Abstract: A formwork frame for supporting decking and a fresh concrete floor on the decking includes a horizontal beam whose upper surface contacts the concrete and a vertical shaft that supports the beam. The beam is formed in three separable extruded aluminium sections, a central section mounted on the shaft and a pair of outer sections. The central beam section has opposing ends mitred to converge in a downward direction, and each outer beam has an end mitered to meet one end of the central beam section. The beam has a horizontal channel in each of its sides, and a pair of horizontal ledges close the channels from below. A pair of extruded aluminum bridging members fit closely into the channels and are effectively reinforced by the beam sections to resist bending moments. Pins extend horizontally through the bridging members and the outer beam sections to secure the bridging members to the beam. The pins are not subjected shear forces or bending moments.