简单和清晰。本文收集了128根FRP全包裹的、以FRP断裂破坏为主的钢筋混凝土梁的抗剪实验数据,通过对主要影响因素的统计分析,建立了等效有效应变简单可靠的计算公式和基于FRP断裂的抗剪承载力设计方法。128根实验梁的抗剪计算结果表明,本文提出的方法简单可行,意义明确,且精度要比已有的建议公式稍高。

Shear Prediction of RC Beam Bonded with FRP

During the past decades,substantial research has been carried out on the external bonding of Fiber Reinforced Polymer(FRP) strips to deficient Reinforced Concrete(RC) beams,for the well-known superior properties of FRP. Numerous shear predictions have been established by using the effective strain of FRP or introducing an ultimate stress discount coefficient. Latest design concept is the use of stress distribution factor. In the paper,an equivalent effective strain of FRP is advanced which contains the concepts of maximum strain,stress distribution factor and the effect of critical shear crack angle. To develop a simple,accurate proposal of such equivalent effective strain,major effect factors are first studied and explicit by the statistical independent hypothesis test on a database of 128 RC beams wrapped by FRP or failure with FRP rupture in literatures. Finally,a simple and rational shear design proposal is presented which has a higher accuracy than the existing models using the above database.