应变硬化水泥基复合材料加固钢筋混凝土构件弯曲破坏分析方法研究

Analytical method on RC member strengthened by strain hardening cementitious composite in flexural failure

依据应变硬化水泥基复合材料单向拉伸试验结果,提出评价该类材料单向拉伸特性的考虑断裂能的三折线模型。提出采用虚拟材料的零跨拉伸模型反映应变硬化水泥基复合材料加固层紧邻既有钢筋混凝土构件裂缝处的细小裂缝扩展过程,得到应变硬化水泥基复合材料加固既有钢筋混凝土构件时加固层数值单元的单向拉伸平均应力-应变曲线,该曲线考虑紧邻混凝土梁某裂缝的加固层细小裂缝(置于同一单元内)对单元单向拉伸应力-应变曲线的影响,继而以该平均应力-应变曲线作为加固层单元的应变硬化水泥基复合材料单向拉伸本构关系。该方法可避免不同单元尺寸对数值分析结果的影响,因此,对该类材料加固既有钢筋混凝土构件可以采用较大尺寸的单元划分进行数值分析。

Based on result of uniaxial tensile test for strain hardening cementitious composites, a tri-linear curve model considering fracture energy was proposed to evaluate the uniaxial tensile property of this material. A type of zero-span tensile model with a pair of fictitious was also proposed to reflect the crack propagation behavior of multiple fine cracks in strain hardening cementitious composites layer, used as a repair material for RC substrate member with existing crack. Moreover, the average tensile stress-strain curve of numerical element for strain hardening cementitious composites strengthening layer was obtained, considering the influence of multiple fine cracks （placed in one numerical element of strain hardening cementitious composites layer） limited in a ranged area adjacent to localized crack （in RC substrate member） , and then the effect of RC member strengthened by strain hardening cementitious composites in flexural failure was evaluated numerically using the obtained average tensile stress-strain curve, which was considered as the uniaxial tensile property for strain hardening cementitious composites while strengthening RC member. This method avoided the dependency of numerical result on element size, and strain hardening cementitious composite flexural strengthening RC member could be analyzed with large mesh size.