London Stock Exchange, 10 Paternoster Square
London
This challenging project for the new home of the London Stock Exchange has been built on one of the most prestigious squares in the world. This new building, which has been designed and developed by Eric Parry Architects and Sheppard Robson Architects with technical consultancy from Arup Façade, is situated at one of the most attractive architectural locations in London, adjacent to St. Paul’s Cathedral, The building has an essentially clean architectural solution, which blends in with the texture of this important area. This was achieved by the use of Portland stone in conjunction with Focchi’s curtain walling technology.Credits
Architect: Eric Parry Architects/ Sheppard Robson
Contractor: Bovis Lend Lease Ltd/ Stanhope PLC
Photographer: N. Kane/ Charlotte Wood
The tecnology
Unitised curtain walling for the external envelope Suspended structural silicone glazing acting as sun shading Specialist pressure plate system for round floor and Atrium roof areas Structural silicone glazing for the internal light weels and balustrades
1.Unitised curtain walling for the external envelope 2.Suspended structural silicone glazing acting as sun shading 3.Specialist pressure plate system for ground floor and Atrium Roof areas. 4.Structural silicone glazing for the internal light wells and balustrades. 1.Unitised curtain walling The sobriety of a site such as Paternoster Square has been preserved by using non-reflective glazing with thermally broken Polyester Powder Coated (RAL 7030) profiles, which are harmoniously inserted into a grid of Portland stone. The perimeter curtain walling consists of 2 different types of units: Units inserted into the vertical strips formed between the Portland stone clad columns from floors 1 to 5. A continuous zone of curtain walling crowning the upper floors of the building (the 5th – 6th and 7th ) with sunshading formed by feature glazed panels. A total nr. of 1100 curtain walling units were used, the largest dimension used was 1600mm x 5100mm. A strict testing regime totalling 15 no. tests were carried out to ensure the integrity of the design of the system: 3 no. weathertightness test sequences to a mock up of 6000mm x 4000mm 1 no. safety test to an ultimate pressure of 4 Kpa. (to simulate bomb blast pressure) 2 no. frontal acoustic tests 2 no. flanking acoustic tests 2 no. bomb blast tests using a TNT charge of 500 Kg. 2 no. impact tests to the suspended structural silicone laminated glazing 3 no. on site watertightness tests during the installation process. Every individual unit, including those used at the corners, was prefabricated in our factory and then delivered to site, ready for the installation. This allowed for thorough quality control procedures to be carried out “in-house” and minimise on-site operations. A particularly interesting feature is the arrangement of the curved façades where the use of curved fascia, stone and coping elements permitted the use of facetted glass units without interrupting the radial aesthetic of the façade. 2. Suspended structural silicone glazing acting as sunshading The 220 no. laminated glazed panels (15mm, 1.52pvb, 12mm, average dimension 900mm x 4800mm, weight 300 Kg), were formed using heat soak tested toughened glass panes and have been purposefully “randomly” arranged. The fixing of the glazing was by a structural silicone bonded channel to a continuous stainless steel rail. This silicone is screened from view externally by a satin polished stainless steel fascia. A sequence of impact tests was carried out to ensure the reliability and security of this innovative fixing method of the glazing. It was demonstrated that the period of at least 24 hours would elapse from the initial fracture of either one or both panes forming the laminated pane until complete failure of the glazed panel. Though it is important to note that the test panel collapsed from it’s frame only after it had been inclined at an angle, not when it remained vertical. 3. Pressure plate stick system The importance of the Stock Market as an institution and the particular location of this building encouraged the Client to request bomb blast tests which would guarantee the ability of the curtain walling system to absorb the dynamic pressure caused by an explosion. The installation of double glazed units (4500mm x 1500mm) at roof level required a detailed method study. Though this also helped to provide a suitable glass replacement strategy in the event of failure. A concealed fixing system and non-slip glazing allow for both normal cleaning operations and also the extraordinary maintenance. 4.Structural glazing The need for natural light inside the building has been realized successfully by the use of a succession of heat soak tested toughened and laminated glazed panels (both panes 8mm with 1.52mm pvb) 4300mm x 1500mm, at the open areas. These panels continue along the line of the external decorative stainless steel strip at the floor slabs, but blend in effortlessly both internally and externally due to the application of a bespoke ceramic frit. The appearance of the circulation areas has been enhanced by the use of a structurally glazed balustrades in order to minimise visual impact and provide an inbuilt elegance to these zones.
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