Cutting Debonded Strands

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ScotLarson
Cutting Debonded Strands

Can PGSuper handle cutting top flange strands that are debonded in the middle? We're in the process of designing a 190' single span PCB bridge and are looking for a program that can properly handle cutting of strands in the final condition to better handle stresses.

bricer
Cutting Debonded Strands

Glad you asked... yes, PGSuper can handle that.

The top flange strands are modeled as temporary strands. Temporary strands can be pretensioned or post-tensioned. When post-tensioned, they can be installed before initial lifting from the casting bed, after lifting (at the beginning of storage), or at the end of storage (before transport). Temporary strands are assumed to be detensioned (cut/removed) prior to casting of intermediate concrete diaphragms and the deck.

The effect of temporary strands on prestress losses, initial concrete strength requirements, and camber are all taken into account. Elastic rebound from temporary strand removal is also accounted for.

Temporary strands are often bonded over a short distance, and then debonded through the center portion of the girder. When detensioned, some residual precompression remains in the bonded region. The software does not consider this. Once removed, temporary strands are considered to be completely removed from the girder.

The basis for the temporary strand capabilities in PGSuper is "Design Optimization for Fabrication of Pretensioned Concrete Bridge Girders: An Example Problem", Brice, et. al. 2009, PCI Journal V54 No 4.

Temporary strand use is associated with girder stability considerations. PGSuper supports PCI's Recommended Practice for Lateral Stability.

That's probably more information than you wanted

Rick

ScotLarson
Cutting Debonded Strands

Appreciate the thorough response!

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