Load Slip Behaviour of Bolted Timber Joints Made of “Hora” Timber Species

The strength and load slip behaviour of bolted timber joints depends on such as embedment strength of timber, bending strength of the bolt and on the joint geometry. This paper discusses an experimental study in which bolt diameter and timber member thickness ratio between side member and middle member were varied in three member bolted joints of “Hora” (Dipterocarpus zeylanicus) timber species consisting of a single bolt. Specimens were tested in compression applied parallel to grain direction. Load slip curves were plotted and compared to obtain influence of geometry parameters on load slip behaviour. In most cases load per unit slip is greatly increased with increase in bolt diameter. It was also identified that load per unit slip did not change considerably with timber member thickness ratio. British Standards are widely used in Sri Lanka. These are based on empirical approaches developed on European softwoods. In Sri Lanka hardwoods are frequently used. Experimental values were compared with predicted values from BS 5268-Part 2:2002. Failure modes predicted from BS 5268-part 2: 2002, compared well with those observed experimentally. Up to the predicted permissible load, experimental and theoretical joint slip values are very similar; the difference was less than 1mm.