Contractor is taking Dunfermline’s 19th century Carnegie library and overcoming tricky piling and structural challenges to turn it into an institution fit for 2015.
Project: Dunfermline Museum and Art Gallery
Client: Fife Council
Project value: £12.4m
Contract value: £8.7m
Contract type: Design and build
Main contractor: Bam Construct
Architect: Richard Murphy Architects
Structural engineer: Aecom
Start date: January 2015
Completion date: September 2016
The future of public libraries has provoked outcry across UK communities as local government budget cuts force many to close and borrowing rates come under increasing pressure.
Councils across the UK have to decide whether to expand, merge or terminate services.
Where funding is being made available, however, they are being expanded to meet the needs of a broader community.
Dunfermline’s central library in Fife is a case in point, with a £12.4m overhaul set to bring it into the 21st century.
This investment will improve the existing library built in 1883 and its 1993 extension, as well as extending its footprint to include a museum and art gallery.
To make the facility appeal to more people, the new buildings will house exhibition space, a children’s library, café, retail units, offices, computer pods and activity spaces.
There is also a wider historical context to this investment.
The library was founded by Dunfermline-born industrialist and philanthropist Andrew Carnegie who later went on to fund 2,810 other libraries around the world.
The Dunfermline Museum and Art Gallery, as it will be known, will also have a permanent display about the history of the town, which was once the capital of Scotland.
The museum will also chart Mr Carnegie’s rise to fortune and how he gave away the majority of his earnings to education and community establishments.
HUB East Central is leading the project on behalf of client Fife Council using a ‘hub bespoke’ design-and-build contract.
HUB and was set up in February 2012 to develop and improve local services across East Central Scotland and is made up of private and public sector bodies, including Fife Council.
The original library is orientated north/south and fronts onto Abbott Street to the north. Margaret Street runs along its eastern elevation, which also includes the 1993 extension to the library.
The 1993 building will be renovated to accommodate back-of-house facilities for staff and the new museum and gallery.
The new building will connect back to the western elevations of the library and the 1993 structure via dramatic walkways at first-floor level, which will span a former alleyway.
The finished development will extend onto land formerly occupied by a neighbouring bank on Abbott Street and the car park of the historic Abbot House.
Although heritage body Historic Scotland allowed the bank to be demolished, its sandstone neo-classical façade dates from 1838 and is of regional importance -being grade B listed – and so has had to be retained.
This façade will be supported by a temporary steel frame during construction and then another steel frame permanently (see box).
Aside from the steel structure supporting this retained façade and extending back along the length of the library, the remaining new structure will be concrete-framed.
Choosing a frame
Bam Construction Scotland construction director Martin Cooper explains that 12 months were spent value engineering the high-end design by Richard Murphy Architects to make the scheme more cost-effective.
This included scrutinising the structural frame as well as the minutiae of every specification and finish.
“We currently have a hybrid steel and concrete frame, but we looked into using a [totally] steel-framed design,” he says.
The lengthier lead-in time outweighed quicker erection for the steel option so that both options came out costing about the same, he explains.
In the end, concerns over access via steep, narrow streets cast doubt on the feasibility of transporting steel to the tight site, so a concrete frame was preferred.
In another cost-saving measure, the specification for a polished plaster wall-finish has been replaced with a skimmed plaster and paint finish and using ceramic floor tiles instead of a polished screed floor.
Bam Construction is currently carrying out the groundworks to support the new three-storey structure.
This has involved installing 134 piles and underpinning beneath the junction of the original library and 1993 building where the library’s original buttress supports were removed.
This library wall was also tied back into the structure to stabilise it. When Construction News visited the site in June, workers were trimming piles and groundbeams and constructing pilecaps.
Continuous flight auger piles between 450 mm and 600 mm diameter have been installed to a depth of 10 m in rock across most of the site.
Since piling cannot physically sit along the new building line adjacent to existing buildings, piles supporting new perimeter walls are inset up to 1,500 mm.
This has meant piling contractor Roger Bullivant has had to beef up the groundbeams to transfer the eccentric wall loads coming down.
Near the retained façade, a smaller sectional flight auger rig was used to install piles where there was limited headroom.
The retained façade and surrounding buildings are regularly surveyed during construction to check for movement.
The new building design is characterised by its non-uniform elevations and floor levels.
There are mezzanine levels at ground, first and second floors and the façade, with multiple cladding materials, cantilevers out in some locations and is recessed in others.
“Aecom and Bam’s biggest challenges have been to co-ordinate the multiple façade contractors and phase the order in which the different materials can be installed,” says Bam Construction site manager Lauren Miller.
“We are using weathering steel, for example, which is designed to rust, but could discolour other types of cladding [glazing or stone].”
Much of the design has exposed steelwork and complicated connections – stair landings that appear to float without the need for vertical support, as well as link bridges suspended from roof steelwork or supported on sliding bearings on the existing structure.
These have been developed by the architect and structural engineer working closely together.
A single tower crane with luffing jib will service the site – without oversailing other properties in its rest position.
“We’ve designed the building using [BIM software] Revit to check for clashes and to develop critical junctions,” says Aecom principal structural engineer Lee Stewart.
Due to the sloping site and differing ground level of the library, the 1993 building and the old bank, a new ground level has had to be established.
Coupled with the new building having steps in the 250 mm-thick ground floor slab, computer modelling has been essential to visualising the scheme.
Following completion of the groundwork, the new steel and concrete structure will be erected while the existing library is refurbished.
Landscaping around the completed development will connect it to neighbouring Abbott House and Dunfermline Abbey to unify these historic buildings.
Fife can look forward to its revitalised civic centrepiece being completed in 2016 – no doubt Carnegie would be proud.
Retained bank building façade
Temporary works contractor Mabey Hire designed the bank building façade retention scheme in a way that allowed most of the temporary steelwork to sit on the street side of the façade rather than on site.
This left as much room as possible for site work such as piling and constructing ground beams to take place.
A mass in-situ concrete foundation at street level anchors the temporary braced towers, which restrain the 14 m tall by 12 m wide façade, plus its 6 m return walls at either end.
The ends of the return walls are restrained by full-height vertical trusses, built to straddle the walls.
These trusses support waling beams spanning onto the main system on its street side, but are interrupted on the site side to accommodate the permanent steel frame.
Co-ordination between Mabey Hire and Bam Construction ensured openings were created in the inner walings to allow the permanent steel columns to fit through.
Timber packing between the walings and the masonry then keep the façade in its original vertical plane.
However, due to the need to accommodate a piling rig adjacent to the façade, the traditional approach of using horizontal diagonal braces at each floor level could not be accommodated, as Mabey Hire projects team leader Lawrence Smith explains.
“We could only apply diagonal bracing at a very high level so that there was sufficient headroom for the mast,” he says.
This high-level, site-side diagonal bracing transfers horizontal forces from the return-wall trusses back to the street-side steelwork towers via another high-level truss.
With the temporary system erected, the adjoining walls, floors and roof could then be safely cut away and demolished, keeping the façade fully restrained.
Once the permanent steel frame has been connected to this façade, the temporary support system can be removed.