Teoretisk och experimentell utvärdering av Lättelement AB
s takinfästning
Lattelement AB in Ornskoldsvik is one of the leading companies in Sweden in composite elements in walls, floors and roofs in particular. The company supplies elements to buildings located with a wide geographical variation, which means that the products are subjected to very different climate with regard to snow, wind and humidity. This places high demands and requires the elements to withstand large variable loads.The elements are made of lightweight beams with flanges of structural timber and beam webs made of OSB. These are bound together by nogging pieces with the same kind of structure. On top of the beams a nailed and glued plywood is added to absorb compressive forces and on the underside of the element a sheet of steel is added for tensile absorption.These elements are then attached to the building framework in different ways depending on the particular element height, loads and the structual supporting material of the frame work. In this thesis, one of the company's more common attachment arrangements has been closely investigated. Experimental laboratory tests on the attachment has been performed where the pressure perpendicular to the fibers of the top flange of the lightweight beam and the axial pull-out capacity of the screws have been investigated. This has then been compared and evaluated against theoretical calculations on the bracket.The results shows that the lightweight beam can sustain loads up to 17.0 kN in experiment as to comparison with the theoretical limit 7.6 kN. This in contrast with the screws that passed lower forces experimentally, 5.8 kN, than theoretically, 12.48 kN.