Dynamic Tornadic Wind Loads on Tall Buildings

A mathematical model is developed to study tornadic wind loading on tall buildings. Based on a theoretical solution, a wind field model is constructed, in which the variation of wind velocity within the tornado vortex boundary layer is considered. The dynamic wind loading and response of a tall building is investigated. A method of evaluating the probability of maximum response due to tornado is also presented. It is found that: (1) the inertia force component, usually neglected in conventional wind force formula, plays an important role; (2) Dynamic effect is important and the response level can be extremely high if the building is close to the tornado path; and (3) dynamic tornado effect dominates, as compared with ordinary winds, in the risk range where structural failure is of primary concern.