Overview of NRC’s Newly Released Seismic Upgrading Guidelines (SUG) for Existing Buildings in Canada

Abstract

Earthquakes are among the most destructive natural disasters, capable of causing severe casualties and significant economic losses. For building owners, assessing and mitigating seismic risks in existing buildings poses both technical and economic challenges. In Canada, there has long been a need for nationwide technical guidelines for seismic evaluation and upgrading. The National Research Council Canada (NRC) first addressed this in the 1990s by publishing Guidelines for Seismic Evaluation of Existing Buildings and Guideline for Seismic Upgrading of Building Structures. However, these documents were never updated and have since become outdated.

Currently, the National Building Code of Canada (NBC) Commentary L recommends ASCE 41 Seismic Evaluation and Retrofit of Existing Buildings as a reference for seismic evaluation and upgrading. While comprehensive, ASCE 41 is based on American design and construction practices, and its direct applicability to Canada requires careful consideration.

Recognizing this gap, the Seismic Resilience Team at NRC’s Construction Research Centre has spent the past seven years developing updated, Canadian‑specific technical guidelines—the newly released Level 3 – Seismic Evaluation Guidelines (SEG) and Seismic Upgrading Guidelines (SUG) for existing buildings in Canada.

Designed to help professionals apply these new guidelines for effective implementation, and to improve safety and resilience of existing buildings, a series of webinars and training workshops are being delivered by the NRC in partnership with CAEES.

While the SUG may be considered the Canadian counterpart to ASCE 41, there are several significant differences:

1. Linear analysis methods in the SUG are force-based and aligned with the NBC and CSA design standards.
2. A Canadian multi-modal pushover analysis method has been adopted for carrying out non-linear static analysis.
3. Modelling parameters and acceptance criteria for non-linear analysis of existing buildings have been adapted to the Canadian context.
4. Upgrading design details from existing standards and guidelines have been synthesized and adapted to suit Canadian construction practice.

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