APPENDIX. 



FORMULAS FOR DESIGN IN MILL 

 CONSTRUCTION. 



The design of the timber members of a mill construction 

 type of building may be separated into the following divisions: 



Floor and Roof Panels. 

 Girders and Beams. 

 Columns or Posts. 



The various formulas used in the design of such members 

 contain letters representing the quantities indicated below. 



NOTATION FOR FORMULAS 

 L 



a = 

 d 



b = Breadth of beam or girder in inches. 

 C = Strength of column in pounds per square inch of cross- 

 section. 

 c = Allowable working compressive strength of timber in 



pounds per square inch with the grain. 

 D = Deflection in inches, 

 d = Depth of beam or girder, or least dimension of post in 



inches. 

 E = Modulus of elasticity of material in pounds per square 



inch. 



f = Allowable unit bending stress in extreme fibers of sec- 

 tion in pounds per square inch. 



L = Unsupported length of post or column in inches. 

 1 = Length of span of beam or girder in feet. 

 P = Load concentrated at any point on beam or girder in 



pounds. 

 s = Allowable unit shearing stress in direction of grain in 



pounds per square inch. 



t = Thickness of underfloor, or roof plank in inches. 

 W = Total uniformly distributed load on beam or girder in 



pounds. 

 Wi = Total uniformly distributed load on a section of floor 



or roof plank 1 foot wide and "x" long. 

 x = Length of span between centers of girders or beams in 

 feet. 



Floor and The minimum thickness of plank to be used in 



Roof Panels floors and roofs has been stated in the sections 



devoted to general construction and found in 



the earlier pages of this bulletin. The thickness needed to 



Page fifty-two 



