Abstract: A building construction system for progressively forming a plurality of vertical superimposed concrete segments. A plurality of screw jacks form support columns and carry at their upper ends sub-frames upon which an overlying main frame is positioned. Formworks are suspended from the main frame and are moveable into position for pouring concrete to form the segments. The screw jacks are supported on a horizontal building element preceding a previously constructed horizontal building element and are retractable. The main frame is supported on adjustable struts for repositioning the screw jacks prior to extension to a subsequent segment forming position.

Abstract: A frame has channel members extending along each edge of the frame material with each channel member abutting another member at the corner of the framed material. A locking member is slidable between the frame material and the pairs of abutting channel members at each corner of the frame material to hold the channel members together against the frame material. The channel members may have slots therein and the locking members may have protrusions to extend into the slots when the locking member is inserted between the frame material and the channel members. The frame material includes a transparent sheet for displaying an object therethrough and a rigid backing sheet on the other side of the object, and the channel members have a channel width substantially the same as the combined thickness of the transparent sheet, the object, the rigid backing sheet and the locking member.