The Jersey City news. (Jersey City [N.J.]) 1889-1906, 1895-03-05

the main span and the towers w,ll hs
formed OF rigid. members capable o1
resisting either tension or compression
THE transverse and longitudinal beams
Will be rivited plate girders, there must
be two long3tudillal giasaers on each track
The. anchorage bars VIII be eye bars ot
medium steel. The anchorage psdestals
will be built from forms of medium steel
W fssa baned Cd nao e gaajonng
st3nry, Each baS4ier can select such
depth of vers.ne, number and arrange
ses and general details as he deems best
| Within the requirements of these specl-
fications;, The main piers and the anch9r- tgs,l
! Viaduct piers may be founded upon the
rock, or upon plies, or such other form
| of foundation as may be approved by the
/ THE PROPOSALS.
"BiGders must submit with their pro,
! posals plans for the anchofages and
piers. showing the proposed methods OF
the character of the masonry. The ex.
posed faces OF all masonry wild be OF
saBte Ss se or Ssha agPfHyeSS sPa Se s9ae pTopooned
to carry the following loads -
First; The weight Of rails, ties, guards; ga9,5
track ginders, shall be taken as 400 pounds
per lneal foot of each track. Second.
The weight of metal in the structure T ts re
1
| constitute the dead or permanent load.
| Third. Trains weighing. 5000 POUNDS per
| lineal foot of track covering All the tracks rack
from tower to tower. at rest or moving
'fot Fourth. Trains 1000 feet in length and
upog eaeh sf of the Gu SIX tracks, these trains
being supposed to be moving at h9gn
speeds either AL in one direction, or tne
and the three on the south tracks in an
opposite direction. -,
members, which will get their. greatest
stress from engine loads uniform load
of 5000 pounds Increased by coneentraf-
Stems 8. and will be known as the
''live loads"
Sixth Wind, the structure covered with
trains of cars Will be assusnS5a ls g n9,r5s 70 9s
per square foot of surface; or wind
force of 100. pounds per square rpos q
q a9Ffcff S Feet Sf tFs se Dae wnd vii Gn be isr
80 degrees above or below the horizontal;;
be considered
Seventh Temperature; a range Of tenn;
perasure of rs degrees, Fair, above and I'd
Thee MODULUS of elassicity Of the, cables
viii be assumed as 90, 100000 pounds; ,,1a aad
from sstrieturai steel as 2S,o06,O00 pounds;
The co-efficient. of expansion for steel
Ealhr. All parts Of the structure shah
be proportioned to meet the naxifnuma m
conditions produced by c4laoinatosn,s s,,,s,, q
ioals 8, A and 5. the wind and tempera-
ture.
ALLOWED UNIT STRAINS.
members subject to tension-Gables.
Under the above spec1fled ae i9aas Iae IN the III
cables shall not exceed maximum OF
$4,000 pounds per SQUARE aroh. Suspen-
ders shall not exceed 10000 pounds per
square inch OF the section of the wires
Cross, ross stays-The, wire ropes used for
strained to $4,000 pounds per square 1nch
of the wires. Anchor barsEThe ancnor
bars may be strained to 10000 ,yGs,ad psnndds@ @ per
hangers and similar niembers shaiI nol
be strained more III than 500 ,pegadST, T,,dr for
e.irders-These girders shall be propor-
toned upon the suppoSition that the
bending of chord strains are resisted
and that the shearing or web strains are
resisted entirely by the web plates. Nc
part Of the well plate snail @ pc es5amIasea
the lower fanges of the longitudinal fioor
girders shall not be strained above 10000
ton. The lower hangs Of the trans
verse floor girders. when subject. to ten
sion only. shall not be strained above
1900 pounds per square inch Of net sec
ton. The top fianges of such girders VIII
be made of the same gross section as the
lower flanges: but the fanges must be
STAYED against transverse crappltng al
distances not exceeding 20 times their
width.
Stiffening Trusses-The chords of the
stiffening trusses shall not be strained
above 1900 pounds per inch of net sec
ton by the live loads, nor more than r.
800 pounds by the combined action of live
loads temperature and wind.
Tension members of the lateral and
sway systems shall not be strained in
oh
inch of net section.
Members subject to compressfon-Th
columns of the towers shall ibe so pro-
Dortioned that the maximum compression
per spare inch. will never exceed that
Civen by the following formula:-
P-20, ,000-70x1-r.
For the compression of struts in the
lateral or sway system of bracing the
P-1T. .500-75x1-r
Where P-AIowed unit strain
I-Length in inches
R-Least radius of gyration in inches.
The chords Of the stiffening trusses:
when subject to compression only. shall
not be strained by live loads above
ton of live loads. Temperature and wind
A'ieIS Pa 5oo-sox1-r.
Members subject to reversal of strains
by live loads-UnGer the reversal of
strains by I've loads. the chords of the
stifrened trusses shall not: be strained
above the unit strains given by the fol-
lowing formulas
10000. !