Author(s): Christopher Valela, Colin Rennie, Ioan Nistor
Keywords: Scour; Bridge Pier; Countermeasure; Collar;
Abstract: Collar Prototype No. 1, which was first introduced in 2018, is successful at reducing bridge pier scour but could perform even better if some flaws in the design were addressed. Collar Prototype No. 2 is presented in this paper as a revision of Collar Prototype No. 1, with the intention of reducing scouring along the sides and front of the collar. To do so, the collar shape was made more streamlined to prolong the point of flow separation and to allow the passing flow to exit at the rear of the collar rather then being redirected off the sides. Constructing the physical model of the collar was done using three-dimensional printers and PLA plastic which deemed to be a better approach over conventional metal machining because of its low cost and ease of use. The design changes to the collar resulted in the elimination of scour from the mid point of the pier until the upstream extent of the study, ultimately addressing the main issue pertaining to Collar Prototype No. 1. However, greater scour was experienced downstream, such that a 15% deeper maximum scour depth was achieved when compared to Collar Prototype No. 1. Despite the reduction of scour upstream, Collar Prototype No. 2 is not better at mitigating scour then Collar Prototype No. 1, due to the resulting downstream scour. Both numerical and experimental methods were used to evaluate the collars performance and the numerical shear stress results were found to be a good predictor of scour.