|The main structure of a tall building and its façade must be designed to safely withstand the extreme winds that the building will be subjected to during its expected life. An important part of achieving this is determining what the wind loads will be for specific mean recurrence intervals and what the uncertainties are in these loads. |
While for ordinary buildings the wind loads and appropriate load factors that allow for uncertainty are often prescribed by the analytical methods given in building codes, for tall buildings, in view of the importance of wind loads to their cost and safety, these analytical methods often lack the precision needed. They do not account well for important wind phenomena such as crosswind excitation, aerodynamic interactions between adjacent buildings and aerodynamic instability, all of which affect not only loads but also may cause building motions that occupants find excessive.
For these reasons the wind loads and motions of tall buildings are typically determined by wind tunnel tests on scale models of the building and its surroundings, through which much more precise, project specific, information is obtained.