Transactions of the American Society of Civil Engineers, vol. LXVIII, Sept. 1910 | Page 5

sewage carried through Pipe R. Foot
Walk carried on Girders C in place on West Side of Avenue.
No. 4
Elevated Railway carried on Bents under Columns. Temporary Shoring
Girders removed and Permanent Bents resting on Girders C in place.
Bents in place on Girders C carrying Surface Railway. East and West
sides of Avenue excavated down to Sub-Grade and Five rows of
Permanent Steel in place on each side. Bents erected on Permanent
Steel to catch ends of Girders C while 2 outside Concrete Piers are
removed and 6th row of Permanent Steel on each side is put in place.
No. 5
Two outside Concrete Piers removed and 6th row of Permanent Steel in
place. Girders C carrying all structures now resting on Bents on
Permanent Steel. 48" C.l. Sewer carried on Brackets on Girders C.
No. 6

Excavation Completed. ]
Temporary raker braces were placed against the structure to prevent
lateral movement. Four sets of these temporary shoring girders were
used in this manner, two sets starting at the north end and two sets at
about the middle of the work, and these sets were moved south as they
were released.
The columns being thus supported on temporary shoring girders, the
old foundations were removed and the excavation was taken down to a
level about 16 ft. below the surface.
Two sets of three of the girders "C" were then put in place under the
avenue at each column, each set being placed on four concrete piers 6 ft.
square with spaces of 4 ft. between them, so that the outside of the
outside pier would be 18 ft. from the center of the avenue and 32 ft.
from the house line. This is shown on Fig. 5 and on Fig. 3, Plate XLVII.
Four small piers were used, as they could be more easily removed than
one continuous pier. The girders "C" were set to line and grade, and the
piers were built under them, great care being taken to get the concrete
well under the girders so as to give a firm bearing.
After these girders "C" were in place it was necessary to remove the
temporary shoring girders before the bents could be erected on girders
"C" to support girders "B," being in the same plane; and provision had
to be made to support the structure while this was being done.
Therefore, double bents were erected directly beneath the columns, as
shown by Figs. 2, 4, and 5, and by Fig. 3, Plate XLVII. These were
built with their sills resting on the girders "C," and blocking was put in
between the sills and the rock to carry the full weight of the structure.
Later, when the weight of the structure was carried on the permanent
bents, this blocking was knocked out, but the bents were left in to carry
the weight of the column itself, which was swinging more or less from
the structure above. The weight of the structure was placed on these
bents directly beneath the columns by jacking up the temporary girders
again, putting blocking between the bents and the base of the columns,
and taking out the blocking which had been put in previously under the
temporary shoring girders. The 24-in. water main was carried over the

excavation on cables from the temporary shoring girders, except when
they were being jacked up, at which time posts were placed beneath it.
Anchor-bolts were put in place between the column bases and the bents
directly beneath, in order to increase the lateral stiffness, and raker
braces were also used. This having been done, the temporary shoring
girders were moved south to the next column, where the process was
repeated. The timber bents, shown in detail by Fig. 2, were then put in
place as shown by Figs. 4 and 5, and by Fig. 3, Plate XLVII. These
bents were framed as tightly as possible, using generally a 20-ton jack,
and they were erected simultaneously at each pair of columns. The
weight was taken on these columns by jacking up directly beneath the
column base and taking out the blocking between this base and the bent
directly beneath the column. On releasing the jack the weight was
transferred to the permanent timber bents, and the east and west
columns of each pair were transferred on the same day. One 80-ton jack
was used on the easterly columns and two were necessary on the
westerly columns, one on each side of the 24-in. water main. The raker
braces of these permanent bents were not framed as tightly as the main
posts, in order that the main post should carry the entire weight and the
raker braces merely steady the structure.
Timber bents were erected on girders "C" to carry the I-beams under
the surface railway structure,