DEFLECTION OF CANTILEVER AND SIMPLE BEAMS 69 



143. A built beam is composed of two 10-in. steel channels, 40 lb./ft., placed on 

 edge and connected with latticing. The span is 20 ft. Find what uniform load per 

 linear foot the beam can carry under the condition that the maximum deflection 

 shall not exceed ^ in. 



144. A 15-in. steel I-beam, 42 lb./ft., spans an 18-ft. opening. Find the maxi- 

 mum deflection for a maximum fiber stress of 16,000 lb./in. 2 



145. The total load on a car axle is 10 tons, equally distributed between the two 

 wheels. Distance between centers of wheels is 66 in., and between centers of bear- 

 ings is 68 in. Find the maximum deflection of the axle measured from a horizontal 

 line joining the centers of bearings. 



146. A 10-in. steel I-beam weighing 30 lb./ft. rests on two supports 16 ft. apart 

 and carries a uniform load of 200 lb./ft. in addition to its own weight. A third 

 support just touches the beam at the center. How much must this central support 

 be raised so that it shall carry all the weight, and the beam just touch the two end 

 supports ? 



147. A cast-iron pipe 20 in. \nternal diameter and 1 in. thick rests on supports 

 30 ft. apart. Find the maximum deflection when the pipe is full of water. 



148. A beam of uniform section, carrying a concentrated load at the center, 

 has a maximum deflection equal to 1 per cent of the span. Find the slope of the 

 beam at its ends. 



149. Three beams of the same material are laid side by side across an opening 

 of 12-f t. span, and a load of 1000 Ib. rests across them at the center of the span so 

 that they must all bend together. The beams are each 2 in. wide, but two of them 

 are 6 in. deep, while the third is 12 in. deep. How much of the weight is carried 

 by each beam ? 



150. A steel bar 2 in. square rests on knife edges 5 ft. apart, and its maximum 

 deflection under a central load of 1000 Ib. is found to be .1125 in. Calculate from 

 this experiment the modulus of elasticity of the bar. 



