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ENGITECT
Issue
Two - Winter 1997
Introduction
Welcome to the second edition of the
Hurst, Peirce and Malcolm newsletter. Our aim is to keep in
touch with our clients and fellow colleagues in the construction
sphere and to build on relationships which in some cases extend
back to the 1920’s.
We were gratified to receive over
20 written responses and many more verbal compliments about
the first issue. We hope the standard has been maintained for
the second issue which we hope you will find interesting and
informative.
All Change at Waterloo
Station!
Users of Waterloo Station will be aware
that construction activity in, around, and beneath the station
has been nigh on continuous for the last decade. Work to develop
the International Terminal for Eurostar and the construction
of the Jubilee Line tunnels and platforms beneath the station
complex has meant hard hats and fluorescent vests have been
a common sight on the main concourse. However, it is quite possible
that even regular commuters may not have appreciated that another
multi-million construction contract has been recently completed
before their very eyes! This work involved a major (£23m) refurbishment
of the 3 to 4 storey Edwardian offices which line the concourse
including the retail accommodation at platform level.
 Waterloo
Station was first developed in 1848 when the terminus of the
London and South Western Railway was moved from Nine Elms to
a more central location not far removed from Westminster. The
station platforms are raised on a series of masonry arches which
are in themselves the culmination of a viaduct comprising nearly
300 arches and extending almost as far as Clapham Junction.
By the early 1900’s the station facilities
were overcrowded and a major expansion scheme was developed
based on studies of railway termini in the USA. The work was
phased for financial considerations and involved re-constructing
platforms adding new ones and building new office accommodation
which eventually realised a building some 800’ (243 metres)
long.
Work on the office building commenced in
1909 at the south eastern end of the concourse. The front and
gable walls are of loadbearing Portland stone ashlar work backed
with fletton brickwork. The walls to the concourse elevation
are of facing brick with stone dressings including a large stone
cornice at second floor level.
The fireproof floors consisted of Frazzi
hollow unreinforced clay blocks spanning between the lower flanges
of steel beams. Timber joists were arranged to span on to the
steel beams to support floor boards. In most cases the Frazzi
blocks were topped by 3" of concrete to provide a degree
of fire protection to the timber floors. (For further information
on Frazzi systems, see 'Frazzi Blocks' below).
The floors are supported on internal steel
stanchions with steel grillage foundations, themselves placed
on massive brick piers, punched through the earlier arches,
and extending down up to 10 metres in to the marshy ground beneath
the station. Internal office walls were built up in hollow clay
blocks.
Work continued in phases working northwards
with a general suspension of activity during the Great War.
The final stages constructed immediately following the War encompassed
the well known Victory Arch which now stands proud at night
under floodlights. Different materials were introduced to the
floor construction suggesting that there were difficulties in
obtaining items in the aftermath of the First World War. These
floors comprised the Kleine system with hollow clay blocks,
6" wide and 10" long, long laid and jointed in cement
mortar reinforced with a thin steel strip. (For further information
on the Kleine system see overleaf).
During our initial surveys we found the
building to have been largely untouched apart from Bomb damage
inflicted during the Second World War.
Refurbishment work comprised the removal
of all timber floors, partitions and some brick walls. Three
new lift and stair cores framed in structural steel work were
formed, the floors were strengthened to a specification in line
with contemporary office requirements together with the insertion
of a full air conditioning system.
The work was carried out under a design
and build contract led by Bovis Construction Ltd with Wilson
Mason & Partners providing architectural input and Hurst,
Peirce & Malcolm responsible for structural engineering
matters.
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Frazzi blocks
The Frazzi system is just one of the types
of terracotta fireproof flooring introduced in the late 19th
century. The difference from the other systems was that the
components were made in Cremona in Italy, from where they were
imported, and the clay there enabled them to be extruded with
much thinner walls than similar native products.
Frazzi invariably used "joist
covers" to enclose the bottom flanges of the filler joists
and provide bearings for the flat or arched lintols or tubes
spanning between them. Frazzi also provided 23 mm. thick cellular
blocks with tongue & groove joints for fireproofing stanchions.
We have seen Frazzi floors in building dating
from the 1890's up to the First World War, but not later, even
though they were still advertising in the mid-1950's with an
invitation to apply to their office in Norfolk Street, Strand
for a brochure. We would be interested to hear of any Frazzi
floors after 1915 seen by our readers.
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"Kleine"
Floors
Kleine was another type of fireproof flooring
incorporating terracotta blocks, but dispensing with iron or
steel filler joists and using steel strip or rods between the
hollow blocks as tensile reinforcement, in conjunction with
the concrete topping. Kleine floors were first used in this
country in 1906 and the early floors incorporated hoop iron
or steel in the mortar joints between the hollow clay blocks.
In later floors the lines of blocks were spaced out to form
concrete ribs between them, in much the same way as the hollow
pot floors most of us remember, which continued in use until
London Brick ceased to produce hollow tiles in 1984.
Unusually there was no structural concrete
topping with the Kleine floors at Waterloo. Load tests on the
floors above near Victory Arch at Waterloo found it capable
of sustaining loads equivalent to contemporary specifications
albeit lacking in overall robustness and resistance to concentrated
point loads.
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The Bells Rang Out
The bells of St Mary Magdalene, Cowden,
East Sussex rang for the first time in thirty years recently
as part of an exercise to assess what would need to be done
to the fourteenth century oak timbers of the entirely timber
framed tower and spire to enable the bells to ring in the next
millennium.
The 127ft spire was notorious for swaying
during ringing. Full circle ringing stopped in the 1960's when
the timbers were found to be weakened by decay and death watch
beetle.
As part of the investigation, movement of
the tower was monitored during the ringing with accelerometers
to determine the natural frequency and modes of the hollow pot
floors most of us remember which continued in use until London
Brick ceased to produce hollow tiles in 1984.
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CDM and All That
In 1989 and 1990 the European Council of
Ministers agreed to a Framework Directive on construction health
and safety, together with five other directives . The latter
dealt with health and safety requirements for the workplace,
work equipment, personal protective equipment, manual handling
and display screen equipment. Readers will recognise these as
the Health and Safety at Work regulations 1992.
The next piece of the legislative jigsaw
dealt with the management of health and safety on temporary
or mobile construction sites. This Directive lead to the implementation
of the Construction (Design and Management) Regulations 1994
and the Construction (Health Safety and Welfare) Regulations
1996 in the UK.
Those striving to comply with these statutes
may be interested to note that the EC's tentacles do not appear
to have reached the Greek islands.
Lawrance Hurst was glad all Hurst, Peirce
& Malcolm's appointments as planning supervisor are in the
UK when he recorded this activity during his summer vacation.
Readers are invited to forward suggestions
as to what the man in the foreground is saying to the decorator
perched so precariously at eaves level!
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Waitrose Salisbury
Waitrose Ltd., part of the John Lewis Partnership,
recently opened their new Food and Home Store in Salisbury.
The store is only the second of its kind within the John Lewis
Partnership to combine food, clothes and home style items. It
is located on an island site within the flood plain of the River
Avon with the main river running to the East on a branch stream,
Summerlock Stream to the West.
Although the site had previously been a
cattle market the Environment Agency insisted that the development
should not affect the existing flooding situation. This meant
demonstrating that in a 1 in 100 year flood, flood levels upstream
and downstream will not change once the building is complete.
Initially, this lead to the development of a scheme of extensive
flood alleviation works upstream of the site. However, by refining
the hydrological model for the River Avon, it was possible to
show that much smaller flood alleviation provisions would suffice,
much to the relief of the local residents who did not want flood
banks built across their local green.
Hurst Peirce & Malcolm were asked to
design these works in conjunction with assistance from hydrological
consultants. The final scheme included a flood relief culvert
through the site and automation, with remote control, of a rising
sector flood gate which provides the main control of the river
level through Salisbury. In addition, environmental works were
carried out to improve the river margins upstream of the development
and water margin control facilities were provided to a set of
reed beds in an area of scientific interest to prevent them
drying out. The local children now have a ‘dipping platform’
where they can sample the water of the River Avon for aquatic
life.
We are now advising Waitrose on the complications
of developing a site at Cheltenham which is also in a flood
plain, where the River Chelt currently passes under the proposed
development site in an old brick culvert.
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Partnership News
We would like to welcome three new members
to our technical staff. Mark Dicks who joins us from Waterman
Partnership as Senior CAD Technician, Mrs. Alex Elliot who has
just graduated from the Royal Military College of Science, Shrivenham
as a Graduate Engineer and Michael Chung who has just graduated
from Trinity College, Cambridge also as a Graduate Engineer
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Road Scrapings For
Mortar
Readers will recall the back page article
from our last issue where the 19th century practice
of using road scrapings (sand laid on metalled surfaces to prevent
horses’ hooves from slipping) and ash pit refuse for mortar
and plaster was described.
Confirmation of this practice in Victorian
London comes from Johnny Johnson, whom many of our readers will
remember as Hillier Parker’s Chief Building Surveyor for more
years than he or we care to remember.
In 1951 Johnny was refurbishing three houses
in Cromwell Road originally dating from 1874, opposite the Natural
History Museum, for the Canonesses of St Augustine. The back
additions had to be demolished because of an extensive attack
of dry rot with which the brick walls were found to be riddled.
This had started with dry rot in timber lintols and had travelled
up to 20 or 30 feet through the brickwork to internal timbers,
fed by horse manure in the road scrapings used as aggregate
for the mortar in which the bricks were laid.
Knowledge of practice – good and bad – used
by our predecessors in the building industry is usually interesting,
sometimes useful, and, as in this case, can provide the answers
to questions that modern analytical methods would find inexplicable.
This same theme is continued in the strip
cartoon below, which confirms the use of other dubious materials.
It comes from a book originally published in 1880.
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And Finally...
To continue our theme on 19th Century building
practices, here is an article taken from the Complete Builder
by J. F. Sullivan published in 1880.
Readers may empathise with the building
owner as speculative housing of this date was built to the least
possible cost using materials of questionable quality.
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