Controlled rocking steel systems: from concept to design

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The public generally assumes that new buildings are “earthquake-proof,” meaning that they could be used after an earthquake without repair. However, current design codes attempt only to ensure that a building can be safely evacuated after an earthquake. Therefore, code-compliant structures are likely to be damaged by design-level earthquakes, even if they behave exactly as intended. This was recently demonstrated in Christchurch, New Zealand, where a series of earthquakes in 2010-2011 has led to the demolition of 70% of the buildings in the central business district. In 2013, a report commissioned by the Insurance Bureau of Canada warned of $75 billion in losses due to the kind of earthquake that is expected to occur off the west coast. The extreme socio-economic cost of such disasters calls into question the wisdom of a design philosophy that accepts damage. However, this philosophy is unlikely to change unless systems with better performance can be built without greatly increasing the initial construction cost. This research program will greatly improve the resilience and sustainability of built infrastructure, which is at the core of the Canadian economy, by developing economical systems that can withstand earthquakes without structural damage. One particular system that shows promise for improving seismic resilience at a competitive initial cost is a Controlled Rocking Steel System. Although significant progress has been made on understanding this system, several key questions prevent it from being implemented widely. Over the next 5 years, this research program will answer the most pressing questions that prevent Controlled Rocking Steel Systems from moving from concept to design. As these questions are answered, a Canadian design guideline will be developed, and over the next 5-10 years, this is expected to lead to Controlled Rocking Steel Systems being specified as an acceptable seismic force resisting system in the National Building Code of Canada (NBCC), with appropriate provisions in Section 27 of the Canadian Steel Standard CSA S16. The long-term objective of this research program is to make damage avoidance a routine part of seismic design for all structures in Canada, rather than being a special design objective that is reserved for exceptional structures.