Development of innovative strategies for durable bridge design and rehabilitation by use of high and ultra-high performance fibre reinforced concretes

暴露在恶劣环境条件下的混凝土桥梁中，有很大一部分会出现严重的劣化。在桥墩、横梁和桥面上观察到的主要现象是钢筋锈蚀和混凝土剥落，其后果是降低基础设施的承载能力和改变其耐久性。自20世纪90年代S以来，人们对高性能和超高性能纤维混凝土(HPFRC和UHPFRC)的发展进行了大量研究。与普通强度混凝土相比，HPFRC和UHPFRC在力学性能和耐久性方面都有显著的改善。因此，这些材料在桥梁基础设施的设计和修复中的应用潜力是显而易见的。必须进行研究，以完成HPFRC和UHPFRC的特征，从而促进其在基础设施中的使用。拟议的研究计划分为两个主题。题目(1)旨在介绍HPFRC和UHPFRC的透水性和自愈性的基本知识。将研究材料参数(纤维含量、粘结剂的类型和体积)和结构参数(静态和循环荷载)的影响。题目(2)的目的是评估结构中纤维取向对高荷载下FRC尺寸效应和蠕变的影响。因此，可以估算HPFRC和UHPFRC在不同条件下的硬化和软化行为的开始和程度，以及裂缝对粘弹性的贡献。研究课题将把实验测试和非线性有限元分析相结合。拟议的研究将导致HPFRC和UHPFRC在正常使用时应变和强度能力的最佳利用，并制定确保基础设施的最佳机械性能和耐久性的规定。该研究计划将促进新的设计和修复策略的发展，降低维护成本，并提高桥梁的长期性能。它将涉及1名技术人员、1名博士和4名硕士。在校学生7名，本科生7名。在这项研究计划中，HQP将有许多机会加深知识和获得新技能。

A large proportion of concrete bridges exposed to severe environmental conditions present significant deterioration. The main phenomena observed on piers, beams and bridge decks are reinforcement corrosion and concrete spalling, which have for consequences the reduction of the load-carrying capacity and the alteration of the durability of infrastructure. Since the 1990's, considerable research has been focused on the development of High and Ultra-High Performance Fibre Reinforced Concretes (HPFRC and UHPFRC). Compared to normal strength concrete, HPFRC and UHPFRC present outstanding improvements in terms of mechanical properties and durability. Therefore, the potential of application of those materials for design and rehabilitation of bridge infrastructure is obvious. Research must be performed to complete the characterisation of HPFRC and UHPFRC, and thus promote their utilisation in infrastructure. The proposed research program is divided in two topics. Topic (1) aims to bring fundamental knowledge on water permeability and self-healing of HPFRC and UHPFRC. The influence of material parameters (fibre content, type and volume of binder) and structural parameters (static and cyclic loadings) will be studied. Topic (2) has for objectives to evaluate the impact of fibre orientation in structures on the FRC size effect and creep under high loads. Thus the onset and the extent of hardening and softening behaviours of HPFRC and UHPFRC will be estimated in various conditions, as well as the contribution of cracking on viscoelasticity. Research topics will combine experimental testing and nonlinear finite element analysis. The proposed research will lead to the optimized utilisation of strain and strength capacities of HPFRC and UHPFRC at serviceability, and to elaborate provisions ensuring an optimal mechanical behaviour and durability of infrastructure. The research program will promote the development of new strategies for design and rehabilitation, reduce maintenance costs and improve the long term performance of bridges. It will involve 1 technician, 1 Ph.D. and 4 M.Sc. students and 7 undergraduate students. Many occasions will be given to HQP to deepen knowledge and acquire new skills within this research program.