Effect of Six-Legged Elements installation arrangement on bed topography around Wing-Wall Abutments

The reviews of past researches have shown that abutment scour plays an important role in bridge failures. Hence, protection of bridges against scour is a significant issue. For existing bridges, armoring methods, like riprap, has a wide application. In areas where providing stones is expensive concrete blocks or similar techniques have been applied. In this study for the first time, the application of six-legged concrete elements has been experimentally investigated. The six-legged elements have been placed in three different densities (open, medium and dense) and three different placement depths (under the bed, above the bed and medium case). Each alternative have been tested under different flow conditions. Generally the results proved that the six-legged elements can considerably reduce the scour depth under different flow conditions so as it reduced the maximum scour depth of abutment nose up to 100%. The maximum reduction of scour depth has been obtained when the high dense six-legged elements are placed above the bed. In this case, the elements protect the abutment by creating coverage and also alter the sour from the abutment tip to the channel midway.