Sensitivity of gust responses of bridges to spatiotemporal varying wind excitations

Use of the gust factor approach is an acceptable practice in evaluating wind-induced structural responses. The gust factor concept was developed by Alan G. Davenport in a series of studies published in the early 1960s. A simple approximation for evaluating the gust factor for bridges under fluctuating wind load and including the aerodynamic effects is also given by Davenport. Although sophisticated methods and techniques have been developed, their use to verify and possibly improve the approximation for bridge design has not been conducted. The needed verification and development of possible improvement are carried out in the present study. The analysis adopts the frequency domain approach, uses the finite element method, and considers the aeroelastic forces. It shows that the gust factor due to the buffeting force can be conveniently expressed as a function of only two parameters: a scaled exponential decay coefficient and a normalized frequency considering the first vibration mode. Based on the parametric investigation, an improved approximation to evaluate the gust factor used in calculating the wind-induced bridge responses is also proposed.