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Feasibility Study of Continuous For Live Load Steel Bridges

Morales, Daniel Enrique

Currently in the United States, the precast, pre-stressed concrete design method dominates the new construction market in the short to medium span range bridges. One approach to help make steel bridges more competitive with pre-stressed concrete bridges is the continuous for live load method (CLL). The method employs a simply supported interior end restraint configuration for dead loads and a subsequent modification to a continuous span configuration for live loads by way of a concrete diaphragm at interior supports. To determine the feasibility and effectiveness of this method, a cost analysis, an in-situ field load test, and finite element analysis were performed on two CLL bridges in service in New Mexico, USA. The continuous for live load method was found to be more cost and time effective as compared with traditional continuous steel bridge construction. Additionally, it was determined that both case study bridges maintained continuity across the interior supports.