RISK ANALYSIS OF WIND LOADING INCLUDING FUTURE CHANGES IN SURROUNDING BUILDINGS

摘要

Wind tunnel tests of tall buildings are capable of accurately determining the wind loads on a building in its current surroundings, since the surroundings are included in the wind tunnel modelling. The tests may also include some future developments if they are known to be imminent. However, the question of the effects of possible longer term changes in surroundings needs to be considered. In some cases the development of the city may be mature resulting in little likelihood of future changes, but in rapidly developing cities the possible changes may be significant. It is known that buildings very close to the building under test can have significant sheltering effects in some cases and may amplify wind loads in other cases. Cases have been seen where the removal of an important adjacent building more than doubled the wind loads. Wind tunnel testing can readily determine loads in the different scenarios but the question of how to treat the data requires some thought. This paper presents a method called the Combined Risk Method in which the results from the various test scenarios are combined to provide a single risk consistent relationship between load and return period. It does require that the various stakeholders agree on a reasonable probability for each scenario, but once this is done the method makes the path clear to developing appropriate design loads. The paper includes examples of application of the method to several projects.