DESIGNING. 207 



SURFACES, AREAS, AND WEIGHTS. 



Dimensions and Capacities. Pounds. 



Cyl. \ in. pi., nDA X 10.2 24,990 



5/i6-in. cir. girder, nD .4X12.75 2,405 



5/i6bot. pi., *7rZ) 2 Xi2.76 . 8,017 



3/16 con. cover, knDA, sec. 0X 7.66 4,144 



3/16 facia pi. and angles, 289X7.66 2,214 



Eaves angle, 78.5 X 4.7 369 



5/16 pi. floor, 3 ft. wide, 2i68X 12.75 2,764 



8 brackets 1,520 



37~ft. ladder 242 



3-ft. Z trolley 422 



Weight of metal 47,087 



10% allowance for overweight 4,708 



Total weight of metal 51,795 



Weight of water 896,840 



Total weight of tank and contents 948,635 



In addition to the above, allowance must be made for the 

 laps of plate, for the weight of the rivets, and that of the necessary 

 flange angles and stiffeners of the circular girder and to be exactly 

 determined later, but approximated as follows: 



Laps 3,000 



Rivets 4,500 



Angles and stiffeners 2, soo 



Approximated 10,000 



Stress in the Girder. The total weights as found above 

 being taken as 958,000 Ibs. must be supported by the circular 

 girder, and in this case upon four points of support. 



From formula previously given, the bending moment of the 

 girder at the point of support where four columns are used is 

 found to be 0.0341 4^Fr, where W is the whole weight and r the 

 radius of the tank in inches; substituting, the bending moment is 



0.03414X958,000X120 = 3,270,612 inch-pounds. 



