Laminated glass, endless possibilities

Last 20th of October of 2012, Tecnalia  invited me to give a lecture for the Technical Conference: Perforated Sheet Metal for Enclosures and Architectural Meshes.

The lecture was based upon the use of metallic meshes within the laminated glass. I showed the point of view of Cricursa, who have developed lamination technologies followed by the requirements for laminating innovative designs in curved glass.

The facade industry is steadily making progress by demands of Architects and Designers.

Glass is still the one and only transparent filling for curtain walls and interiors designs because it offers versatility, through compatibility with a range of materials and the added value of being bent. Therefore, glass is offering adaptability to meet complex geometries.

The main technologies available for laminating either curved or flat glass are described as follows:

• Screen printing: the colour is baked during the tempering process, bonding it permanently to the glass.

Screen-printed laminated annealed curved glass

• Colour interlayers: the combination of different colour layers of 0.38 mm PVB thick creates a wide range of more than 600 colors.

Color laminated glass

Color laminated glass

• Solar control interlayer: high-technology solar control film is placed  between two layers of PVB, obtaining a high visible light transmission, in the meantime being controlled infrared solar energy.

• Ink-jet printig on interlayers enables the production of designs and photografic images in a laminated safety glass.

Ink-jet printing on PVB

• Metallic meshes have been for the last decade in fashion in architecture, being considered by Dominique Perrault, who has enhanced the use of stainless steel in his most distingued projects.

Metallic mesh laminated glass

• Plastic meshes has been threatening the place of the metallics, because of easiness to get laminated versus metallics and it requires less energy cost to manufacture. It is also manufactured from metal diposits that use the latest technological advances and provides solar control control and privacy functions, as well as unrivalled asthetic value.

Plastic mesh laminated glass 1 way vision 

Plastic mesh laminated glass 1 way vision 

The purpose of the industry is to achieve the quality required in those products, this means to develop adequate lamination strategies to suit different materials all put together.

This post is under construction because future innovative designs will demand further investigation to create new products to meet architectural requirements.

Spherical double curved glass

  

The rhomboidal bubble double curved glass pane exhibited at the Fad Gallery in Barcelona

The latest achievement in curved glass fabrication was shown at the Fad Gallery in Barcelona.

The façade was designed by  Rafael de La-Hoz and comprises of thousand rhomboidal bubble glass units for a hospital in Mostoles. Cricursa was selected to manufacture the glass panels, also giving technical support during the design process.

The geometry is a double bending, first in one of the axis of the rhomboid, and secondly a spherical shape  sited at the centre of the pane with around 400 mm of deflection.

The glass dimensions are 4900 mm in width, 3360 mm in height and 12 mm thickness. 

 

The composition includes a low iron glass, with screen-printed in white with a particular pattern, achieving privacy and solar protection.

This is another example how curved annealed glass technology offers versatility and opens up to endless structural possibilities.

 

 

The rhomboidal bubble glass pane exhibited at the Fad Gallery in Barcelona

Photos courtesy by Marketing Cricursa

Facade Trends

"We know how to make the biggest pieces of glass in the world for architectural use'' Steve Jobs, Apple CEO, recently stated this during the speech regarding the new Apple Headquarters in Cupertino (California, USA).

Facade units get bigger and bigger every year. Some colleagues engineers have thought that cladding world has gone mad, but it is not true. Innovations are moving ahead. The market demands it.

Architecture is demanding larger pieces, such as Apple Store in Shanghai, where the height of every glass facade is approximately 12 meters.

The main benefits can be noticed immediately and are set out as follows:

• Reduction of glass joints, improving watertightness and increasing light transmission.
• Reduction of supporting claddings.
• Improved load carriage behaviour.

Apple has innovated using largest glass panes in their own worldwide stores.

Apple Store in Sydney, glass panes covering the complete height of the facade

 

It has been recently published (link is hereby included) that Apple is going to renovate the Cube store on Fifth Avenue in New York, removing the 90 glass panes and  supersede them by only 15 larger panes as it is shown in the picture below.

Apple has revealed its plans for the cube with a new informational sign posted on the barrier surrounding the plaza. It can be seen the 15 glass panes instead of 90

 

Another clue regarding this architectural trend was found in the last Glasstech Düsseldorf in October 2010, it was shown a huge insulated glass panel of 18 meters in width and 3.3 meters in height, manufactured by Henze-Glas from Hörden, Germany.

Henze-Glas DGU in the factory, before shipping to Glasstec 2010. Employers are sitting on top of the 18m long glass unit

 

Glass curved technology

The aim of this article is to explain the difference between two glass curving technologies: hot bending and cold bending.

Hot bending technology is based upon the following basic process [1]: a flat sheet of glass is placed upon a mould that has the desired bending radius and is heated evenly to temperature of 650ºC. At this temperature the glass changes to a visco-plastic state, loses its brittleness and stiffness, and can, therefore, be shaped by gravity or mechanical pressure, obtaining the aimed geometry by cooling.

Hot bending allows a broad variety of geometries and compositions -cylinders, s-curves, double curved shapes-  to be achieved. The sheets are bent and then can be laminated and/or assembled into insulating glass units.

Manufacturers are steadily investigating, testing and, if the market demands it, expanding the manufacturing limits of radius, angle, thickness, girth and coatings, in order to offer architects and designers the largest sizes and greatest possibilities.

It is feasible in many cases to use coatings and ceramic frits in concave and convex sides, though the selection can be limited depending on varying factors such as glass thickness, size, radius, location adjacent to interlayers.

In order to attain a spherical, double curved and free form geometry with large deflections, curves with small radius such as 100 mm, processing with high temperatures is required.

Curved annealed laminated glass with a solar control and frit used on 40 Bond Street project, New York, 2006; Architect: Herzog & de Meuron (Produced by Cricursa, who have been bending glass since 1928)

 

Cold bending is a recent fabrication process. Flat glass panes are brought to the desired geometry by means of external contact pressure, which demands holding the curved glass unit in desired form.

Two basic techniques are used here: the glass can be curved at the construction site (and held in place by clamping strips) or  curved in factory before laminating (and held in place by the interlayer).

The company seele sedak has been instrumental in the development of a new lamination bending technology [2], which consists on using shear stiff laminates, to produce extreme large bent glass panels.

The Lamination process of cold bent glass can be divided into four basic steps [2]:

1.- Put together interlayers and flat glass, usually tempered. The glass can also be heat strengthened, annealed, with ceramic frits or coatings though these may affect the limits of what is possible.

2.- The glass is formed into the desired shape by physically pressing it onto the laminating framework and clamped into place.

3.- Lamination process, the aim is to achieve a high shear bond between the glass and the interlayer.

4.- Release from the scaffold form. During and after the lamination process, high quality control and observance of the stresses in the single panes due to the spring back effect is necessary. It is required to increase the curvature in the panel during the lamination process to get the exact shape after releasing the laminated panel from the framework.

Laminated cold bent glass manufacturing process

 

Both technologies provide fully bespoke, custom design solutions and the research and testing ensures the success of the most innovative designs. 

 

Bridge made of cold-shaped glass and spanning seven metres (by seele sedak, Glasstec 2008)

 

[1] Cricursa General catalogue

[2] Bruno Kassnel-Henneberg, seele sedak. Purely structural glass building envelopes (Glass Performance Days 2011)

With editing by charles.bostick@seele.com

Curved glass contributes with the facades of the future

Structural glass symbolizes modern architecture and it is considered an added value to achieve all glass facade and non-metal supported transparent structures.

The prospect of shapping glass has contributed to attain a broad variety of aesthetical and structural options through oversized pieces of glass with complex geometries. Its versatility has allowed to achieve a better integration between the aesthetic and functional objectives.

The Casa da Musica in Porto (Rem Koolhas, 2004) is an example how to make the best of curved glass, because glass develops both functions: structure and enclosure. The glass shape increases the set stiffness and any metallic frame is required. The curved glass pane is mechanically supported at the bottom and at the top, without any other support along the 6 meters in height of the vision area.

Casa da Musica in Porto (Rem Koolhas, 2004)

 

Casa da Musica in Porto (Rem Koolhas, 2004)

 

In glass bending technology, one distinguishes between hot-bending and cold-bending. Hot-bending consists on bending glass at high temperatures, being the most common manufacture method. On the other hand, cold bending can be done in two modes: bending during the assembly at the construction site or laminated bends are done in factory. In both cases, the glass are brought to the desired shape by means of external contact pressure.

In order to achieve a double-curved, spherical, curves with small radius or complex geometries, high temperatures are required during the fabrication process.

This post is under construction. In fact, it will be under construction during a long time. Creativity  is the limit, because curved glass contributes with the facades of the future.

Apple Store in Shanghai and how to make the most of membrane stresses (Bohlin Cywinski Jackson Architects, 2010)

The author of the Blog in front of the Apple Store in Shanghai

Apple Store in Shanghai contributes to the design of buildings considered icons of structural glass achievement today. The store, inagurated last July 2010, is located in the Pudong financial district, situated between the Oriental Pearl Tower and the Shanghai World Financial Center, one of the tallest skycrapers worldwide.

The authors of the design are Bohlin Cywinski Jackson Architects, a prominent american architecture studio, who already designed another Apple stores, such as those in New York and in London.

The glass cilindrical envelope is formed by tempered curved glass panes of 12 meters in height. The design achieves the best integration between aesthetic and functionality through its structural system, because structure and envelope are formed by glass.

The facade resists wind loads through acting all the glass panes together as a shell. This is achieved through the stainless steel conectors that link all the glass panes together. This structural system develops less stress in each glass pane, decreasing the glass thickness accordingly and making the design happen.

The glass panes are supported by a glass laminated fins, forming a frame with the glass roof beams that support the top of the cylinder.

In order to obtain a 12 meters curved tempered glass, an customised oven was built for this project to manufacture the largest pieces of curved tempered glass.

Through this design and materials, Apple communicate perfection, innovation and passion for being the best.

Internal view of the glass roof of the Apple Store in Shanghai

Apple Store in Shanghai



Façade Engineer´s skills and roles

A façade engineers should have many skills. They have to be creative and practical, having a broad knowledge about design, calculations, tests, materials, standards, installation on site, planning and costs.

The list as follows shows the main skills for a façade engineer :

• Be able to imagine every component of façade, such as anchorage, structure, fillings and final elements. It is essential to be able to construct the whole façade in your mind before doing any sketch.
• Every design should be feasible to be installed on site. It does´t make any sense design something if it is not possible to be assembled in a construction site.
• A general understanding of the concepts in relation to energy consumption, light performances,f ire requirements, thermal insulation and acoustics. 
• Sketching is essential as a way of efficient communication between engineer and architect.
• Be capable to understand the methodology of how to calculate a bracket, the inertia of any material section and supported beams.
• An engineer should provide the best technical solution at the optimal cost. You can not design something if you don’t know how much does it cost.
• Good communication skills.

Facade engineers should get used to be on a site. The construction site is where the practical approach makes the most of the technical skills.

An interesting interview published in The Independent a years ago to John Champion, a façade engineer and technical director of James&Taylor firm, he explains his views about this important role in construction.

What does a façade engineer do?

I work with architects and builders to create the façade, or outer skin, of a building. Most buildings have a steel or concrete frame, plus a weatherproof layer on top. The very outer bit of that weatherproof layer – the bit that looks good – is the façade. The nice thing about my job is that I get to influence its design, form, and appearance. If an architect has an off-the-wall idea, but doesn't know how to turn it into reality, we get called in.

What's your working pattern like?

Theoretically, the hours are 9.30am to 5.30pm. But because of deadlines, we usually work much longer. A typical project might start with a meeting with the architects and client to look at various models and drawings. After whittling down various proposals, we mock them up, ending up with one or two versions. The next stage is critical: we construct a large-scale prototype, two or three storeys high, so everyone can stand back and get a perspective of what it might look like from 100m away. It either works, or it doesn't. Then it's a question of logistics – ordering materials, producing drawings for builders and overseeing construction on-site.

What do you love about it?

My favourite thing is playing a part in creating something that looks terrific. I worked on the futuristic Selfridges in Birmingham, and the New Museum of Contemporary Art in New York, which looks like a huge pile of boxes balanced on top of each other. You can stand back on a street corner, look up at an iconic 23-storey building that started as a scribble on an architect's piece of paper and think, "I did that".

What's not so greatabout it?

Dealing with people who don't care. Sometimes you get involved in projects that aren't overtly well-designed, and end up working with a team that doesn't care what the building looks like – they just want it to work. We want it to work and look terrific too. If everything was simply built to the lowest functional denominator, it would be pretty sad.

What skills do you need to do the job well?

You need to be a good engineer, to understand the principles of contemporary construction and be extremely thorough and practical. You can't design something if you don't know how to bolt it together yourself. If you're talking to a guy on a scaffold, he won't buy what you're saying if you haven't ever wielded a spanner, so it helps to have a solid background in construction. Being able to communicate well is important – you've got to be able to get your point across, whether you're talking to a room of 30 people, meeting an architect, or sitting down with a group of builders.

What advice would you give someone with their eye on your job?

The key thing is to choose the company you work with carefully – look at whether they do interesting work. Get into the technical and design department and show you're willing to roll your sleeves up and get stuck in. Ideally, you should try to get an engineering qualification and brush up your skills in computer-aided design. The days of the cigarette packet sketch are long gone, so you need to be pretty hot on computer skills. Companies look for people with an eye for good design and a fixation with all things mechanical – I used to spend hours making Meccano models as a child.

What's the salary and career path like?

Starting out in the technical department of most engineering and construction firms, you might earn about £30,000 a year. You could specialise in a particular area of construction, and work your way up through the management levels if that's what you're interested in.

Peter Rice (1935-1992)

The purpose of this post is to present Peter Rice, one of the most outstanding facade engineers ever. This great Irish engineer contributed in facades and structures disciplines with important innovations, through his involvement in projects considered icons of structures and façades nowadays.

He took on his professional career as Structural Engineer in Ove Arup  firm from 1956 to 1977, afterwards he founded his own engineering firm, partnering with Martin Francis and Ian Ritchie.

The following list is a summary of his vision:

• He believed the best buildings are the result of a symbiotic relationship between the architect and the engineer, where the engineer is the objective inventor and the architect the creative input.
• He was convinced that there was nothing mysterious about the process of innovation. He was never satisfied with mundane solutions. He took risks during the early stages of the design process.
• He combined advanced structural analysis techniques with investigations of materials in order to achieve the best structural systems.
• Peter confessed to learn just what he needed to know when he needed it.

According to Rice, the roles of the engineer are:

• The use of the engineer’s understanding of materials and structure to make real the architectural designs.
•  Innovation and support the creativity of architects.

Sydney Opera House (1973, Jorn Utzon)

Louvre Pyramid (Paris, 1988, Ming Pei)

Lloyd’s of London (London, 1986, Richard Rogers)

Stansted London Airport (1991)

Cité des Sciences at La Villette (Paris, 1987, Adrien Fainsilber)

The Centre Pompidou adopted the gerberette solution to achieve the long spans required to support a heavy library that could be moved anywhere in the building. One of Peter’s main contributions was his insistence on the use of cast steel for these pieces. The gerberette acted as a short beam propped on a circular column and tied down at the ened with a circular bar.

The curtain wall in the Cité des Sciences at La Villette has been the origin of the inexhaustible source of inspiration for the point-supported glass facades worlwide. The main innovations are set out as follows:

• Drilled glass panels with countersunk holes for point fixings supports.
• Spherical bearings keeps all loads in the glass plane and eliminate local bending effects.
• Horizontal cable trusses resists out-of-plane wind forces.

In 1992 he was awarded the Royal Gold Metal for Architecture by the Royal Institute of British Architects for his achievements which let the advancement of architecture.

In 1994, the Harvard University established the Peter Rice Prize in recognition of the ideals and principles that he represented.

After his early death, architects and engineers lost an important source of inspiration and innovation, however, actual designs are still based upon his principles described on his books, as a legacy for the future generations.

An Engineer Imagines (Peter Rice)

Structural Glass (Peter Rice&Hugh Dutton)