Post Tensioning of Cast-in-Place Deck Slabs

In some cases, transverse post-tensioning can be used in cast-in-place concrete bridge decks. For example, transverse post-tensioning may be specified when wider girder spacings are used, and mild reinforcement will not provide sufficient flexural capacity. Depending on the particular situation, a thicker deck may result with the use of post-tensioning and wider girder spacings, and may offset any steel cost and weight savings realized from using fewer longitudinal girders.

Another consideration regarding the use of transverse post-tensioning is whether or not there is sufficient access to the edges of the concrete deck slab. The anchorage for the post-tensioning tendons will be located at the transverse edges of the deck. Sufficient access must be provided to allow for stressing of the post-tensioning tendons with the necessary equipment and personnel. Furthermore, since transversely post-tensioned concrete bridge decks are not all that common, the skilled labor required to cast the deck and properly install the post-tensioning tendons may not be readily available. The labor and construction time associated with transversely posttensioned cast-in-place decks may also prove to be more costly than the costs associated with a conventional reinforced cast-in-place concrete bridge deck.

Cast-in-place deck slabs using transverse post-tensioning should be designed in accordance with the applicable provisions of Section 5 and Section 9 of the AASHTO LRFD (7th Edition, 2014).