Development of hybrid fiber reinforcements of enhancing structures with integrated performances

本研究首先提出了由几种不同性能的纤维组成的混杂纤维增强聚合物（FRP）复合材料的综合设计概念，以实现不同的性能要求，包括抗拉强度、刚度、延性、抗蠕变和抗疲劳性能，并以性价比为最重要的指标之一。然后对材料的蠕变、疲劳等长期性能进行了试验研究。提出了评价和控制不同纤维逐渐断裂过程中应力或载荷下降的定量指标，并通过实验验证了其有效性。验证了采用吸能能力较高的连续纤维的有效性。对于混杂纤维板在钢筋混凝土结构加固中的应用，发现在混杂纤维体系中使用高模量碳纤维可以提高屈服荷载等使用性能。同时，合理设计由三种不同性能的连续纤维组成的混杂纤维增强材料，可以满足结构整体性能的要求。通过合理的混合设计，也可以避免复合玻璃钢板的脱粘破坏。另一方面，提出了一种新型FRP-RC混合结构，作为一种具有综合结构性能的新型结构。然后，基于非线性有限元和断裂力学方法，对frp加固混凝土结构受弯或对角大裂缝引发的脱粘破坏机制进行了数值研究。此外，还建立了frp -混凝土界面蠕变、疲劳等长期性能模型。最后，通过开发复合碳纤维传感器，提出了一种frp增强或FRP-RC混合结构的自传感方式。此外，还开发了基于分布式光纤传感技术的健康监测系统，用于监测frp加固结构的加固效果和其他结构性能。少

In this study, first, a comprehensive design concept of hybrid fiber reinforced polymers (FRP) composites with several types of fibers with different specific properties is proposed in order to realize different required performances including tensile strength, stiffness, ductility, creep and fatigue resistances and cost performance as one of the most important indices. Then the material behavior including the long-term performances such as creep and fatigue is experimentally investigated. Quantitative indices to evaluate and control stress or load drops during the gradual fractures of different fibers are proposed and their effectiveness are experimentally verified. The usefulness of adopting continuous fibers with higher energy absorption capacity is also verified.For the application of hybrid fiber sheets in strengthening RC concrete structures, it is found that the use of high modulus carbon fibers in hybrid systems could increase the serviceability such as yielding load. Moreover, … More it is conformed that structures can be strengthened with appropriately designed hybrid fiber reinforcements of consisting of three type of continuous fibers with different specific properties to meet with the overall requirements of structural performances. The debonding failure of hybrid FRP sheets can be also avoided through an appropriate hybrid design. On the other hand, a novel type of FRP-RC hybrid structures as one of new constructions with integrated structural performances is proposed.Then, the flexural or diagonal macro-crack induced debonding failure mechanisms in FRP-strengthened concrete structures are investigated numerically based on nonlinear FEM and fracture mechanics. Moreover, the modeling of long-term behavior such as creep and fatigue of FRP-concrete interface is developed.Finally, a self-sensing manner of FRP-strengthened or FRP-RC hybrid structures is proposed through developing hybrid carbon fiber sensors. Besides, a health monitoring system based on distributed fiber optic sensing techniques is developed to monitor the strengthening effects and other structural performances of FRP-strengthened structures. Less