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Stairs, bridges and floors showcase the structural strength of laminated glass

Laminated Glass News showcases state-of-the-art developments that leverage the structural strength and design freedom of laminated glass as a 21st century material for bridges, stairs and floors.

Amazing Apple SoHo store staircase uses SentryGlas® Plus

DuPont’s new ionoplast interlayer is used for a glass staircase, bridge and mezzanine ensemble that sources at Apple describe as “levitating, weightless and gravity-defying”.

Apple Computer Inc.’s new store in SoHo, New York (completion: July 2002) uses laminated glass with DuPont™ SentryGlas® Plus ionoplast interlayer for a glass staircase, bridge and mezzanine ensemble that look levitating, weightless, gravity-defying – and simply amazing, architecturally.
While the outstanding structural strength and clarity of DuPont SentryGlas® Plus ionoplast interlayer is used for the stunning, ‘free-floating’ glass staircase, bridge and landing, laminated glass with Butacite® PVB is also used in Apple’s SoHo store for a skylight, vertical walls and handrails that complete the new-age glass and steel look of the store.

Architectural and structural engineering experts have said that the staircase, bridge and mezzanine represent a quantum leap forward in using the strength of glass for a self-supporting structure while demonstrating the aesthetic lightness of glass with a new minimalism.

The splendor of the stair structure is emphasized by the highly-polished, exposed edges of the stair treads which, although they contain a 1.5 mm interlayer of SentryGlas® Plus for phenomenal structural strength, give the appearance of one solid piece of transparent glass per stair thanks to the dedicated craftsmanship of laminator Depp Glass of Long Island, New York.

The construction of the Apple SoHo store stairway is 8mm +15mm +15mm +8mm extra clear Depp Glass Diamond Plate glass, laminated together using 1.52mm SentryGlas® Plus ionoplast interlayers.

The staircase appears to be free-floating but in reality is held to the vertical, laminated glass sidewalls (supplied by Bischoff of Germany) on each side of it by tiny titanium inserts. This is the first time worldwide that glass has been laminated to metal on a large-scale design. The glass-titantium-glass construction around the inserts was made possible by the excellent flow and processing properties of SentryGlas® Plus. The ionoplast flows far better around the metal inserts than PVB would have done.

The outstanding stiffness of DuPont’s ionoplast interlayer means that the stair treads could be made 50 percent thinner than if PVB had been used and twenty times stronger, according to the rigorous load-bearing testing that took place in Germany.

Glass stairs maximize sense of space in small London home

Architects Brookes Stacey Randall of London, working with engineers Michael Baigent and Orla Kelly and UK glazier D.A. Firman, completed ‘The Art House’ for a private client in 1999.

Principal at Brookes Stacey Randall, Nik Randall, said: “There are few opportunities to create a modern house in central London.

The ArtHouse, a private residence in London.

The project is the conversion of an former print works, which needed extensive remedial work to achieve our client’s domestic brief. This included the removal of all existing floors and internal walls, and a total remodelling to maximize the sense of space whilst providing discrete and private areas.

“The client asked for a sociable heart to his home where he could relax with friends to watch sport, have a meal, talk and listen to music. The area should also allow for the enjoyment of a varied collection of art but not to exhibit the works in a formal or precious way. This social space should not infringe on the privacy of the private rooms.

“We proposed creating an open space for various social activities with the more private accommodation of the house arranged in two towers flanking the main space. It was essential that the lightness and sense of volume was enhanced and enjoyed and that al spaces were easily accessed. Maximizing the visual and structural potential of laminated glass in the design of the links between these functions was central to achieving this.”

The design of the house is a response to urban living on a custom designed basis. The main stair, with its laminated glass treads and risers, is centrally located to make the activity of passing between the various areas an enjoyable one that provides different views and perspectives of the house. Its transparency allows light to flood through. The laminated glass is used structurally, forming a folded plate in one direction and with slim stainless steel stringers forming a truss in the other direction. No other structure is required. This creates a visual calmness with all the elements integrated to a unified form.

The edges of the main mezzanine are visually separated from the outer walls by the use of strips of laminated glass, which meets safety needs whilst allowing light into the kitchen and dining areas below.

Randall observed: “From the discreet and compressed street entrance, one passes into the gallery, which is a triple height space designed specifically for the informal display of works of art. Above, you glimpse the edge of the mezzanine and, through the translucent glass, the sense of space beyond, whilst separating the old outer walls from the new elements of the building. Turning the corner into the gallery, one becomes aware of how this space flows into the central volume, which is the social heart of the home. During clement weather the glass walls fold away to provide uninhibited access and enjoyment of the complete site.

“In this project, the subtle separation of cellular private rooms and a main living volume enable a great variety of activities to exist side by side. Linked by light and open laminated glass stairs the drama of the space is enhanced. ”The glass construction of the glass treads consists of a 25 mm thick toughened glass riser made from two 12 mm thick laminated glass panes (0.76 mm PVB)

In the Royal Institute of British Architects (RIBA) journal, John Winter said: “At the Art House the spaces are dramatic, the putting together is beautiful, the detailing immaculate and the workmanship impeccable. If our industry is to improve its performance then we need a few more jobs like this.”

Gateshead Millennium Bridge, Newcastle, UK (completion: 2001)

Wilkinson Eyre Architects of London worked with engineers Gifford, glass supplier Eckelt and glass subcontractor GIG Fassdenbau GmbH for the design of the Gateshead Millennium Bridge, which is a major new crossing over the River Tyne in Newcastle, England (client: Gateshead Council). The bridge links a new riverfront development in Gateshead including the BALTIC Centre for Contemporary Arts and the Northern Regional Music Centre with the successfully rejuvenated Newcastle Quayside.

Project architect Martin Knight explained: “The brief was dominated by the requirement to retain a ship navigation channel whilst creating a low level crossing for pedestrians and cyclists. Thus the whole bridge tilts, transforming into a grand arch, in an operation that evokes the action of a closed eye opening. The soaring arch provides instant visual reference to the Tyne Bridge beyond, but also presents a slender profile against the skyline, interpreting and updating its neighbour.

“The superstructure springs from new islands (caissons) constructed in the river. Each of the caissons is capped with a minimalist glass hall, comprising clear toughened single-glazed walls and roof, tapering 35 mm laminated glass fin columns and twinned glass roof beams up to 5.87 metres in length. The pavilion structures provide enclosure to the bridge control position and offer dramatic views of the operating systems, the structure and the River Tyne. It was important that the buildings maximized the view out (for operators and the public alike) and complement the elegant simplicity of the steel bridge structure. Great pains were taken to design a wholly glass structure and full use was made of the safety and aesthetic qualities of laminated glass for the fin columns.” The vertical glass fins are made from 31.5 mm clear laminated glass comprising 2 x 15 mm clear toughened glass with a single 1.52 mm PVB interlayer.

New Bystronic HQ showcases state-of-the-art glass concepts

The stairway is the centrepiece of Bystronic's glass entry hall.

Bystronic, a leading equipment supplier to the worldwide architectural and automotive glass industry, wanted to showcase state-of-the-art applications for architectural glass when it planned its new North American headquarters in Hauppauge (NY) USA. The building features an ethereal looking yet load-bearing, self-supporting staircase of laminated glass with SentryGlas® Plus ionoplast interlayer in the entrance hall and a laminated glass curtainwall incorporating Butacite® PVB interlayer.

Architect Hans Rudolf Kaeser of Interior Concepts, New York City, said: “Bystronic wanted the entrance hall to be as light and airy as possible; we achieved this by designing glass stairs, mezzanine floor, handrails and a large skylight all in a low-iron, bluish- coloured laminated safety glass that matches Bystronic’s corporate colour. The stairs were finished with exposed edges using Bystronic waterjet machinery; even the metal stringers for the stairs were made with the company’s laser cutting machines. The use of DuPont’s ionoplast interlayer added stiffness to the stairs and meant that the tread could be thinner than usual. This added to the visual effect of lightness.”

Laminator Wesley Depp said: “Normally, the handrails would have needed to be made of laminated heat tempered glass for extra strength. The use of SentryGlas® Plus, which provides five times the tensile strength and 100 times the rigidity of PVB, obviated the need for tempering. In addition, using a triple interlayer of the ionoplast on the stairs meant that we could make the 6 foot wide stairs self-supporting with a tread that is just 2 inches thick.”

Bystronic president Rick Troesch said: “We are very pleased; the stairway is absolutely beautiful and has generated a lot of interest from visiting customers who always ask how it was made. Our aim is to show that laminated glass is an unbelievable material for interior concepts as well as exterior applications.”

Gateway Docklands Trunk Infrastructure Bridge (completed: 2000)

The Gateway Docklands Trunk Infrestructure Bridge in Melbourne, Australia.

The Gateway structure is a major urban design element positioned between the central business district of Melbourne on a bridge that connects the City to the new development of Melbourne Docklands. The main features of the Gateway structure are two steel frame ‘fins’ that are clad in red laminated glass. These fins span a monumental stair and a series of stainless steel sculptures that form a ramped maze. The city of Melbourne is laid out on an orthogonal grid and is serviced by a tramway network. The glass fins are located on axis with Bourke Street and its associated tramlines which link the Gateway directly to the Parliament Building at the opposite end of the City. The form of this structure therefore relates directly to its urban context while also being seen as an iconographic architectural object operating as a sculpture within the built fabric of the city.

By working in this abstract architectural sense the structure allows direct interaction with people moving not only past it as viewers but also through the structure experiencing in it a totally ethereal way. The combined effect for the public is a place of geographic significance that is part of a broader, operating city fabric and network as well as a place of pleasure. The gateway is approximately 28 m long by 30 m wide.

The Gateway structure consists of the 180 mm thick concrete slab, one layer of waterproof membrane and 100 mm thick light grey granolithic concrete topping screed (broom finish).

Continuous handrails at 900 mm high are of polished stainless steel and are supported on 100 x 100 mm polished stainless steel staunchions at 1,500 mm nominal centres. The continuous balustrade extends 1,200 above the deck with clear laminated glass panes in between staunchions. Polished stainless steel channels are fixed to each staunchion supporting the glass infill panels top and bottom.

Project architect David Dennis of Wood/Marsh Pty of Melbourne said: “Laminated glass enabled us to meet our design goals because we used it to clad the steel structure of the Gateway element of the bridge using ‘red’ laminated glass (an inner layer of toughened glass, a middle layer of red lead light glass and an outer layer of clear roughcast glass with a total thickness of 17.6 mm). Toughened laminated glass was used primarily to protect the colour from depreciating over time and to allow for stainless steel fixings through the glass into the steel structure.”

Gerard McCluskey of laminator DMS Glass of Melbourne confirmed: “The glass construction is made up of 5 mm clear tempered internal, 0.76 mm clear Butacite® PVB,
4 mm Spectrum Red tempered, 0.76 mm clear Butacite® PVB and 5 mm roughcast tempered glass on the external side. The glass panels are 2,400 x 600 mm. They are affixed by four point fixing with rotational bolt fittings.”