Design Wood Structures for usage of Sandoricum Koctjope (Merr.) and Azadirachta excelsa (Jack.) as Structural Components in Wood Structures

Abstract

The objective of this technical paper was to propose the usage of Sandoricum Koctjope (Merr.) and Azadirachta excelsa (Jack.) which were two species of fast-growing wood as structural components based on statistical data obtained from 11 series of tests in accordance with ASTM D-143. The number of samples for each test was large enough to assure 99% interval of confidence. Random variables included modulus of elasticity for bending (E), bending strength, shear strength and live loads. These variables could be represented well by normal distribution. Structural reliability was analyzed by accurate methods based on engineering data in Thailand. Results showed that behavior of joists and beams was controlled by deflections. Therefore the value of failure probability (p[subscript f] ) was set 10-4 and the main variable was modulus of elasticity for bending. Whereas loading capacity of columns was controlled by Euler's loads. Thus Pf was set tol0-6 and the major variable was also E. In this technical paper the proposed design procedures were similar to Working Stress Method as recommended by E.I.T. The only difference from E.I.T. standard was the value of live load. Instead of nominal live loads for residence, office and school as stated in the Municipal law, mean live loads based on data gathered in Thailand were recommended. Wood sections obtained from numerical procedures proposed were as large as those obtained from WCCAL Software. It was also interesting to note that the value of E for compression and tension parallel to grain of both species of wood could be used to predict the corresponding value of E for bending.