Proposed Strength Formulas for Wood Box Columns

Douglas fir and sugar pine boards in several lengths up to eight feet, using 2-inch screws and various types of 6- penny and 8-penny nails for assembling, were tested in compression for crushing and buckling strength. A practical and realistic approach was maintained, directed toward economy and light-weight construction, thus de-emphasizing the use of glue or screws. Column strength varied directly with the number of nails used, with an optimum of 36 nails for 4-inch boards, and 68 nails for 6-inch boards. Simplified formulas of the hyperbolic, parabolic, and exponential types were developed for estimating the number of nails required to develop maximum strength and efficiency, the shortest expression for the suggested satisfactory number of nails being n = (b|2)2 in which b is the nominal breadth of each of the four boards. Equal numbers of nails were required whether these square columns were long or short. Strength varied also with the breadth of the boards, and with the slenderness ratio, following the same continuous CRG cubical column curve equation as was developed previously. Some of these columns with square ends tested up to twice as strong as an equivalent pointed solid wood column of the same weight.

You must be logged in to download any documents. Please login (login accounts are free) or learn how to Become a Member