CANTILEVER AND SIMPLE BEAMS 31 



265. A hollow, circular, cast-iron beam, inside diameter 5 inches, 

 outside diameter 6 inches, rests upon end supports 8 feet apart. 

 With a factor of safety for varying stress, what is the maximum 

 safe load that may be concentrated at its center? Neglect weight 

 of beam. 



266. A rectangular wooden beam 14 feet long, 4 inches wide, and 

 9 inches deep rests on end supports. Find the factor of safety if it 

 bears a uniform load of 100 pounds per linear foot in addition to its 

 own weight. 



267. Design a rectangular wooden cantilever to project 4 feet from S 

 a wall and bear a load of 500 pounds at its free end, the factor of 

 safety being 8, and weight of beam neglected. 



268. A wooden beam of circular cross-section rests on end sup- 

 ports 10 feet apart. What load may be hung at the middle, if the 

 radius of beam is 4 inches ? Use factor of safety for steady stress, 

 and neglect weight of beam. 



269. A wooden beam resting on end supports 10 feet apart has a 

 cross-section which is an isosceles triangle with a 6-inch horizontal 

 base. It carries a uniform load, including its own weight, of 120 

 pounds per linear foot. What must he the altitude of its cross-section 

 for a factor of safety of 8 ? 



270. Find the uniform load per linear foot which a wooden canti- 

 lever 6 feet in length, rectangular section 2 inches broad and 3 inches 

 deep, can carry with a maximum fiber-stress of 800 pounds per square 

 inch. 



271. Wooden beams 8 feet between supports, 6 inches deep, and 

 2 inches broad support a floor weighing 100 pounds per square foot. 

 Neglecting the weight of the beams and using a factor of safety for 

 varying stress, how far apart should they be spaced ? 



272. A balcony projecting 6 feet from a wall is supported by 

 wooden beams 4 inches broad and spaced 3 feet apart. Find the depth 

 of the beams if the total uniform load is 120 pounds per square foot 

 and the maximum fiber-stress is 800 pounds per square inch. 



273. A rectangular, wooden simple beam 9 inches deep and 3 inches 

 wide supports a load of \ ton concentrated at the middle of an 8-foot 

 span. Find the maximum fiber-stress, considering the weight of the 

 beam. 



