Site-Specific Snow Load Models and Hazard Curves for Probabilistic Design

Abstract

This paper describes a study to develop site-specific probabilistic snow load models for use in reliability analyses of structures in the United States. Annual maximum snow water-equivalent depth data measured at 93 first-order weather stations was obtained from the National Climatic Data Center. These were then converted to annual maximum ground snow loads and statistics at each site were obtained using graphical fitting techniques. The 50 year maximum roof snow load values (in ratio to code-specified nominal values) were then evaluated site by site using the statistics for annual maximum ground snow, extreme value theory, Monte Carlo simulation, statistics for ground to roof conversion factors, and the nominal ground snow load values in ASCE 7. Finally, the 84 sites in the continental United States (excluding nine sites in Alaska) were grouped on the basis of the 5% exclusion values of actual to nominal 50 year maximum roof snow load. Aggregated statistics for 50 year roof snow load in three geographic ...