Full Strength Round Timber Pole Connection Using Annular Grooves

Hugh Morris, The University of Auckland, Auckland New Zealand; Mark Batchelar, Mark L Batchelar Consulting Engineers, Auckland, New Zealand & Kenneth Teh, The University of Auckland, Auckland New Zealand

TTT Products Ltd developed the technology to quickly lathe 15m long poles into “Unilogs” up to 480 mm in diameter. The development and testing of 250 mm diameter connections that are capable of full strength connection for effective structural performance of pole structures is described. As each pole is manufactured in a lathe, it is a simple operation to cut four annular grooves into the outside of both ends. A tubular steel connector, manufactured with raised annular bands on the inner surface to fit the timber grooves, is clamped across the connection. The system modifies an existing tubular connection designed for manual erection of the towers in difficult terrain. Tests on one and three annular bands are compared with four annular bands used on site. Failure occurred in timber bearing and/or compression at an average of 820 kN before the connection load decreased. The new connection performs well and provides new opportunities for large scale round timber construction.

TDJ 17-2

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