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，±10000座桥梁中有35%仍需修复以满足重力荷载和耐久性要求[1]。由于传统混凝土修复的耐久性有限，这个修复过程很快就变成了一个永无止境的循环。过去几十年来对地震危险和若干混凝土结构缺陷的了解表明，1980年以前建造的结构很脆弱。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%的桥梁是在现代抗震规定之前建造的，只有极少数经过修复以符合当前的抗震标准。这影响到许多生命线和主要路线桥梁。 将传统钢筋与纤维增强混凝土（FRC）和超高性能纤维增强混凝土（UHPFRC）相结合，由于其出色的结构性能和耐久性，已被证明是设计，修复和加固结构元件的最有前途的技术和经济解决方案[12，13]。虽然世界各地的一些司法管辖区和加拿大在有限的试点项目中正在缓慢但肯定地采用这些材料，但加拿大的标准和行业尚未准备好实施这些创新材料。在混凝土结构的设计和修复必须采用健全和可靠的规范之前，仍有几个问题需要解决。这是本研究提案的目的，该提案侧重于开发知识，分析工具和设计要求，以在加拿大桥梁规范中实施，以基于合理原则在结构应用中使用这些创新材料。 该应用程序包括四个项目，结合联合收割机大规模测试的结构构件，材料测试和非线性有限元分析（NLFEA），以评估行为的结构元件在成员或局部水平。两个项目与混凝土桥墩的抗震加固和设计有关：1）大型矩形桥墩基础中的塑性铰长度和应变穿透，以及2）UHPFRC主动保护层和钢筋对抗震加固或加速桥梁建设（ABC）项目柱强度的限制作用。两个项目的重点是制定加拿大桥梁规范中引入FRC和UHPFRC的设计要求：3）UHPFRC中锚固和搭接钢筋的粘结强度; 4）一个是制定FRC和UHPFRC设计的可靠性框架。该项目将与一个平衡的HQP组实现：一名高级研究助理，一名PDF，4名博士，8名硕士生和至少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.