Effects of approaching flow on response characteristics of a cantilever bridge model in the wake of a hill

Response characteristics of a flat plate cantilever, which can be thought as a simplified model of a cable-stayed bridge under construction, in the wake of a conical hill were studied experimentally. The response was found to be much larger and spikier than that in the approaching boundary layer. It has been observed that both response magnitude and spikiness are very much dependent not only on the nearby hill but also on the characteristics of the approaching flow. The non-uniformity of the flow field has been incorporated in the conventional gust response analysis formulation and showed its unsuitability in estimating the bridge response in the wake of a hill. With a view to identifying the flow structure that causes the spiky response, visualization of flow has been carried out and it is believed that the large-scale vortex that has large correlation along the bridge span can cause the spiky responses.