EFFECT OF DISCRETE MEMBER SIZE ON RELIABILITY OF WOOD BEAMS

Unlike other building materials, dimension lumber is available only in a very limited number of sizes. Typical low-rise building constructio n uses common ''two-by'' lumber ranging in size from nominal 2 x 4 to 2 x 12 (38 x 89 to 38 x 296 mm). The implications of sizing up to the next available discrete lumber size on the reliability of wood members in flexure are reported in this paper. Consideration is given to both strength and deflection serviceability limit states and the new load and resistance factor design (LRFD) specification for wood constructio n.