Wood Structural Design Data (WSDD) tabulates two different types of column load tables: simple solid columns and spaced columns.
Typically, a user will enter the tables with a known length for the column and a given load. The user can select a species, size, and grade for trial use. Using the Design Values for Wood Construction Supplement, the user determines the modulus of elasticity and compression parallel to grain design value of the species, grade and size of lumber. These design values need to be modified for all applicable adjustment factors including load duration from the Design Values Supplement and NDS. The user should determine the length to depth ratio based on the size of member selected. With this information the user enters the load table with the given modulus of elasticity and compression design value and determines the allowable load for the calculated length to depth ratio. If the allowable load is greater than that required for the application, the species, grade and size selected are adequate. If the allowable load is less than required then the user can either select a larger member, or select a higher lumber grade.