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Tim Macfarlane: "Achieving the Impossible" with Laminated Glass

Tim Macfarlane is an architectural engineer whose London-based practice, Dewhurst, Macfarlane and Partners, works with architects and clients worldwide. Tim's pioneering work with beams, columns and cantilever canopies of laminated glass has been honored four times (1995, twice in 1996 and 1997) in the DuPont Benedictus Awards for innovation in architectural laminated glass.

Tim Macfarlane and partner, Laurence Dewhurst

Laminated Glass News: What do you think drives the architects you work with the keep requesting more and more elements in glass?

Tim Mcfarlane: A growing number of architects today want to take away the closed character from the rooms in which we live and, in the words of modernist guru Paul Scheerbart: "Let in the sun, the moon and the stars not merely through a few windows but through every possible wall which will be made entirely of glass."

All architects dream of being able to build things in monolithic materials. Rather than bolting a steel beam to glass using a metal fixing, there is a sheer joy in reducing the number of materials to the absolute minimum.

The lamination process is key when you want to make all-glass structures because laminated glass provides unparalleled safety. It takes away the unpredictability of glass; while retaining its beauty, its delicate nature and its sensuousness, it provides a failsafe mechanism – which for a structural engineer is vital. The lamination process therefore makes it possible for us to develop a design approach to glass. PVB is the ideal laminate material; it provides an excellent barrier to dirt and moisture and so provides excellent sealing.

LGN: In the many award-winning projects you've worked on, whose idea was it to use glass for daring structural uses such as beams, ceilings, lintels and canopies: yours or the architect's?

Macfarlane's tension net staircase in Chicago was a distinguished finalist in the 1996 DuPont Benedictus Awards.

TM: It certainly takes a 'leap of faith' to walk into a building where there is no visible structure in that there is a laminated glass roof supported by laminated glass beams and columns! Not so long ago, the vast majority of engineers – myself included – would run a mile from using glass as a structural material because of its perceived unpredictability and potential to injure people by breakage or falling shards. As engineers, our paramount responsibility is the safety of people using the building so I must admit that we originally had to be almost forced into designing structurally with glass by architects of vision like I.M. Pei and Rafael Vinoly.

Winning DuPont Benedictus Awards over the past few years has not only given us great exposure but has helped people to realize that laminated glass can be used safely and successfully in working situations by major architects in projects that are recognized by the UIA and AIA.

LGN: When did you first start using laminated glass for structural strength?

TM: I will never forget the first time we used laminated glass beams to support a structure (a glass extension to a private terraced house in Hampstead, London) – partially because the client was a high court judge! Rick Mather Architects kept asking if we could make the structural steel members smaller and smaller. In a fit of either inspiration or exasperation, I suggested using beams of laminated glass instead of steel!

We were apprehensive about using a single pane of toughened glass for the beams supporting the horizontal load of the roof because toughened glass could easily break, so we decided to laminate three panes of glass together for optimal safety. Even if all three of these beams were to break, the crack pattern in the annealed glass would ensure that the glass stuck to the PVB and did not fall down, causing injury. Laminated glass thereby acts as a true failsafe solution. Even if a crack appears, there is no immediate danger as you have time to repair it, just as you would for a crack in your plaster wall. These laminated glass beams have now been in place for 10 years with no problem.

Tim Macfarlane originally came up with the idea for the Tokyo International Forum's cantilevered laminated glass canopy in a Chinese restaurant.

LGN: What was the main structural challenge you had to solve in designing the laminated glass cantilever canopy at the Tokyo International Forum?

TM: The structural problems posed by Rafael Vinoly's dream of an all-glass cantilever canopy for the Yurakucho subway station entrance in the Tokyo International Forum plaza took us six or seven months to solve. The building owners were looking for a really spectacular entrance to the Forum – yet safety was obviously a paramount concern to us all, especially since the canopy had to be able to move multi-directionally, due to the many earthquakes and typhoons that Tokyo experiences.

The structural concept for the cantilever canopy with its eleven-meter span is based on the structural principle of controlling which allows the long span to be formed from smaller sections generously lapped to avoid high loads in the connections.

The cantilever canopy was something really new because for the first time we were able to create a long-span glass structure from smaller elements using traditional bolted connections to join them. The laminated glass beams support overhead panes of laminated glass which also serve to brace the roof.

LGN: Could you tell us about current laminated glass projects you're working on?

TM: We are working on a specialist glass installation for Daewoo Electronics in South Korea with architect Sir Normal Foster using a chevron-shaped compression arch of laminated glass and a 20 meter-long glass ramp and stairway built on the same technology which allows light to come down in the middle of the space.

Also in South Korea, we are working with Rafael Vinoly on specialist glass installations in a new headquarters for Samsung. The principle element is a huge laminated glass wall suspended over 50 meters and bolted together in a similar way to the Tokyo International Forum's cantilever canopy.

The Daewoo building in South Korea uses a chevron-shaped compression arch of laminated glass.

Dewhurst Macfarlane is also involved in three Middle East projects; an eight-meter, structural glass cube reading room for the new main library at the Arab Urban Development Institute (AUDI) in Riyadh; a structural glass façade and skylight based on notched glass beams for a new office development and a structural glass façade and perimeter glass 'moat' above an underground printing press (all three projects are with architect Nabil Fanous).

Another project of note is a 15 meter-high, laminated glass cone-like structure for Swiss Bank Corp. in Connecticut, USA with artist Brian Clarke and Skidmore Owens Merrill Architects. This is interesting because it is built around a central framework of laminated glass beams structured like the poles of a wigwam.

LGN: What do you believe the future holds for architectural laminated glass?

TM: I believe that in the future we will see more all-glass buildings that allow the architect maximum transparency while introducing opacity where needed through the switching glass now in development. Such buildings free modern architects from masonry walls, steel frames and beams and allow more space and freedom. Instead of planning windows that let light in, you simply have to take the decision to place a screen in a wall or not. You may not want every single floor and wall transparent but you have all your options open.

You could compare the current architectural era, where we are coming to understand the many possibilities for laminated glass in structural terms, to the Victorians' discovery of reinforced concrete at the end of the nineteenth century; at the beginning you're piloting a new technology but gradually it becomes part of the building industry vernacular. As we learn to make buildings lighter and more open in feel we will help to improve everyone's quality of life, in the sense that Paul Scheerbart intended.