Abstract: To describe the mechanical properties of the embedded CFRP (carbon fiber reinforced polymer) reinforced concrete beams, an analytical model based on crack propagation was proposed, which took into account the post-cracking tensile stress in concrete, as well as the bond-slip behavior between CFRP and concrete, accurately describing the initiation and propagation of cracks. Twelve samples were fabricated, taking into account the differences in loading ages of 7 days and 14 days, as well as the disparities between plain concrete and CFRPgrid-reinforced concrete beams. The proposed analytical model was employed to perform mechanical analyses on both plain concrete beams and CFRP grid-reinforced concrete beams. Experimental and theoretical analysis results were compared. The research results show that the load-crack mouth opening displacement curve of plain concrete beam exhibits a typical single-peak curve. After the first peak point, the plain concrete beam becomes unstable and the cracks rapidly open. The load-crack mouth opening displacement curve of CFRP grid-reinforced beam also exhibits a descending segment due to the sudden release of local fracture energy. However, due to the bond between the CFRP grid and the concrete, the grid begins to repeatedly exert its tensile strength, resulting in a second ascending segment of the curve, reaching a second peak point.

Key words: bridge engineering; CFRP grid; concrete; cracks; fracture analysis model; cracking

摘要： 为了描述内嵌CFRP(carbon fiber reinforced polymer)增强混凝土梁的受力性能，提出一种基于裂缝扩展的分析模型。该模型考虑了混凝土中的开裂后拉应力、CFRP和混凝土之间的黏结滑移行为，精确地描述裂纹的起始、扩展。考虑了7、14 d的加载龄期及素混凝土和CFRP网格增强混凝土梁差异的情况下，制作了12个样本；基于提出的分析模型分别对素混凝土和CFRP 网格增强混凝土梁开展力学分析，对比了试验和理论分析结果。研究结果表明：素混凝土梁的荷载-裂缝端部张开位移曲线呈现典型的单峰值曲线，第一个峰值点后，素混凝土梁失稳，裂缝快速张开；CFRP网格增强梁的荷载-裂缝端部张开位移曲线也因为局部断裂能的突然释放，表现出下降段，但由于CFRP网格和混凝土间的黏结力，网格开始重复发挥其抗拉强度，曲线出现第二个上升段，直到到达第二个峰值点。

关键词: 桥梁工程； CFRP网格； 混凝土； 裂缝； 断裂分析模型； 开裂