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

《2019年加拿大基础设施报告卡》明确指出，加拿大桥梁的快速老化令人担忧。截至2019年，加拿大处于“差”或“非常差”状态的桥梁比例自2016年以来增加了两倍，达到12%左右。修复或更换这些老化的桥梁将导致车道和/或道路封闭造成严重的交通中断。因此，通过加速桥梁建设（ABC）采用预制混凝土桥梁构件和系统（PBES）的需求比以往任何时候都大，这可以大大节省施工时间。然而，由于缺乏抗震设计准则，PBES的部署仅限于低地震活动地区。关于PBES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PBES的采用。预计气候变化将加快退化速度，从而给持久性和生态系统的耐久性带来更多的不确定性。为了应对上述挑战，拟议的研究计划旨在提高暴露于偶发（地震）和慢性（气候变化背景下的腐蚀）危害的PBES的复原力。为了实现这一目标，该研究将利用材料科学的进步，利用具有卓越机械和耐久性的超高性能混凝土（UHPC）。在未来五年内，该研究将做出以下独特贡献：1）通过使用基于UHPC的低损伤连接技术和提出定量地震损伤状态，开发具有地震弹性的PBES。2)描述PBES在气候变化下的腐蚀相关劣化，并研究UHPC以提高PBES的耐腐蚀性。3)建立一个分析框架，以评估气候变化对PBES生命周期地震脆弱性的影响。该研究将通过生成高质量的测试数据、开发经验证的计算方法和设计工具、绘制加拿大“腐蚀”危害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，推进PBES的地震和气候复原力的最新水平。定量的地震破坏状态将有助于加拿大公路桥梁设计规范适应PBES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PBES的使用寿命设计，以实现持续的可用性和地震安全性。桥梁设计者和业主将受益于PBES的抗震设计和面向决策的长期性能评估的研究。这是非常需要的，以释放ABC的潜力，在加拿大地震地区的桥梁维修和建设，也受到气候变化的影响。HQP将接受先进桥梁设计和施工技术的培训，并成为加拿大人建设和维护安全和可持续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.