GRAPHIC CALCULATION OF REACTIONS 



The correct value of H is given by the proportion 

 H \ H^ :: A : A' 



= 33400 Ibs. 



.574 



In Table IX the deformation, A, for the same arch considered as 

 a simple truss and acted upon by dead and wind loads is 1 . 357 inches, 

 and 



20000 X 1.357 =473Q01bs . 

 .574 



Graphic Calculation of Reactions. In the graphic solution of 

 the horizontal reactions the total amount of the deformations, A and A 

 are found by means of deformation diagrams. Before con- 

 structing the deformation diagrams the quantities in the first 

 seven columns in Tables VII and VIII or VIII and IX must be 



10' 20' 30' 



Ri 



Simple Truss 

 Vertical Loads 

 (a) 



-0. 



Simple Truss\ 



H =20000 Ibs- 



(c) 



20000 40000 



Dead Load Stress Di< 

 Simple Truss 

 (b) 



H^OOOOlbs. 

 Y 



Stress Diagram , H=20000lbsi 

 (d) 



FIG. 71. 



