Abstract: A cross-like structural joint element having a pair of aligned lateral arms each formed with an anti-slip pedestal projecting from one face; a U-shaped first connector member having a pair of spaced legs projecting perpendicularly from said one face at adjoining ends of the lateral arms, facing surfaces of the legs having inwardly inclined teeth, and a second connector member projecting perpendicularly from the other face of the lateral arms at the adjoining ends; this connector member having a narrow neck portion joining the lateral arms and a wide portion extending from the narrow neck portion.

Abstract: A structural joint has a pair of elongated members each provided with an elongated groove with an opening narrower than the inside of the groove. A connecting key has a pair of legs configured, in cross-section, like the cross-section of the grooves and slidably fitted each into one of the grooves with side faces of the legs engaging opposed side walls of the grooves. Set screws are threaded through bores of the key legs from the openings of the grooves and up to the bottom of the grooves so that when the screws are tightened, they force the leg side faces into engagement with the side groove opposed side walls to lock the legs into the grooves. The adjacent ends of the legs are articulated to one another.

Abstract: A structural building unit comprising a bar-shaped member having a central section and two edge sections with first connecting means projecting from the central section and second connecting means in each edge section. With a connecting member and/or connecting plates, one or more of the bar-shaped members are used to construct various structural modules.