Böjprovning av spikplåtsskarvad träbalk
Sammanfattning: This thesis examines the bearing capacity, stiffness, shear and moment force of a continuous wooden beam and how the parameters of the beam changes when the beam is spliced with nail plate. A literature study has been conducted to examine which studies have been carried out in this field. Construction timber is the most common wooden element for wooden constructions but has limitations in available lengths since the maximum length manufactured is 5400 mm. If larger lengths are required, splicing must occur or use of other materials. The study examines a 2 series, a 3-point series (moment and shear) and a 4-point series (moment). Each series consists off 3 trials in each series to see how shear and moment force affect the strength. The study also shows which off the joints that gives the least strength. The samples are tested in a draw and pressure machine lying on 2 supports and with a point load for the 3-point method and 2-point loads for the 4-point method. In the trials pressure is applied until the beams break. The study investigates the lab results, fracture state and use state for the wooden beams being tested. The result of the study shows that a splicing will lower the wood's carrying capacity between 21-60% compared to a non-spliced beam for the 3-point method and a reduction of 40-66% compared to a non-spliced beam for the 4-point method. Despite the lowered bearing capacity all the experiments are still within the characteristic value and approved for use. A larger dimension on the nail plate would probably have given a better value.
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