Next Generation Earthquake-resilient Precast Concrete Bridges in a Changing Climate

《2019年加拿大基础设施成绩单》明确指出，加拿大桥梁的快速老化令人担忧。截至2019年，加拿大“差”或“非常差”桥梁的比例自2016年以来增加了两倍，达到12%左右。维修或更换这些破旧的桥梁将因车道和/或道路封闭而造成严重的交通中断。因此，通过加速桥梁施工(ABC)采用预制混凝土桥梁构件和系统(PBE)的需求比以往任何时候都更大，从而可以极大地节省施工时间。然而，由于缺乏抗震设计指南，PBE的部署仅限于地震活动较少的地区。关于PBE耐久性的知识差距在很大程度上受到环境暴露的影响，也减缓了PBE的采用。气候变化预计将加速恶化速度，给多国经济的持久性带来额外的不确定性。为了应对上述挑战，拟议的研究计划旨在增强暴露在间歇性(地震)和慢性(气候变化背景下的腐蚀)危险中的PBE的弹性。为了实现这一目标，这项研究将利用材料科学的进步，利用具有特殊机械和耐久性能的超高性能混凝土(UHPC)。在接下来的五年里，这项研究将做出以下独特的贡献：1)利用基于超高强度混凝土的低损伤连接技术，通过提出定量的地震破坏状态，开发具有地震弹性的PBE。2)表征PBE在气候变化条件下的腐蚀劣化特征，并研究超高性能混凝土以提高PBE的耐腐蚀性。3)建立一个分析框架，以评估气候变化对PBE终身地震脆弱性的影响。这项研究将通过生成高质量的测试数据，开发经过验证的计算方法和设计工具，创建加拿大的“腐蚀”危险图，以及开发基于超高性能混凝土的地震损害控制和气候变化适应解决方案，来推动PBE的地震和气候恢复能力的最新发展。开发的定量地震损伤状态将有助于加拿大公路桥设计规范采用基于性能的抗震设计。通过考虑未来的气候条件，寿命预测方法将改善PBE的使用寿命设计，以实现持续的可服务性和地震安全性。桥梁设计者和业主将受益于抗震设计和面向决策的PBE长期性能评估的研究。这对于释放ABC在加拿大地震区修复和建设桥梁的潜力是非常必要的，这些地区也受到气候变化的影响。HQP将接受先进的桥梁设计和施工技术培训，并成为为加拿大人建造和维护安全和可持续的桥梁基础设施的重要贡献者。

The 2019 Canada Infrastructure Report Card makes it clear that the rapid aging of Canada's bridges is alarming. As of 2019, the percentage of Canadian bridges that are in `poor' or `very poor' condition has tripled since 2016 to around 12%. Repairing or replacing these deteriorating bridges will cause significant traffic disruptions due to lane and/or road closures. As such, the need for adoption of Prefabricated Concrete Bridge Elements and Systems (PBES) through Accelerated Bridge Construction (ABC), which can offer tremendous savings in construction time, is greater than ever. However, the deployment of PBES has been limited to low-seismicity areas due to the lack of seismic design guidelines. Knowledge gaps on PBES durability, which is largely influenced by environmental exposure, also slow down the adoption of PBES. Climate change is expected to accelerate the deterioration rate, creating additional uncertainty in the durability of PBES. To tackle the above challenges, the proposed research program aims to enhance the resilience of PBES that are exposed to both episodic (earthquake) and chronic (corrosion in the context of climate change) hazards. To fulfill this goal, the research will take advantage of advances in materials science by utilizing Ultra-high-Performance Concrete (UHPC) with exceptional mechanical and durability properties. Over the next five years, the research will make the following unique contributions: 1) Develop seismically resilient PBES by using UHPC-based low-damage connection technologies and by proposing quantitative seismic damage states. 2) Characterize corrosion-related deterioration for PBES under a changing climate, and investigate UHPC to enhance the corrosion resistance of PBES. 3) Create an analytical framework to assess the climate change impact on the lifetime seismic vulnerability of PBES. The research will advance the state-of-the-art of seismic and climate resilience of PBES by generating high-quality test data, developing validated computational methods and design tools, creating Canadian `corrosion' hazard map, and developing UHPC-based solutions for seismic damage control and climate change adaption. The developed quantitative seismic damage states will assist Canadian Highway Bridge Design Code in adapting performance-based seismic design for PBES. By incorporating future climate conditions, the lifetime prediction methods will improve the service life design of PBES for sustained serviceability and seismic safety. Bridge designers and owners will benefit from the research for seismic design and decision-oriented long-term performance evaluation for PBES. This is much needed to unlock the potential of ABC for bridge repair and construction in seismic areas of Canada that are also affected by climate change. HQP will be trained in advanced bridge design and construction techniques, and become important contributors to build and maintain safe and sustainable bridge infrastructure for Canadians.