Improved relationship for drift loads on buildings

Abstract

In terms of structural failure, drift loads at changes in roof elevation are the most important snow load. In this paper, present building code provisions and recent research results are reviewed. The mechanics of snow drift formation as well as the parameters that influence these drifts are discussed in depth. Finally, a new empirical relationship for peak drift height and drift load is presented. The input parameters for the new empirical relationship are the width, length, and height of the upper level roof, the elevation difference between the upper level roof and snow on the lower level roof, and the ground snow load. Comparisons with case history measurements indicate that the new empirical relationship is a marked improvement over existing relationships. Key words: snow, loads, roof, drift, fluid mechanics, building codes.