Utdragshållfasthet av inlimmade skruvar i limträ

Sammanfattning: In this thesis tests has been performed on the pull strength of screws glued into glulam beams. The experiment is based on the already approved method whereby the diameter of the drilled holes is the same as the screw outer diameter of 1 mm or bigger. The screws strength class shall not be less than 4.6 (EN ISO 898-1:1999, 1999). The difference in the experiments that were performed where that the drilled diameter were 1 mm smaller than the outer diameter of the screw so that the screw thread was worked into the wood. In the tests the gluing where made on M8 glulam beams. The screws where drilled at and angel of 90°tangental to the fiber direction with a diameter of 7 mm. The gluing of the screws where made in three different depths and where later exposed to pulling forces. The results showed both pulling breaks and screw breaks when they reached their maximum capacity. This conforms to the assessments made before the tests. From the evaluation of the tests the characteristic values have been calculated so that the method can be compared with nails and bolts in the roof trusses. The experiments showed that the glued screws with adapted drill-depths have similar pull strength as the corresponding wood screws and glued screws according to standards. There is a great need for continued research in this method of glued screws if they are going to be used in roof trusses and fulfill the same function as bolted joints does today. Tests should then be made on amongst others glued screws in different fiber directions, drill diameters, screw dimensions, glue types and climate tests.