— 169 — 
比 ft g the inner plate i r, thick and the outer one 為’', tlie total area of section will be 
just right ami the plates of procurable sizes. Although one plate lias a considerably 
gieatex area than the other, we must still consider that one half the stress on the 
uel is carried by each plate, for such is tlic probable division. It is impossible 
ermine tlie exact method of division, but this one will cause no undue stress 
^ eitliev plate, because the actual intensity of working stress for tlie plates may be 
ea st one fourth greater than that for the strut itself. 
8 ^gss on each plate on tlie side of the joint nearest tho middle of the span 
jg eie ^°i*e, about G.3 x 8.548 = 22.3 tons, which multiplied by i (1 + 3) gives 
• 3 iuch tong as the bending moment, upon tlie rivets. Dividing tliis by 0.494, the 
lu g bending moment for a l ,r rivet, gives 32 as the number of rivets required 
011 he centre side of the joint. 
the inimLer required for the other side, we ascertain the stress by 
沿 11 jplyiug % を by 8.548, making 16.(5 tons, multiplying this by i (I + i) and 
1 the product by 0.494, which gives 19. 
y making a sketch of tlie connection and using the same arrangement for the 
a' the liip, a plate about four feet long will be required. 
s hnilai’ calculation for tlie next joint shows that tlie inner plate should be J", 
of tli め ° U ^ ei * 01ie ^ f， thick ami that tbe length should be about The thicknesses 
j eil j for the middle joint will be tlie same as those last determined, but the 
1 Aould be a little greater, say 5.5'. All these dimensions of plates are to be 
P ro reriy entered on the bill of iron. 
111 江 ke tli MW 16 c ^ meils ^ ons a coüiiectiug plate for tlie bottom chord strut, let us 
c j la e area of tlie section of same through the pin hole equal to the area of oi】e 
似ぬ 116 ’ 饥 s< l llare inches. If d be the width of the plate at this point and t tbe 
will ミ 物， 幻 10 effective area will be t (d — i). Assuming t — and equating to 2.85 
1 〇" 言:; ゴ ロ 9.7 say 10" •• this can be gradually reduced to at the ends, but the 
^ s h ou W extend at least six inches on each side of tlie panel point for tlie 
of appearance. 
The ^!° o rea ^Gst tensile stress which need be provided for is 5 x 2.85 = 14.25 tons, 
the 1 11C me8s of the web of a 6"— 9.5* 匚 is given by Table XVI. as 0.3", making 
Dividier a :! U 备 （〇,3 - 卜 0 .5) = 0.4"， and the moment 11.25 x 0.4 = 5.7 inch tons, 
uuinbe ， も 卜 わ 0 心 (^ ie working bending moment for a rivet) gives 82 as tlie 
it Cail ^ ° required on each side of tho joint. By making a drawing to scale 
^ith a a % 8cer ^ a ^ ne ^ that it is just possible to use three i-oavs of rivets lV r apart, 
0 f 11" b °t 1ZOn ^ r i ve t spacing of 2V\ Allowing for the joint and pin hole a distance 
心 " nearest rivets would make the length of the connecting plate about 
Hvets / C わ excess ^ ve, It would be better to employ two rows of staggered 
^°W c l】 arme l would then be weakened by only one rivet liole, and there 
^mcrit r 7 ^ er r i ve t 8 nee 3ed. The number required is 12 it is found by dividing the 
tli 〇, * ^ ^ 16 resisting moment 0.494. Using a pitch of S ,r ■will not 
wilier i a lrVe t holes too closely together : this will make each plate about 4’ long» 
8u bject:i' 0 t も 00 . g rea l It will be noticed that we assumed the whole section to be 
0 an intensity of five tons instead of only tbe effective section, as would 
