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UDC 624
Paper to be read beforehe Inst itut ion of Structural Engineers at Upper Belgrave Street, ondon SW l X 8BH, on Thursday8 November 1973
Civil engineering wo rks for the new float glass
plant for Pilkington Brothers l im it ed St. Helens
J.
D.
Harr is
BSc(Eng), CEng, FIStructE, FICE, FIMunE, MConsE, FIE(Aust)
Partner. Harris Sutherland
A
E.
Johnson, BSc(Eng), CEng, FICE
Chief Civil Engineer, Pilkington Brothers Limited
I./
,t
--
After service in the Royal Navy, Mr. J D. Harris joined the Surrey
County Council to work in their Highways and Bridges
Department. In 1951 he was appointed chief engineer of the
Prestressed Concrete Company n Australia and spent six years on
Asia. In 1957 he returned to London and set up
in private practice
design and construction work both inAustralia
and south east
wi th his brother and Mr. R. J. M. Sutherland. Since then he has
been responsible or the design of structures of all kinds, bridges
and industrial works. Both in the U and abroad he has
collaborated closely wi th contractors and manufacturers for the
design and erection of specialist precast concreteproducts. He is
a Miller prizewinner and Culrnann Travelling Fellow of the
Inst itut ion of Civil Engineers, and a Bronze medallist of the
Institution of Municipa l Engineers.
On release from the services, Mr. A.
E
Johnson spent three years
at Portsmouth Municipal College where he obtained an external
degree to London University. He then spent one year as a pup il
engineer wi th the Nigerian Railways, but on return to the
U
he
spent 12 years wi th the Central Electrici ty Generating Board. He
Palmer Tritton before joining Pilkington Brothers Limited where
then worked for the Portsmouth Corporation and for Rendel,
he has been chief ci vil engineer for the last five years.
Synopsis
A new loa t glass plan t has beenconstructed nside he
boundaries of the Cowley Hill Works of Pilkington Brothers
Limited, St. Helens. The site of the plant was extremely varied
due both to the natural topography and geology and to the
man-madeobstructionsofa very large ndustrial ipand
massive foundat ions for an o ldrocess.
A float glass plant t o produce massive quantit ies of clear
plate or windo w glass consists of fo ur major components: a
tank furnace operating at above500 C; a bath r flo at section;
the annealing section (Lehr); and the cutting and handling of
the finished product (automatic warehouse).
The Structural Engineer/October 1973/No. 1O/Volume 51
In constructing such a plant t o produce glass efficiently,
there are tw o major problems for the civil engineer, namely,
the dispersion of heat through the furnace column foundations
carrying loads of between 15 and
350
tonne (150 and350
ton) and the fact that each major component of he plant
must remain horizontal during ts working ife as well as at
precisely the same relative level to the aqo ini ng sections, in
spite of he arge expansions of steel and refractories. The
refractory ined tank must also retain the fluid molten glass
without leakage through the block joints.
Brief outline of the flo at lass process
There are fourmajor stages in he loat glass process,as
follows
:
Melting. The raw materials are fed into a tank furnace and re
meltedatabove 1500°C. From he ank hemolten glass
passes to the bath.
The bath, or float section. The ribbon of glass is ormed by
floating on a molten metal n an nert atmosphere t o give a
truly flat surface finish. The ribbon then passes t o the Lehr.
The Lehr, or annealing section.The ribbon
o
glass is annealed
and cooled at a controlledate so that it may be cut and worked.
Automatic warehouse. The finished product s cut nto trade
sizes and withautomatichandlingequipment ormed nto
packs for storage in the stockrooms or for direct distribut ion
outside the works.
This process replaces the old grinding and polishingrocess
in which cast glass was ground and polished to give ruly
flatand parallel surfaces. Theby-productof hisobsolete
process was a material known t o the glass trade as burgy ,
comprising fine waste sand, glass dust and cast iron. At the
endof he process theburgy became aslurry which was
pumped into agoons, thus progressively raisingthei r banks. In
thecentury or so duringwhi ch these operationswere in
progress, three tianks containing some 3 million m3
4
million
yd3) of burgy were formed, one within the works boundaries
on the site of the proposed float glass plant, and two in th e
immediate vicinity.
Descript ion of the site
The site chosen was alongside the existing float plants ith in
the boundaries of the Cowley HillWorks, St. Helens. The area
availablecontained he old discgrindingshedwithplant
foundations some 7.6 m
25
ft)
deep, aburgybank some
9
m 10.6 m (30 ft 5 ft) above ground level, and a .river
valley in which he water evelwas15.2m 50 t)below
ground level.
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Main civ i l works
The main civil works were s foll ows :
demolition of existing buildings and their foundations
culverting of Rainford Brook for 333 m (1 100 ft)
levelling and filling site
construction of tank furnace basement and main buildings
whichcompri sed: he ank urnace house, bath house,
Lehr building, automaticwarehouse, S2 stockroom, finished
size stockroom, Lehr end size stockroom
construction of reinforced concrete chimney of0 m (300 ft)
in height, ervice ucts, ncillary uildings,oads nd
railways.
Geology
The Cowley Hill Workswere established originally on the high
ground to the west of the flood plain of Rainford Brook, and
the waste products of the glass-making process consisting of
ash, cullet (scrap glass) and burgy had been used for ill ing
the old alley. The result was hat Rainford Brook was confined
into
a
narrow ravine on he eastern side of the plain and
a
burgy bank had been formed some 24.3 m (80 ft) above the
normal brook level.
The St. Helens area is a highly faulted complex of the coal
measures overlain with drift consisting mainly
f
boulder clays
and sands. For this reason, a detailed sub-soilsurvey involving
some 300 boreholes was completed before the work began.
Simplified soil profiles are shown in Figs 4 and 5. The profiles
were further supported by the evidence from the batch plant
foundations constructed in 1968 and fromarlier investigations.
Generally, the stratum dipped rom south west to north east
across the site with sandstone at, or about,basement wall
foundation level in hesouth western ornerof the ank
house. This was further confirmed when the excavation was
completed at chimney base level. Along the line f the Rainford
Brook and beneath the base level of the proposed culverthere
was 3 m
4 . 5
m (1
0
t 15 ft) of soft alluvium. These con-
dit ions wou ld have produced arge differential settlements of
the completed structure and would have equired expensive
temporary works for construction. Boreholes sited to the east
of the existing water course showed that the alluvium ran out
andwasplacedbyboulder clay. It wasbysiting henew
culvert along his ine hat he whole operation was carried
out in open cut with the exceptionf the south end.
A coal seam was ocated beneath he ank basement but
this did notcause concern because it was not within a signifi-
cant distance. As a precaution combustion tests were carried
out on the upper shales, bu t the results showed less than one
per cent of combustible materials in
all
samples.
Coal measures and mineshafts
There have been extensive workings of the coal measures in
the St. Helensarea over the last two centuries. Some ndication
of past activities is shown by the fact that some 29 old mine-
shafts exist within the boundaries of Cowley Hill Works.
The measures beneath the sitehad not beenworked or
some 100 years
so
there were no subsidence problems from
this source. It willbe noted that here were several shafts near
the new line. These were owned by the National Coal Board
and could not be built over unt il consolidated t o their satis-
faction. The procedure equired by the NCB was s follows :
1. locate byprobing he shaft whichcould becovered
by feet of fill (in one case a t Cowley Hill to
a
depth of
17.1 m (57 ft) )
;
2. drill to the bottom f the shaft;
3. backgrout he shaft wit h PFA cement gro ut;
4 cap off theshaft
a t
rock head or where this was at depth,
pressure grout
a
series of boreholes from rockhead to
ground level to form
a
solid plug.
This was
a
costly and aborious operation, and at Cowley
Hill-although the NCB had checked the location-only one
shaft out of seven which we tried to ocate n order to con-
solidate has been found. In one case, some 15 0 probes were
sunk before agreement was reached thathe shaft had merged
with the sub-strata and hat we could acquire the shaft and
proceed wit h the works.
Rainford Brook culvert
RainfordBrooks ontrolledbyheMerseyand Weaver
River Boardwho, as a matterofpolicy, do not permit ong
culverts although they did agree to the proposal on the basis
that heculvertcould pass a 1 in 5 year flood of 1100
seconds3. On this basis a cross-section for flow was 17.2 mz
(1 85 t’), wit h
a
dry weather channel of 8.1 mz (27 ft’).
Whatever construction was used the culvert would have to :
-have an indefini te ife with minimal maintenance.
ustain heavy irregular loading during construction
-sustain up to 16.2 m 54 t) of fill ndefinitely
-resistandomattack from corrosivemedia from the
Steelculvertsectionswereconsideredanddiscarded ona
short life basis, whilst their use as permanent formwork would
have beenuneconomic.Concretebox sections, in s tu or
precast, were examined, but discarded on economic grounds
and because of theancient argument thata structure i n tension
would not withstand ong-term oading n bad conditions, or
wi th inevitable maltreatment during construction, as would
a
structure designed to act in compression.
A more economic and satisfactory solution was ound to
be an insitu concrete two-pinned parabolic arch 0.46 m (1 in)
thick with 50 mm (2 in)over to the twoayers of high tensile
reinforcement. The links and spacers were of mi ld steel.
Thedesignof the culvert had to take in to accountvarious
loadings
-fill-embankmentondition (very wideub-trench
ill- wide sub-trench condition
uperload due to buildings and contents over
A loading on access road a t new ground level
onstruction plant passing before fill is placed
orizontal earth pressures a t construction period.
The bearing pressures under the footings were within the
limits of the ground as revealed in the borings. However, extra
excavation had to be carried out n some sections where, on
inspection,ariations ad ccurred. heoncrete ad a
minimum design strength of 26 N/mmz (3750 bf/inz), using
sulphate esistingcement. Extra protect ion against chemical
attack from he ground and ground water was provided by
three coats of Tretolastex over the arch. The base was cast
against three layers of Visqueen wit h lapped and rolled joints.
The total length of the culvert was 333 m (1 100 ft)nd it was
cast in lengths of 9 m (30 ft) . Expansion join ts were made at
36.6 m (1
20
ft) intervals, but contractors and settlement oints
were at 9 m (30 ft) intervals. The minimum concrete strength
of 13.8N/mm2 2000 bf/inz)was requiredbefore striking
shutters.
Fill around he culvert was designed to be carried out n
compacted 600 mm 2 ft) thick layers simultaneously on both
sides, but weather conditions prevented this and a condition
arose where
a
considerable surcharge was made on one side
of the culvert which moved
it
1.283 m (4 ft 2 in) ou t f line.
Due to the choice of construction, no damage was ncurred
and the culver t was left in itseflected state. The opened joints
were f illed with
a
9 mm ( in) aggregate concrete.
The culvert was constructed in open cut up to the junction
with the existing brick culvert, at the point where the existing
culvert changed rom
a
tw in to single circular brick section.
This point was some 7.6 m (25 ft) away and 15 .8 m (52 ft)
to invert from the main railway access to the works and thus
required careful consideration.
industrial waste in thearea.
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Fig 1 Locat ion p lan
Three sides of the rectangular chamber were formed using
theentoniteiaphragmwallechnique. As excavation
proceeded the three walls were exposed and braced apartith
a steel frame. When the new culvert section had been cast up
to he U-section of diaphragm walling, he ourth wall was
cast, thus closing the gap.
arth moving
Burgy is
a
man-made material being the residue from the past
glass-grinding processes. Merseygritcombined wi th emery
wasoriginally used as anabrasive under rotating cast iron
runners to grind glass whil e it was held n position on a wet
bed of gypsum. The composition of burgy s approximately
90 per cent of
a
rounded silt sized siliceous material with the
remaining percentage cons isting of particles of cast iron,glass,
gypsum and ewellers' ouge. As a waste material this was
dumped on he burgy bank ip by means of suspension in
water. The burgy bank was started in 1875 and believed o
be last used fordumping n he1930s. n he meantime,
woodland had been planted and thearea had become
a
nature
reserve for the animal kingdom. The bank would have to be
moved but was found o be in a hard state because of he
cementitious action of the gypsum, the method of deposition
and age. It was doubtful if, after moving, the hard state could
be reinstated in the time available.
During compaction rials before he start o construction,
burgy was aken rom various parts of the ip and found o
have a moisture content of about 35 per cent. This was after
a
long dry summer hence it was fair tossume that the minimum
moisturecontentofburgyunder hebuildingswas never
likely to all much below 30er cent. This is againstn optimum
moisture content of 27 per cent. Earth moving was begun
using ubberwheel scrapers and
D9
bulldozersbutwithin
three weeks it was apparent that this method was noteasible.
Continued unningon henewlydepositedburgyplus ain
did not permit the compaction of the materialnd
it
also made
it impassable. To continue operationso meet the glass-making
target date, theburgywasexcavatedby71 R.B. Cranes
equipped as face shovels, transported in Euclid trucks and end-
tipped. I n moving some 0.38 million m3 (0.5 million yd3) of
burgy, some 38 000 m3 50 00 yd3) of quarry waste etc. was
used toprovide unning roads, but heoperation eftun-
compacted burgy, which gave settlement problems.
Settlement problems
It is essential that n a continuous ine process, such as float
glass, each element-tank, bath, Lehr, and cuttting line-must
remain horizontal and at the correct relative evel to the next
element throughout he ine. n these buildings and hose
adjoining it was necessary that hedifferentialsettlements
should be kept small for the following reasons:
-t o ensure that hebuildingswould remainwatertight
for he ife of the structure:
-t o allow the safe and continuous operation of fast over-
head travelling cranes;
- s o
that the pallets when fully aden with glass could be
stored ourhigh providing heslopedidnot exceed
25 mm n 3 m
1
in n
10
ft))
;
o
that in the
area
of the glass storage racks, differential
settlementwouldnot exceed 25mm n
3 9
m
1
in
in 13 ft)
The Structural Engineer/October
1973/No. 1
O/Volume
5
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Fig
2
Simpl i f i ed s i te p lan
F ig
3
Aer ia l v iew of s i te before const ruct ion
- s o that the front nd side loaders who would be handling
glass packsof he order of 10 tonne
10
ton)could
safely traverse all operational areas of the warehouses.
The above limitations imposed restraints on the design of the
structure and there were the following complications of the
site
:
-the sub-stratum at the underside levelof the tank furnace
basement slab lay partly on compacted sand and com-
pressible boulder clay. The tank urnace column loads
varied from 150 -3 30 tonne 150- 330 on) and he
heat affected the clay;
-the site of the bath building nd foundation consisted of
loose fill verlyinghe rift material which was in
places some 2.4 m
7
ft
10
in) below the finished level;
-th e Lehr building also Lehr endstockroom)and he
plant oundation covered the area on which the burgy
bankwassi tuated,andthusgavegood
bearingconditions;
-t he remainder of he main buildings and plant were toe
sited over the area of newly tipped oose burgy fill and
an old waste tip.
To liminatehe roblems of ifferential ettlement,he
following action was taken :
-tank suppor ting steelwork large diameter bored piles
-bathuildingnd slab vibroconsolidation
ehr, Lehr buildinganddirect oundingon he
and bath foundation
Lehr end size stockroomundisturbedconsolidated
stockroomolduildingoundations,iled
utowarehousendloor slabs, vibroconsoli-
-finished size stockroomdirect oundingon he
burgy
l
dated
undisturbed consolidated
burgy
-automatic uttingine art large iameter ored
piles
Design and con struction
o f
low level tan k b asement
Genera l
The area inwhich hewallshad obeconstructedwas
encumbered by old works, some known and some unknown,
which founded t about half the required heightf the proposed
tank walls. These oldworkscomprisedmainlyengineering
brick combined with mass concrete slabs and steel and cast
iron sections. The total depth of these from ground level was
7 6 m 25 t). Three solutions were onsidered in the foll owing
order:
-steel sheet piling with ties;
a 1.5 m 5ft) thick reinforced concrete wall tied back;
-a diaphragm wall with counterforts.
The sheet pili ng scheme was rejected because nobody could
be sure there would be no further underground obstructions.
Phis proved obe
a
wisedecision despite theeconomic
savings thatcommended it Theother tw o schemes both
allowed orconstructionup to half he inishedheight n
excavation ndhe rest free nd backf illed behind. The
diaphragm wall scheme, as wel l as costing 1 per cent more
350
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Y S
S H A L f
6 MU D S1
OHE
B B
T Y P I C A LE O L O G I C A LO N G I T U D I N A LE C T I O N
T H R OU GH
T A N K
B A T H
Fig 4 Geolog ical sect ions in furnace and bath area
than he concrete wall scheme,also had he disadvantages
of that technique, i.e. the disposal of bentonite and spoil, the
requirement of a working area, and would have had
a
finished
concrete appearance. The scheme adoptedwas he1 e5 m
(5
ft)
thick reinforced concrete wall ith ties to anchor blocks
the dimension of 1 e5 m being the practical minimum for men
to work in. The base slab was reinforced and varied in thick-
ness from 753 mm (2 ft 6 in) to 543 mm (l f t 6 in) depending
on the superimposed oads. Blind ing varied from 75 mm (3 in)
to 153 mm (6 n) thick, the greater thickness being over the
clay areas. This scheme had the advantage of taking less time
to construct, and the contractor was able to carry it through
efficiently and economically.
Tank foundation
Lo
W level area
The foundation was primarily 24 1 a053 m (3 ft 6 i n) diameter
The Structural Engineer/October 1973/No. 1O/Volume 51
l 5
boredpileswhichhad anaverage length of 5.2 m 17 t).
They wereeach toed 305 mm (1
t)
into firm rock. he concrete
was 26 N/mm2 (3750 Ibf/in2) using sulphate resistingement.
1.6 mm (1 6 gauge) x 3 m (10
ft)
long x 1 e053 (3 t 6 n)
diameter steel liners were placed evel wi th the cut-off evel
of the piles. These liners gaveextra protectionagainst he
variable sulphate ontent in the round nd houldhe
furnace heat penetrate the ground, the liners would also hold
the top of the pile together.
High level area
The foundation was again mainly 24 1a053 (3 ft 6 in) diameter
boredpilesbut in his case theyhad anaverage length of
10.9 m (36 ft). A s the heat problem was not so acute as in
the low level basement, steel linerswerenotemployed. In
both the high and low level areas the piles were capped with
0.9 m (3 t) thickness
of
highaluminacementconcrete to
act as
a
heat barrier to the pile.
351
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-_
T Y
P l C A L O N G l T U D lNA L GEOL.OGICA-L->ECTION THROUGJ VA_LLE _V_
T Y P I C A LO N G I T U D I N A L G EO -L OG IC AL S E C T I O NH R O U G HE f l
Fig 5 Geolog ica l sect ions In L ehr and warehouse area
Genera l
The main civil engineering problem encountered in thedesign
of oundati ons or ank furnaceswas aused by lackof
knowledge of underslab temperatures and
on
the heat osses
through the bases of the regenerators. The emperatures en-
visaged would cause
a normal concrete base slab to disinte-
grate and the ground beneath to become very hot. It had been
considered that ventilation underneath the regenerator, either
by naturalor orceddraught,couldkeep he emperature
within reasonableoperating limits or he concrete. If he
amount of ventilation required were underestimated, however,
there would have been the problem of keeping he air space
clear of debris whi lst too much entilation wou ld increase the
costs. Furthermore, any heat removed wou ld be a loss of heat
from he regeneratorand
it
would need tobe replaced by
more fuel. It was decided, therefore, that
it
woul d be better to
avoid heproblem han ry to overcome it. Thishadbeen
donepreviously n
1966
byconstructing he base lab in
refractoryconcretecomposed
ot
highalumina cement wit h
a firebrick aggregate.
Temperatures
Temperatures normally experienced below the 75 mm (3 n)
firebrick lining covering the reinforced concrete raft ere
:
a t
thebottomof he regenerator 55OOC
inhenterconnectinglues 450°C
mainhimney pulllue 400°C
352
L
.1
n
I 5
The maximum temperature for the use of reinforced concrete
in PortlandCements 15OOC. Theemperature at whi ch
PortlandCementconcretes made wi th siliceous aggregates
breaks down whe n subsequently cooled is 250
-
300OC. The
breakdown is of tw o types
-
mechanical and chemical
:
the expansiveeffectsof iliceousype aggregatesover
lime s released from he concrete in he orm ofquick
limewhich subsequently s slaked as the concrete s
cooled down.
Specia l concre te mixes
The following concreteswere used in he areas where he
heat would affectrdinaryortland Cement reinforced
concrete
:
Pi le cap covers A concrete composed of Ciment Fondu and
Firebrick aggregate produces
a
concrete of 17
-
20 N/mm2
(2500
-
3000 Ibf /in2) ompressive strength under temperatures
up to 12OOOC. The mix used wa s:
Cimentondu
1
part
Fine aggregate
2
parts byolume
Coarse aggregate 2 parts
Aggregate-35 per cent alumina crushed firebrick
Fine aggregate 3 mm
X
in)-dust
Coarse aggregate 1 9 mm (% in)-3 mm
(%
in)
3OOOC ;
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Fig 6 Furnace basement
/
Type
2 c f r o c t o r y o n c r t t c
j y p a r e f r a c to r y
c o n c r e t e
t-<
4, S o n d r t o n c
H I G H
L E V E LO W
T Y P I C A L P I L E S
Fig 7 Furnace pi les
with as low water content as possible. Strengths
a t
24 hours
were 6000 - 7 bf/inz. Strengths after fi ring a t 450 - 50OOC
were approximately 25.5 N/mm2 3700 Ibf/in2).
Grou nd s lab under regenerators The mix used was :
Cimentondu 1 part
Fine aggregate
Coarse aggregate
l
2 parts
by volume
2 parts
irebrick
Thewatercement ratiowas as lo w as possibleconsistent
wi th complete compaction water cement of
0.35- 0.4.
The
concrete strength after firing at 55OOC was about
25.5
N/mmz
3700 Ibf/in2). The maximum bay size in one pour was306 m
320 t2).
Stanch ion base plates
The dry packing under the base plates
of a 3 :l mortar with a low water content ratio made from fine
3 mm (?h n)-d us t) firebrick, 35 per cent alumina aggregate
andCimentFondu.
Peripheralareas
of
the tank basement
As the heat effects wou ld
be less, a refractory concrete of the fol lowing mix was used :
Cimentondu 1 part
Medium solite 1 part
by volume
Fine soli te 3arts
The water content ratio was
0.5.
This concrete produced
a
minimum cube crushingstrength of 6.9 N/mmz 1 bf/in2)
after firing a t 55OOC. The maximum bay size permitted in one
pour was 306 m Z
(320
h ).
Cold end foundations
The area covered by this complex of buildings-which includes
the S2, stockroom, the automatic warehouse and the finished
size stockroom-was largely the old ravine of Rainford Brook.
Thevalley ormedwas illed, as alreadydescribed, by end
tipping with depths of fill up to 15.8m 52 t) in depth. This
produced settlements over the f ill area because of :
compaction of the looseill under its own weight nd ground
water movements ;
varyingamountsdue to consolidationof heunderlying
compressible ub-stratum caused by constantly arying
depths of fil l across the area;
the different hicknesses of compressible sub-strata affected
by the fill.
Apart from he building column loads the plant loadswere
generally not significantcompared wit h thesuperimposed
loads of the fill, namely 20 to 30 tonne/m2 2 to 3 ton/ft2).
Based on he opography of the site and wit h the above
information in mind, a plan was prepared which showed the
predictedettlements across the site. This howedhat
settlements up to458 mm 1 8 in) could occur across the site,
while within 15 m
(50
ft) spacings there could be differential
settlements of the order of 75 mm to 127 mm 3 n to 5 in).
Such results were clearly unacceptable in view of the criteria
for the storage racks and the bui lding structures.
In 1968 the vibroconsolidation technique was successfully
used to eliminatesettlements on heoriginal S1 stockroom
which was constructed on loosely tipped fill of ashes, glass,
bricks, etc. The structure was monitored for a year after com-
pletion but no ettlement wasobserved. The vibroconsolidation
process was then investigated for the end of the line, and a
similar plan was prepared which showed predicted settlements
after treatment. The results showed that by setting the floor
slabs high a t the outset, the final positionfter settlement would
be within theacceptable limits. Thisprocess was thus adopted
for the floor slabs.
B y
superimposing the column grid on the
layoutplan
it
was evident that there would be differential
settlementsbetweencertainpairsof frames of the order of
75 mm 3 n) to100 mm
4
in) which was learly unacceptable
if
a
watertight building was to be achieved. The problem was
caused by
a
large amount
of
fill on differing depths of clay
which were not affected by vibroconsolidation. The problem
could only be resolved by pili ng under the building columns,
but since these and the adjacent columns supported the crane
tracks thepilinghad obe extended to hewholeof he
buildings. As a further complication the stratum which would
not be affected by settlement, .e. the sandstone, was some
24 m to 42 m 80 ft to 140 ft) below foundation level, thus
large diameter bored piles were used. This decision was taken
wi th reluctance because due to the ground conditions some
40 to 50 per centof he otalpile design oad wou ld be
negative skin friction owing to the fill and sub-stratum with
an additional 10 to 20 per cent or heself-weight of the
ground beams spanning between the piles to carry the dado
brickwork.
Because thedifferential settlement limits weregenerally
tighter or S2 stockroom, the probesweresunk
a t 1
a 8 m
6 ft ) centres on an equilaterial rangle over the area to an
average depth of 10.6m (35 ft). Elsewhere 2.1 m and 2.4 m
7 ft and 8 ft ) spacings of an average depth of 6.7 m 22
ft)
were used.
Tank furnace house steelwork
The tank furnace house steelwork followed the ou tline of t he
basement walls (seeFig I O ) with bay centres arranged as
shown in Fig 13. The design parameters for the frames were
as
follows :
loading to CP3 : Chap. V ; Pt I ;
wind loading to CP3, Chap. V : Pt II using the wind speed
for the area with a 1 in
5
year probability actor;
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INSPECTION
C H A H B E R .
Proposed new road
-
trrincdiatc ins
GENERAL RRANGEMENT
OF
RAINFORD BROOK
CULVERT
76mm.(J )blinding
7 926 m(2603
REINFORCEMENT
To
CULVERT
SECT IO N
TYPICAL CULVERT
SECTION
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T A N KU R N A C E
S U P P O R T I N G S T E E L W O R K
S E C T I O N
A A
Fig 9 Furnace support ing steelwork
D E T A I L
Fig 10 Furnace hous e steelwork
The Structural Engineer/October 1973/No. 1O/Volume 51
D E T A I L
OF
K N E E
_-
E T A I LTP E X
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Fig
l l
Furnace basement -o ld foundat ions
Fig 13 Furnace suppor t s tee lwork -h igh leve l
Fig 12 Furn ace basement-walls
loading due to 3.34 m (1 l f t) throat monitor ventilators;
provision for loadings fromservices, etc. of 1 tonne 1 ton)
an estimated rise in ambient temperature in the bui lding o f
From these parameters ahree-pinnedportaldesignwas
selected sincehis would givehemaximumlexibility,
particularly with the temperatures anticipated in the building.
The frames were abricated rommild steel andhigh-yield
steel autofab beams, withmade-up haunches. Sincehe
services provisions were not fixed t was necessary to analyse
the frames as follows:
loads at 3.7 m (1 t) centres across the frames;
5OOC.
- ead load plus superload
-dead oad plus superload with ull services;
-dead load plus superload with services on one side only;
-dead load plus wind.
Frame numbers 2 and 3 were specially designed to carry the
tank urnace eedingequipment inaddit ion o he service
loads. It was fortunate that provision was made for theervice
loads because the feeding equipment during the development
of the design ncreased in weigh t by a factor f three between
the ordering of the steel and the erection of the equipment.
Other main features of the design were as foll ows :
-w in d reactions on he gable were carried through he
purlins in compression and tension and thence distributed
through the central bracing ystems do wn to he column
anchorages
-the roof purlins were stayed, thus a brace which also
restrained this langewasprovided rom hebottom
-th e portal knee was abricated in high-yield steel wit h
profiling and welding detailed to ensure transmission of
bending moment around the haunch;
-the rafters at the apex pin were shaped to transmit the
loadings hrough he centroid of the pin, and similarly
at the column bases;
-th e parapet to hebuildingwas ormedbya attice
girder which lso supported thesag rodsfrom the sheeting
rails.
l an k furnace supporting steelwork
The steelwork contractor proposed a novel solution to cater
for the expansion of the tank supportingrillage. The calculated
overall expansion was of the order of 1.71 m (4 ft 2 in) based
on measurements of thesteelworkofexisting anks which
showed a emperature of 150OC. The structure was anchored
near the central point by vertical bracing in wo planes whilst
horizontal bracings were provided over the length of the tank.
In each column was ocated a cast cup and socket bearing
at he opandbottom,
so thatshould there beanysmall
flangefheafter; Fig 14 Generaliew of si te Apr i l 97
356 Thetructuralngineer/October 1973/No.
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m
1 I ,
Fig 75 Furnace house roof steelwork
movement no momentwou ld be transferred to the column and
the load would be virtually axial.
Organization
The whole project was arried out under the overall control of
Mr. C. J. Schofield, BSc(Eng), FIMechE, FIEE, chief engineer
of
Pilkington Brothers imited. The direct control wasxercised
by Mr. D. N. Cledwyn-Davies, BSc, FIMechE, and the project
manager was Mr.
J.
G.Freeman, BSc(Eng), MIEE. Harris
Sutherland were responsible for the design of the tank base-
ment and building, the main plant foundations, and Rainford
Brook culvert andearthworks. The remaining civil engineering
workswere designed in he offices of PilkingtonBrothers
Limited, with Gerald
R.
Smith Partners of Belfast as consul-
tant architects.
Contractors
Mainivilontractorolland Hannen Cubitts
(North West) Limited.
Sub contractors
Piling
Cementation Piling Foun-
Vibroconsolidation
Cementation Ground Engin-
Road surfacing Val de Travers Limited.
dations Limited.
eering Limited
Structuralteelwork
RobertWatson Co.
(Constructional Engineers)
Ltd.
Fig 76 Furnace house Apr i l 7971
Sub
contractors
Cladding
Glazing
Folding doors
Ventilators : roof
side wall
Reinforced concrete chimney
Painting
Aerial survey
Site investigations
R. M. Douglas Limited
Crittall-Hope Limited
Mather
t
Platt Limited
H.H. Robertson (UK)
Limited
Crittall-Hope Limited
Tileman Company Limited
Hawkins Holmes Limited
Hunting Surveys
GKN Foundations Limited
Acknowledgements
The authors wish o thank the directors and the chief engineer
of Pilkington Brothers Limited for their permission to publish
this paper.
References
1.
2.
3.
4.
5.
6.
7.
AmSocCE Paper no. 2868, October 1957.
Rowe,
R.
R. Rigid culverts under high overfills , Transactions
Jones, G .
A.,
The construction o shallow tunnelsanddeep
Brown, C. B. Forces on igid culverts underhigh fills , AmSocCE.
culverts , f r o c .
South Wales lnst of Engineers
Vol. LXXV, June
1960, p.66.
Spangler, M G. The structural design of flexible
pipe
culverts ,
Iowa
Eng. Exp. Stn 1941.
Clarke, N W. B., The oads mposedon conduits laid under
embankments or valley fills , f r o c . ICE, Vol. 36, January 1967,
p.63;Wide renchcondition , f roc . lCE Vol.26,September
1963, p.105.
Keller, J. D. The flow of heat through hearths , American Soc.
of Mech. Engineers 1928.
Robinson, T. D., High alumina cements and concretes Contrac-
tors Record, 1969.
The Structural Engineer/October 1973/No. 1O/Volume 51
357