CONTECH Written

Written

Author: BRIAN LOONEY, P.E

Water always wins if you give it enough time. It carves canyons, flattens coastlines and (more quietly but no less powerfully) erodes the very foundations of the bridges we depend on every day. This process, known as scour, is responsible for more bridge failures in the United States than any other hydraulic force1. It’s not dramatic like an earthquake or a hurricane. It doesn’t strike in an instant. Scour works in silence, grain by grain beneath the surface, until the supporting material is gradually removed and the structure above is left unstable. Ironically, the key to preventing scour might not lie in resisting the flow but rather reshaping how we engage with it. Concrete Armor Units (CAUs) can provide an alternative approach by transforming the way flowing water interacts with the foundations that support our bridges.

LEARNING OBJECTIVES

At the conclusion of this article, the reader should be able to:

• Understand the hydraulic mechanisms that contribute to scour at bridge piers and abutments.

• Gain familiarity with Concrete Armor Units as a scour protection solution and how they interact with flow and sediment under varying hydraulic conditions.

• Evaluate site-specific factors to guide sizing and installation of Concrete Armor Units.

• Interpret key design methodologies to establish limits.