Structural assemblies for constructing bridges and other structures. A structural assembly may comprise an elongated member defining an internal space. The structural assembly may also comprise a plurality of framing members connected to the elongated member at a plurality of pin connection nodes, each pin connection node comprising a pin interconnecting the elongated member, a first one of the framing members, and a second one of the framing members, the pin having a first longitudinal end and a second longitudinal end, at least one of the first longitudinal end and the second longitudinal end of the pin being located in the internal space of the elongated member.