E1VETED JOIJMTS 17 



For a single-riveted butt joint with two cover plates 



(p d) ts t = strength of riveted plate, 



tds c = compressive strength of rivets, 



7Q 



2 s s = shearing strength of rivets. 



For a double-riveted butt joint with two cover plates 



(p d) ts t = strength of riveted plate, 



2 tds c = compressive strength of rivets, 



4 s s = shearing strength of rivets. 



In any riveted joint let n be the number of rivets and m the num- 

 ber of rivet sections subjected to shearing in a repeating section ; then 



(p d) ts t = strength of riveted plate, 



ntds c = compressive strength of rivets, 



79 



m s s = shearing strength of rivets. 



The efficiency of the joint will be the least value obtained from these 

 expressions, divided by pts t , or the strength of the unriveted plate. 

 In our computations we shall use, for iron or soft steel plates and 



iron rivets, 



s t = 55,000 pounds per square inch, 



s c = 80,000 pounds per square inch, 

 s s = 38,000 pounds per square inch. 



If we use a factor of safety of 5, and divide these values just given 

 by this number, we shall have safe working unit-stresses of 



11,000 pounds per square inch for tension, 

 16,000 pounds per square inch for compression, 

 7,600 pounds per square inch for shearing. 



In determining the efficiency of a joint these working unit-stresses 

 may be used in place of the values given for s t , s c , and s 8 . 



Let P t = strength of riveted plate, 



P c = compressive strength of rivets, 



P s = shearing strength of rivets, 



P = force transmitted by a repeating section ; 



