Wooden Ship Hulls as Box Girders with Multiple Interlayer Slip

Abstract

The difficulties of modeling the vertical flexure of mechanically fastened wooden ship hulls as that of box beams, a mainstay of naval architecture when applied to iron and steel ships, can largely be overcome by factoring the incomplete composite action of timber components in terms of a reduced shear modulus, an increased shear lag, and a reduced sectional area in tension (owing to butt joints). Sample computations on a large wooden hull indicate that its deflection can be limited to about twice that of a completely composite hull if stiff fasteners (drift pins) are used at a much greater density than is typical of traditional construction. The lengths of timber pieces become severely limiting only if they are below 1/5th of hull length. The methodology has broad application to the preliminary design of many-piece timber box beam structures in general.