基于“梁段”模型的FRP加固混凝土梁端界面剥离破坏分析

ANALYSIS ON END DEBONDING FAILURE OF FRP STRENGTHENED RC BEAMS BASED ON A 'BEAM SEGMENT' MODEL

由各种纤维复合材料(FRP)加固混凝土梁端斜裂缝诱发的"端头FRP-混凝土界面剥离"是一种常见破坏模式,而用有限元方法对有多条裂缝的整根加固梁进行分析难度很大。该文提出一个简单的以加固梁端第1条斜裂缝为边界的"梁段"空间非线性有限元计算模型,并用圣维南原理和数值分析证实其合理性和可靠性。进而对此模型进行参数分析,探讨FRP拉应力、FRP层数、FRP-混凝土粘结滑移本构关系和加固梁端第1条斜裂缝到支座的距离诸因素对剥离应力的影响。经比较,模型计算结果与既有实验数据吻合较好。

In order to analyze the diagonal crack-induced-debonding of the fiber reinforced polymer（FRP）-concrete interface of FRP strengthened concrete beam ends more efficiently,a simple three-dimensional-nonlinear finite element model based on the ＇beam segment＇ between a beam end and the first diagonal crack was proposed.The difficulty to analyze the debonding stress by taking a whole strengthened beam with many cracks as a finite element model,therefore,was avoided.The proposed model was validated to be rational and reliable by the Saint-Venant principle and a numerical study.Based on this model,the distributions of the debonding stress under the influence of FRP stress levels,layers of FRP,the distance between the support and the first diagonal crack,and FRP-concrete bond-slip constitutive laws were analyzed.The numerical study results show a fairly good agreement with the existed experimental results.