THE COLLIERY GUARDIAN
and
JOURNAL OF THE COAL AND IRON TRADES.

Vol. CXI.

FRIDAY, MAY 5, 1916.

No. 2888.

Ferroconcrete Bunkers at the Brymbo Works, Wrexham.

By F. C.

One of the interesting features of an important exten-

sion scheme recently completed at the Brymbo Steel
Works, near Wrexham, is the structure illustrated in
the accompanying drawings. Provision was necessary
for the reception of large daily consignments of iron
ore and lime from a high-level railway siding passing
through the Brymbo Works, and also for the storage of
several days1 deliveriesv of these materials in elevated
bins, from which supplies could be drawn conveniently
as required. The’’ necessary storage capacity for ore
was 500 tons, and for lime 50 tons; and the rail level
of the siding, at the point most convenient for tapping,
on account of its proximity to the furnaces, afforded a
height of approximately 24 ft. in which to provide this
storage capacity and to leave a headroom of 10 ft. 6 in.
below the discharge openings in the bottoms of the bins,
under which would run the trucks carrying the charges
to the furnaces. The site chosen for the bunkers was
adjacent to, and running parallel with, the existing low-
level , sidings over which the high-level siding crossed
(approximately at right angles) on a steel girder bridge

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Fig: 1 (Plan).—Iron Ore and Lime-handling Bunkers at the Brymbo Steel Works.



with masonry abutments. The lay-out and the pro-
posed working arrangement of the low-level rail tracks
made it essential that, the site of the bunkers should be
70 ft. to 80 ft. distant from the high-level siding, and
therefore the intervening space had to be bridged to
carry the main line traffic on to the hoppers. Such
were the general requirements of the scheme, when the
Brymbo Steel Company, after consultation with the
Trussed Concrete Steel Company Limited, of West-
minster, decided to adopt reinforced concrete for the
entire structure. This decision was arrived at, not only
by reason of.the economy, in first cost, but by reason of
the advantage in the annual cost of maintenance. The
illustrations afford a good idea of the manner in which
the scheme has been executed. The three nearest
hoppers are intended for the storage of ore, each bin
having a capacity of 170 tons, whilst the fourth hopper,
which is used for the storage of lime, has a capacity of
approximately 50 toms* The bridge connecting the
hoppers with .the high-level siding is of three spans, and
has been designed to accommodate the heaviest Great
Western Railway main line goods traffic. The abutment
at the siding end of the bridge forms one of the masonry
wing walls of the previously existing girder bridge,
already referred to; and this was strengthened and
re-constructed to take the. additional loads. In explana-
tion of the plan and section drawings, it may be said
that the two parallel beams carrying the rail track over
the bunkers are supported by main beams spanning
across from column to column. The cross beams in the
bunker portion of the structure act also as the transverse
vertical walls of the bins, and carry their proportion of
the load from the hoppered bottoms. The space between
the rail-carrying beams is left open for the full length
of the structure, and the ore bins are left entirely
'uncovered. The lime bin is decked over in reinforced
concrete, except for the space between the" rail beams,
which is fitted with a sliding cover to close the bin when
not being charged. A reinforced concrete platform

COLEMAN.

extends the full length of the structure, and this is
cantilevered out over the face line of the bunkers, longi-
tudinal deck beams, carried direct on the columns,
continuing this, line of support over the bridge spans.
This peculiar design of the bins was called for by the
size and shape necessary for the discharge openings, and
also by the accommodation which had to be given for
".the shafting and gearing of the mechanical arrangements
. for controlling the discharge.

The outline dimensions of lime and ore bins are
identical, and, as will be seen from the drawings, are
about 19 ft. by 15 ft. by 12 ft. deep. The two longi-
tudinal sides are vertical for a depth of about 9 ft. from
the top, whereas the transverse sides are vertical only
for a depth of about 4 ft. . The hoppered bottoms are
sloped at an angle of 48 degs. in both directions. Trans-
verse beams, spanning from column to column, below
the hoppers, carry the main supports for the discharge
controlling apparatus; and brackets, projecting from the
columns and from the bottoms of the bins, are provided
as supports for the various parts of the gearing. An

operators’ platform cantilevered out from the columns
at a height of about 5 ft. above ground level, runs along
one side, of the structure for the full length of the
bunkers, and there is a reinforced concrete ladder
spanning from the ground up to the main bridge deck.
The columns, carrying the hoppers and the bridge, are

Masonry

ORE

'oSi'ain

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Fig. 2 (Longitudinal Section).—Iron Ore and Lime-handling Bunkers at the Brymbo
Steel Works.

founded/ upon a raft, consisting of a rectangular slab
118 ft. long by 21 ft. wide, which reacts on two parallel
continuous beams running longitudinally from end to
end of the slab, under the centre lines of the two rows
of columns.

The ' details of the principal reinforced concrete
members are as follow :—

The rail bearers are designed as continuous beams over
the six intermediate supports, the first bridge span of
37 ft. being calculated for a total train load having an
equivalent distributed value of 2’88 tons per lineal foot
of track; the tsecond and third spans, each of 17 ft. 6 in.
between , the first and < third column supports, for
equivalent distributed loads of 3’6 tons per lineal foot;
and the fourth span of 19ft., extending over the lime
bunker, for 3’47 tons per ft. run of track, the whole of
these first four spans,- commencing from the high-level
siding end of the 'Structure, being designed to take'the

heaviest Great Western Railway goods engines. The
remaining three spans of 19 ft., carrying the rails over
the three ore bins, were calculated for a train of the
Brymbo Steel Company’s 20-ton capacity hoppered ore
wagons, exclusive of locomotive, giving an equivalent
distributed load of about 1’75 tons per lineal ft. of track.

The maximum values of the positive and negative
moments, on the seven spans and over the supports,
were based upon the most effective dispositions of the
above train loads. • On the 37 ft. span these bridge
members are 50 in. deep by 15 in. wide, designed as L
beams in conjunction with the 44 in. deck slab, and are
provided with 12’65 sq. in. maximum cross sectional
area of tensile reinforcement, and the same sectional
area of top compression steel, seven out of the group of
10 main tension bars being bent up, singly, from point
to point as required’ to act as shearing reinforcement in
the usual way, giving a sectional area of -2’2 sq. in. of
steel per lineal ft. of beam in resistance to the maximum
shear stress.

The two parallel beams are cross stiffened at three
intermediate points by 12 in. by 12 in. braces reinforced
with four bars each of 0’39 sq. in. sectional area, braced
transversely by means of in. diameter ties at 9 in. c.c.
The rail beams on the 17 ft. 6 in. spans and on the
19 ft. span across the lime bin are designed in a similar
manner, the outline dimensions being 23 in. deep by
15in. wide, and each has 6’76sq. in. tensile reinforce-
ment and 6,sq. in. compression steel. Each bay has
one 12 in. by 12 in. cross stiffener, as above described,
at the centre of the span. These beams continue of the
same outline dimensions over the three 19 ft. spans,
crossing the ore bunkers, the cross sectional areas of
tensile and compressive reinforcement being reduced to
3’38 sq. in. and 1’69 sq. in. respectively, on account of
the lighter loads. The continuous reinforcement. over
supports is provided partly by continuing a number of
the cranked up tension bars from each bay across on to
the adjoining spans, and partly by the addition of extra
rods. The transverse beams of 13 ft. 6in. effective span
bridging across from column to column, and carrying the
loads from the rail beams are, at the first support, 50 in.
deep by 15 in. wide, with 7’59 sq. in. tensile
reinforcement and 5’06 sq. in. top steel; at the

second support, 32in. deep by 15 in. . wide, having
7’06 sq. in of steel reinforcement in both tension and
compression. The third cross support, which also carries
its proportion of the load from the lime bin, of which
it forms a vertical side, is 50 in. deep and 12 in. wide-
reinforced with 8’8 sq. in. steel in tension, and in
compression by 1’69 sq. in.,' contained in spiral
reinforcement composed of two overlapping helicals of
4 in. diameter round rods coiled to .8 in. diameter and
14 in. pitch, embracing the full width of the beam.
The end supporting beam forming the vertical wall of
the end ore bin is of the same, dimensions and designed
similarly, as also are .the three cross beams which form
the vertical division walls between the ore hoppers.

All these beams, which act also as bin sides, are
additionally reinforced, close to, their vertical iacee,
between column and column,, to resist the horizontal
moments due to the pull from the loaded hoppered