148 



TOWERS AND TANKS FOR WATER-WORKS. 



Thickness of plate | in. = decimal 0.375. 



Diameter rivet-hole \\ in. = decimal 0.9375. 



Area of rivet-hole = decimal 0,69. 



Pitch of rivets 3 T ^ ins. = decimal 3.0625. 



Shearing-resistance of iron rivets per square inch, 38,000 

 Ibs. 



Then 3.0625 X 0.375 X 55,000 = 63,164= strength of 

 solid plate. 



(3.0625 0.9375) X 0.375 X 55>ooo = 43,828 Ibs. = 

 strength of net section. 



0.69 X 2 X 38,000 = 52,440 Ibs. = strength of two rivets 

 in single shear. 



Net section of plate is the weakest, therefore 43,828 -f- 

 63,164 = 69.3 per cent, efficiency of joint. 



70 per cent, is usually assumed in practice. 



FIG 41. DOUBLE-RIVETED JOINT. 



Triple-riveted Joint (Fig. 42). In a triple lap-riveted joint 

 we still gain in strength for reasons similar to those above. 



Steel plate, tensile strength per square inch of section, 

 55,000 Ibs. 



Thickness of plate | in. = decimal 0.375. 



Diameter of rivet-holes || in. = decimal 0.8125. 



Area of rivet-hole = decimal o. 5 185. 



Pitch of rivets 3| ins. = decimal, 3.25. 



Shearing-resistance of iron rivets per square inch, 38,000 

 Ibs. 



