Abstract: The subject structure comprises at least one assembly of premanufactured components. Each component comprises at least one beam with a fixture attached at each end. The fixtures are box shaped, having tops, bottoms, ends and side faces. The fixtures are longer (from end to end) than they are high (top to bottom) or thick (face to face) and the faces are perpendicular to the length of the beam. The fixtures are generally symmetrical about a plane perpendicular to and bisecting the faces. Each fixture has a flange extending from one end and a groove in the other. The components are pivotally connected to form an assembly, the pivotal connections being pins inserted through holes to hold the flange of one fixture in the groove of the next, the pin locations being near the tops of the fixtures. The fixtures are frusto-triangular in plan view, the tops being the bases of the triangles. Cables are threaded endwise through the fixtures near their bottoms.