Using FRC and UHPFRC with conventional reinforcement for the seismic design and rehabilitation of bridge piers and for the design of bridge superstructure elements

加拿大是世界工业化国家之一，其战略基础设施受到最恶劣的气候条件的影响。在魁北克，由于重力荷载和耐久性问题，大约10000座桥梁中仍有35%需要修复。由于传统混凝土修复的耐久性有限，这种修复过程很快就变成了一个永无止境的循环。在过去的几十年里，人们对地震危险和一些混凝土结构缺陷的了解表明，1980年以前建造的结构是脆弱的。这尤其影响到加拿大人口稠密地区的桥梁。事实上，魁北克80%的桥梁是在现代地震规定之前建造的，只有极少数的桥梁被修复以符合当前的地震标准。这影响了许多生命线和主要路线桥梁。******将传统增强材料与纤维增强混凝土（FRC）和超高性能纤维增强混凝土（UHPFRC）相结合，由于其卓越的结构性能和耐久性，已被证明是设计、修复和加强结构元件的最有前途的技术和经济解决方案[12,13]。尽管全球一些司法管辖区和加拿大正在以有限的试点项目缓慢但肯定地引入这些材料，但加拿大的标准和行业尚未为实施这些创新材料做好准备。在健全和稳健的规范成为混凝土结构设计和修复的强制性规范之前，仍有几个问题需要解决。这是本研究计划的目的，其重点是开发知识、分析工具和设计要求，以实现加拿大桥梁规范中基于合理原则在结构应用中使用这些创新材料的要求。******该应用程序包括四个项目，结合了结构构件的大规模测试，材料测试和非线性有限元分析（NLFEA），用于评估构件或局部水平结构元件的行为。两个项目与混凝土桥墩的抗震修复和设计有关：1)大型矩形桥墩基础的塑性铰长度和应变渗透；2)UHPFRC主动覆盖物和加固对抗震修复或加速桥梁建设（ABC）项目柱强度的围合作用。两个项目的重点是制定在加拿大桥梁规范中引入FRC和UHPFRC的设计要求：3)UHPFRC中锚定和搭接钢筋的粘结强度；4)FRC和UHPFRC设计的可靠性框架的开发。该项目将由一组均衡的hqp来实现：一名高级研究员，一名PDF， 4名博士，8名硕士学生和至少10名本科生。

Canada is one of the world industrialised countries where strategic infrastructures are subjected to the most severe climatic conditions. In Quebec, 35% of the ±10000 bridges still need to be rehabilitated for gravity loads and durability [1]. This rehabilitation process quickly becomes a never ending cycle due to the limited durability of repairs with conventional concrete. Knowledge gained in the past decades on the seismic hazard and on the deficiencies of several concrete structures demonstrated the vulnerability of structures built before 1980. This particularly affects bridges in densely populated regions of Canada. In fact, 80% of bridges in Quebec were built prior to modern seismic provisions, from which only a very few have been rehabilitated to conform to current seismic standards. This affects many lifeline and major-route bridges.******Combining conventional reinforcements with fibre reinforced concrete (FRC) and ultra-high performance fibre reinforced concrete (UHPFRC) has been shown to be the most promising technical and economical solution for designing, rehabilitating and strengthening structural elements due to their exceptional structural performances and durability [12,13]. Although they are slowly but surely being introduced by some jurisdictions worldwide and in Canada in limited pilot projects, Canada's standards and industries are not yet prepared for implementing these innovative materials. Several issues still need to be addressed before sound and robust specifications become mandatory for the design and rehabilitation of concrete structures. This is the aim of this research proposal which focusses on developing knowledge, analytical tools, and design requirements to be implemented in the Canadian Bridge Code for using these innovative materials in structural applications based on rational principles.******This application includes four projects that combine large scale testing on structural members, material testing, and nonlinear finite element analysis (NLFEA) for assessing the behaviour of structural elements at member or local levels. Two projects are related with the seismic rehabilitation and design of concrete bridge piers: 1) on the plastic hinge length and strain penetration in footings of large rectangular bridge piers, and 2) on the confining effect of UHPFRC active cover and reinforcement on column strength for seismic rehabilitation, or for accelerated bridge construction (ABC) projects. Two projects focus on developing design requirements for introducing FRC and UHPFRC in the Canadian Bridge Code: 3) on the bond strength of anchored and lapped reinforcing bars in UHPFRC and 4) one the development of a reliability framework for designing with FRC and UHPFRC. The project will be realised with a well-balanced group of HQPs: one senior research associate, one PDF, and 4 PhD, 8 MSc students and a minimum of 10 undergraduate students.