高延性预应力碳纤维增强复合材料板加固钢筋混凝土梁的有限元分析

Finite Element Analysis of Reinforced Concrete Beams Strengthened with Prestressed CFRP Plates with High Ductility

碳纤维增强复合材料(CFRP)以其轻质、高强、耐腐蚀的优势,在混凝土结构加固中得到了较为广泛的应用,现已发展出外贴、内嵌、预应力等多种加固方法。然而,由于CFRP及与其黏结的混凝土界面的弹脆性,加固后的混凝土受弯构件常表现为脆性破坏,延性较低。因此,在以往提出的跨中顶撑张拉预应力CFRP板加固方法的基础上,提出了一种高延性预应力CFRP板加固方法,通过改进顶撑装置的属性,在局部设置弹塑性机构,大幅提升加固梁整体的延性。经过有限元分析证实,提出的加固方法可以延缓CFRP板的应变增长并使其始终维持在较高应力水平,在极限承载力降幅不多的情况下,加固梁的极限挠度最大提升了137%,大幅度提高了加固梁的延性,并且为后续新型加固方法的研发提供参考依据。

Carbon fiber-reinforced polymer(CFRP)has been widely used in structural strengthening due to its light weight,high strength and anti-corrosion.Specifically,in strengthening RC beams,various strengthening techniques,such as external bonding,near-surface mounting and prestressing,have been developed so far.However,due to the brittle nature of the CFRP material and the interface of concrete bonded with CFRP plates,strengthened beams used to exhibit brittle failure at low ductility.Therefore,a novel strengthening method with high ductility and prestressed CFRP plates was proposed based on previous findings on the mid-span-supported strengthening technique by changing the mid-span deviators to elastic-plastic devices.The effectiveness of the proposed strengthening method was verified by finite element analysis.The finding indicated the new method could maintain the CFRP at a high stress level and increase the ultimate deflection up to 137%in limited loss of ultimate strength.The results could be reference to further development of structural strengthening methods.