FO UND A TIONS. 24 1 



Constant weight of tank and water J 776 tons 



Wind-pressure exerted over foundation-base 517 " 



Whight of masonry 634 ' 



Total applied weight and stress 2927 tons 



Then if B, or allowable bearing-value, =W t total weight 

 or 2927, -r- A t total area or 1520, the actual bearing under the 

 given conditions is 1.92 tons, or a bearing slightly less than the 

 assumed safe bearing-value of the soil. 



In designing the foundations for a tower and tank, the same 

 formulae and methods are employed. To determine the wind 

 stress, however, the moment of inertia / is, of course, that of a 

 rectangle or polygon, with sides bounding the figure formed 

 by the base of the tower instead of that for a circle. 



The supporting column of a tower must be provided with a 

 footing or pedestal at its base. This should consist of a steel 

 base plate, reinforced by angle connections and securely riveted 

 to the tower post. Holes of proper area must be drilled for 

 anchor rods. 



The bearing-plate is subjected to direct shear from the total 

 load concentrated and delivered by the metal of the column 

 cross-section, and its unit stress should not be less than 10,000 

 pounds per square inch. In water-towers of small capacity 

 the area of the bearing-plate may be made sufficient to safely 

 distribute the load directly to the masonry, or a cast-iron cap 

 may be provided, in either case, with area great enough to dis- 

 tribute the load upon the bearing surface so that it shall not 

 exceed 100 pounds per square inch pressed. 



Generally, however, it is considered more desirable and orna- 

 mental to surmount the piers with a capstone. 



When this is specified the stone should be a monolith, sound 

 and of close texture, preferably granite; its bearing surfaces 

 at least should be "patent-hammer" dressed. An empirical 

 rule for its dimensions is that its lowest bearing surface must 



