Development of Damage-Resislient Structures Using Smart Materials

基于力和基于性能的抗震设计方法指定目标最大漂移作为性能水平和损坏的指标。震后勘测观测进一步确定了剩余漂移作为量化结构性能和结构运行状态的措施的额外重要性。因此，残余漂移决定了结构物是否可以使用、是否需要修理或是否必须拆除。本研究的总体目标是开发弹性混凝土结构系统，用智能材料加固或改造，以控制地震激励反应过程中产生的永久性损伤，从而使结构立即可用。形状记忆合金（SMA）是一类具有控制永久变形能力的智能材料。该材料具有承受大应变的能力，该应变水平将在钢筋中引起显著的永久应变，但具有在去除应力（超弹性（SE）SMA）或施加热（形状记忆效应（SME））后恢复其原始形状的上级能力。这是使材料在地震应用中具有吸引力的主要行为特征。除了稳定的滞回响应外，其他显著特征包括与钢筋相当的强度和位移能力。*本文的重点是利用SE-SMA的机械性能开发弹性结构，包括新的和旧的建筑。具体而言，将开发改进的建模能力，为SE-SMA钢筋混凝土结构的性能评估提供工具。这将通过一个新的非线性迟滞本构模型SE-SMA和有限元建模程序。针对现有的抗震性能较差的钢筋混凝土框架结构，提出了一种新型的屈曲约束支撑加固方法，该支撑中含有SE-SMA内芯作为保险丝。将设计和测试替代SE-SMA桥柱，以评估与加拿大公路桥梁设计规范（CHBDC）的兼容性，并建立基于性能的设计所需的损坏指标。最后，SE-SMA钢筋混凝土结构的长期性能将通过在桥梁柱中诱导腐蚀来评估，然后通过实验测试来确定横向强度和位移能力，以及柱在腐蚀损坏后重新居中的能力。

Force-based and performance-based seismic design approaches specify target maximum drifts as indicators of performance level and damage. Post-earthquake reconnaissance observations have further identified the additional importance of residual drift as a measure to quantify structural performance and the operational state of a structure. The residual drift, therefore, determines whether a structure can be serviceable, requires repair, or must be demolished. The overarching goal of this research is to develop resilient concrete structural systems, reinforced or retrofitted with smart materials, to control permanent damage that arises during response to seismic excitations leading to structures that are immediately serviceable. Shape Memory Alloys (SMAs) are one class of smart materials that have the ability to control permanent deformations. The material has the capacity to sustain large strains, levels that would induce significant permanent straining in steel reinforcement, but with the superior capability to return to its original shape after removal of stress (Superelastic (SE) SMA) or with the application of heat (Shape Memory Effect (SME)). This is the main behavioural feature that makes the material attractive in seismic applications. Other salient characteristics include strength and displacement capacities comparable to steel reinforcement, in addition to stable hysteretic response.****The focus herein is to exploit the mechanical properties of SE-SMA towards the development of resilient structures including new and old construction. Specifically, improved modelling capabilities will be developed to provide tools for performance assessment of SE-SMA reinforced concrete structures. This will be achieved through a new nonlinear hysteretic constitutive model for SE-SMA and finite element modelling procedures. Retrofitting with a novel buckling restrained brace that encompasses an SE-SMA inner core acting as a fuse will be developed for existing seismically deficient reinforced concrete frame structures. An alternative SE-SMA bridge column will be designed and tested to assess compatibility with the Canadian Highway Bridge Design Code (CHBDC) and to establish damage indicators required in performance-based design. Finally, the long-term performance of SE-SMA-reinforced concrete structures will be assessed by inducing corrosion in bridge columns followed by experimental testing to determine the lateral strength and displacement capacities, and the ability of the columns to re-center following corrosion damage.******