Evolution of the seismic provisions of the National Building Code of Canada

This paper describes the evolution of the seismic provisions of the National Building Code of Canada (NBCC), beginning with the status of NBCC as a model code. The major changes of seismic provisions are traced from the 1953 to the 2005 editions of NBCC. The most recent changes from NBCC 1995 to NBCC 2005 are presented and discussed in more detail, including numerical comparisons of seismic design forces for typical building structures located in regions of high, moderate and low seismicity. The paper includes a discussion of the implications of these changes for seismic design practice and comments on potential future directions for seismic code development.