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

2019年加拿大基础设施报告卡清楚地表明，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年以来增长了两倍，达到12%左右。维修或更换这些老化的桥梁将会因车道及/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元件和系统（PBES）的需求比以往任何时候都要大，这可以节省大量的施工时间。然而，由于缺乏抗震设计指南，PBES的部署仅限于低地震活动性地区。PBES的耐用性很大程度上受环境暴露的影响，这方面的知识差距也减缓了PBES的采用。预计气候变化将加速PBES的退化速度，给PBES的耐用性带来额外的不确定性。为了应对上述挑战，拟议的研究项目旨在提高PBES在面对偶发性（地震）和慢性（气候变化背景下的腐蚀）灾害时的恢复能力。为了实现这一目标，该研究将利用材料科学的进步，利用具有卓越机械性能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的地震损伤状态，开发具有地震弹性的PBES。2)表征气候变化下PBES的腐蚀相关劣化特征，并研究UHPC提高PBES耐腐蚀性能的方法。3)建立气候变化对PBES全寿命地震易损性影响的分析框架。该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“腐蚀”危害图，以及开发基于uhpc的地震破坏控制和气候变化适应解决方案，推进PBES的地震和气候恢复能力。开发的定量震害状态将有助于加拿大公路桥设计规范对PBES进行基于性能的抗震设计。通过结合未来气候条件，寿命预测方法将改进PBES的使用寿命设计，使其具有持续的使用能力和抗震安全性。桥梁设计者和业主将受益于PBES的抗震设计研究和决策导向的长期性能评估。这对于释放ABC在受气候变化影响的加拿大地震地区桥梁修复和建设的潜力是非常必要的。HQP将在先进的桥梁设计和施工技术方面进行培训，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.