Characterisation and advanced modeling of multidimensional strain-rate effects on structural steels for enhanced seismic design of building structures in Canada

低层钢结构建筑用于轻工业、商业和娱乐目的，在加拿大的建筑存量中占很大比例。这些建筑物大多位于太平洋沿岸和沿着圣劳伦斯河和渥太华河的活跃和中等地震活动水平的地区。对于这种类型的建筑，加拿大国家建筑规范对各种抗震系统（SFRS）的设计规定了能力设计理念，预计在地震等严重动态激励下会发生非弹性响应。在这种类型的事件中，韧性SFRS中的应变率往往非常高，这导致材料的行为与缓慢加载时不同。因此，在设计和/或数值模拟结构响应时，不考虑应变率可能会导致对结构预期行为和预期失效模式的错误结论。本研究计划的主要目的是：1）研究应变率对结构钢屈服和极限应力轨迹的影响，2）开发精确预测复杂动力非弹性要求下结构构件响应的数值工具，3）通过偏心支撑框架杆件（EBF）的动力试验结果验证这些工具的有效性。（4）研究应变率对当前设计实践的影响，即识别可能导致结构整体倒塌的断裂模式的潜在变化。最终，目前的研究计划旨在：1）更好地了解应变率对延性钢元件的影响; 2）考虑应变率的影响，提出更好的抗震设计准则。更好的设计通常会产生金融经济，但更重要的是在发生大地震时更安全的结构。

Low-rise steel buildings used for light industrial, commercial, and recreational purposes, represent a vast proportion of the building stock in Canada. Most of these buildings are located in regions of active and moderate seismicity levels on the Pacific coast and along the St-Lawrence and Ottawa rivers. For this type of building, the National Building Code of Canada imposes a capacity design philosophy for the design of various seismic force resisting systems (SFRS), for which inelastic response is anticipated under severe dynamic excitation such as earthquakes. During this type of event, the strain-rates in ductile SFRS tend to be very high which causes the material to behave differently than when loaded slowly. For this reason, not taking into account strain-rates when designing and/or numerically simulating the response of a structure in such context might lead to erroneous conclusions on the structure's expected behaviour and expected modes of failure. The main objectives of the research program are: 1) to characterise the effects of strain-rates on the yield and ultimate stresses loci of structural steel; 2) to develop numerical tools to accurately predict the response of structural elements submitted to complex dynamic inelastic demands; 3) to validate those tools from dynamic test results on eccentrically braced frame links (EBF); and 4), to investigate the effects of strain-rates on current design practices, i.e. to identify the potential changes of rupture modes in structures that could lead to a global collapse. Ultimately, the current research program aims at: 1) better understand the effects of strain-rates on ductile steel elements; and 2) proposing better seismic design guidelines taking into account the effects of strain-rates. Better designs generally yield to financial economies, but more importantly in safer structures in the event of major earthquakes.