n6 



STRESSES IN PORTALS 



(c) Fig. 61. The anchorage required on the windward side is a max- 

 imum and may be calculated as follows : Let T be the tension in the 

 windward anchor bolt, 20 be the distance center to center of anchor 



6 -1000 F t3000 EL R=2000 



96000 m- 1 bs- 



Shear 

 (a) 



Portal 



Columns Fixed 

 (b) 



FIG. 61. 



Moment 



(O 



k-za - 



Base of Column 

 (d) 



bolts, and P be the direct load on the column. Taking moments about 

 the leeward anchor bolt we have 



(58) 



2 Ta (P V}a + 



T _ 



' 



Hd , P V 



If the nuts on the anchor bolts are not screwed down tight, there 

 will be a tendency for the column to rotate about the leeward edge of 

 the base plate, and both anchor bolts will resist overturning. 



The maximum pressure on the masonry will occur under the 

 leeward edge of the base plate and will be 



' W Me 



