report on - 30 st. mary axe

30St.MaryAxe,

CityofLondon,

England

Preparedby:DamianB.Ennis

30St.MaryAxe,LondonDamianB.Ennis

Table of Contents 1) Introduction 2) Site History 3) Early Proposal – London Millennium Tower 4) Swiss Re Building5) Glazing Problems 6) Ownership7) Awards and Honors

Introduction 30 St. Mary Axe, nicknamed “The Gherkin”, or Swiss Re Building, (after its original owners) is a sustainable 41-story skyscraper,[1] built in the Financial District of the City of London. It was designed by Ken Shuttleworth (while at Foster and Partners), Lord Foster, and ARUP Engineers, and built by Swedish contractors Skanska.[2]

Constructed commenced in 2001 and was finished on March 2004[3] It was officially opened in April 2004.[4]

30 St. Mary Axe is part of London’s ‘Open Weekend’, which takes place every penultimate weekend in September.

Site History The site was formally occupied by the Baltic Exchange Building, which was a Grade II listed building designed by T.H. Smith and Wimble, and built by George Trollope & Sons. It opened on 21st April 1903.[5] The building was irreparably damaged by an IRA bomb in 10 April 1992.[6] English Heritage and the City of London Corporation insisted that the old façade onto St. Mary’s Street must be restored in any new development, and as a result the Baltic Exchange sold the site to the investment group Trafalgar House PLC in 1995. A redevelopment scheme was drawn up by GMW Architects, with Donald Insall Associates preparing a full set of drawings and specifications for the reconstruction of the Exchange Hall and associated lobbies.[7] With the restoration provisions, they did not have the funds to finance the project. What remained of the façade was dismantled, and stored for possible future use. The trading hall itself stood for a few years longer, with the hope of housing it within a new building on the site.[8] After a survey deemed the damage too great, English Heritage withdrew insistence of full restoration. The total cost of total dismantling, recording, and moving the Baltic Exchange salvage cost £4 Million.[9] What remained of the Baltic Exchange was razed in 1998 with the permission of the then Planning Minister John Prescott, despite protests from conservationists (including Save Britain’s Heritage).[10] On 25th August 2000 Prescott went on to grant permission for a much larger building than the old Baltic Exchange on the site.[11] The Baltic Exchange salvage was bought for around £750,000 from Extreme Architecture by two Estonian businessmen, Eerik-Niiles Kross and Heiti Haar. It was shipped to Tallinn, where it will be rebuilt as part of an office / housing development.[12]

Early Proposal – London Millennium Tower The unique conditions of the site made it an ideal location for a skyscraper, it is not in a conservation area, it lies outside the strategic view corridors of St. Paul’s Cathedral, and there are no underground railway tunnels to restrict foundations.[13] The London Millennium Tower proposal dates back to 1996, and was like the final building was designed Foster and Partners.[14] After the plans were revealed, The Guardian newspaper coined the term the “erotic gherkins”.[15] The unconventional floor plan consisted of two asymmetrical ellipses joined at one point. The tower was to be 92 storeys, with a height of 385.60M.The tower was to be multi-use, and this proposal included plans for a hotel, residential use, commercial offices, and commercial use.[16] There was also a provision for a viewing platform at 305M (1000ft). Had the tower been built, it would have been the tallest building in Europe.English Heritage (one of the project’s


largest backers) withdrew it’s support, after Heathrow Airport objected that the height of the building would adversely effect their flightpaths.[17]

Figure 1 – View of Millennium Tower proposal from St. Paul’s (©Foster and Partners).

Swiss Re Building The form of the building is a product of site requirements, light penetration, wind loads and sustainability considerations. It bulges from the base, with it’s maximum width on the 16th floor.[18] The external articulated structure, illustrate the 5° anti-clockwise rotation from floor-to-floor. The cross-section taper allows more light to penetrate to the tower base, and provides a more generous plaza space. Wind turbulence is minimized by the lack of hard corners and the taper allows the air to pass over the top of the building more easily. This reduces the stresses on the structure and cladding. The building’s taper also casts a significantly reduced shadow, in comparison to a more traditional shaped skyscraper.[19]

Figure 2 – Norman Foster’s sketch of the building form (©Foster and Partners).

It has been billed as London’s first sustainable skyscraper, and incorporates full height light-wells, as well as utilizing both recycled and recyclable products during construction.[20] The building employs energy-saving methods which allow it to consume 50% of what a similar tower would consume. The six light-wells are expressed externally with the grey-tinted glass that counters solar glare. They serve as both a natural ventilation system, and deliver natural light. The “chimney” is interrupted by fire breaks every six floor, and are ventilated by exhaust air from the offices. The shafts create a double-glazed effect, which acts as an insulator to the offices. The shafts pull warm air out of the building during the summer, and warm the building during the winter using passive solar heating.


Figure 3 – Wind Study Diagram.

This characteristic form of the building is a response to site constraints, and this has been achieved by using a diagonal steel structure (a ‘diagrid’). This perimeter diagrid is formed from intersecting steel tubes that frame the light wells. It follows the curvature of the building and provides vertical support to each floor, and creating column-free office spaces. The shape gives the impression of a less bulky building than that of an equal area building, with a rectangular plan. This allows the creation of a public plaza at street level. The form of the building also provides the least resistance to wind, improving the environment for the people at street level, and reducing the overall load of the building. [Ref Arup]

Figure 4 – Engineering Simulation (©Courtesy of Hilson Moran).

As a result of the 5° rotation, every floor in30 St. Mary Axe is different. The span and orientation of the floors, and the angle at which they meet the walls vary throughout the building. This created some unusual design challenges for ARUP. In order to simplify construction, 360° steel nodes were designed to connect the complex diagrid together. The nodes consist of three steel plates, welded together at different angles. The connections helped to make the diagrid more simplistic and cost-effective to build. 3D computer modeling was used to resolve the sizes of the steel frame. It also helped the steel fabricator to generate the information needed to produce the 10,000 tonnes of steel in the building, 2,500 tonnes of which make up the diagrid structure. This also allowed the process of transferring information from office to site to be performed more easily. [Ref Arup]


Figure 5 – Typical Floor Plan.

Glazing Problems The tower's exterior cladding consists of roughly 5,500 flat harlequin-shaped glass panels covering an area of 24,000 M². On 18th April 2005, a triangular glass panel fell from the 28th storey of the building, and hit the plaza below. The plaza was sealed off, and engineers were brought in to examine the remaining 744 triangular glass panels that are automatically opened and closed by computer. The opening was temporarily filled by a wooden panel, and the plaza was sealed off. As the building remained open, a temporary covered walkway was erected from the buildings reception across the plaza for visitors and workers. No injuries were reported.[21]

Ownership The building was put up for sale in September 2006 with a price tag of GB£600 million. Many prospective buyers were listed, which included; Prudential, Land Securities, the Abu Dhabi royal family, British Land, and ING. The skyscraper had a potential annual income of GB£27 million. Rumors in late 2006 suggested a sale was imminent. On 21st February 2007, UK investment firm Evans Randall and IVG Immobilien AG finalized their joint purchase of 30 St. Mary Axe, for GB£630 million (US$1.26 Billion circa 2007), which at the time was a record for an office building in Britain.[22]

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Awards and Honors • The Royal Institute of British Architects (RIBA) Stirling prize in 2004 (for the first time in the award’s history, the judges verdict

was unanimous). • Voted “The Most Admired New Building in the World” - BD World Architecture 200, 2005. • The Civic Trust Award – 2006. • Winner of the Emporis Skyscraper Award 2003. • In 2006, to celebrate Architecture Week, British 1st class stamps were issued with an image of 30 St. Mary Axe. • Special Steel Award - Detail 2004. • Best Central London Office Development - IAS/OAS 2004. • Best New London Building - The Inaugural London Architecture Biennale in Clerkenwell. • Honorable Mention - The International High-rise Award 2004. • Future Projects Award - Architectural Review 2003. • Best British Innovation - Walpole Award for British Excellence 2003. • European Steel Structures Award - ECCS-CECM 2003. • Outstanding Development Of The Year - The Variety Club 'The Props' 12th Annual Luncheon 2003.


References [1] Retrieved August 7, 2009, from http://www.emporis.com/application/?nav=building&lng=3&id=10008

[2] Retrieved August 7, 2009, from http://en.wikipedia.org/wiki/30_St._Mary_Axe

[3] Unused.

[4] Unused. [5] Retrieved August 21, 2009, from http://www.lap-architects.com/downloads/notes.pdf [6] Retrieved August 22, 2009, from http://en.wikipedia.org/wiki/List_of_terrorist_incidents_in_London [7] Retrieved August 23, 2009, from ht[8] Retrieved August 22, 2009, from

http://news.bbc.co.uk/2/shared/spl/hi/pop_ups/07/magazine_baltic_exchange_bombing/html/6.stm [9] Retrieved August 22, 2009, from http://www.heritage.co.uk/apavilions/baltic.html [10] Retrieved August 22, 2009, from http://en.wikipedia.org/wiki/Baltic_Exchange [11] Retrieved August 23, 2009, from

http://www.cityoflondon.gov.uk/Corporation/our_services/development_planning/planning_apps/register/data/51/5173.htm [12] Retrieved August 22, 2009, from http://www.salvoweb.com/news.html?key=baltic+exchange [13] Retrieved August 23, 2009, from http://findarticles.com/p/articles/mi_m3575/is_n1196_v200/ai_18950150/ [14] Retrieved August 23, 2009, from http://www.emporis.com/application/?nav=building&lng=3&id=102960 [15] Retrieved August 23, 2009, from http://en.wikipedia.org/wiki/Millennium_Tower_(London) [16] Retrieved August 23, 2009, from http://www.emporis.com/application/?nav=building&lng=3&id=102960 [17] Retrieved August 23, 2009, from http://en.wikipedia.org/wiki/Millennium_Tower_(London) [18] Retrieved August 23, 2009, from http://www.emporis.com/application/?nav=building&lng=3&id=100089[19] Retrieved August 23, 2009, from http://web.utk.edu/~archinfo/a489_f02/PDF/Swiss%20Re%20Building.pdf [20] Retrieved August 23, 2009, from http://www.emporis.com/application/?nav=building&lng=3&id=100089[21] Retrieved May 17, 2010, from http://www.thisislondon.co.uk/news/article-18148925-safety-fear-over-gherkin.do [22] Retrieved May 17, 2010, from http://www.propertymall.com/press/article/16841

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