Mohammad Vaghefi

Bridges are the most important river structures that are destroyed due to erosion. The change in the shape of the river geometry along the course of the river leads to erosion of the river bed and can also affect scour around the pier. Therefore, in this paper, the effect of the convergence and divergence ratio of 15% in the 180º bend was investigated on the amount of scour around the pier of the circular bridge using the SSIIM numerical model. The results showed that the SSIIM software has a high ability and accuracy in determining the scour pattern in bend channels. The most scour depth appeared in the bend with 15% convergence and it increased by 1.75 and 2.33 times compared to the uniform and divergent bend, respectively. Also, the most sedimentation height occurred in the bend with 15% convergence and it increased by 3.25 and 4.33 times compared to the uniform and divergent bend, respectively.