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Idea#333

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Bridge and Structures »

Effect of temperature on PC strand stress during construction

Idea Submitted by:
Catherine French
List your MnDOT Office,District,City, County, Univ. or Other:
University of Minnesota - Twin Cities
Idea Champion - Who at MnDOT/LRRB? :
Paul Rowekamp

Why is this a priority for the State/County/City? : State

During fabrication of prestressed concrete bridge girders, the strands are pretensioned in the precasting bed prior to casting the concrete. Because the beds are fixed length, changes in temperature affect the mechanical stress in the strands. Currently, the strand stress is adjusted during tensioning to account for the difference in temperature between strand pull and the temperature of the concrete at placement. It is believed that temperatures may increase to the hydration temperature (e.g., 160 degrees Fahrenheit) prior to bonding. The implication is that the strand may undergo larger losses in prestress prior to bonding that currently are not accounted for in design.

Comment

Submitted by Cathy French 11 months ago

Vote Activity

  1. Moderator
    Agreed
    11 months ago

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