Spectacular office building opens for business
Buro Happold provided multi-disciplinary engineering for Palestra, London’s latest landmark office development
International consulting engineer Buro Happold rose to the considerable engineering challenges posed by London’s new landmark office development, Palestra. The practice provided multi-disciplinary structural, building services, geotechnical, fire and façade engineering services, as well as disability design.
As well as Buro Happold’s structural engineering team accommodating a cantilevered section which overhangs Blackfriars Road by 7.5m – forming the building’s distinctive feature and a talking point for Londoners – without any loss of internal floor space, the building services team had to incorporate lighting, heating and insulation to Part L standards within testing space constraints and on a fully glazed building.
Designed by the award-winning architects SMC Alsop, the impressive spec-built office building in Southwark is now home to the London Development Agency and officially open for business.
Buro Happold had to find many innovative solutions to meet the unconventional demands put on the structure by the architecture. The introduction of the cantilever and raking columns were key to achieving this. It allowed Palestra to be built using conventional materials of steel frame and concrete slabs on metal decking, while creating a technically different finished product.
At Palestra’s west end the upper box is offset by one grid width from the lower, creating a three-storey deep 7.5m cantilever. This dramatic feature was achieved without the introduction of any visible diagonal elements in the façade or any disturbance to the internal floor space. The cantilever was formed by means of a stiff bending moment frame – like an industrial portal frame plugged on to the building.
Palestra has raking columns at two levels which exert large horizontal forces on the building. The cantilevered section also exerts a large horizontal force so, combined, the structure must withstand up to 30 times the wind load normally applied to a building. The structure resists this load through conventional braced steel frames built into its core.
Structural engineer and project leader for Buro Happold, Andrew Lacey, said: “It’s been a real privilege to work on one of London’s most talked about new buildings and to take a holistic approach to deliver a structure true to the architect’s daring and uncompromising vision.
“It was certainly a challenge to accommodate the various cantilevers, transfer structures and the raking columns, all within a 900mm space, while maintaining 12m clear spans inside and on a site directly above the Jubilee Line Extension. But it’s immensely satisfying to see the finished building looking great, having met all those demands.”
Buro Happold wrote a computer program that allowed SMC Alsop to adjust the column angles in all locations, while maintaining the building’s integrity in terms of foundations and column sizes. The design team could adjust the complex column layout until late in the construction programme with confidence that the structure would work.
The column construction is designed to be very high strength, achieved using composite columns. A circular hollow section (CHS) outer tube was reinforced by an internal CHS and both tubes filled with concrete to form a solid section.
Buro Happold’s building services team also faced significant challenges. Although the design was drafted before the Part L regulations came into force, the client requested it be compliant anyway. This was achieved, in part, through the innovative double glazed façade. This is tinted, fritted and insulated to reduce heat gain and loss, while providing good diffuse daylight levels inside. As the façade contains a range of differently tinted sections, the darker areas hide the insulated panels.
Building services engineer and Buro Happold associate, Pirooz Kani, said: “One of our biggest challenges was working towards the then untested Part L regulations, which we did through adding insulation to parts of the glass façade. But this has been cleverly disguised so that the whole building appears seamlessly fully glazed.”
The double glazing also significantly reduces noise caused by trains running on the adjacent railway lines so that it does not disturb the occupants.
Space was another serious constraint, not least in the parts of the building containing the cantilever. With a floor to floor height of 3.65m, which contains a raised floor of 150mm and 2.75m floor to ceiling, just 750mm of space was available for structure and services, including the ceiling and lights. Services had to be threaded through holes in the beams and fan coil units were specified for ventilation, as they are particularly space efficient and versatile.
Pirooz Kani added: “In the cantilever sections the structure was more robust and so, working closely with the structural engineering team, more holes were made in beams to make space for the services that tenants demand.”
Ends
Project team:
Client: Blackfriars Investment Ltd and Royal London Asset Management
Project Manager: CB Richard Ellis
Architect: SMC Alsop
Main contractor: Skanska
Buro Happold services: Structural, building services, geotechnical, fire and façade engineering services, disability design
Buro Happold team: Structural – Project Principal Steve Brown, Project Leader Andrew Lacey, Sally Preston; Building Services – Neil Billett, Pirooz Kani; Infrastructure – Andy Murdoch; Geotechnical – Justin Phillips; Facades – Peter Thompson; FEDRA – Andy Nicholson; CoSA – Ian Matthews.
Buro Happold
Press office and practice information at www.burohappold.com
Images of Palestra and more detailed information are available, please contact:
Louise Hawgood
Press Officer
Tel +44 (0)1225 320600 ext.2178
Fax +44 (0)8707 874148
Email louise.hawgood@burohappold.com
Buro Happold is a multi-disciplinary international practice of consulting engineers established in 1976. It offers civil and structural engineering, mechanical and electrical engineering, quantity surveying, building services and environmental engineering, health and safety management, infrastructure and traffic engineering, ground engineering, façade engineering, fire engineering, computational fluid dynamics analysis, disability design consultancy, project management, urban design and a range of specialist CAD services.
