The latest version of the National Building Code of Canada, the 2020 edition, was released in early 2022. New provisions were added in the 'Earthquake Loads and Effects' portion of the code regarding additional performance requirements for PostDisaster buildings, High Importance category buildings, and a subset of Normal Importance category buildings.
Prior to NBC 2020 (in the NBC 2015) all buildings were to be designed for only one earthquake level, based on a 2% probability of exceedance in 50 years. The performance objective for Normal Importance buildings is to 'minimize loss of life' (i.e., life safety) with the understanding that there could be extensive damage. The use of importance factors and reduced drift limits for High Importance and Post-Disaster buildings is to address performance objectives of 'immediate occupancy' and being 'functional', respectively. These requirements remain in NBC 2020 for the noted earthquake level.
The new provisions in NBC 2020 provide design requirement for other earthquake levels. The provisions require Post-Disaster buildings and High Importance buildings in defined hazard areas to 'behave elastically' with a performance objective of 'no structural damage' for earthquake demands based on a 5% probability of exceedance in 50 years and 10% probability of exceedance in 50 years. Reduced drift limits and additional requirements for connections of non-structural components are also specified. The new provisions require Normal Importance buildings more than 30-m high in defined hazard areas to have structural framing elements not considered to be part of the Seismic Force Resisting System, to 'behave elastically' with a performance objective of 'no structural damage' for earthquake demands based on a 10% probability of exceedance in 50 years.
This paper provides further details about the new provisions and provides some information on the building cost impact of these new provisions.Read the full paper