High Performance Concrete in Washington State SR 18/SR 516 Overcrossing: InterimReport on Girder Monitoring

摘要

In the mid 1990's the FHWA established a High Performance Concrete (HPC) programaimed at demonstrating the positive effects of utilizing HPC in bridges. Research on the benefits of using high performance concrete for bridges has shown a number of benefits. These include increased span capacities, or wider girder spacings (and hence a fewer number of girders); increased concrete compressive and flexural capacities; and improved concrete durability. However, inspite all of these positive research results, relatively little has been done regarding the implementation of high performance concrete in bridges in the United States. The general goals of the FHWA program are: to encourage the States to implement HPC in bridges; to develop appropriate mix designs and establish quality control procedures; to encourage the use of larger diameter (15mm (0.6ft)) prestressing strands in the girders; to evaluate the performance of the structure; and to provide for technology transfer through development of a workshop (showcase). This report presents interim results of the effectiveness of using HPC in prestressed precast concrete girders on a bridge in the state of Washington. State Route 516 utilizes WSDOT 74G pretensioned I-girders with a 190 mm cast-in-place composite deck. The girders were fabricated with 15mm diameter prestressing strands at 50 mm spacing, and designed for a concrete compressive strength of 69 MPa at 56 days. This report documents fabrication of a test girder and the bridge girders; provides a description of the instrumentation program; presents the measured data including strain, camber, temperature time histories, and prestress losses; and evaluates the accuracy of the prestress loss equations in predicting observed prestress losses.