Precast concrete cap beams are the most common prefabricated elements in bridge substructures. These are generally the most difficult elements to construct on site using cast-in-place concrete, where shoring and forming can be extensive. This issue shows the amount of benefit that can come from prefabricating the element off-site and only needing to be concerned with transportation and connection of the element on-site.
Precast concrete cap beams connect to the tops of the piles/columns of the bridge substructure and support the bridge deck
Due to the tolerance of cast-in-place columns and piers, large blockouts in the pier caps have been used successfully. Another type of connection used for this situation is large grouted pockets to develop semi-moment connections. Simple bolted connections can be used as well as a pinned connection.
Due to the time and difficulty involved in the placement of a cast-in-place concrete cap beam, a prefabricated element should be considered; it is easier and faster to transport and connect the element than it is to cast the element on-site.