ME CHA Nl CA L PRINCIPLES. 



107 



12.000 Ihs. 11,000" 



10,000 9,000" 



70 



20 



8.000" r 7,000- 



6,000 



5 000 Ibs. 





12,000 Ibs. 11, OX' 



10,000' 



9,COO> 

 P 



P.OOO' 



7,000' 



6,000" 



30 



SO 



5,000 Ibs. 



DIAGRAM or STRAIGHT-LINE COMPRESSION FORMULAS. 



Formula: P 12,500 500 (t-*-r\ 

 P = compression in pounds per square inch, 

 / = unsupported length of member in feet, 

 r = radius of gyration in inches. 



Explanation. Find the required r on the line r r, then follow the diagonal which 

 crosses at that point, until it crosses the line representing the required / (read at the sides 

 of the diagram). The vertical line through this intersection represents /*(read at the top 

 and bottom of diagram). Diagonal lines representing r are drawn at each half-inch only. 

 Lines for intermediate values may be drawn in, or a ruler or thread used to indicate them 



