JOINTS AND CONNECTIONS 



157 



order that the joint may be well pulled together at the time of 

 framing and the bolts be able to hold the tables in place when the 

 stress comes. The joint is dependent to a very large degree on 

 the tightness with which the timbers are held in place by the 

 bolts, and excessive shrinkage in the timber would allow the fish- 

 plates to be overstrained. If it is not certain that the timber will 

 be well seasoned before use, the fish-plates should be made larger 

 than computations indicate to be necessary and it will be advisable 

 to use about ten per cent more bolts than those provided by com- 

 putations. Spikes can be toe-nailed into the fish-plates and will 

 be a great help. 



Depth of cut for table and chord: Area required for cut 

 45,000 



1600x2x8^ 



Length of table for shear: Area required 



45,000 



22.4 



8 X 2 x 120 

 ins. (make it 23 ins.) 



Size of bolts required: The stress is transmitted from the uncut 

 portion of the chord to the uncut portion of the fish-plate past the 



joint, where it is again transmitted to the other section of the 

 chord. The resultant stress thus travels through the center of 

 the uncut portion of the fish-plate, which in this case is two inches 

 thick, so the center of stress is 1 in. from the face. The resultant 

 of the pressure on the table where it transfers stress is at the 

 center of the cut, which in this case is 1 in. from the inner side of 

 the fish-plate. There is a moment arm between the compressive 



