Joist failure analysis for J.Hamilton & Associates

"In December 1992, Ms Jennifer Hamilton of J. Hamilton & Associates contracted TWP to evaluate a specimen comprising a failed timber joist taken froma building site in the Glenwood Estate, Mackay. The timber was provisionally identified visually as Forest Red Gum or Red Ironbark, most probably Structural Grade 4 because of grain orientation. There was considerable cross-grain in the region of the failure. The grain ran at an angle of 40 degrees to the length of the joist. Before installation, the top surface of the joist had been painted with a "whitewash" which had evidently penetrated into an open shake (grain oriented split). All unpainted surfaces of the joist, including the region of failure, indicated substantial exposure to the weather because of the grey colour of fibres. There were no fresh, unexposed fibres apparent in the region of failure. The ambient density (963 kg/m3) of the joist was determined by measuring volume and weight. The ambient moisture content (12%) was determined using a moisture meter and by correcting readings for species factors. Measurements were taken at 23 deg.C and 65% relative humidity."--p. (i).