Investigation Of Stability Of Dimensionlumber Members Under Axial Compression

In timber structure design, calculating the stability coefficient of wood-based component which is stressed on its axle center is inevitable. The stability coefficient formula given in Code for Design of Timber Structures GB50005 is applicable only to solving the traditional sawn or round timber, but is not applicable to modern wood produtcs like dimension lumber and glued laminated timber. This paper uses theoretical analysis methods and simultaneously compares the timberwork design specifications in China and the United States to demonstrate that the stability coefficient formula for design of timber structure is not applicable to modern wood structures design.The axial compression tests based on the SPF dimension lumber of grade is NO. 2 and cross section of 2 × 6 and 2 × 8(inch) have obtained the material elastic modulus, intial bending curvature amplitudes at the beginning and load-displacement curves under different slenderness ratio of each test specimen. Meanwhile, this paper has also obtained the compressive strength of each specimen from compressive strength tests carried on by some certain fixed length and intercepted from both ends components chosen from instable tests which had already finished its loading program.This paper uses test parameters for numerical simulation on each specimen, then gets a load-displacement curve. At last, having compared the test results with the simulation results, we could verify the accuracy of the numerical simulation. Since discoverd the axial compression rule for wood through analysing both test results and simulation results, thus determining to use statistical methods to the research and eventually we do obtain certain relevant distribution factors.Based on the stochastic finite element numerical analysis, this paper gets the bearing capacity’s statistics in different sizes、grades、species and pillar curves under each circumstance. The stability coefficient formulas basic form is proposed through theoretical derivation, which is not only applicable to the nomal wood but also the dimension lumber, additionally stochastic finite element numerical analysis is used to get the curve fitting and the specific coefficient of formula, finally the correctness of the formula is verified by calculating examples.The stability coefficient formula which proposed in this paper solves the current problems existing in Code for Design of Timber Structure, at the same time also provides reference for the future study on compression problem of wood-based component.