OF ENGINEEBING FOBMULÆ.
Cast-ibon Gibdebs.
D = Depth of girder in inches. f__
A = Area of bottom flange in inches. ? I
S = Span in inches. P J ___
W = Breaking weight in tons. J. I ' ^*“1
Supported at both ends with load) w — 25 AD
on centre____________________J — g
Supported at toth ends with load I yy ___ SOAP
distributed .. .. ...J S
If the depth. = of the span, W = A 4 • 171 it
If tlie depth = of the span, W = A X 5 J distributed
Area of top flange if the load is I __ &
applied on the top___________/ 3
Area of top flange if the load isl __ A
applied on bottom flange 2
. , 2D
Depth at the ends may equal —-
O
Safe deflection inch for each, foot of span,
under a test load of |rd of the breaking weight.
169
____________________________________________________
________
Breaking Weight of Cast-iron Girdebs.
(In tons distributed.)
Span Depth Size of I Breaking Size of Breaking
in feet. ininches. bot. Hange. | weight. bot. flange. weight.
10 10 6 X H = 31 » X li = 41
15 15 8 X li = 50 12 X H = 75
20 20 10 X H = 62 16 X U = 94
25 25 13 X If = 94 19 X 2 = 158
30 30 15 X 2 = 125 22 X 2 = 183
35 35 17 X 2 = 141 25 X 2 = 208