Structural timber floor assembly

Abstract

A method is described of forming a joint between the end of a timber I-beam joist and a transverse closure such as a rim-joist, in which two holes are formed a short distance from the end of the I-beam to be butt-jointed to the rim-joist, one in each of the upper and lower rails of the I-beam section, the two holes being coaxial and generally aligned with and parallel to the web of the I-beam section. The closure is positioned relative to the I-beam and two further holes are formed through the closure and into the ends of the upper and lower I-beam rails, generally perpendicular to and intersecting the first two holes. Two cross-dowels are inserted into the two first holes, each having a transverse threaded opening, and the dowels are inserted so as to align the openings with the holes which intersect the holes containing the cross-dowels, and threaded bolts are introduced into the intersecting holes and screwed into the threaded openings in the cross-dowels so as to draw the joist towards the closure, and thereby clamp the joist thereto. The cross-dowels may be formed from metal, or from a rigid plastics material or from a composite material and may have a smooth exterior or may be externally threaded or formed with one or more annular barbs for securing them in place. The technique may be applied on site, but more preferably in the course of constructing a roofing or flooring panel off-site, the joints serving to resist distortion or bending during handling of prefabricated panels, during storage, transportation, and / or final positioning on site.

Description

[0001] This invention concerns structural assemblies of timber which serve as prefabricated roofs or floors (often referred to as decks) for buildings, particularly but not exclusively, timber framed buildings.BACKGROUND TO THE INVENTION[0002] Prefabricated timber buildings are generally delivered to site in the form of prefabricated wall panels and roof trusses. The ground floor wall panels, when erected, provide load-bearing supports for first-floor flooring, the peripheral regions of which will in general provide a bearing for the first floor load bearing wall panels.[0003] Timber I-beams are now used in the construction industry as an alternative to solid timber beams, and comprise a thin vertical web, typically made from oriental strand board, and top and bottom chord members (rails or flanges) made from solid or laminated timber. The I-beam section is more structurally efficient than a solid rectangular section and can be made to larger dimensions than is available in solid ti...

AI Technical Summary

Benefits of technology

[0018] A load spreading washer may be located between the head of each bolt and the rim-joist, or each bolt head may include an integral load spreading flange for increasing the area of the bolt head which is to make contact with the rim-joist.

[0027] It has been found in practice that a roof or flooring panel constructed in accordance with the invention is less susceptible to distortion damage during handling, storage and / or shipment, than are similar flooring panels when constructed using conventional cross-nailing techniques.

Problems solved by technology

However the handling of such flooring panels or decks, after prefabrication, during storage, shipping from factory to site, and when lifted (usually by crane) into position at first floor level, can result in twisting and distortion of the panels, generating significant bending and shearing forces on the joints between the component parts.

The result is that the flooring panel can become weakened and in particular joints between the ends of the I-beam joists and rim-joists can open-up.

Site assembly techniques using nails, screws and metal joist hangers do not provide the strength and rigidity suitable for large prefabricated components subject to the loads imposed during handling and lifting.

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