Prestress Losses in High Performance Lightweight Concrete Pretensioned Bridge Girders

Abstract

This research investigated prestress losses, creep and shrinkage of pretensioned girders made with expanded slate high performance lightweight concrete. The purpose of the investigation was to determine how long term behavior affects the prestress losses in high strength precast, prestressed concrete bridge girders. The two high performance lightweight concretes (HPLC) developed for this study had strengths of 8000 and 10,000 psi, and air dry unit weights of 116 and 118 lb/ft. Prestress losses were estimated using the American Association of State Highway and Transportation Officials (AASHTO) refined, AASHTO lump sum, Precast/Prestressed Concrete Institute (PCI), and American Concrete Institute (ACI) 209 methods. All these methods overestimated the time dependent losses. This result means that these methods are conservative for estimating time dependent losses of expanded slate HPLC girders.