Camber Control in Precast/Prestressed Concrete NU Girders

It has been known that precast prestressed girder camber at prestress release and at time of erection can vary significantly even in cases where two identically prestressed girders are stored in the same manner and erected at the same time. The variations become more significant as high strength concrete, high span-to-depth ratio, and heavily prestressed girders are used, which create challenges for owners, contractors, and producers. Camber variability, prediction, and control are widely discussed issues during design, production and construction. Camber at prestress release is not complicated to predict as it is not impacted by creep, shrinkage, girder support condition, or the environment. However, it is highly influenced by the modulus of elasticity (MOE) and elastic shortening losses at prestress release. Therefore, accurate prediction of those parameters would allow for accurate prediction of camber at release. Cambers at shipping, erection, and time of deck placement for girders made composite with cast-in-place decks, are highly influenced by girder age, prestress losses, creep behavior, and girder support conditions. Long-term camber/deflection is commonly predicted using constant PCI multipliers. These multipliers were originally developed in 1977 for building Double Tees (DT) with 2 in. composite topping are not suitable for use in bridge applications.

Language

• English

Project

• Status: Programmed
• Funding: $85,575.00
• Sponsor Organizations:

  Nebraska Department of Transportation

  1500 Nebraska 2
  Lincoln, NE  United States  68502
• Project Managers:

  Halsey, Lieska

• Principal Investigators:

  Morcous, George

  Maguire, Marc

• Start Date: 20250701
• Expected Completion Date: 20270531
• Actual Completion Date: 0

Subject/Index Terms

• TRT Terms: Bridge construction; Curvature; Girders; Modulus of elasticity; Prestressed concrete
• Subject Areas: Bridges and other structures; Construction; Materials;

Filing Info

• Accession Number: 01945351
• Record Type: Research project
• Source Agency: Nebraska Department of Transportation
• Files: RIP, STATEDOT
• Created Date: Feb 10 2025 11:24AM