Strengthening of Slab Action in Transverse Direction of Damaged Deck of Prestressed Box Girder Bridge

Abstract

The deck slab of a prestressed concrete (PSC) box girder bridge serves as an integral part of the structural box section, and any damage to the deck may seriously affect the load-resistance mechanism of the bridge. This paper discusses a case study of a PSC box girder that developed early damage to the deck because of the poor placement of concrete at the time of construction as established by in situ nondestructive and core tests. The possibility of total replacement of the top deck was ruled out because of the disruptive and tedious nature of the process, which could have endangered the overall stability of the box girder. Strengthening of the deck was performed by installing a series of steel joists at the underside of the deck slab and adding a thin overlay of concrete at the top to restore it to the requisite strength. This approach was best suited, for it not only improved the stress distribution in the deck, but also maintained the original load resistance mechanism provided by the prestressing arrangement in the girder. The presented scheme was easy to implement and could be used for similar damages occurring to the deck of PSC box girder bridges.