REPORT ON PRELIMINARY STRUCTURAL
INSPECTION
VICTORIA PIER, COLWYN BAY
Prepared for:
Prepared by:
Design & Engineering Services
Datrys
Conwy County Borough Council
Consulting Engineers
Library Building
3-5 Church Street
Caernarfon
Mostyn Street
Gwynedd
Llandudno
LL55 1SW
LL30 2RP
Tel
01286 671027
E mail
[email address]
09205/B02
Date
9 December 2009
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REPORT ON PRELIMINARY STRUCTURAL INSPECTION OF
VICTORIA PIER, COLWYN BAY
1.0
Introduction
1.1.
In November 2009 Datrys were instructed by Conwy County Borough
Council to undertake a preliminary condition survey of the structure of
Victoria Pier, Colwyn Bay. The purpose of the inspection was to
determine the form and general condition of the pier structure so that
the scope of remedial works that might be required to bring to an
acceptable condition for public access could be outlined.
1.2
The inspection of the fabric of the buildings and their services did not
form a part of the brief.
2.0
Location
2.1.
Victoria Pier extends from the Promenade at Colwyn Bay to a point
some 80m from mean low water. The whole pier length is therefore
exposed at low tide. The location is sheltered from the predominant
winds from the west by Rhos Point but has a 165km long fetch to the
north. The site is susceptible therefore to wind generated waves from
this direction with a potential significant wave height of 4m ignoring
local beach effects.
2.3
The beach is generally sandy although coarse gravel and cobbles are
located beneath the Promenade wall. The coastline forms a shallow
embayment from Rhos Point in the west to the limestone headland at
Penmaen Rhos near Llysfaen in the east. The beach has been
stabilised by the installation of timber groynes.
2.4
The general arrangement of the Pier is illustrated in the accompanying
drawings. Its construction is described in greater detail below but may
be summarised as comprising of timber decking on timber joists
supported on longitudinal steel lattice girders. The girders span
approximately 12m onto braced cast iron columns fixed into cast iron
piles embedded in the beach.
2.5
The Pier supports two areas of buildings. The retail area dating from
the 1970’s which links with the Main Entrance; these occupy the first 3
bays of the Pier. The buildings are single storey and of recent steel
construction. The Pavilion is a much larger and more elaborate
structure constructed in the 1930’s.
2.6
The Pier may be divided into 3 distinct areas (all dimensions are
approximate):
• The Promenade End of 3 bays measuring 40 x 15m.
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• The widened Pavilion Area of 8 bays length and 9 bays width
measuring 52 x 47m.
• The Seaward End of 14 bays length measuring 128 x 10m.
The structural form of each area comprises the same basic
construction as described above with local strengthening beneath the
buildings.
3.0
History
3.1
The Pier was opened in 1900 and from historic photographs and
written descriptions appears originally to have extended only as far ar
grid line 12 as shown on the appended drawings being approximately
half its present length. The widened Pavilion area was an original
feature although it may have been 1 bay narrower and shorter than at
present. The seaward area was constructed from 1903 and
photographic evidence indicated that this reached as far as grid line 22
some 40m short of the present Pier Head. A 600 seat theatre was then
constructed at the Pier Head in 1917 extending the Pier to its present
length. It is possible that the Pavilion area was widened at this time to
its present dimensions.
3.2
The Pier suffered from a several fires during its lifetime which caused
the loss of the original Pavilion and its replacement building. The
present Pavilion is the third structure and was opened in 1934. The
theatre at the Pier Head was destroyed by fire in 1933 and was never
replaced.
3.3
From 1968 and into the 1970’s the buildings at the Promenade End
were built as part of a modernisation programme of the Pier by its then
owner, a subsidiary of Trust House Forte. Finally, the Promenade End
was widened around 1980 by the subsequent owners.
3.4
The Seaward End of the Pier was closed to the public on safety
grounds in 1987 and the whole Pier was closed in 2008.
4.0
Survey work
4.1.
The survey was carried out on a visual basis only. No sampling, testing
or uncovering was carried out.
4.2.
The initial survey was undertaken on 12 November 2009 with members
of the Council Engineering and Design Department, the Pier owner and
agent. All areas of the decking were accessed with the exception of the
worst affected Seaward End which was deemed unsafe. The Pavilion
building could not be accessed and its inspection was therefore limited
to the external elevations only. The roof was not inspected. The
Entrance Building was accessible for at hand inspection.
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4.3.
The underside of the Pier was viewed from the beach only and at-hand
inspection of the steel girders and bracing was not therefore possible.
The comments given below regarding the condition of the steelwork
that was viewed at some distance is therefore necessarily subjective
and should be confirmed by closer inspection and evaluation.
5.0
Observations
Promenade End
5.1
The flat roof of the Entrance Building between grid lines 1 & 2 consists
of rockwool slabs supported on metesec lattice beams spanning onto
universal steel beams supported on SHS posts. The posts coincide
approximately with the positions of the piles of the Pier structure. The
structure is generally sound and would require only minor
maintenance. The floor structure was not examined.
5.2
The building between grid lines 2 and 4 is again single storey with a
nodal space frame roof supported on its edges by SHS posts. The form
of the roof with its many valleys will lead to maintenance difficulties and
problems of water ingress. The means of achieving lateral stability of
the building was not apparent and may derive from the racking effect of
the external timber frame cladding. The floor structure was not
examined.
5.3
Most of the Pier steelwork in this area is of a condition that could be
refurbished. Some relatively recent repairs are apparent and the
bracing to the piles on grid lines 2 and 3 are significantly different from
the remainder of the Pier structure and are more recent. Some of the
detailing of the new components will however lead to water entrapment
and future maintenance problems suggesting that their replacement
might prove more effective.
5.4
No particular problems were noted with respect to the piles in this area.
Pavilion Area
5.5
Access into the Pavilion Building was not possible. From the inspection
of its perimeter it is of a steel construction clad in rendered expanded
metal cladding. In many areas the galvanised cladding has corroded
and the render has significant cracks which will allow water entry. In
areas the render has become detached revealing both the metal
cladding and the steel structure. The roof structure is hipped with a
pagoda form and its geometry is somewhat complex which could lead
to problems of water ingress. It appears to be clad with an asbestos-
cement sheet the condition of which is doubtful with cracked sheets
apparent whilst some were missing.
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5.6
The decking in this area showed some signs of decay and extensive
moss growth. It is probable that a significant proportion will need to be
replaced or at least refixed. The condition of the supporting soft wood
joists could not be determined as they were generally obscured from
view but again extensive replacement will probably be needed. In some
areas such as the corner cantilever the timber structure is clearly
unsafe and is close to collapse.
5.7
The decorative handrail was found to be in place for most of this area.
The detailing is poor however and leads to water entrapment and
decay of the timber kerb to which the standards are fixed. In most
areas the kerb showed decay and the whole length will need to be
refixed or replaced with a suitable new detail.
5.8
The Pier structure in this area is in a varied condition. There are
instances of bracing failures near grid lines 12 and 13 whilst the degree
of corrosion of the girders varies considerably. Beneath the building
there are lines of deep riveted plate girders in place of the usual light
lattices. The steelwork of the plate girders appeared to be sound but
their rivets could not be assessed. Many of the tie bars in this area
would need to be replaced and many turnbuckles had spilt
longitudinally. Whilst much of the lower steelwork was heavily
encrusted in marine growth the horizontal struts to the piles and the
piles themselves appeared to be sound.
Seaward End
5.9
The Pier structure in this area is in the worst condition. Much of the
decking has either been dislodged or is decayed. The steel girders
exhibit general corrosion and elements of the column head bracing
have, in instances, corroded through. Many of the column bracing ties
have failed.
5.10 A length of approximately 45m of the decorative hand railing had failed
along the Pier Head and east side. Elsewhere the timber kerb to which
the standards are fixed was noted to be decayed.
6.0
Discussion
Promenade End
6.1
Repairs and alterations were carried out in this area in the 1970’s and
the structural components reflect the commercially available and
popular structural systems of that period. The structural form of the
buildings between grids 1 and 2 is considered to be appropriate subject
to consideration of lateral stability and only localised repair and
maintenance would probably be required.
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6.2
The nodal space frame whilst popular at the time of its construction is
now unusual and the ease with which it could be easily maintained for
a long period is doubtful. The form of the roof should be simplified to
minimise the risk of rain penetration. The means of providing lateral
stability to this building should be established as it may be dependant
on the racking resistance of the timber cladding whose condition will
deteriorate.
6.3
The condition of the floor decking in this area should be established in
any future inspections.
6.4
The changes to the bracing system on lines 2 and 3 without doubt date
to the time of the erection of the buildings. The heavier and lower
sections would provide greater resistance to lateral wind loads imposed
on the piles by the increased elevation of the buildings.
Pavilion Area
6.5
The large number of columns and the extensive bracing coupled with
shelter offered by the structure itself have resulted in the original
structure in this area being in relatively good condition.
6.6
As it was not possible to inspect the superstructure of the Pavilion it is
not possible to comment meaningfully on its condition. However the
loss of roof sheets and wall panels will inevitably lead to an
acceleration of its deterioration. If it were to be refurbished it is
probable that the building would need to be stripped back to its steel
structure which would also in all probability be in need of some degree
of repair and strengthening as well as general maintenance.
6.7
A detailed inspection of each bay of the Pier structure is required to
properly determine the extent of repairs required to the Pier structure in
this area. The piles generally appeared to be sound however cast iron
is susceptibly to cracking and testing of the integrity of the piles and a
check on their embedment should be carried out, initially, on a sample
basis.
6.8
The condition of the column bracing systems varied. The horizontal
struts appeared to be sound and would probably only require
repainting. Their connection to the columns would need to be checked
in detail and allowance should be made for bolt replacement. The tie
bars and their turnbuckles in many instances show signs of corrosion
or have failed. Allowance should be made for their replacement.
6.9
The decking is far from pristine and allowance should be made for
replacing it in its entirety together with the supporting joists. This would
then allow access to the girders beneath to carry out any necessary
work.
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6.10 The handrails will need to be removed refurbished and refixed to a new
kerb detail.
Seaward End
6.11 The Pier in this area is in a very poor condition. In areas the columns
are unbraced and rely on cantilever action to resist any lateral loadings.
6.12 The Pier superstructure in this area will need to be replaced. This
would probably entail the dismantling of the columns and their off-site
refurbishment. The adequacy of the piles would need to be confirmed
prior to re-erecting the columns followed by the new superstructure.
6.13 The lost handrails would need to be replaced with a suitable replica
pattern.
7.0
Conclusions
7.1
The Pier structure should be inspected in detail and its adequacy
assessed in relation to the loads to which it is subjected arising from its
intended use and its environment.
7.2
The condition of the Pier superstructure is varied and is particularly
poor at the Seaward End. In this area the superstructure should be re-
built. Elsewhere the superstructure could be repaired and refurbished.
7.3
The deck timbers and the supporting joists should be replaced.
7.4
The handrails should be removed, refurbished, supplemented as
necessary and refixed to a suitable edge kerb detail. It may be
necessary to raise their level to meet current standards or to seek a
relaxation under the Building Regulations.
7.5
The roof and cladding of the Pavilion Building should be removed and
allowance made for repair of the underlying structure.
7.6
The feasibility of retaining the nodal roof structure is questionable and
consideration should be given to its replacement.
7.7
Areas of the Pier are in a state of near collapse and could present a
danger to the public. The public should be excluded or at least
discouraged from walking beneath these areas.
7.8
The Seaward End of the Pier is now in a condition whereby it may be
lost within the next 5 years. The Pavilion Area with its high degree of
redundancy could survive in an increasingly weakened state for a
period of up to 10 years. The highly unpredictable nature of significant
sea states should however be borne in mind when considering these
timescales which could be exceeded in a single event.
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8.0
Recommendations
8.1
An inspection and assessment of the pier structure should be
undertaken, if necessary on a sample basis, to gain a more accurate
view of its form and condition.
8.2
A Cost Plan should be prepared from the findings of the Structural
Assessment.
8.3
The public should be excluded from beneath or at least warned of the
dangerous nature of parts of the Pier. The unsafe areas should be
secured as matter of urgency.
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Costings
The following are intended as indicative costings only and are based upon
unit rates derived from past pier refurbishment work and published unit rates.
The figures quoted are for the first quarter 2009.
Pier Refurbishment at £450/m2
£1.8M
Pavilion Refurbishment at £1,500/m2
£2.1M
Shops and Entrance Refurbishment at £750/m2
£0.375M
Contractors overheads at 15%
£0.64M
Total allowance for Construction
£4.915M
The above excludes fees, supervision costs and any contingency.
In order to a gather enough information on the form and condition of the
structure and the extent of the repairs required a Structural Assessment
should be carried out. This would include a topographic survey of the columns
and deck, surveys and inspections of girders and columns on a sample basis.
The information would allow a preliminary loading analysis of the Pier to be
carried out to determine areas that could be repaired and those that would
need to be replaced. The purpose of the Structural Assessment would be to
provide information for a Cost Plan to be prepared and would need to be
supplemented by further detailed surveys, testing and inspections during later
stages of the design process.
Topographic survey of Pier structure
£2,000
Sample survey and inspections of Pier
(allow 2 engineers 1 week on site)
£3,000
Inspection of buildings
(allow 1 engineer 3 days)
£900
Assessment calculations and report
£4,500
Hire of access equipment and travel
£1,000
Total allowance for Structural Appraisal
£11,400
All the above costing are net of VAT
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