Crack and mechanical behavior of CFRP plate-reinforced bridge roofs under high temperature with different anchoring measures

Abstract This paper investigates the crack and mechanical behavior of CFRP plate-reinforced bridge roof under high temperature with different anchoring measures. Six CFRP-reinforced test beams with different anchoring schemes were designed and constructed. The beam specimens, after the high temperature effects, were tested under four-point bending loads. The crack propagation, beam deflection, mid-span strain and the damage modes were observed and recorded until failure. The stiffness variation and the debonding failure mechanism of the test beams were comparatively investigated. The results indicate that the debonding bearing capacity of the specimens can be improved by the additional anchoring measures. The concrete shrinkage at the crack and the average crack spacing are more effectively reduced, when the additional anchoring measures are placed at the mid-span and the support position. In addition, a theoretical model is proposed for calculating the intermediate crack debonding bearing capacity. Based on the comparative analysis of various models and test results, it is shown that the proposed model could accurately calculate the intermediate crack debonding bearing capacity of the test specimens.

摘要 本文针对不同锚固措施下高温环境中碳纤维增强复合材料（CFRP）板加固桥梁顶板的开裂与力学行为展开研究。设计并制作了6根采用不同锚固方案的CFRP加固试验梁。对经高温作用后的梁试件开展四点弯曲加载试验，全程观测并记录试件破坏过程中的裂纹扩展、梁体挠度、跨中应变及破坏模式。对试验梁的刚度演化与剥离破坏机理开展对比分析。研究结果表明，增设锚固措施可提升试件的剥离承载能力；当锚固措施布置于跨中和支座位置时，可更有效地缩减裂缝处的混凝土收缩量与平均裂缝间距。此外，本文提出了一种用于计算中间裂缝剥离承载能力的理论模型。通过多种模型与试验结果的对比分析，验证了所提模型可精准计算试验试件的中间裂缝剥离承载能力。