Flexible structures such as cable-stayed bridges are subject to dynamic wind loads. These are usually divided into two categories, flutter which is a motion-induced load and buffeting, which is generally considered as an uncoupled load. When these two phenomena are intertwined, it becomes difficult to use spectral methods and time simulation represents a relatively new and better alternative. The present study focuses on a new time-delayed model for the motion-induced pitching moment which can be combined with the effect of a gust. The experimental validation in wind tunnel is provided where flexibly mounted deck sections are submitted to a single gust. Three typical sections, stable or unstable, are considered: the Millau bridge, the Tacoma bridge and the NACA-4412 section.