A Study of the Use of Para Wood as Sleepers for Concrete Piles

Abstract

The propose of this research was to find the most effective pattern of using Para wood as sleepers for prestressed concrete piles were studied structural reliability theory, statistical analysis of Para wood sleepers, statistical analysis for compressive strength perpendicular to grain, proposed algorithms for finding compressive stress perpendicular to grain and finding suitable patterns for stacking of prestressed concrete piles. Results of study showed that fifty Para wood sleepers of the mean square section of 7.0 cm in width and 1.146 m in length were sawn from tree branches and tree slabs. Two hundred forty-five Para wood specimens of square section of 5 cm in width and 15 cm in length were tested. The mean compressive strength perpendicular to grain was 105.2 ksc. The best fitted distribution was gamma. Monte-Carlo simulations together with importance sampling technique under the conditions of the acceptable failure probability for temporary structure less than 10^-2 and standard error not more than 1% yielded the allowable compressive stress perpendicular to grain of 41.6 kg/cm² which is 1.65 times higher than that of the case of normal distribution assumption. This allowable stress could be used to analyze the suitable numbers of layers and the numbers of Para wood sleepers at supports of any type of prestressed concrete piles. The maximum layers for I and square concrete piles supported by Para wood sleepers at 0.207 of the length from both ends were summarized as in the following: I22&[]22 - 24 layers, I26&[]26 - 21 layers, I30&[]30 - 18 layers, I35&[]35 - 16 layers, I40&[]40 - 14 layers.