Fort Worth gazette. [volume] (Fort Worth, Tex.) 1891-1898, 1891-11-07

Since the auxiliary cables are doubled,
this total must be increased by 1888 wires,
making in all 1881 wires passing from one
anchorage to the other. This is with the
loads named in the specifications, and a
factor of safety of D. All wires No. O. Bir-
mIngham gauge of 10000 pounds per
square inch ultimate strength.
2 To further add to the stiffness of the
floor system, it would be well to change its
construction by using two 5x16-inch floor
beams at each hanger, say ten feet apart,
and across these lay, lengthwise of the
bridge, floor joists 2X16 inches and twenty
feet long, SO as to overlap, alternate ioists
being Spiiced on successive beams. These
joists might be LAID twenty-four inches c.
to C. The floor plank should then be laid
diagonally as shown on the plans, to assist
in stiffening the bridge against wind press
ure, and the floor JOists should also be well
bridged, as is also shown in the design SUBJ
united.
A further advantage of this arrangement
is that the floor system is more directly
suspended from the cables than in the orig
inal plans.
The stays, in this case, would be attached
to the auxiliary cable at the 10, 30 and so
foot distances from the tower, where the
floor beams rest and the hangers are at
tached. These sizes might be the same as
given above, viz: 20, 80 and 100 wires on
the sides and 80, 60 and 120 wires in the
center.
We have made drawing showing gen.
eral plan and elevation of the structure on
this basis. and submit it for your considera-
ton. If it is not too late to modify the de-
sign we think these changes would add
greatly to the satisfactory operation of the
bridge. When stiffening truss is omitted
every precaution should be taken to supply
its place as nearly as possible in the con-
struction of the other parts. The light,
truSsed. hand-rail shown in the plans does
not serve to stiffen this bridge to any mate
rial degree, but the diagonal tie rods should
be increased to %-inch if screw threads are
to be cut on them. With this floor system as
here described, and with the diagonal wire
guys and wire stays as shown on our draw
ing. and with the diminished says of cables
herein specified, we believe the bridge
would be very rigid under all ordinary con-
ditions of traffic, and would be abundantly
strong for even the excessive loading as
sumed in the specifications.
OF course it is assumed that the details of
construction will be carefully worked out,
many of which are not shown on
the drawings submitted, and that the work
will be done by intelligent and competent
parties, familiar with this kind of con-
struction.
1t is, we believe, perfectly practicable to
protect and preserve the cables, by the
methods Indicated, II 1t is properly done.
AS to the foundations Of the towers, they
are evidently sufficient as shown, if pro-
tected from caving OF into the river, which,
we presume, there is no danger of their
doing. If such a fate should at any time
become imminent, it should not be difficult
to slope off and rip-rap the bank. or protect
by piling and cribwork, and so save the
foundations.
We believe we have now answered fully
all the inquiries you have put US, but If not
will you please make such further demands
upon US as will enable US to fully meet the
exigencies Of the case. Very respectfully
yours, JOHNSON & F'LAD,
Consultin~ Engineers.