38 PROBLEMS IN STRENGTH OF MATERIALS 



347. A hollow circular cast-iron beam 8 feet long, inside diameter 

 5 inches and outside diameter 6 inches, rests upon end supports. 

 Calculate the maximum deflection due to a load of 4000 pounds at 

 the middle. 



348. A beam is 4 x 12 inches section area and 16 feet long. Another 

 beam of the same material is 6 x 8 inches section area and 10 feet 

 long. What is the ratio between the maximum deflections, if the 

 longer side is vertical in each beam, and the manner of loading and 

 supporting is the same ? 



349. A beam 16 feet long, 2 inches wide, and 6 inches deep has a 

 maximum deflection of 0.3 inch. Determine the maximum deflec- 

 tion of a beam of the same material 12 feet long, 3 inches wide, and 

 8 inches deep, with the same loading and manner of support. 



350. Find the maximum deflection of a 12-inch steel I-beam, 40 

 pounds per foot, resting on end supports 20 feet apart, and bearing a 

 total uniform load of 900 pounds per linear foot. 



351. A 9-inch steel I-beam, 21 pounds per foot, supported at its 

 ends and 10 feet long, bears a concentrated load of 25 tons at its 

 center. Determine the maximum deflection due to this load. 



352. Find the deflection at a point 4 feet from the left end of the 

 beam in Problem 351. 



353. A floor is to support a total uniform load of 100 pounds per 

 square foot. The 10-inch steel I-beams, 25 pounds per foot, have a 

 span of 20 feet and are spaced 6.5 feet apart between centers. Does 

 the maximum deflection of the beams exceed ^i- ff of the span ? 



354. Determine the proper distance from center to center of 12 -inch 

 steel I-beams, 35 pounds per foot, 24 feet span, to support a total 

 uniform load of 100 pounds per square foot of floor area, with a maxi- 

 mum deflection of -gj^ of the span. 



355. Solve Problem 354 for 15-inch steel I-beams, 50 pounds per 

 foot and 26 feet span. 



356. Find the distance between supports for 9-inch steel I-beams, 

 30 pounds per foot, spaced 7.5 feet from center to center, to support 

 a total uniform load of 100 pounds per square foot of floor area, with 

 a maximum deflection of -gj-^ of the span. 



357. Solve Problem 356 for 8-inch steel I-beams, 18 pounds per 

 foot, spaced 9 feet apart from center to center. 



