AS APPLIED TO WORKS OF CONSTRUCTION. 271 
following manner :—The maximum moment of flexure due to the 
two cone penttabed en is 1600 x 17°125 = 27,398°4 
Wt. Wx 44°35 
Bieta 3 
= 27,398°4, 
954 the equivalent distributed load, or 2,477 
= the equivalent einem load. The mean central breaking load 
may therefore be taken as ——— = 2,288 Ibs. 
And the nee central load for the full sized beam 29 ft. 6 in. 
span will be 64 x 2,288 = 70 tons nearly, which agrees with 
the result given in the report of the Railway Bridges Inquiry 
Commission 
a Toads and deflections produced are shown in the following 
ble 
: ral ral : Central 
W. Sewieot W. Gamscuan W. ennai W. Deflection. 
ib. inches. ib. inches. Tb. inches. tb. inches, 
100 | 0°05 900 0°39 1,700 0°79 2,500 1°38 
200 0:08 1,000 0°43 1,800 *84 2,600 1°50 
300 0°10 1,100 0°50 1,900 0°89 2,700 1°59 
400 0-13 1,200 0°53 2: 0:97 2,800 1.87 
500 0°17 1,300 0°59 2,100 1-04 2,900 1°97 
600 | 0°25 1,400 0°63 2,200 1:09 3,000 2°05 
700 0°30 1,500 0°71 2,300 118 3, 100 2-29 
800 0°35 1,600 0-76 2,400 Ae 2s 3,200 eeitis 
The compound beam is therefore, ne tem three times as strong as 
one of the simple beams of whicl 0s' 
By observing the behaviour of a beam while the above tests 
were in progress, or even by inspecting the fractured model, it is 
seen that the beam is deficient in horizontal shearing resistance. 
It can be proved that the distribution of shearing stress on any 
‘Section of a solid rectangular beam is represented | graphically by 
parabola represents the total shearing stress on any section per 
unit of breadth, so that if F = the total shearing stress at any 
section ; and « = the central ordinate of oe hk = depth 
of beam, and 6 = breadth of beam 
-P =—azhv 
