1 1 2 STRESSES IN PORTALS 



is assumed to take all the shear. The maximum compression in the 

 upper flange G F occurs at P, and is 



(53) 



h d 

 The maximum tension in the upper flange G F is 



' 



(54) 



The maximum stress in the lower flange D C is 

 || DC-^-j^ (55) 



maximum tension occurring at C, and maximum compression occurring 

 at D. 



The maximum shear in the portal strut is V, which is assumed as 

 taken equally by the lattice members cut by a section, as a a. 



Maximum moment, shear, and stresses in the columns are given 

 by the same formulas as in (a) Fig. 58. 



Portal (/). The maximum moment in the portal strut I F in (f) 

 Fig. 58, occurs at H and G, and is 



M = + H h Fa (56) 



The maximum direct stress in H G is + H, and in / H is 



The maximum stress in G F is given by formula (49). 

 The maximum shear in girder / F is equal to V. The stress in G C 

 is V sec and in H D is + V sec 0, as in (a) Fig. 58. 



Portal strut / F is designed as a girder to take the maximum 

 moment, shear and direct stress. 



Maximum moment, shear, and stresses in the columns are given 

 by the same formulas as in (a) Fig. 58. 



Graphic Solution. To make the solution of the stresses statically 

 determinate, replace the columns in the portal with trussed framework 



