150 TOWERS AND TANKS FOR WATER-WORKS. 



assumed by some writers that such is the case, and up to this 

 time most engineers allow a double value to rivets in double- 

 shear. In the former the rivet is sustained by the plates 

 above and below, while in single-shear the resistance is con- 

 fined to one point. 



An examination of the sheared sections of rivets in single- 

 shear usually discloses a slight elongation in the direction of 

 the force applied. The experiments on rivets in single-shear, 

 and from which we get our data, have almost always been made 

 on single-riveted joints, with narrow strips of iron, as shown 

 in Fig. 43. 



FIG. 43. 



And it is reasonable to assume that there is a slight 

 tendency in the rivet to lean in the direction of the force ap- 

 plied, which would account for the slight elongation of the 

 sheared section in that direction. An examination of the 

 sheared sections of rivets in double-shear shows little or no 

 elongation. The rivets being supported by the plates above 

 and below, the shear is direct, and the section is normal in 

 form. Experiments made by the English Admiralty with J- 

 inch rivets showed that the double-shear was about 90 per 

 cent, stronger than the same diameter of rivet in single-shear. 

 Chief Engineer Shock, U.S.N., found by experiment that 

 the resistance of bolts of iron to single-shear was 40,700 Ibs. 

 per square inch, and in double-shear 75,300 Ibs. This 

 gives an increase of strength of 85 per cent. The results 

 of numerous experiments, both in this country and in Europe, 

 show the resistance to double-shear to be from 85 to 90 per 

 cent, greater than the same rivets in single-shear. From the 

 foregoing I assume 85 per cent, as a fair and safe estimate of 



