ii4 STRESSES IN PORTALS 



The stresses in the remaining members are found in like manner, taking 

 joints C, E, F, etc. in order, and finally checking up at the base of the 

 column B. The full lines in the stress diagram represent stresses in 

 the portal ; the dotted lines represent stresses in the auxiliary members 

 or stresses in members due to auxiliary members, and are of no con- 

 sequence. The shears and moments are shown in the diagram. 



-3500 -50O ^+3000 +5500^ H-ZOdO 



I 



CASE I 



Columns Hinged 

 Stress Diagram 



O 1000 2000 3000 



Compression 

 Tension 



FIG. 60. 



Simple Portal as a Three-Hinged Arch. In a simple portal the 

 resultant reactions and the external load R meet in a point at the mid- 

 dle of the top strut,, and the portal then becomes a three-hinged arch 



