304 



CAMBRIA STEEL. 



STRENGTH OF HOLLOW BOUND AND HOLLOW 

 RECTANGULAR CAST IRON COLUMNS. 



For various values of -r in which: 



d 



L = length of column in feet, 

 d = least outside diameter in inches. 

 P = ultimate strength in pounds per square inch. 



Based on Oordon's Formula) for Columns with Square Ends. 

 Hollow Bound. Hollow Rectangular. 



80000 80000 



P = 



800 d* 



1 + 



1067 d 



Safe loads for any given hollow round or hollow rectangular columns, corre- 

 sponding to any suitable factor of safety, can be found from the above table as 

 follows: 



Find from the table the ultimate strength in pounds per square inch corre- 

 sponding to the given value of -r . Multiply this by the area of the column in 



square inches and divide the product by the safety factor which will give as a 

 quotient the required safe load in pounds. 



EXAMPLE: Required the safe load for a hollow round cast iron column 16 feet 

 long, 10 inches external diameter with metal 1 inch thick with safety factor of 



eight. The ratio of -: in this case is = 1.6 and the corresponding ultimate 



d lu 



strength from the tables is 54 766 pounds per square inch. 



From the table of areas of circles it is found that the net area of the column is 



28.3 square inches. The safe load is, therefore, 54 ^^X 28 - 3 193 735 pounds 

 or approximately 97 net tons, which is the required result. 



