71 



3( 



Having obtained D by this formula, the total stress in 

 tons equals 



from which the size and number of bars running in each 

 direction can be computed. These bars may be made in 

 two lengths as shown on plan, Plate II, the shorter length 

 being equal to W + P. The total height H should not be 

 less than D + 4 in. 



I,r U~ 10 in. Load =r 80 tons. Safe bearing power 

 of soil = 2 tons. The required area of base of footing is 

 40 sq. ft., and the width W\ equals the square root of 40 

 = 6 ft. 4 in. or 76 in. and P 30 in. 



8V 80V 30 

 D equals the square root of - 17 in. 



O /\ . 



The total stress would therefore be 



22 

 X 17 =47 tons 



requiring 9-K in. bars or 19-J4 in. bars in each direction. 

 These bars should be spaced equally over IV / D 



The total height // would be D + 4 in. 



FORMULAS FOR RANSOME FLOORS. 



1st. Flat Floors: Our K^iioral formula for calculating 

 the maximum tensile stress or the maximum oompressive 

 stress in any beam supported at both ends and uniformly 



loaded Is stress = 



In which L equals total live and dead lond snpportod. In 

 tons: N f<]u:ils spun, in inches; and 7> M|u:ils distance 

 from top of beam to center of bar, in inches. 

 When the beam is not uniformly loaded the formula for 



B MXS 

 maximum stress is Stress = 



7X/>> 

 in \\lii.-h /; U equals maximum bending moment, in inch tons. 



