STATUS: To be published as NCHRP Research Report xxx
Long-span bridges are often used in environmentally sensitive terrains, water crossings, and in locations with traffic and geometric restrictions. Bridges with long-span precast pretensioned girders are advantageous due to their ease and speed of construction, lower cost, and long-term durability. The use of 0.7-in. diameter strands would help bridge designers extend the spans of the existing girder shapes. However, the current AASHTO bridge design and construction specifications do not address the use of 0.7-in. diameter strands for precast prestressed girders. Bridge owners, fabricators, and contractors need specifications and guidelines to implement the use of 0.7-in. diameter strands in practice.
The objectives of this research were to develop: (1) proposed modifications to the AASHTO LRFD Bridge Design Specifications and the AASHTO LRFD Bridge Construction Specifications to incorporate the use of 0.7-in. diameter strands in precast pretensioned girders for various span lengths; (2) guidelines for precast pretension girder fabrication using 0.7-in. diameter strands; and (3) guidelines for handling, shipping, and erection of long-span girders. Accomplishment of the project objectives will require at least the following tasks.