高性能碳-玻璃纤维布加固混凝土梁的非线性响应

摘要

针对高性能碳-玻璃-环氧树脂(CF-GF-EP)混杂纤维布加固钢筋混凝土(RC)梁, 研究了一种三维非线性混杂组合单元, 并推导了统一单元模式, 对RC梁的刚度退化、 应力重分布等进行了分析.首先根据实体退化单元理论, 研究了组合单元模拟RC梁, 并利用选择积分技术推求了高性能CF-GF-EP纤维布单元对混杂组合单元刚度矩阵的贡献.运用Jiang屈服准则、 Hinton压碎准则和Madrid强化准则等描述混凝土材料非线性, 研制了相应的三维非线性分析程序.与试验资料对比分析可知, 计算结果与试验数据吻合良好, 表明本文构造的非线性单元模式的正确性和研制程序的可靠性, 推导的混杂组合单元能准确用于混杂CF-GF-EP纤维布加固RC梁的非线性响应分析.加载初期高性能CF-GF-EP纤维布加固梁未有明显的刚度折减, 其后达到屈服荷载和极限荷载时, 加固梁刚度折减系数分别约为0.6和0.9.在开裂荷载前, 高性能CF-GF-EP纤维布应力发展较为平缓且应力重分布系数变化较小, 其后应力重分布系数逐渐增大直至结构失效.%For the typical concrete beams reinforced with the high performance carbon fiber-glass fiber-Epoxy(CF-GF-EP) sheet, a new three dimensional nonlinear hybrid composite element was studied for the nonlinear performances including stiffness reduction, stress redistribution etc.According to the theory of the solid degradation element, the RC beam was modeled with composite element.Then the contribution matrix of hybrid CF-GF-EP sheet to the new nonlinear hybrid composite element was completed through selective integration technique.The corresponding three-dimensional nonlinear analysis program was developed with the material nonlinearity of the concrete such as Jiang yield criterion, Hinton crushing criterion and Madrid criterion.Compared with the experimental data, the calculated results are in good agreement with the experimental data, which shows the correctness of the nonlinear hybrid composite element and the reliability of the developed program are both testified.The derived hybrid composite element can be accurately used for the whole process of analysis of the beams reinforced with the similar high performance CF-GF-EP sheet.In initial loads, the beams reinforced with the high performance CF-GF-EP sheet have no obvious stiffness reduction and then when the yielding loads and ultimate loads are reached, the stiffness reduction coefficients are about 0.6 and 0.9, respectively.Before cracking loads, the stress of the high performance CF-GF-EP sheet increases slowly and the stress redistribution coefficient of the high performance CF-GF-EP sheet changes little and in the following stage, it increases more rapidly until the structure fails.