'38 



STRESSES IN TWO-HINGED ARCH 



1.357 inches 



0" 0-1" 0-2" 0-3" 0-4" 



Deformation Diagram 



for 



Simple Truss 



H =20000 Ibs, 



(C) 



\ ^X^ ^f Deformation Diagram 



\ /.-X ^~t c.'\ 



Simple Truss 



Dead and Wind Loads 



(b) 



FIG. 75. 



The deformation diagram for the simple truss with a horizontal 

 thrust, H 1 , of 20000 Ibs. is given in (c) Fig. 75 and is the same as that 

 given in (c) Fig. 72. 



The true value of H is found by the proportion 

 H : 20000 : : 1.357 : -574 

 H = 47300 Ibs. 



The stress diagram for the two-hinged arch with dead and wind 

 loads and a horizontal thrust, H, of 47300 Ibs. is given in (b) Fig. 76. 

 The stresses in the arch for this case may be found from the stresses 

 in Tables IX and VIII by adding the stresses in column 4, Table IX, 

 to the corresponding stresses in column 4, Table VIII, multiplied by 

 2.865, tne r ^tio between the actual and assumed horizontal reactions. 



