reinforced concrete beam / prestressed concrete / rectangular
Short span steel
reinforced concrete, prestressed concrete
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.