Probabilistic Description of Buffeting Response of Long‐Span Bridges. II: Extended Analysis

Abstract

The buffeting response of long‐span bridges in turbulent wind is dealt with in the present investigation. Herein the analysis is based on linear models describing the structural behavior and the fluid‐structure interaction. Accounting for both parametric excitation (motion‐induced loads) and buffeting (flow‐induced) loads the bridge response is described by differential equations in the time domain. The basic concept of the method of analysis presented in the first paper is now extended to multidegree‐of‐freedom systems. First, a critical mode, which is significantly affected by parametric excitation, is isolated. Utilizing Markov process theory a statistical description of this critical mode in terms of probability density functions is given. Classical spectral analysis constitutes the basis for the analysis of the remaining (noncritical) modes. Employing the so‐called Nataf model statistical information is obtained for the response quantities including exceedance rates of torsional and vertical bending displacements. Thus a most valuable basis for engineering decisions is provided by the present investigation. The suggested approach is then exemplified in the numerical examples showing among others the role of parametric excitation for the bridge response behavior in the region of stable motion.