CHAPTER X. 
RIYETTING. 
The subject of rivetting is 0110 wliicli seldom, if ever, receives its duo amount 
of attention from britlgo designers. 
Many structures otherwise very strong are extremely weak in detail, owing to 
the insufficient number of rivets employed in tlie connections, and to their improper 
arrangement. 
The principal rules for rivetting have been given ia Chapter YL 
• Rivets should be proportioned for bending and bearing pressure, i. e. for any 
connection the number of rivets necessary to resist properly each of tlieso 
8 leases should bo determined, and tlio greater number chosen. 
Table XVII gives the working bonding moinents and bearing pressures for rivets 
ln trusses and floor systems. It can be used for lateral systems also by making a pro- 
P er ret hiction in tlie calculated stress : this will be exemplified in Chapter XVIII. 
In tliia table the first two liodzonbal lines coutaining vulgar fractious and 
decimals give the widths of bearings, and the other horizontal lines in the portion 
Jßlciting to bearing give tlio working bearing stresses for rivets of different diameters, 
he rest of tlio table needs no explanation. 
The diameters for rivots ia railroad bridges vary from half an inch to an inch, 
1 far the larger number aro from three quarters to seven eighths. 
When two plates aro rivettod together, the rivets, being driven when hot f 
contract or tend to contract in length when cooled, thus drawing tlie plates together 
ail( l P r °Jucing a friction which it is necessary to overcome before shear can como 
Upon tlie rivets. Whether this friction will dontinue indefinitely is doubtful, for 
Rivets .occasionally become loosened wLcn tlie structure is subjected to oft repeated 
0a d s ; so it« is not legitimate to depend upon the friction in order to reduce tlie 
う 11111 her of rivets. Perhaps it is on account of tlxis factor that rivets are. seldom, 
1 evei ， Proportioned to resist tlie bending moments that come upon tliem , notwith- 
standing the fact that it is this last consideration which in most cases should 
L eteunaie tlio uumber to be employed. 
It will probably have been noticed by tlio reader that shear iug stress upon rivets 
las been entirely omitted from consideration. The author would hesitate before 
faking the broad assertion that rivets cannot shear, altlioagli it is probable^that 
lu u】g is tlie stress which ruptures rivets that arc generally considered sdeareli: 
