Wind-induced response and serviceability design optimization of tall steel buildings

Trends towards constructing taller and increasingly slender buildings imply that these structures are potentially more responsive to wind excitation, causing discomfort to occupants. This paper seeks to develop an integrated wind tunnel load analysis and automatic least cost design optimization procedure to assist structural engineers in the prediction of wind-induced response based on the High Frequency Force Balance (HFFB) technique and on the serviceability design of tall steel buildings. It has been shown that the wind-induced acceleration is inversely related to the natural frequency of tall buildings within the range of frequency for serviceability checking. An Optimality Criteria (OC) method is developed to minimize the structural cost of steel buildings subject to targeted frequency constraints in which the limiting frequency threshold is derived from the motion perception design criteria of ISO Standard 6897. The effectiveness of the proposed integrated wind tunnel analysis and numerical design optimization procedure is illustrated through a full-scale 45-story symmetric tubular steel building example. This building was initially found to vibrate excessively under wind loading and then the automated optimization procedure was used to determine the optimal structural stiffness satisfying the stipulated ISO Standard 6897 occupant comfort criteria.