104 



STRESSES IN A TRANSVERSE BENT 



are designed for a horizontal wind load of 20 Ibs. per sq. ft., the nor- 

 mal wind roof load being obtained by Hutton's formula as shown in 

 Fig. 6. 



The point of contra-flexure is found by substituting in formula 

 (41) to be at a point y = 17.0'. The external forces are calculated for 

 the bent above the point of contra-flexure by multiplying the area sup- 

 ported at the point by the intensity of the wind pressure. For example, 

 the load at B is 32' X 6.75' X 20 Ibs. = 4320 Ibs. 



24 



Trusses 310 c.fy e.. 

 DeadLoad=ZOIb. Sq.Ft. 

 Wind Load' tO Ib. 



T A 



WIND LOAD STRESS DIAGRAM 

 COLUMNS FIXED 



(0 



FIG. 57b. 



The line of application and the amount of the external wind load, 

 2 W, is found by means of a force and an equilibrium polygon. 2 W 

 acts through the intersection of the strings parallel to the rays O-B 



