Time-Domain Buffeting Analysis of a Cable-Stayed Bridge Considering Frequency-Dependency of Unsteady Aerodynamic Forces

A time-domain nonlinear buffeting analysis procedure is presented to estimate geometrical nonlinear effects of a cable-stayed bridge on buffeting responses. Since the self-excited forces are formulated in terms of motional frequency of a girder, a linear frequency-domain approach is straightforward to consider the frequency-dependency of the unsteady aerodynamic force. A time-domain approach, however, requires much complicated techniques and procedures. The current nonlinear buffeting analysis procedure approximated flutter derivatives as rational functions and then the unsteady forces are calculated through a convolution integral. An actual cable-stayed bridge was numerically modeled and a series of buffeting analysis were performed to estimate the effects of the frequency-dependency of unsteady aerodynamic forces and the geometrical nonlinearity of cable-stayed bridge structure on buffeting responses of girders. The consideration of these two properties in buffeting analysis was found to change the overall magnitude of buffeting responses of the examined bridge to a certain extent as mean wind velocity increased.