一 105 — 
a middle strut in a span with an even number of panels tho formula is 
G =^ 4 ^ W + \ [Eq.^A.] 
where W is tlio pressure on the train which is concentratel at one panel point or 
40 times the panel length in feet divided by 2000, W\ is the panel pressure upon 
°wer half of the trusses and the floor system, calculated for a wind pressure of 
Ul y pounds per square foot, autl tlio other quantities have the same values as 
before. 
When the span is empty tlie stress in the lower lateral strut at the free end of 
a s P au わ given by the following formula 
2 n — 1 
c n パ 
TVa 
w b - ^ (G-2Ö0. [Eq. 5] 
^lieie Tf a and Wb are the panel wind loads (both windward and leeward) for tlie 
Wer and 
u Ppör systems respectively, l is tho length of span, G the cloud load per 
ü eal foot 0 f bridge and G[ the released load p*er lineal foot u actor tlio assumed 
Maximum wind pressure. 
. the span is covered by tlio moving load the stress in tlie same member is 
Gj: 
2 n 一一 1 
JVa 
WV- 占 (G f -2 G.'MEq. 6] 
4 a 1 4 
『heie TP a i 8 tlie total panel load (both windward and leeward) for the lower system 
e . tlio sum of the fixed and moving panel loads, IF* the panel load (both wind- 
and leeward) for tlie upper system at thirty pounds pressure per square foot, 
le of span, G r tho sum of tlio assumed live and dead loads por lineal f jot 
a e en ° llie excess is not considered) and (7/ the released load per lineal foot under 
Pressure of thirty pounds per square foot ou trusses and train, 
• he stresses in Eqs. 1 aucl 8 are to be increased for initial tension as tlircdel 
la P^i* VI, or, what amounts to the same tiling, those stresses arc to bo used 
g Ut sizes of tlie rods determined by Table YI : and tlie stresses in Eqs. 2, 4, 5 and 
公 こ re ^ he increasoil by tlio sum of the components in tlie direction of tlio strut of 
of t ふ 111 t eils i 0üs iu all tlie lateral and vibration rods meeting at tlie windward end 
If the track upon tlie bridge be curved, the stresses upon that lateral system, 
c resists the centrifugal force, are to be found by adding to tlio value of W in 
I s . 3. and 4. tho value of Wi from the last oliaptor, and by combining these 
^ ressos tlioso due to the centrifugal force of the engine excess as calculated 
y the following formulae 
T = 2 (w ， 一 1) 
0=2 (が一 1) 
and On = 2 (n — 2 ) 
色* . 
Ei 
