Lateral‐Torsional Motion of Tall Buildings to Wind Loads

The lateral‐torsional motion of tall buildings is investigated. For a square cross‐section building, expressions for the alongwind, acrosswind and torsional loading are developed through the use of spatio‐temporal fluctuations in the pressure field around the building. A simplified formulation is used to represent the dynamic behavior of torsionally coupled buildings by considering a class of buildings in which all floors have the same geometry in plan, the eccentricities between the elastic and mass centers are the same for all stories, and the ratio of the story stiffness in lateral directions is about the same for all stories. Methods of random vibration theory are used to estimate the rms and peak values of various components of response. The results indicate that the torsional response contributes significantly towards the overall dynamic response of a symmetric building. Inclusion of coupling between the lateral and torsional degrees‐of‐freedom further increases the building response. The procedure presented here provides a convenient checking procedure, from a structural reliability viewpoint, for serviceability and survivability limit states, thus ensuring serviceability under normal conditions as well as safety under extreme loads.