What is the term for the support structures that hold the beams on top?

The term for the support structures that hold the beams on top is known as beam seats. Beam seats are specifically designed to provide a stable platform for beams in bridge construction or similar applications, ensuring that the beams are secured and able to carry loads effectively. They are typically part of the superstructure and are critical in distributing the weight of the beams and the loads they carry to the supporting elements below.

In bridge design, the choices involve different components that serve various purposes. Piers serve as vertical supports for the bridge, transferring loads to the foundation. Caps, although related, usually refer to the horizontal members placed on top of the piers. Abutments are the structures at the ends of the bridge that provide lateral support and connect the bridge to the earthen embankment. Each of these components plays an essential role in bridge stability and structural integrity, but the specific function of beam seats is to support the beams directly.