Delaware state journal. [volume] (Wilmington, Del.) 1870-1883, 1873-06-07


SOME RECENT TESTS OF THE STRENGTH OF
BRIDGE IRON From NJ. b. sTOTsKNBRRG
4 co.
A very lHtprestng and important test
of the strength of bar iron for bridges,
was recently made for NJ. b. siptsenbery
" Co., Of this CITY at the works of the
Lobdell Car Wheel Company. The ex-
periments were observed by j. Duttou
Steele, Esq Civil Engineer, and he thus
reported them at the meeting OF the Amer
lean Society of Civil Engineers recently in
session at Louisville, Ky.
The next test was OF round truss rods
from NJ. B. StOtsenburg d Co.'S works,
Wilmington, bel, IA inches ia diameter,
Of PencOyd Iron, made OF SELECTED scraps OF
the best quality, with an eye At one eud and
"a screw At the other. The specifications AS
TO strength were the same rs in the former
case. That 1t should have an elastic
strength of 2i,O00 pounds aud a breaking
strength of 5O,OOO pounds.
The eyes Epie made by turning the ends
Of the rods round the pita aud welding
them to the body Of the bar and the screw
ends were either upset or split, and u
wedge.shaped piece welded IN them, and
swedgtd into shape 50 w 10 produce an
enlargement that would enable the nuts to
pass over the body Of the rods, and the nuts
had depth equal to the diameter Oi the
was hydraulic press, supplied by n force
pump with a One-inch plunger.
FIRST application 10000 pounds per square
inch, stretch II OF an inch In IA feet
recovered.
Second application a, OOO pounds pei
square inch, stretch SIG of an inch in Il
tept-recOyered.
Third application D. 900 pounds per square
inch, stretch 4 OF an inch In IA feet-re
covered Hearit,
Fourth application $4,000 pounds pei
square inch, stretch inches In Il teet-re
| covered Of an inch.
Fifth application $4,000 pounds per square
| inch, stretch inches In Il feet-recol eret
! =, OF an inch.
Sixth application $1,000 pounds per square
! inch, stretch II inches in II feet-recOy cree
| y, Of an inch.
| Seventh application h0OQQ broke In th'
/ body of the bar, near the eye, after q per
manent stretch of 81 feet in length OF ?
| feet. The pecularity In this last appica
tion was that the bar stretched under
pressure of 50 900 pounds as fast rs TIT
force pump could supply the power neces
sary to move the piston OF the press with
| pressure gradually running down below
| 10000 pounds until IL broke; neither thu
eye nor the screw received any injury from
the tests TO which the bar had been sub
jected. The important difference indicated
BY these tests on the two descriptions o
iron, the one new and the other made from
scrap, and both Of the best quality of thei
kind, is that the elasticity OF the former In
creased rs II became gradually weakene,
by successive strains, whilst in the latte
it decreased although there was create
cApability Ut stretching before II finally
gave way. They also tndi0Hte how en-
phatically II is the elastic strength aud no
the breaking strength that should govern
the use OF iron in bridges, as each success
siye strain beyond that limit must weaker
/ the bars and ultimately produce failure
1t may also be doubted II, where the up
setting process Ia used, process which, II
accuracy and uniformity Is superior to all
others for making eyes, there should not b.
| a greater section round the eyes to com
peusate for the arrangement Of the hben
produced by the operation.