Incremental Engineered Improvements for Enhanced Seismic Performance in Steel Framed Structures

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In Canada, while the greatest seismic risk is on the west coast, many other regions in and around major urban centers (e.g. Montréal, Ottawa, Québec) are prone to lesser but damaging risks. It is essential to ensure that the built environment is resilient to all levels of seismic hazards in an efficient and cost-effective manner. Earthquake-resistant systems available in contemporary building codes are calibrated for good performance at the life safety or collapse prevention limit states often under very high intensity ground shaking levels. They do not guarantee good structural performance at other less severe but frequent levels of ground shaking. In other words, the current designs do not offer reliable and adequate structural performance across all limit states. The proposed research aims at developing new types of brace elements that are inherently optimised to meet multiple performance objectives. In this respect, multiple steel materials with different mechanical behaviour properties (i.e. regular carbon, high strength and austenitic Type 304 stainless steels) are employed in the buckling-restrained brace element to complement each other when subjected to different levels of earthquake forces, while enabling effective control of the component`s behaviour and the overall structural response. Comprehensive testing and analytical programs are designed. Incremental improvements are made by comparing performance of the novel brace types to the traditional design technique. Important design rules are consequently established to deliver enhanced performance at all limit states and to improve reliability. The research findings will be beneficial to both new construction and retrofitting of existing deficient framed structures. The anticipated outcome of this research is significant, in terms of both delivering an improved technology and the training of highly qualified personnel who would lead its implementation in practice.