Structural engineering is the servant of architecture in Rogers Stirk Harbour + Partners’ Las Arenas mixed development in Barcelona, writes FelixMara
Facade retention was not the most simple and economic strategy for Rogers Stirk Harbour + Partners’ (RSHP) reworking of Las Arenas, a decommissioned bullring in Barcelona which re-opened as a mixed retail, leisure and commercial complex in March.
The last bullfight at the venue was in 1977 and the city council was keen to retain its 1899 facade as a memento to bullfighting which was banned in Catalonia in July last year. It was built in a Neo-Mudéjar idiom, once favoured in Spain for bullrings and other leisure buildings because of its playful, Moorish and nationalistic connotations but, like bullfighting itself, the object of mixed opinion in more recent times. The retained facade also circumscribes development of the site, leaving public realm space on what remains of the urban block within which it sits.
‘It was a long, arduous, delicate process,’ says project architect James Leathem. The facade was leaning by as much as 350mm, outwards in some locations and inwards in others as a result of centripetal forces from the seating and roof, settlement and prolonged differential thermal movement. These problems were conflated by vertical cracking in the facade and crenellations falling from its parapet.
Although local remedial work had been undertaken in the mid-1970s, the metamorphosis proposed by RSHP required a comprehensive strategy, not only to stabilise the facade but also to accommodate its movement. The facade had to be integrated with other aspects of the design and, because of safety and site access requirements, work on the existing structure was on the critical path from the beginning of operations on site.
RSHP and structural engineer Expedition proposed a 3.5 metre-wide zone behind the existing facade for a permanent stability system that resists leaning and braces the existing masonry, using curved horizontal frames spanning between a circular array of cores and stair towers. To an extent this adds visual interest by introducing additional vertical layers to the facade but, though exquisitely detailed and constructed, it is all but eclipsed by the retained facade. Visually, the most striking move is at low level.
Ground level within the arena was originally constructed at grade, but the adjacent roads and pavements were subsequently constructed 4.5 metres below this when the falls and levels of the new tram network were determined. RSHP decided to lower ground level within Las Arenas by 4.5 metres as well, providing direct links at pavement level. This also improved access during the construction stage.
Pile foundations were required for the facade and other elements of the structure but it was impractical to build these immediately below the existing facade. Instead, they have been built to either side of it and radial concrete beams between them provide support for V-piers that audaciously hold the facade aloft and form an arcade below it. Temporary beams and micropiles above ground level were used to support the existing facade while the substructure below was excavated. In situ concrete circumferential beams sit on top of the V-piers, with release bearings to accommodate movement and, to an extent, rhyme with the capping beams at the top of the facade where the rather spooky crenellations have been removed.
A new 100 metre-diameter dish structure appears to float above the capping beams, supported by substantial pairs of bifurcated steel tubes, which are independent of the facade. At its perimeter, this acts as a public platform from which to view Barcelona and within this there is a domed, multipurpose column-free enclosure. Because of height restrictions set by the city council, the 76 metre-diameter dome is only nine metres-high so its hybrid timber and steel lamella leaf construction, though designed to impose minimal loading, generates substantial radial forces which are transferred to the concealed steelwork supporting the dish structure by sculptural fabricated steel boomerang-shaped supports which raise it above head height.
This dish is accessed by lifts, some of which have guides spanning from ground level to a platform which cantilevers from a new telecommunications tower. There is also a sequence of Pompidou Centre-style escalators that rise through the cruciform atria below the dish, giving access to a cinema complex, a fitness club, a museum of rock music and circles of retail purgatory or paradise, depending on one’s preferences.
‘One in 10 residents of Barcelona visited Las Arenas over the weekend it opened’, says RSHP associate Jan Güell and Leathem explains that former RSHP director Laurie Abbott, who had a central role in the design of Las Arenas, was disappointed when the Pompidou’s external escalators, once regarded as the best free ride in Paris, were restricted to ticket holders. At Las Arenas the escalators are vital conveyors for the passing trade on which it depends, so this is unlikely to happen.
Start on site January 2004
Completion March 2011
Form of contract Lump sum
Total cost €200 million
Cost per m2 €1,890
Client Metrovacesa (originally Sacresa)
Architect Rogers Stirk Harbour + Partners
Co-architect Alonso Balaguer y Arquitectos Asociados
Structural engineer and existing facade consultant Expedition Engineering and BOMA
Services consultant JG and BDSP
Retail consultant Sociedad Centros Comerciales España
Acoustic consultant BDSP and Audioscan
Cost consultant TG3
Project & construction mannager Bovis
Main contractor Dragados
Bullring facade contractor Joan Obré
Office facade contractor Strunor
Roofing contractor Finnforest
Services contractor IMTECH and EMTE
Steel contractor for the dish Martifer
Estimated annual CO2 emissions Not disclosed