Abstract: A method of constructing and erecting a post-tensioned steel frame structure consisting in:1. Constructing on the ground a center span of the structure to each end of which are hingedly connected column structures;2. Post-tensioning the center span by means of a cable to bring the span to a desired shape; and3. Post-tensioning cables connected between each said column structure and the center span to produce relative rotational movement between the column structures and the center span about the hinge joints to raise the column structures from a substantially horizontal to a substantially vertical position thereby elevating the center span to its final position.

Abstract: As a means of casting concrete floors in concrete and other structures the invention provides a type of formwork in which a platform is supported from vertical elements of the structure, the platform having vertically extending housing means depending from its under side which are associated hinged formwork members. The arrangement is such that the formwork may be set up so that one or more concrete floors of a building may be cast, the hinged formwork members being arranged in a horizontal position so as to form a support for the floor or floors. After casting and setting of the concrete the hinged formwork members are folded into the housing so that the platform may be raised vertically drawing the housing and formwork members through apertures left in the cast floors. The floors are completed by filling the apertures with concrete.