When Samsung Life Insurance staff move into their brand new office in Seoul later this year, they will be working behind one of the world's largest structural glass walls. The stunning new 363m tall Samsung Life Insurance building is the latest landmark in the South Korean capital Seoul. It so striking that people stop to stare at it amid the busy rush hour bustle.
The building's futuristic look is due in part to the structural glass wall on the front elevation. Devised by British structural design consultant Dewhurst Macfarlane & Partners the 50m by 50m facade builds on previous work carried out by the firm in Japan.
There it engineered a glass canopy with structural glass beams over the entrance to the subway station at the Tokyo International Forum in Japan. The Yurakucho canopy is the world's first glass cantilever roof structure, and the project received recognition with a special commendation at the 1997 British Construction Industry Awards.
In Japan DMP worked with New York based Rafael Vinoly Architects. The two firms have continued their collaboration on the Samsung building in Seoul.
The £2.8M Samsung facade is a true glass curtain, in that it hangs from the 12th floor of the building and is only attached laterally to the main structure at 11m centres at each floor height. The weight of the whole assembly is resisted at the top, adding to complications in dealing with the extreme temperatures in Korea. It is often minus 15 degrees centigrade in the winter and up in the mid-30s during the summer, causing up to 30mm of vertical movement at the bottom of the facade. It also has to cope with a maximum wind load of 1.5kN/m2 and must also conform to the country's seismic codes.
'It seems almost perverse to be engineering something as delicate as glass to accommodate such movement,' says DMP associate James O'Callaghan. 'You'd be worried about doing it in steel or concrete, but it seems to have worked well. It's already been through one cycle of temperatures and seems to be quite successful.'
All the structural glass elements, including the horizontal members that act as beams spanning between the main columns, are formed with two pieces of 15mm thick toughened glass separated by a PVB interlayer.
If one layer should fail the beam will remain integral, as the odds on two breaking at the same time are statistically very long. The horizontal members are also fritted to act as sun louvres, cutting down solar radiation entering the building by 50%.
'It's certainly the biggest structural glass facade in the world that is hung in that manner,' claims O'Callaghan. 'The important thing about glass design is that it is not as forgiving as steel or concrete, as its stress is very linear. One of the aims of DMP and Tim Macfarlane is to understand where stresses build in glass in different configurations.'
'Detail was everything with this project. That is something that Rafael Vinoly Architects is particularly adept at; a complete eye for detail and an understanding that unless you make the detail right, the overall picture will be wrong.'
The latest glass masterpiece was conceived by DMP partner Tim Macfarlane and developed through a series of three day design workshops involving key players on the project.
The meetings were held in both Seoul and London and included the project's structural engineer, Tokyo-based Structural Design Group, US fixings consultant Tripyramid Structures, and Ove Arup Facades, consultant on the weathering aspects of the design.
O'Callaghan oversaw the detailed design process in Seoul. 'The contractor for the facade, Hanglas, turned to us to design a more cost efficient system while maintaining the required aesthetic. There were six or seven workshops over the six month design period.'
'That was a nice way to work because it was bouncing ideas off people and experience was gained from people from many different fields. We did all the drawings and the final developments of the detailed design, and the fittings and the castings from August 1997 to January 1998.'
It was a typically tight Korean construction programme (the glass and the fixings were eventually manufactured in just three weeks) but the 1997 currency crisis interfered, and scheme was subjected to a design review and a value engineering exercise. A large glass skylight at the bottom of the facade, with views into the subway station below, was the unfortunate victim of the review.
Construction got under way in February 1998 and was originally due for completion in October of that year. However, the devaluation crisis forced main contractor Samsung Construction to slow down construction, and the programme was extended by nearly a year. Samsung is now gearing up to occupy the building as the fit out programme nears completion.