Experimental Study on the Drag force on Bridge Abutments

The drag force exerted on a bridge abutment, representative of wall-attached structures, is studied with different geometries in various flow conditions. The drag force was quantified by two methods here: 1) direct method by using strain gauges and 2) employing the conservation of momentum equation which takes advantage of the flow characteristics. . The momentum equation results differed considerably from the direct method, mainly related to even the smallest inaccuracy in depth measurements. We suggest a modified momentum equation to enhance accuracy because of its independence on downstream flow depth measurement. The experimental results also revealed that the constriction ratio at the bridge abutment section and the abutments geometric shape are the most influential parameters on the drag coefficient. On the other hand, the effect of flow characteristics is negligible. Finally, we proposed an empirical relationship to estimate the drag coefficient.