MILL CONSTRUCTION BUILDINGS 



Table G. Average Values of Modulus of Elasticity for Various 

 Species of Timber. 



Modulus of Elasticity 



Species of Timber in Bending 



*Fir, Douglas Lbs. per Sq. In. 



Dense Grade 1,600,000 



Sound " 1,200,000 



Hemlock, Western 1,400,000 



Oak 1,300,000 



Pine, Eastern White 1,300,000 



Pine, Norway 1,400,000 



*Pine, Southern Yellow 



Dense Grade 1,600,000 



Sound " 1,200,000 



Spruce 1,000,000 



Tamarack 1,200,000 



*See note at bottom of page 62. 



Since the values of maximum spans in Tables D and E for 

 a deflection of one-thirtieth inch per foot of length are based 

 upon a value of 1,620,000 pounds per square inch for the 

 modulus of elasticity, the lengths given in the "deflection" 

 lines of these tables should be multiplied by a constant when 

 timber having another value of the modulus of elasticity is used. 



The following constants are based upon the value of moduli 

 of elasticity given in Table G : 



1,600,000 use tables as they stand. 

 1,400,000 multiply lengths in tables by .952 

 1, 300,000 multiply lengths in tables by .929 

 1,200,000 multiply lengths in tables by .904 

 1,000,000 multiply lengths in tables by .852 



Posts or Text-books on strength of materials contain many 

 Columns different formulas for determining the load to be 

 carried by a column, or the fibre stress resulting 

 from the application of a definite load. Some of these formulas 

 are based upon theory, others upon experiment and a few upon 

 a combination of theory and experiment. While the loads and 

 stresses obtained from such formulas do not vary greatly, it 

 is considered that those of an empirical nature which corre- 

 spond with the results of actual tests are more to be depended 

 upon. 



Page sixty-three 



