JOINTS AND CONNECTIONS 



139 



two side pieces were placed on the table of a testing machine and 

 the center piece was pressed down until failure resulted. 



The following table is recommended as giving proper safe loads 

 corresponding to a slip not exceeding ^y in. They are for end 

 bearing with bolts having a driving fit and the thickness of each 

 side piece equal to, or greater than, one-half the thickness of the 

 main timber. For side bearing (across the grain) the values can 

 be taken at six-tenths the values given for end bearing in the 

 table. 



The values in the table are for double shear, that is, for three 

 pieces of timber having two shearing planes. For cases of single 

 shear, two timbers bolted together, use one-half the values given 

 in the table. 



The working values given are for Douglas fir. For other timbers 

 the values are to be multiplied by the factors following: 



Long-leaf yellow pine 1.05 



White pine 78 



Norway pine 65 



White oak 78 



TABLE OF WORKING STRENGTH OF ONE BOLT IN TIMBER JOINT 

 IN DRY TIMBER, AS FOR USE IN INTERIOR OF BUILDING 



(Bolt in double shear bearing against end of grain.) 



For single shear take one-half the above values. For bearing 

 against the side of grain take six-tenths the above values. 



Joints in timber are sometimes made with a large pin on which 

 a timber rests. The pieces are joined at an angle less than 90 

 degrees and the tearing per square inch on the fibers will be some- 

 thing less than the allowable safe bearing with the grain and con- 

 siderably greater than the allowable safe bearing across the grain 

 for broad surfaces. 



