Seismic performance improvement of buildings with self-centering bracings

支撑是建筑物中用于抵抗侧向荷载的对角结构构件。传统的支撑基本上承受轴向载荷。它们在轴向拉伸下表现良好。然而，在压缩下，支撑倾向于屈曲并失去其承载能力。研究人员提出了屈曲约束支撑、屈服支撑等方法来克服屈曲问题。然而，它们的缺点包括：a）重量大，B）制造困难，以及c）地震后潜在的永久性损坏。在这里，提出了新的支撑系统，以克服这些缺点。这些系统重量轻，即使在大地震中也能保持运行，不会造成永久性损坏。所提出的系统将利用超弹性形状记忆合金（SMA）杆安装在一个气缸活塞，或SMA板在约束橡胶混凝土组件。设计合理的自定心支撑框架结构由于其自定心能力，即使在大地震事件后也有望保持运行，从而提高安全性和生存能力。它还将在减少灾后情况下所需的维修/更换工作方面节省大量费用，并有可能就地修复而不是拆除。这项研究的意义是至关重要的，因为这项新技术将帮助加拿大提高地震期间建筑基础设施的安全水平。第一阶段将涉及评估SMA杆/板的机械性能以及将SMA连接到钢部件的耦合器的性能。将对支撑元件和支撑框架进行一系列大型准静态循环和动力试验。所产生的实验数据将被用来确定影响地震响应和极限状态的重要参数，这将有助于制定基于性能的支撑框架设计指南。所提出的设计准则将通过混合仿真试验进行验证。研究小组将与合作伙伴和设计规范委员会密切合作，制定适当的框架，以便将拟议的设计建议纳入设计规范。

Bracings are diagonal structural elements in a building for resisting lateral loads. Traditional bracings essentially carry axial loads. They perform well under axial tension. However, under compression, braces tend to buckle and lose their load carrying capacity. Researchers have proposed buckling restrained bracing, yielding bracing, etc to overcome this buckling problem. However, their disadvantages including: a) heavy weight, b) fabrication difficulty, and c) potential permanent damages after an earthquake. Here, novel bracing systems are proposed to overcome these shortcomings. These systems will be light-weight, and will remain operational with no permanent damages even during a large earthquake. The proposed system will utilize superelastic shape memory alloy (SMA) bars installed inside a cylinder piston, or SMA plates in confined rubberized concrete assembly. A properly designed self-centering braced frame structure is expected to remain operational even after a large seismic event due to its self-centering capability, increasing safety and survivability. It will also provide large savings in reduced repair/replacement work necessary in a post-disaster scenario, and potential for remediation in place rather than demolition. The significance of this research is paramount as this novel technology will help Canada improve the level of safety of building infrastructure during earthquakes. The first stage will involve evaluating the mechanical properties of SMA bars/plates and performance of couplers that connect SMA to steel parts. A series of large-scale quasi-static cyclic and dynamics tests will be performed on bracing elements and braced frames. The generated experimental data will be employed to determine the important parameters that affect the seismic response and limit states, which will help develop performance-based design guidelines for braced frames. The proposed design guidelines will be validated with hybrid simulation tests. The research team will work closely with the partners and design code committee to formulate the appropriate framework with which the proposed design recommendations can be incorporated in the design codes.