Electronic Thesis and Dissertation Repository

Degree

Master of Engineering Science

Program

Civil and Environmental Engineering

Supervisor

Hanping Hong

Abstract

The current National Building Code of Canada (NBCC) recommends a wind load factor of 1.4 and the nominal wind velocity pressure corresponding to 50-year return period value of the annual maximum hourly-mean wind speed, VAH. This study is focused on mapping wind hazard for Canada and on calibrating the required design wind load to improve reliability consistency of the designed structures.

Extreme value analysis of VAH was carried out by considering surface wind observations from approximately 1300 stations. The results indicate that the spatial trends of the estimated mean of VAH are similar whether the data from stations with at least 20 or 10 years’ useable wind observations are considered, but the small sample size affects the spatial variations of the coefficient of variation (cov) of VAH. The estimated 50-year return period values of VAH based on the at-site analysis differ from those inferred from two previous versions of the NBCC, and the differences persist if the estimates were obtained by using the region of influence approach. Potential reasons for the discrepancy were elaborated.

It was shown that an improved reliability consistency can be achieved if a wind load factor of 1.0 is employed and the nominal wind velocity pressure is assigned using 500-year return period value of VAH. It is also shown that a further improvement on the reliability consistency can be achieved if a variable return period as a function of cov of VAH is used to assign the nominal wind velocity pressure.

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