Multivariate simulation for assessing the joint wind and ice hazard in the United States

Multi-hazard assessment is receiving increasing attention as often commonly occurring hazards may contain a second or even a third associated hazard. Generally, multi-hazards could be joint hazards (i.e. these hazards occur at the same time), for example, a hurricane usually comes with strong wind, storm surge, and heavy rainfall. They can also be one hazard preceding another, for example, an earthquake generating a tsunami. The jointly occurring hazards in some cases can be more devastating than a single hazard. This paper will describe the assessment of two jointly occurring hazards, wind and ice formation by using an advance numerical simulation. First, multivariate (hourly wind, temperature and precipitation) simulation for many years in the Midwestern US is undertaken. By setting a condition for freezing rain, these parameters were input into a simple ice-accretion model to estimate ice-thickness. A joint hazard curve for wind and ice was then constructed and compared to the existing prescribed treatment of these two hazards in design loading guidelines, such as ASCE 7 in the United States, ISO 12494 (International Standard); and the results from our previous model.