Steel Beats Concrete for Idaho Bridge

As an alternative to prestressed concrete design, the State of Idaho and the Federal Highway Administration encouraged the use of cable-stressed steel girder design for the Bonners Ferry Bridge in Northern Idaho. By implementing the same materials and techniques used in prestressed concrete, a cable-stressed steel girder results. Cable-stressed steel is defined as high-strength steel cables and structural steel working in combination to resist the external moment. The combination reduces the amount of structural steel required, limits tension stresses in the structural steel section, and provides redundancy by multiple tension stress paths. Stressing steel reduces the weight of structural steel and improves structural performance. Cable-stressed steel substitutes high-strength cables for lower strength structural steel. The cable-stressed steel concept promises savings in construction cost, better control of deflections, and improved stress distribution and provides multiple load path redundancy and solutions to some of the concerns of steel bridges.