Rumoer 53: Structural Glass| BouT | TU Delft by RuMoer

RUM ER

Periodical P eriodical ffor or tthe he B Building uilding T Technologist echnologist

53. Structural Glass

Driebergen ~ Delft

Praktijkvereniging BouT University of Technology Delft Faculty of Architecture - 02.West.090 T E I

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RUMOER 53 March 2012 19th year of publication Praktijkvereniging BouT Room 02.West.090 Faculty of Architecture, TU Delft Julianalaan 134 2628 BL Delft The Netherlands tel: +31 (0)15 278 1292 fax: +31 (0)15 278 4178 www.PraktijkverenigingBouT.nl publications@PraktijkverenigingBout.nl Printing Sieca Repro, Delft

Circulation The RUMOER appears 3 times a year, 250 printed copies circulation. Digital versions are available online at: www.PraktijkverenigingBouT.nl Membership Amounts per calendar year (subject to change): € 10,- Students € 20,- PhD Students and alumni € 30,- Academic Staff € 80,- Companies Single copies Available at Praktijkvereniging BouT for € 7,50.

ISSN number 1567-7699 Credits Edited by: Text editing: Cover design:

RUMOER is a periodical from Praktijkvereniging BouT, student and practice association for Building Technology (AE+T), Faculty of Architecture, TU Delft (Delft University of Technology). This magazine is spread among members and relations.

Shuai Min Zhang Marieke Dijksma Marcello Soeleman Dayanara Franken Marieke Dijksma

Sponsors Praktijkvereniging BouT is still looking for (main) sponsors. Sponsors make activities possible such as study trips, symposia, lectures and much more. There is also a possibility of advertising in the RUMOER: Black & White, full page € 100,Black & White, full page, 3x (once in every edition througout one year) € 250,Full color, full page € 200,Copy Files for publication can be delivered to BouT in .doc or .indd, pictures are preferred in .png or .jpg format. Disclaimer The redaction does not take any responsibility of the photos and texts that are displayed in the magazine. Images may not be used in other media without permission of the maker. The redaction keeps the right to shorten or refuse publication without prior notification.

CONTENTS

Editorial

From the board

ABouT 7 Bucky Lab students won all three prizes

Structural glass

All glass cube

Maritime Museum

Glass entrance

Glass design innovations

Graduation Project

Attention! BouT is currently looking for new board members. The following occupations are vacant: - Editor - Website administrator

If you are interested to join or want to know more you can contact us at: info@praktijkverenigingbout.nl â&#x20AC;&#x153;

Or just come by our office:

Praktijkvereniging BouT Faculty of Architecture Cabinet 02.West.090

EDITORIAL

This edition of the Rumoer focuses on the topic of structural glass. Glass is the only available material that is durable, water- and weather proof and transparent. It has captured the fascination from the more artistic architects to the pragmatic engineers. After its discovery in the Mediterranean during classical times it has been subsequently developed further, not only for its esthetical value but for its mechanical properties as well. By using glass planes in the façades man has made it possible to view the outside world from the comfort of his dwelling. However, the disadvantage of using to many glass planes is that the space will become overheated during the summer. Students of the Bucky lab design course were assigned with the task of developing an innovative façade that addresses these problems. Their results exceeded all expectations as the TU Delft entrees won the top three prizes in this year’s façade fair. The use of glass is still being further developed for different kinds of applications as ir. Fred Veer’s explains in his introduction on the discovery and development of the material. He also briefly elaborates on the research and application of glass as structural elements. 4

Standing on the square of the historical city of Haarlem is a glass cube designed by architect Kraayvanger Urbis and developed by ABT. This magnificent object is made stable by the glass planes in the roof and its four walls. Incorporating a more freeform approach are the roof shells of the maritime museum in Lingang New City designed by Werner Sobek. The roof shells symbolize two ships that are setting sail in the harbor like configuration of the museum wings and the sculptured open spaces. Glass as part of the decor for historical buildings. For the Textile Museum in Tillburg, Cepezed collaborated with BRS structural glazing to design the entrance building that was based on the textile and processing techniques. Elegant double curved glass surfaces. Mick Eekhout discusses the cold twisting glass in order to create double curved surfaces. Several projects from his company Octatube are being highlighted as examples. And finally, this editions graduation project was done by 2 students from the Master Façade. With their topic of transforming offices into dwellings.

FROM THE BOARD

ir. Dayanara Franken A lot has been going on around the office, the last half year have been trying for us as an practice association. In the last Rumoer we mentioned that the implementation plan has had some effects on the BT department. This has resulted in the merge of the RMIT and BT department, as was mentioned before the track Hyperbody had already found a home at the BT department. I´m happy to mention that hyperBmit hasn´t become the official name for the department, but it´s with a sense of nostalgia that I mention that the BT department has changed its name into Architectural Engineering + Technology. It´s still strange to think of the BT department as anything else than that. When I joined BouT, the Building Technology track was a well-defined unit. It´s going to be a challenge to find out how BouT is going to fit in, considering that BouT is short for Building Technology. For now we plan to concentrate our efforts on the three tracks that still represent Building Technology, those three being Façade design, Green Building Innovation and Computation & Performance. For anyone wanting to read more about these implementations concerning the BT department, Marcello Soeleman wrote a very good article in the B Nieuws that pretty much represents the same concerns that

BouT as a practice association holds. The article can be found here: http://bnieuws.wordpress.com/2012/02/06/buildingtechnology-live-or-die-by-marcello-soeleman/ Another big thing that happened is that we finally managed to put closure to a prolonged dispute that was the India/Dubai excursion. Unfortunately in doing that I had to accept that BouT nearly went bankrupt. We’re alive and kicking again but the whole mess that we inherited taught us that BouT should live up to its strengths and that is to promote the relation between the Building Technology students, the BT (AE+T) department and the corresponding industry that is related to BouT. Because of the budget setback we suffered we couldn´t afford much the past six months so we kind of lost our contact with the new students inhabiting the AE/BT department so the main objective for the Events Committee will be to organize frequent excursions within the building industry where interaction between both students and building company will play a central part. I´m happy to say that our new Event board member Bart Pieters has settled well within the board and has organized some interesting events that lives up to the BouT standard, for more info and dates check the aBout pages or keep an eye out for your

mailbox where heÂ´ll invite members to participate in these excursions. If you are familiar with our association you probably noticed that last year I extended my term as chairman within the board but as tradition demands when one graduates a new Chairman (or in this case Chairwoman) takes over. The two and a half year that I was involved with BouT belongs to the best time I spent on the University. Therefore I can advise all of you to do 6

something else next to your study program. In that way you pick up a lot of experience, get to know people within and outside the faculty and of course you get a chance to expand your organization skills. That is why I am sure that my successor, Marieke Dijksma, is going to have a great time. I would like to wish her all the luck when she starts with fresh ideas and the continuation of the policy of the last years.

ABouT

Agenda March 23rd – Excursion stedelijk museum Amsterdam

March 30th till April 3rd – Excursion to Cologne

A visit to the construction site of the city museum: The high-tech design by Benthem Crouwel for the city museum is characterized by a futuristic extension with a structure that ‘floats’ above the entrance to the museum square and will be filled with a sandwich construction of twaron-and carbon hybrid fibers. The strong material is chosen because it does not react to temperature fluctuations and thus can be seamlessly executed.

BouT will be organizing an excursion to the city of Cologne with stops in Bonn and Dusseldorf. A great opportunity to visit buildings from internationally renowned architects and to meet more fellow Building Technology students.

December 11th 2011 till March 25th 2012 – The art of inhabitation The exhibition presents ideas from the Smithsons on the house: a space that the inhabitants should be able to claim as their own. In other words, inhabitants should have the freedom adapt the space of their house to accommodate their own lifestyles.

April 17th till 19th – Building Holland 2012 The building plans for the future are changing considerably, with an increasing emphasis on renovation and redevelopment, and fewer new building projects. Moreover, in a shrinking market there is only space for products and services that set themselves apart: smarter, more flexible, more efficient, more sustainable and fewer breakdown costs. Building Holland is the event where market leaders and innovators present their clever solutions and new concepts for the future. Location: RAI Amsterdam.

From left to right: Marieke Dijksma - Bart Pieters - Erik Boer - Shuai Min Zhang

New board Since february 2012, Praktijkvereniging BouT has a new chairman and her name is Marieke Dijksma. Along with the current board members and new addition Bart Pieters we are hoping to keep our readers updated with the developments within Building Technology. Three boardmembers are in their graduation year; Marieke is graduating in Architectural Engineering, Bart and Erik are in Building Technology. Shuai (Sam) is doing his MSC2 at the moment. As you might have noticed, this is not the ideal situation for a student association board. We need fresh MSC1 students! If you think you fit in this team, just drop by our office on the second floor some day. 8

Marieke Dijksma - Chairman

Erik Boer - Secretary & Treasurer

Bart Pieters - Events

Shuai Min Zhang - Publications

BUCKY LAB STUDENTS WON ALL THREE PRIZES dipl.ing. Marcel Bilow During this year’s student façade award ‘Bold and Beautiful’, that was organized during the national façade trade fair gevel2012 in Rotterdam Ahoy, the team of the TU Delft first semester master course was able to receive all three prizes.

The jury was not only asking for bold and beautiful ideas but also for ideas that show innovative-, new-, transferrable- and sustainable concepts that at the end also addresses current problems within the building envelope.

The competition was addressed to Dutch and Belgian universities to compete against each other with innovative façade prototypes that have been developed in the semester before the competition. Finally the teams from Eindhoven, Twente, Amsterdam, Leuven and the TU Delft were able to present 3 prototypes per university. So at the end 15 different projects were exhibited.

Having been successful with Bucky lab entrees in the previous award hopes and pressure were very high for us to perform well again.

The jury, consisting of Architect Nanne de Ru (Powerhouse Company), façade expert Esther Hebly (Oskomera), Designer Guido Marsille ( Buro Marsille) and author Merel Pit ( de Architect), took their time to have a closer look at each of the concepts while the students had the opportunity to explain their ideas briefly. The competition was of a very high level and, having organized this kind of award before in the history of the façade fair, it has to be said that this year’s contributions were the best of all years. All the competing universities put a lot of effort in developing and building the façade prototypes, some of them also had support from companies and sponsorships.

On the first day of the fair, the jury presented their final decision. All students from the Bucky lab were present including the 6 that were chosen by the course supervisors Peter van Swieten and Marcel Bilow to be part of the competition. Overwhelmed and also a little bit surprised the TU Delft projects were chosen for all of the three prizes. The first prize went to the thermal expansion sunshade project from Katerina Doulkari and Ka Shun Cheung that is based on a smart concept to use the sun’s radiation on the façade to activate the sunscreen. The façade consists of three areas that are connected internally and placed vertically above each other. In the bottom the parapet area, an air sealed volume containing a radiation absorbing panel and a liquid filled reservoir is embedded. In the middle zone the

transparent area is made out of two layers of glass that creates a cavity of only one millimeter between them. If the temperature rises within the parapet area the dyed liquid will rise into this cavity and cover the transparent area of the faรงade. The top area of the faรงade consists of a similar element like the bottom area to allow the overpressure to equalize. The principle is simple but effective, when the radiation from sun hits the faรงade, the temperature will rise along with the liquid within the faรงade and provide a self-regulated shading. If the temperature cools down, the sunscreen layer will also disappear.

Bucky L Fina

Ka Shun Katerin

The second prize went to the stretching sun screen, which amazed the jury to wonder why this concept has not already existed yet. Developed by Jos Noordzij and Arash Khosnevis, the basic principle of this invention was inspired by the phenomenon of a balloon that becomes more and more transparent as its volume increases during inflation. In the prototype a sunscreen textile that is powered by two tube motors can be raised and stretched to shade the faรงade completely while further stretching changes the dense and closed phase into a transparent and less shading state. The internal sun shades and other components were made possible by Somfy, Verosol and De Groot en Visser. The third price was received by Marius Otte and Christopher Koster for their particle sun shade concept. Within a wooden faรงade element covered with EFTE cushions a smoke generator is able to block the transparency and therefore create a sunscreen. When filled with smoke, a set of LED lights can also illuminate the space and create a glowing impression on the faรงade. The whole team from the Bucky lab is very proud of this huge success, which also illustrates that the way the course is set up and supervised worked out. The students not only build wonderful concepts but were also able to address the background information, to convince the jury that this idea is proper development for a new faรงade solution. An exhibition in the Why Factory will be opened on the 13th of March to present the winning concepts and also the rest of the total 13 prototypes built in the last semester. So please feel invited and have a look. More information about the concepts can also be found on www.imagineblog.tumblr.com The Bucky lab course will change a little bit, in the future we will build fewer but bigger prototypes and the whole lab will become mobile, we will write more about these developments in the next issues of Rumoer. 13

STRUCTURAL GLASS

dr.ir. Fred Veer Glass is the only durable, water and weather proof transparent material that we have. The simple word glass is misleading in that glass is a large family of materials. What most people call glass is what is more exactly named soda-lime glass. As Pliny the elder in De RE NATURARI wrote, glass was invented by the Phoenicians. Ancient ship faring merchant transporting among others natural soda, a mineral used for mummification, around the Mediterranean world. One night when barbecuing on a beach they used soda blocks to support the spit. In the morning, they found little pieces of glass where the fire had heated a combination of sand, soda and chalk (sea shells). As good merchants they collected these and sold them as jewels. Centuries later glass making became a craft in Syria and slowly diffused around the roman world. This glass was used for cups, plates, jars and other items. Until the invention of fining agents transparent glass was rare. Fining agents clean the molten glass binding impurities, leaving the glass transparent. The first use of glass in windows was by the romans around 58 BC. Pliny wrote the following description of a theatre: “The lowest storey of the stage was of marble,

and the middle one of glass, an extravagance unparalleled even in later times.” This glass is likely to have been translucent and not transparent. Unfortunately no glass windows survive from this period, only some fragments. Modern reconstructions of roman glass windows survived. The poor quality of this glass by modern standards is misleading as it was the ultimate and most expensive material in its time. There was little improvement in glass technique until the late middle ages. In Venice the famous glass centre on the island of Murano was a centre of development. Glass from here was unparalled in quality. Glass plates were used by royalty to entertain guests as they were more expensive than gold plates. How the glass was processed was a state secret. Any glass blower who betrayed the secrets was executed, usually in an exemplary way “pour encourager les autres”. High quality glass manufacture was a venetian monopoly until Louis the XIV built the palace of Versailles. When the famous hall of mirrors was designed the Sun King asked for venetian mirrors, but even he balked at the price, deciding to manufacture them in France.

The investment in technology paid for itself and spread throughout Europe. Scientist like Anthony van Leeuwenhoek in Delft did a lot to improve glass recipes and processing. The price of glass went down but it was still a luxury material. Houses with large windows were a sign of wealth. The great orangeries were a sign of opulence. The industrial revolution led to an enormous increase in manufacturing. This also affected glass production with the first glass drawing processes being developed in the mining and steel districts of southern Belgium. The drawing processes increased the size of windows while significantly lowering the cost. While late 18th century technology had problems manufacturing glass windows less than a square meter, the drawing process made it possible to produce single pieces of glass of 1.5 m wide and 2 or 3 meters long. The quality was not what we have today as the glass had stripes from the drawing process. The decrease in cost and increase in production volume made it possible to build the great 19th century Crystal Palace. As the glass was mounted using rigid putty it actually was providing the in plane stability and was thus structural in one sense of the word.

Figure 1: Fragments of early roman window. Figure 1. Fragments of early Roman window

Figure 1: Fragments of early roman window.

Further improvements in technology decreased the glass price and made larger scale use of glass possible. There was however little development in glass structures, the great fire of the Crystal Palace showed the danger of this type of structure while falling glass from numerous passages underline the dangers of the material. Although the invention of the float glass process in the 1950’s increased the size and the quality of the glass available while decreasing the cost this did not directly lead to an innovation in architecture until Peter Rice made his design for the glass serres of the Cité des Sciences et de l’Industrie. This structure worked

Figure 2. Reproduction of a Roman window

Figure 3: 18th century orangerie as an inspiration for many designers resulting in an explosion of glass structures and systems. Impressive as Peter Rice’s work was, it was limited as the glass was only used in compression. The strength of glass in compression is much higher than in tension. However, development of glass structures was limited for a number of reasons; there were no standards for structural glass design and there was an insufficient body of knowledge about the material. In itself this is historically comparable to steel and concrete which needed decades of experimentation and practice before design rules were codified and standardised steels and concretes such as (ST37, FE 360) S235) or B30 were formulated. Glass as a structural material In the past 3 decades there has been a lot of research into the structural role of glass as a structural material and there has been a lot of building of structures where the glass has increased its structural role. Critical have been the developments in laminating glass. Laminating car window glass has been sued to provide passenger safety for a long time. Using glass laminates in architecture has allowed structural engineers to use lamination techniques to build in safety. This by dividing the glass into panels, if one panel fails the others can still carry a load. The glass research group of Delft University has played a role in this. If you check the number of Delft University papers on glassfiles.com you get a picture of the relative contribution. The PhD researches of Freek Bos and Chris Louter, available on internet, are certainly unique and world leading. Additionally some 50 students have made a contribution doing their MSC thesis work in building technology or civil engineering. This has resulted in a more clear view of the possibilities of glass as a structural material. Table 1 summarizes some important points. In terms of compressive strength and young’s modulus glass seem to be more metal like. In terms of fracture strain it 16

Figure 4: Crystal palace Figure 3. Crystal Palace

Figure 4. Cité des Sciences et de l’Industrie

looks like concrete. Looking at the typical shape, large plates, people think of it as a metal. It is dangerous to look at glass with preconceptions. The nature of glass with a greater strength in compression than in tension means that our reference material is ultra-high strength concrete, the differences is that glass is not poured into a mould; we have to assemble it from layers (sheets cut to size). The second critical part is the hardness. Glass is both hard and brittle. Drilling into it is difficult and costly. More important, the material is easily damaged which leads to high stress concentrations. Glass with holes needs to be tempered which makes it more sensitive to impact damage. The simple answer is to adhesively bond glass. Modern adhesives have shear strengths of 20 MPa. A properly designed detail can thus be very strong.

These design principles have used in the combined architecture/civil engineering minor, ‘Bend and Break’. This has a structural glass project where students are taught the basics of structural glass design. Glass bridge In 2011 as part of the minor ‘Bend and Break’ a glass bridge was build. This was made of water jet cut annealed glass using adhesive and bolt connections. Several important innovations were tried including lead as an intermediary between glass plates to transmit compression forces and a hinged stainless steel tensile connection using bolts and adhesives.

Table 1: Comparison of properties Material

Young’s modulus (GPa)

Yield strength in tension (MPa)

Yield Fracture Hardnes strength in strain (%) s (Hv) compression (MPa)

S235 steel

210

235

100

Annealed glass

200

500

Heat strengthed glass

200

500

Fully tempered glass

100

200

500

B80 concrete

Al 1010

100

Table 1. Comparison of properties

Glass tower In 2012 as part of the minor ‘Bend and Break’, a glass tower was build. This uses a new design of glass Iprofiles for columns with laminated glass floors and diagonals. Glass carries tensile and compressive forces while there are bending stresses in the glass plates because the columns are not in the same line. The elements are joined using a minimalistic stainless steel joint. Summary The use of glass as a structural material has made significant progress in the last decades. Glass structures are possible if you use the right rules. Using these rules several prototype structures have been made.

Figure 5. Glass bridge

Figure 6: Glass bridge

Figure 6. Glass bridge detail in compression zone

Figure 7: Glass bridge detail in compression zone

Fred Veer is a full time tenured assistant professor of materials science at the Faculty of Architecture of Delft University of Technology since 1994. He is the responsible researcher for materials science in the faculty. Since 1996 he has been a co-ordinator of a personal research laboratory with a continuous population of 4 to 6 undergraduate students working on glass research. In total over 20 students have graduated working on this project. Figure 7.â&#x20AC;&#x201A; Glass tower

Since 1988 Veer has been the main author of over 40 papers on the mechanical behaviour of materials and co-author of over 20 other papers.

Figure 8: Glass tower.

Figure 8.â&#x20AC;&#x201A; Glass tower connection detail

ALL GLASS CUBE a transparent cube in the middle of the city Rob Nijsse & Ronald Wenting On a square in the historic city center of Haarlem in the Netherlands on top of an underground car park a fully glass entrance building was designed by architect Kraayvanger Urbis.ABT developed the glass structure for this spectacular building. The fact that the stability was provided by the glass panels in the roof in combination with the glass panels in the four walls of the cube makes it something special. Also the application of full glass rods in the structure of the roof is an innovation in the world of making glass structures. Surrounded by new stores, new apartments, office buildings, leisure facilities, pubs and an old church at the back, the glass cube rises on top of an underground car park (capacity for 1.000 cars) on the new Raakssquare in Haarlem. The whole area is part of a new urban development close to the historic city center. It’s presence on the square betrays the underground car park beneath the square. People parking their car in the car park are coming up by the elevator in the cube or by the stairs on the side. They are walking from the ‘dark’ underground world to the daylight above. Once they are above the ground, they are standing in the middle of the square. Despite his transparent appearance the cube is a real

eyecatcher on the square and because of the function of entrancebuilding there is a lot of movement in and around the cube. This makes the cube an attractive object on the square and his presence creates a lively atmosphere. Glass structure The dimensions of the glass cube are 7.05x7.05x7.05 meters. ABT designed this cube structurally with the following glass elements: four glass walls forming the façades, each composed of 9 glass panels of 2.35 square meter, and the glass roof, also made from 9 glass panels of 2.35x2.35 meter. The glass panels in the roof consists of 2 heat strengthened glass panels with each a glass thickness of 12mm (clear glass thickness11,7mm) laminated by 2 PVB-foils (total glass 12.12.2). The glass panels in the façades are formed of laminated heat strengthened glass with a glass composition of 10.8.2. The glass walls of the façades are strengthened in order to take up the wind load and to take up the loads out of the roofstructure by 2 vertical glass fins of 7 meter long and 450 mm width in each glass wall. The glass fins are also made out of laminated tempered glass with a glass composition of 12.12.12.2.

Figure 1.â&#x20AC;&#x201A; Glass cube at Raaks Square at dusk - source: http://www.architectuurfotografie.com/?p=1082

Glass roof The glass panels on the roof of the glass cube are supthe connection between the glass and the steel eleported by a slender stainless steel rectangular hollow ments since bending moments in the glass rod would section (RHS 140*80) stiffened by a cable suspension “kill” this glass element immediately. So that’s why it’s in both directions of the roof. This undertensioned so important the glass rod would only be loaded by structure is formed by a steel cable with a diameter a centric pressure force in the combination of forces of 8mm and a glass rod with a diameter of 30mm and in the undertensioned beam. Just for indication: the a length of 400mm. These composed hybrid beams stresses in the glass rod are about 15 N/mm2 in the are supported by the glass façade fins. In this way the ultimate limit state. design of the roofbeams fits with the cable suspension in the façade and its presence is as slender as Glass façade possible. In the calculation of the slender beams the The four glass walls of the façades are standing on top failure of the glass rod is taken in consideration. In that of a concrete plinth covered by tiles of natural stone. By case the rectangular hollow section (RHS 140*80) will lifting the glass cube a little bit the glass panels at the be strong enough to carry the loads on the roof. The bottom are better protected for breaking caused by any deformations of the roof will increase when that hapaction of streetlife. The structure for the four façades is pens, but the roof will not collapse. the same for all the glass walls: the glass panels are In the first design of the cube the glass panels in the standing on top of each other and are supported in roof were supported by glass beams so the cube would the middle by two glass fins. For stabilizing the glass be an all glass structure, but because of the complex fins a cable suspension is connecting the middle of 2.2.2 Glass rod in the roofstructure meeting of the glass roof beams with the glass façade fins andThe to reduce costs, these glass beams have glass rod in the undertensioned roof been beam is a replaced by theglass undertensioned steel Unfor- glass and massive cylinder made outbeams. of borosilicate tunately, this place the roof some steel is added,glass is a is at delivered by inSchott Germany. Borosilicate but by type usingof a glass glass element is integlass rod, withanother the main glass-forming constituents gratedsilica in theand finalboron design. The glass panels glasses in the roof oxide. Borosilicate are known for are connected to each so theyof can act together having very low other coefficients thermal expansion, as a stiff plane them for stabilizing glass cube. Themore roof than making resistantthe to thermal shock, common glass.with Such glass for is commonly used of the cube is made a slope transporting thefor the construction of reagent bottles. rainwater from the roof to the façade.

A close-up of the detail of the glass rod in the roof is

The glass rod undertensioned a paid given at in thethe photo in figure 4. Inroof thebeam detailisABT massive glass attention cylinder made out aofclear borosilicate special to create hinge inglass the connection and is delivered by Schott Germany. Borosilicate between the glass and the steel elements glass since bending is a type of glass the main glass-forming moments in with the glass rod would “kill” thisconglass element stituents silica and boron oxide. glasses immediately. So that’s whyBorosilicate it’s so important the glass rod would be loaded a centric pressure force in the are known foronly having very lowbycoefficients of thermal combination forces in the to undertensioned beam. Just expansion, making of them resistant thermal shock, for indication: the stresses in the glass rod are more than common glass. Such glass is commonly about 15 2 N/mm in the ultimate limitbottles. state. In the detail used for the construction of reagent ABT paid special attention to create a clear hinge in Fig. 4: Close-up glass rod Figure 2. Close-up of glass rod 22

2.3

Glass facade

The 4 glass walls of the facades are standing on top of a concrete plinth covered by tiles of natural

inconspicuous as possible. Those different point of views results i the arch coll All des goo stru

Fur cub with ske We slen whe eac bolt sup can is c Fig. 6: Design “crossdetail” glass cube the backside of the glass fin with the stiff corners of sible impact. The slope in the roof makes the meas- the the glass cube. The connection of the glass panels in urements of the glass panels in the upper layer of the the corner and the cable suspension is made by using glass cube all different from each other. Also the main cov a small steel connector. This is the only place in the entrance in the south façade of the cube makes this cube where the glass is connected with a point-fixing. façade different from the other façades. The entrance dim To protect the edges of the glass panels on the corners is integrated quite easy in the cubedesign by replac- hole of the glass cube a stainless steel hollow section of ing one glass panel in the middle of the south façade 25*25*3mm is integrated in the design to avoid posby glass sliding doors. Since the glass panels in the thro betw 23 and Figure 3. Design ‘crossdetail’ glass cube

Fig. 6: Design “crossdetail” glass cube walls are stacked on each other and are stabilizing the glass cube from a structural point of view this was not that easy to incorporate in the structural design of the cube. By incorporating a frame made out of stainless steel of hollow section of 25*25*3mm at the entrance door it is possible to spread the forces around the door to the foundation. This profile also protects the edges of the glass at the entrance like they do at the corners of the glass cube (figure 7). The biggest challenge in the design process of the cube was optimizing the connections and the interaction between the glass and steel elements. From a structural point of view the stresses in the glass panels are the highest in the connecting points, and the structure asks for a good detail to transport the forces through the glass panels. On the other hand, from an esthetical point of view, it is necessary to minimize the dimensions of the steel in the connections to make the connection look as inconspicuous as possible. Those different points of view result in contradictory requirements for the connections and challenges the architect and the engineer to collaborate for an optimum solution. All the details of the glass cube are designed in such a way that there is a good balance in the esthetical and structural aspects of the detail. Furthermore the connections in the cube are designed as much as possible with the same principal solution. We designed a detail composed of slender steel ‘crosses’ in the joints, where the glass panels corners meet each other, in combination with the bolted connections with the glass fins supporting the walls. The glass panelscan be stacked on a steel cross which is covered with neoprene strips. To fix the glass panels, the steel cross is covered with stainless steelplates with dimensions 200mm*200mm with holes in it for the countersunked bolts through the glass panels. The space between the glass hole for the bolts and the bolts is injected by Hilti Hit HY70. This is an injectable mortar with a high compression strength. By injecting the mortar in the

Figure 4. ‘Crossdetail’ glass cube Fig. 7: Photo “crossdetail” glass cube

glass holes the forces in the glass panels are trans-

is th co di ho th be an H w in th tra an co tra th re pr us th cr ho an w pr 25

In case of abetween broken glass panelpanels the stainless steel plates at the sid ferred the glass and the steelplates and the broken glass panel can be taken away. The glass at the edge of this connection. This force will also bepanel a a wing of the steel cross in the heart of this connection so additio transferred by the friction between these steelplates and glass panels as a result of prestressing the bolts. The principal of this connection is used for the details in the façade and for those in the roof as well. In the roof the steel crosses are welded to the rectangular hollow sections profiles of the roof and in the corner the steel crosses are welded to the stainless steel corner profile (hollow section of 25*25*3mm). In case of a broken glass panel the stainless steel plates at the side of the connection can be removed and the broken glass panel can be taken away. The glass panel above the broken panel is carried by a wing of the steel cross in the heart of this connection so additional supports are not necessary.

2.3.3 Stability facade 2.3.2 stability Glass in theby facade Overall is fins provided the in plane action of each façade. So the 9 individual In the middle of the glass cube the glass plates are panels of glass have to work together to supported perpendicular to the plane by the glass fins. These fins are 7 meters long and have a width become one structural wall. This means that of 450mm. To avoid difficult connections halfway the connecting details should be able to the glass fins, at the place where the biggest bending transport the compression and the tensile moments are located, the fins are made out of 1 forces caused by the actions of the wind. For piece. Because the 7,0 meter length it was necessary this purpose the details with the slender steel “crosses” in the joints have an important role. to produce the fins in China. We made finite elements computer Beside supporting the façade panels the glass fins calculations of this connected together kit of function as columns for the roofstructure. Herefore parts composing a structural wall in order to the steel beams of the roof are put with an extended check the stresses called up in the glass and steel box with an opening below on top of the glass the connecting detail. Figure 9 shows the fins and are connected with only one bolt to be sure stress trajectories in the planes of the façades the load will be introduced in a centric way in the caused by the wind load. You can see the way glass fin. This principal is also used for the the pressure (blue lines) and tensile (red forces) connection with the foundation. forces are running through the façade planes One problem had to be solved. The 7 meter long and find their way to the foundation. By connecting the glass plates as described a stiff monolithic glass fins with a depth/span ratio of 1 to presents serious buckling problems especially if plane The maximum deformations 16Fig. Figureis 5. created. Glass fins in the façade Figure 6. Stress in the façade 9: Stress trajectories in theglass glass facade the glass façade istrajectories pushed outside due to the wind due to wind loads are less than 1 millimeter. pulling at it. We solved this by attaching halfway the In the middle of the glass cube the glass plates are span of ing7atmeter it. Thisa was solved by attaching a cablea support cable support that presents stable supported perpendicular to the plane by the glass point halfway which presents a stable point to the fin. to the glass fin. By halving the span the glass critical fins. These fins are 7 meters high and have a width buckling By halving the span the critical buckling force went force went down a factor 4. The architect of 450mm. To avoid difficult connections halfway the considered down athese factorsupporting 4. The architect considered these supcables in the façade glass fins, at the place where the biggest bending porting cables in the façade walls to be ‘related’ to the walls to be “related” to the cable forming the moments are located, the fins are made out of one cable forming the suspension of the roof beams and suspension of the roof beams and was happy with it. piece. Because the 7 meter length it was necessary was happy with it. 8: Glass façadeof thesupporting glass toFig. produce thefins finsininthe China. Beside the cube façade panels the glass fins function as columns for the roofstructure. Therefore the steel beams of the roof are put on top of the glass fins and are connected with 2.3.3 only one bolt Stability to be sure facade the load will be introduced in a centric waystability in the glass fin. This principle is also used Overall is provided by the in plane for the connection with theSo foundation. action of each façade. the 9 individual One problem hadhave to betosolved. The 7 meter panels of glass work together to long monolithic glass fins with a depth/span ratio of that 1 to 16 become one structural wall. This means presents serious buckling problems especially the connecting details should be able to if the glass façadethe is compression pushed outsideand duethe to the wind pulltransport tensile

forces caused by the actions of the wind. For this purpose the details with the slender steel “crosses” in the joints have an important role. We made finite elements computer

Overall stability is provided by the in plane action of each façade. So the 9 individual panels of glass have to work together to become one structural wall. This means that the connecting details should be able to transport the compression and the tensile forces caused by the actions of the wind. For this purpose the details with the slender steel “crosses” in the joints have an important role. We made finite elements computer calculations of these connected parts composing a structural wall in order to check the stresses in the glass

and the connecting detail. Figure 6 shows the stress trajectories in the planes of the façades caused by the wind load. You can see the way the pressure and tensile forces are running through the façade planes and find their way to the foundation. By connecting the glass plates as described a stiff plane is created. The maximum deformations due to wind loads are less than 1 millimeter.

client: MAB development architectural design: Kraayvanger Urbis structural design: ABT bv glass supplier: Alverre bv

ABT is a multi-disciplinary consultancy firm in structural engineering with locations in Velp and Delft in the Netherlands and in Antwerp, Belgium. ABT has a staff of more than two hundred, working in the consultancy groups Structural Engineering, Architectural Engineering, Construction Management, Civil Engineering and Installations. Both separately and jointly, these groups provide integral advice for projects at every level of scale.

Vandalistic behaviour Since the glass cube stands on a square in the heart of the city a lot of possible vandals are likely to pass the glass structure. Detailing of the glass panels should be in such a way that each glass panel, either in the roof or in the façades, should be replacable. This is why every glass panel can be shifted out of the cube. The glass panel behaviour may not result in an unstable 3.broken Vandalistic structure since the glass panels provide overall staSince glasswas cube stands onthing a square inwith the heart of the city a lot of possible vandals are likely to bility. Thisthe aspect an important to deal pass the glass structure. So detailing of the glass panels should be in such a way that each glass while detailing the design of the glass cube. To reduce panel, either in the roof or in the facades, should be replacable. This is why every glass panel can be the effect of vandalistic behaviour even more we proshifted out of the cube. The broken glass panel may not result in an unstable structure since the tected the edges of the glass panels on the corners of glass the glass cubeprovide by a stainless hollowThis section panels overallsteel stability. aspect was an important thing to deal with while of detailing 25*25*3mm. little profile plays a role in the theThis design of thealso glass cube. transportation of the horizontal forces of stability.

To reduce even more the effect of vandalistic behaviour we protected the edges of the glass panels on the corners of the glass cube by a stainless steel hollow section of 25*25*3mm. This little profile plays also a role in the transportation of the horizontal forces of stability.

Rob Nijsse (1953) is professor Structural Design, and he works as an engineer at ABT. His focus lies with the use of composites in the building industry and the application of glass as a structural member within a construction.

Figure 7. Small stainless steel profile the corners Fig. 10: Little stainless steelat profile

at the corner of the glass cube 26

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MARITIME MUSEUM

Lingang New City, China Werner Sobek Among the many new towns in China, Lingang New City is probably the one with the most exceptional design history and urban layout. Inspired by a drop hitting the water’s surface and causing ripples, Meinhard von Gerkan’s (gmp Architekten) design for the town, 60 km south of Shanghai for 800 000 people, is being built entirely on reclaimed land. Water plays a pivotal role in every sense in the urban scheme. The centre of the town is marked by a huge artificial lake covering 8 km², thus creating the paradox of what one might call an “empty” centre. It therefore does not come as a surprise to learn that China’s first National Maritime Museum is one of the first buildings to be realized in Lingang New City, a town literally built on water. Maritime Museum The rectilinear and symmetrical layout of the Maritime Museum is situated directly adjacent to the large central lake. The museum is organized around a raised plaza, beneath which all the functions are accommodated. In the centre of the museum, towering above the plaza, two 58 m tall roof shells lean against each other, touching at one point only, approx. 40 m above ground. The triangular roof structure was designed as two layers of gridshells that are connected by a series of diagonals, thus creating a spatial structure. The two base points of each triangular “sail” are approx. 70 m apart. A pretensioned cable-net structure clad in glass 28

forms the façade. The analogy of two huge “sails” befits the nature of the museum as well as that of the city of Lingang with its harbour. Symbolically, two ships are setting sail in the harbour-like configuration of the museum wings and the sculptured open spaces. The maritime-inspired roof shells transform the museum into a landmark that is visible from miles away. Form-finding Without doubt the project’s structural challenge was the design and structural form-finding of the expressive roof shapes. The architect’s vision of very slender and pointed edges for the two leaning roofs had to be translated into a structural solution. A form-finding process was therefore used during the concept phase in order to create the shape of the roof structure within the given boundary edges. A sail under constant internal pressure and constant stress was simulated with the help of a three-dimensional finite element membrane model. The geometry derived is identical to the shape of a soap film that spans between solid edges while being inflated. By calibrating the interior pressure load in the analysis model, this geometry was shaped as closely as possible to the original architectural form. The final form that has been found is a natural shape. The two halves of the roof structure are only supported at their common apex and along the curved base of the side façade. Therefore, the structure requires a certain

Figure 1.â&#x20AC;&#x201A; Maritime Museum

Figure 2.â&#x20AC;&#x201A; Glass faĂ§ade

bending stiffness to transfer the loads to these points. By increasing the interior pressure in the analysis model in yet another form-finding process, a second surface was created at a certain distance from the inner surface. The two surfaces form a double-leaf enclosure and define the space available for the structure. Their maximum spacing is 3.60 m.

Structure of the sails The roof structure is designed as two gridshell layers that are connected by a series of diagonals to form a spatial structure. Diagonals are also placed within the gridshell surfaces. Along the edges, or at distinct locations, stiffening beams are required within the shell.

Figure 3. Glass façade

These beams were finally realized as a mixture of steel truss elements with stiffening steel plates in a triangular fashion in order to achieve the slim roof edges desired by the architect. Steel has been chosen as the preferred material for this type of structure due to its relatively low weight and high stiffness. The reduction in the dead load is always a priority, especially when designing structures in earthquake regions. Low weight also reduces the cost of materials and of erection. And the use of pre-

fabricated elements speeds up the erection process significantly. The rectangular grid for the beams is laid out with a 2.50 m spacing. The actual position of each beam is determined such that the rectangular grid, which is located in a plane defined by the three corner points of a “sail”, is projected onto the two “sail” surfaces determined by the form-finding process. The advantage of this method is that every crescent-shaped beam is curved in one direction only, which makes it feasible

to construct each beam individually as a flat element. Moreover, all connections are located in planes that are perpendicular to one another. All posts within the beams are kept parallel. All assembly points are also parallel, which was a great benefit during erection. The trusses were prefabricated with shop-welded joints and assembled to form larger units on site. Connections were welded on site – the preferred method of the Chinese contractors.

The cladding consists of 10 mm aluminium honeycomb panels in double curvature with a spray-on polyurethane insulation and waterproofing layer underneath which was applied to a trapezoidal metal substructure. Joints between the white aluminium panels are sealed by elastic gaskets in order to protect the foam from UV radiation. Glass façades The façades are highly transparent. They thus create on the one hand a spectacular atmosphere in the interior and on the other hand, they minimize the visual barrier between the museum’s interior and its surroundings. For this reason and due to the given edge geometry, a pretensioned cable-net structure was chosen for the façade. The insulated glass elements are clamped to the cable net to form the building envelope. The outer pane consists of 8 mm toughened glass, the inner pane of laminated glass comprising two panes of 8 mm toughened glass. Between the outer and the inner panes there is a low-e 12 mm argon-filled cavity. Another form-finding process was chosen in order to derive the structural shape for the façade: a two-way cable net forms an anticlastic (negative Gaussian curvature) surface where the cable forces are in equilibrium. This can be compared to a membrane that is stretched across given boundaries. The resulting

Figure 4. Structure of the ‘sails’

Figure 5. The structure in layers

shape forms an elegant transition between the two roof shells and corresponds to the thematic concept of the Maritime Museum. Edge beams to carry the loads from the cables are integrated into the roof structure. The cable net – typically 24 mm dia. open spiral strand cables in the horizontal direction and 32 mm dia. open spiral strand cables in the vertical direction – was chosen to be of approx. 0.90 m meshsize. This enables relatively lightweight glazing elements, that can adapt well to deformation of the net. The size of the cable mesh also allows for good access during construction. The net design employs single cables that are prestressed to withstand the loads. The ratio of prestress between vertical and horizontal cables is approx. 3:1 in order to achieve the desired shape and curvature. The vertical cables are located outside of the horizontal cables. The forces from the curvature are thus in equilibrium at the connection detail. The detailing is such that the cables are connected with a pin that allows for unrestricted rotation and adaptation to changing angles. The cables are anchored to the concrete foundation and the ‘sail’ structure at the base of the surrounding edges. A three-point truss is integrated into the shell structure along the curved edge of the cable net. This truss accommodates the tension forces from the cable net. The side façades are an integral part of the overall structure. The posts are used as loadbearing columns for the “sail”. Due to the curved arrangement on plan and the inclined edge beam, a certain stiffness against rotation of the “sail” is achieved. The moment that is generated, e.g. from wind loads on the broad side of the building, induces high axial loads in the posts. The connections between posts and edge beams are bolted, with minimum tolerance between bolt and hole.

Loading Due to the proximity to the open sea, wind loads were the most significant loads in the design of the Maritime Museum. Additionally, the extraordinary shape and configuration of the building meant that the building was not covered by any codes. It was expected that the large overhangs would be subjected to high pressure and suction loads. In order to achieve a reliable basis for the design, the building loads were determined in a wind tunnel test carried out by the Tongji University of Shanghai. A time-history analysis was performed to determine the response of the structure. Moreover, Tongij University built mock-ups of the steel connections and the cable-net façade for testing and analysis. Conclusion The Maritime Museum in the centre of Lingang New City turned out to be both an exceptional piece of architecture and a remarkable piece of engineering. As with a number of other great buildings, the transition from architectural to engineering led design is barely perceptible. The end result is a construction of great sophistication that easily fulfils the need for a potent symbol in Lingang New City. The bold and dynamic shape of the two soaring “sails” embodies the idea of the Maritime Museum within their elegant form and silhouette.

Authors: Dipl.-Ing. Arch. Nikolaus Goetze Prof. Dr.-Ing. E.H. Werner Sobek Dipl.-Ing. Frank Tarazi Christian Brensing

Werner Sobek stands throughout the world for engineering, design and sustainability. The firm has offices in Stuttgart, Cairo, Dubai, Frankfurt, Istanbul, Moscow, New York and São Paulo. The work of Werner Sobek is defined by premium design on the basis of highclass engineering combined with sophisticated green technologies. Founded in 1992, the studio has now more than 200 employees. Owner of the firm is Prof. Dr. Werner Sobek. Special emphasis lies on lightweight load-bearing structures, highrise buildings and transparent façade systems. Another focus of the activities of Werner Sobek are special structures in steel, glass, titanium, textiles and wood as well as advanced concepts for sustainable buildings.

Figure 6. Crosspoint detail

GLASS ENTRANCE square glass panels, clamped at two corners

This article is composed of several articles regarding BRS Group’s entry for the Dutch National Steel Prize, with the approval of BRS Group. The reference articles are summed up at the end of this article.

Marieke Dijksma The Textile Museum in Tilburg is located in a former wool-factory. The Delft-based architectural practice cepezed was commissioned to design an new entrance building plus an archives depot, which were realized in 2008. In addition to the museum, the former industrial complex houses a textile shop, a textile laboratory and a textile academy. Textile related activities thus form the core of the complex’ program. That extends into the new entrance building, an abstract glass cube where innovative use has been made of textiles and processing techniques, even if this is not immediately apparent. The rear wall of the entrance building is a fullheight double ‘installation’ wall. Cepezed covered the wall with a silver-colored, stretched and open-weave batyline fabric. The meeting rooms are equipped with a solar shading system of knitted slats, which were produced in the museum itself. Cepezed’s batyline fabric was also used for the ceilings in the meeting rooms and on the underside of the overhead bridges in the entrance building.1 The\ existing factory building is listed as a monument and stems from the heyday of the textile industry: firm buildings from the late nineteenth century with arched windows and ornamental masonry. The new entrance building is in great contrast with this old factory.2

Transparency was an important consideration in the design. The historical building should be as visible as possible through the new structure. This is reached by using the structural properties of glass and eliminating as many steel load bearing elements as possible. This resulted in a structure of relatively large glass panels (2400 x 2400 mm), visually divided in triangles by tension bars. The glass panels are only clamped on two opposite corners by a steel knot, the two other corners have no load-bearing support from the steel structure. This was made possible by only allowing a tolerance on the steel of just 2 mm, while a tolerance of 20 mm is typical for such a construction. By using a 2 mm tolerance, the glass supports could be welded to the steel without the use of a third component. The two clamped corners each have four fixation points; two directly at the corner, and two at a small distance from the corner, which creates a structural couple. The spacer within the glass panel is reinforced to be able to deal with the pressure of the clamped joint. The panels at the sides are made of 12 mm tempered glass. The panels in the middle consist of two layers of 6 mm tempered and laminated glass.

Figure 1.â&#x20AC;&#x201A; Textile Museum entrance

Isolating, sunshading and structural glass

Halved IPE-profile

Clamp

Convector with integrated LED-lights

Steel tube

Figure 2. Section

The load-bearing structure consists of diagonal tubes with half-length tubes welded perpendicular to them. The tubes are connected by half joints, while the bolts are not in sight because of an internal bolt connection in the middle of the tube sections. Aluminum covers make sure that the structure is slim and sleek. All tubes serve as tension bars, but the structure in the corners of the building is slightly different. The diagonal structure is continued, without the use of columns. However, it is not possible to have tension bars in a corner. The bars are there, but only to provide for an extra fixing point, not to serve as a tension bar. 3 At the roof, the glass façade continues in the roof surface for the width of one panel. The largest part of the roof is non-transparent though, mostly to limit the required amount of cooling. However, the diagonal structure does continue under the entire roof surface. The tubes in the roof should have had bigger dimensions than the ones in the façade, but this is aesthetically speaking not desired. The problem was solved by welding a steel T-profile on top of every horizontal tube. This invisible solution structurally strengthened the tubes while providing a good shape to apply the roof cladding.

Within the glass cube, a second volume is placed on columns, thereby keeping the ground floor as an open space. The entrance area connects to the existing buildings at two sides. The short side gives access to the historical hall of the museum. The floor heigth of this part of the existing building was leading for the floor height of the inner volume, which connects to this part by bridges. Because of a limited height, the airducts had to be placed in a thickened wall. The long side attaches to a blind wall, where installations are placed. There is also room for stabilizing structural elements, but these could be limited because the steel structure is stabalized sufficiently already. The stabilizing elements thus mainly serve the inner volume.3 The museum shows different textile techniques in multiple ways. The airducts are covered with white textile cloths, the railing at the stairs have a fall prevention of braided steel wires and applied textile artworks can be found through the whole building. The modern glass entrance shows that textile has nothing to do with the definition of dusty and dull.4

Figure 3.â&#x20AC;&#x201A; Corner view

Figure 4.â&#x20AC;&#x201A; Connection of halved tubes

1 Batyline fabric and knitted slats in ‘A10 – new European architecture’ 2010 #34 page 54 2 Entreegebouw Audax textielmuseum | Nominatie in ‘Bouwen met Staal’ 2010 #217 page 51 3 Glazen entree met diagonale staalconstructie in ‘Bouwwereld’ 2008 #10 page 10-13 4 Textielmuseum en Regionaal Archief Tilburg in ‘ArchitectuurNL’ 2008 #6 page 30-35

client: Municipality of Tilburg architectural design: cepezed structural design: BRS Structural Glazing

The BRS Group designs, produces and constructs innovative steel and glass structures. The commissions are very diverse and their fields of activity are not limited to just one specialism. Their customers are municipalities, architects, contractors and the government, from the construction industry and civil engineering. Because of extensive knowledge and solution oriented capabilities they can find technical solutions that turn out well during the realisation phase.

Figure 5. Transition of façade-plane to roof-plane

GLASS DESIGN INNOVATIONS by using Cold Twisting technologies Prof.dr.ir. Mick Eekhout Developments in Free Form Technology After the Zappi quest the Free Form or Blob technology appeared to be interesting to involve to technical design skills of Delft engineers. Both on the TU Delft as well as in Octatube a number of projects were performed that extended the state of the art of glass in architecture. PhD student Karel Vollers received his doctorate in 2001 on his dissertation ‘Twist & Build’ on the urban and architectural design of twisted buildings. He developed the necessary building technical tools for twisted buildings. Amongst these are the urban design and architectural design implications, but also the building technical compositions, the physical deformations. He researched and developed into material specifications of casting in deformed moulds or deforming flat plates, the production engineering of hot deformed / twisted glass and the window details belonging to this engineering. After these technical research and developments he went back to architectural design and designed architectural applications of twisted buildings. Prominent architects have designed twisted buildings after the publications of dr. Vollers in 2001, without giving him the credits, like one is used to see in architecture: citations without references. One famous example of such an inspiration is Santiago Calatrava’s design for the ‘Turning Torso’ in

Malmö. In my eyes dr. Karel Vollers is the godfather of twisted building around the world. Many architects made beautiful designs of twisted buildings after his publications. Karel Vollers continued his research work in hot deformation of glass panels with an industrially usable mould. The mould exists of mechanically adjustable pins with a flat, rotating surface and a device to smoothen the surface the tops describe. So that, together with a heat resistant glass fiber mat a temporary surface is made to pace the hot glass pane on top before cooling off. Cold Twisted Glass Panels in Alphen Mick Eekhout took another path than Karel Vollers and based his projects on cold deformed glass instead of hot deformed glass panels. One of the projects that this cold twisting process is applied to, is the town hall of Alphen aan den Rijn. The back part of the town hall had a double curved surface over which glass lintels were designed by architect Erick van Egeraat. As these glass lintels did not run concentrically, many of the composing glass panels had to be twisted. The initial solution was to work with timber frames, flat glass panels and saw tooth triangles in between. The same

Figure 1. Twisted high-rise model from 2001

Figure 2. Detail scheme of cold twisted glass panels. Panels are shifted upwards, twisted by hand and lowered in the twisted sill profile.

Figure 3. Construction phase of spaghetti façade with cold twisted glass in Alphen

concept as the façades of the ‘Neue Staatsgalerie’ in Stuttgart, 1983 by James Stirling. In this case the timber window frame producer found it impossible to develop such a system. Octatube was asked for an alternative. Their concept was to make a frameless glass system and to twist all glass panels -cold- on site. The frames caused the problem. Upper and lower profiles were stiff U-channels. The insulated glass panels were maximally 900x2000mm large and consisted of 8 mm outer blade fully tempered and inner blade of also fully tempered 4.4.2. The silicone seals were normal butt seals. The glass was twisted out of its plane maximally 40mm. This work proved to be realizable at very economical costs, although with larger risks than normal (300% breaking of panels on site compared to the normal practice). After having completed the job, one could wonder what had been done. A theory was not yet available. It took TU Eindhoven graduation student Dries Staaks one full year to discover and describe the regularity’s of cold twisting of glass panels. In a collaborative connection a first jump ahead by a design concept, immediate engineering and realization is done on the industrial side with its short time goals, while the academic contemplation with its long term goals lagged behind, but was necessary. Regularities of Cold Twisting of Glass The theory behind the cold twisted double and laminated glass panels in the town hall of Alphen aan den Rijn was taken up as a challenge by graduation student Dries Staaks. His task was to discover, research and develop the regularities of cold twisting of glass (2003). In the laboratory of Octatube he discovered that glass panels can be cold twisted elastically, deforming in a symmetrical way into a hypar surface as long as the enforced deformation out-of-plane is less than 16 times the panels’ thickness. More twisting will evoke a change of deformation pattern resulting in unidirectional bending along the shortest (stiffest) diagonal axis. 42

Figure 4. The schemes of cold deformation between elastic behaviour and buckling

Double curvature of a twisted plate causes membrane forces: pressure in the middle and tension along the edges. For linear increase of twisting the membrane forces increase exponentially until the pressure causes the plate to buckle, resulting in the change of deformation. The amount of twisting at which instability occurs proved to be linear related to the panels’ thickness, independent of material and size except for the length/ width ratio. For small amounts of twisting (‘plates’ thickness) stresses are uniformly distributed. This stress is linear related to the plates’ thickness. A thinner plate will cause equally lower stress. For increasing twisting the stress will increase more than linear due to the growing influence of the membrane forces. In general twisted geometries with a deformation up to 50-100mm2 of the panels’ width are possible using pre-stressed glass. This theory can also be applied to massive plates like aluminum and steel sheets. The increasing demand for freeform transparent building envelops caused by the trend of fluid design in architecture was the main reason to start a research on cold twisting of glass. A fluently shaped transparent building skin is commonly approached with a subdi-

Figure 5. In this first deformed shape the four edges of the plane remain straight;

vision of triangular panels. The use of quadrangular panels is to prefer esthetically and often economically as well. Typically for such a design in a free form geometry, one of the four corners of each quadrangle is out of plane, causing a twisted deformation of the panel. To a certain extent glass panels are capable of coping with this deformation next to its apparent loads as dead load, wind and snow load. This approach was something completely new and therefore lacked a theoretical basis. In the Town Hall of Alphen aan den Rijn cold twisting of double and laminated glass panels was introduced for the first time on an experimental basis. This project proved the practical use of cold twisting but at the same gave rise to questions about the boundaries and regularities of this new technique. For frameless glazing staying within the first deformation pattern is important because all edges remain straight and adjacent panels connect smoothly. Consequently the possibility of predicting the point of instability with its sudden change in deformation pattern became the main focus point of the research. Through a combination of empirical, numerical and finally analytical analysis a profound theory was created. The theory predicted the instability for different material, thickness, size and length/width ratio, summarized in the following conclusions, referred to as the ‘Theory of Staaks’:

Figure 6. after the change of shape all edges are curved

1. dZinstability is largely independent of material 2. dZins and plate thickness are linear related; for a square geometry dZins = 16,8 x t 3. For a Length/Width ratio > 1 dZins increases; for L/W =2 => dZins = 1,3 x 16,8 x t 4. dZinstability is largely independent of size of the plate (considering no presence of out-of-plane loads) 5. Stresses are approximately linear related to dZ for dZins < t (first order stress) 6. Stresses for dZ = dZins are approximately 165% higher compared to first order stress estimation

The gained knowledge about the structural behavior and the determined regularities in deformation and stresses do provide the architect, (structural) engineer with the necessary tools to apply this economically and production technically accessible technique in their latest design. Cold Twisted Glass in Street Canopy At the south side of the inner city of Delft in a masterplan by the Belgian architect Bob van Reeth a canopy was designed by Mick Eekhout as a bus and tram station connecting the inner city with the TU Delft campus. The built environment of shops and city apartments is quite dense and massive. It was answered by an undulating glass roof canopy suspended from masts with a free height of around 6 m to allow for the tram, and a width of 12 m in 80 m length , of which in total 60 m was glass covered. The Delft Arms show undulating lines representing the connection with water and sea. Delft’s harbor, Delfthaven, was the earlier harbor of Rotterdam. The undulating line fitted in the Delft symbolism and gave the opportunity to investigate the possibilities of cold twisted glass panels in a warped roof form. Design and realization were separately tendered. Result is a roof with laminated glass, one pane 6mm green float and one pane 6 mm clear float glass. Both panes fully tempered and produced as standard flat panels. The main structure in tubular steel, hot dip galvanized and powder coated is provided with stainless steel saddles on which the flat panels are laid and forced into the desired undulating form. On top other stainless steel saddles keep the panels in position by their pretension. The theory of Staaks is fully exploited here. Result is a glass canopy produced with standard glass panels with an interesting and surprising undulating form, able to resists the urban impact of the city wall of new apartments. Having done this exercise one knows that the triangulated façade part of the town hall of Alphen, which

could not be twisted hot in 2002 as there was a screening and solar reflective coating on the insides of the double glass panels, currently can be twisted as cold deformed glass panels, inclusive the solar reflective coating and the screening. An area of 10x10m2 could be twisted cold 2m out of its plane. So our combination of practical projects with theoretical research produces distinct steps ahead, even after projects. A little devil on the shoulder whispers that this knowledge could be used in changing the polycarbonate panels of the cable net of the Olympic Roof of Munich

Figure 7. View of the Delft glazed bus station canopy ‘Zuidpoort’ with cold twisted glass

by laminated glass, twisted cold in position and to flexibly deform with the cable net movements! As a contribution to a life long inspiration by prof.dr. Frei Otto. Twisted Glass Panels on Long Glass Fins The super-slender tensile systems of Octatube were developed initially as an alternative for glass fins that originate from the 1960â&#x20AC;&#x2122;s. The technology of the tensile steel trusses gives glass architecture a high class of refinement. But some architects like to play around with glass fins. One example is the Apple cube in

New York. Although its size is modest (12x12x12m3) the very location makes it a prominent glass design. Fins are back in the interest of the public. Glass fins should be tempered and laminated. The length/width ratio of glass fins makes them vulnerable for warping, which is undesirable seen the prominent visual function and the multi-layering. Yet there are enough producers in Europe who produce good quality fins. The larger sizes (larger than 5 m) have to be produced in China. Architect Muma and Tim Macfarlane designed the new Medieval Galleries of the Victoria & Albert museum in

Figure 8.â&#x20AC;&#x201A; View of the canopy

Figure 9. View of the cold bent insulated glass panels in the day lit Renaissance Galeries of the Victoria & Albert Museum

Figure 10. ‘Invisible’ connection between the glass panels and excisting wall

London with large fins, up to 11 m length, in translucent color. These fines were constructed in the Victorian brickwork almost naively, without any details: very abstract. The details are sharp as cutting through the butter. Due to the shape of the roof the glass surface is twisted, not plane. The experiences after cold twisting projects and the theory of Staaks enabled this challenge to be taken up. This resulted in cold twisting of the insulated and laminated glass panels with special details. The project received the prestigious ‘Structural Design of the Year 2010 Award’ in Barcelona.

From 1968 to 1973 Mick Eekhout studied Architecture in Delft. After his graduation (with honours), he worked in an architectural office for two years, before founding his own architectural office where he realised several buildings in eight years time. In 1982 he founded the company Octatube Space Structures, specialized in three dimensional constructions and structures for the building industry. For over 25 years Octatube has realised many design and build projects, both in the Netherlands and overseas. In 1989 Mick received his PhD degree with his thesis ‘Architecture in Space Structures’. Since 1992, he is professor of Product Development at the Faculty of Architecture. In 2003 he was the first designer since 1856 that was accepted to the Royal Dutch Academy of Sciences. In 2012 his book ‘Delft Glass Design Innovations’ will be published, in which his portfolio of glass designs during the last two decades is elaborated. This article is an excerpt from the book.

Figure 11. Horizontal section of the connection between the glass panels and the wall.

GRADUATION PROJECT Transformation from office to dwelling and dwelling to user

High vacancy rates of offices are a major problem in the Netherlands. Especially since the start of the economic crisis, the number of empty office buildings has increased significantly. The highest vacancy rates can be found in non monumental offices with column structures build from 1960 till 1980. This office vacancy is due to esthetical, technical, energetically and functional decay of the façades, installations and infrastructure. Structural vacancy is problematic because the building area and building are not in use, and because of the fact that the structure can probably last for many more years. Also, there are unnecessary losses of energy and money when a building is not in use. The vacancy problem is especially idiotic when looking at the housing demand. To meet the plans of the ministry of housing, in theory every year 80.000 houses must be built. This number is (partly because of the economic situation) far from what is built. These observations are not unnoticed; recently politics and media have given their attention to this problem. Although the mentioned facts would suggest that much transformation takes place from office to dwelling, this is not the case. Several factors ensure that transformation only takes place sporadically or in places with a high cultural and historical value. The following points play a huge role in the lack of transformations: the traditional transformation process can be seen 48

ir. Willem Kok ir. Peter van Luijn as inefficient; there is no flexibility in the process- and product phase; the high book value and the high price of offices; the difference in lettable floor area between office and apartment buildings; the low floor height; the difficulty and impossibility of penetrating and interfering the common used pre strained concrete floors; the fact that high interference is related to more problems and thus higher costs. When a vacant building is finally transformed, an important question or comment can be placed: is the transformation not again part of an existing ‘discard’ cycle? If the user can’t perform his activities qualitative or live in the desired comfort and luxury, then there is a discrepancy between the building and the user. The future can’t be predicted, so are we not building new vacancy? Taking this question into account, a new dimension can be added to the vacancy problem: we do not only need to transform from office to dwelling, but also from dwelling to user. The solution for this problems and observations can be given with the following points: the building must be transformed with an uniform process, façade- and infrastructure system that can be implanted on the previously mentioned building

R TRANSFORMATION METHODOLOGY FO

1. why transformation?

2. inspection, mapping and revitalization RR FO

? ?

RR FO

? ?

? ? ?

? ?

TRANSFORMATION

TRANSFORMATION 3. coordination, TRANSFORMATION

parcellation and routing

4. demand = scenario

5. manufacturing, implementation and transportation

6. assembly on site

process

infill

inner- (outer) layer

etc.

8. outcome2 and future floor plan

2011

7. supply = hypothesis

fit-out / infill-level the ‘flexible’

20??

base building level the ‘permanent’

facade

frame

outer layer

frame

structure with as less interference as possible; the system is able to conform with the (individual) requirements and wishes of the users and government, according to ‘here and now’ and ‘there and then’; extra floor space must be created to make transformation feasible and to offer the needed space for functions that are placed in the façade layer. There are different principles for creating extra space. Each principle has its own pros and cons, options and contradictions. Basically there are three directions to expand; top and bottom, front and rear, left and right. To create the conformability and flexibility, decoupling and defining of levels and layers is needed. The decoupling can be separated between control and decision-makers, permanent and non-permanent, collective and individual and short and long lifetime (esthetical, functional and technical). With this decoupling of levels and layers, the system can be upgraded according to new technologies and the wishes of users and governments, now and in the future. To make the interference with the existing building structure as small as possible, all needed infrastructural interventions are combined with the new façade. Beside the lack of interference with the existing structure, this will also result in almost no differences in floor height and will optimally increase the freedom and flexibility for the design and user. By implementing this points in the transformation process and methodology, we can offer maximal process- and product flexibility. The new system is changing the process, because it is all about the individual user now: first the demand, than the supply. This new system provides a lot of flexibility in the process-, product- and user phase. The final design of the transformation system is based on the principle that the building becomes thicker by expansion of the floors and façade. This principle can easily provide extra square meters and sufficient space for installations and functions without drastic interven-

tions. This principle spans from floor to floor. This extension to the building exists of different prefabricated and flexible elements. The different prefabricated elements act as support and infill for each other: the console facilitates the mounting and connecting of the façade system with the existing structure without interference, this is done by a clamping principle; the horizontal frame is connected with the console and provides the extra floor space and mounting possibilities of the other façade elements; the infrastructure shafts are placed in between the horizontal frames and are forming a collective infrastructure network with flexible connection possibilities; the vertical frame can be seen as the real façade layer and is providing the building physical lines, multiple configurations of the vertical frame are possible; the infills are elements to meet the needed energy, comfort and esthetical wishes. All of the described elements can be changed and replaced individually. The system offers the ability to be placed on existing building structures, the creation of extra indoor and outdoor space, different configurations of façades and infrastructure, free parcellation choice and apartment layout, adaptability to comfort and energy wishes and a free choice in materialization. The system is structurally overdimensioned to make transformation to other functions in the future possible. The uniformity in building appearance is determined by the use of a uniform building grid and the possible plinth and central core. A good realization of the system is depending on a clear separation of tasks and decision makers and the accessibility and demount ability of system parts.

EXPLANATION FACADE SYSTEM

1. remove existing façade

2. retain and revitalize existing structure

- inspection and mapping of the existing structure; - decoupling and removal of existing infrastructure; - disassembly and removal of the entire interior; - disassembly and removal of the entire façade.

- maintaining and revitalizing of the existing structure; - removal and reapplication of sound,- fire,- thermal,- and water barrier for roof and basement; - excavation around building for circulation infrastructure-line; - connect city grid with circulation infrastructure-line.

3. mounting (clamping) consoles

4. placing horizontal frame ‘the support’

- measurement, control and marking work; - place (clamping) steel console plates with the studs and UNP profile around the column and floor; - adjust and fix the console plates on the marking by tightening the bolts.

- place precast horizontal frame with crane; - place the frame between the welded steel lips of the console; - fix the console, cable and frame with a steel pin (hinge); - connect cable and gland with horizontal frame; - adjust the frame horizontal by using the gland.

5. placing horizontal frame ‘the infill’

6. placing vertical infrastructure , vertical frame and support

The construction work on the building site contains mainly placing of the prefabricated elements. Most of these prefabricated elements already include user defined infills. Possible additions, for example the horizontal frame for voids or stairs and the placing of the needed anchors and brackets are already assembled during the prefabrication.

- placing and fix the vertical infrastructure (shafts) between vertical frame; - connect vertical infrastructure with circulation infrastructure- line and installation room; - coupling of vertical infrastructure (shafts); - coupling of horizontal infrastructure with vertical infrastructure.

7. placing components, infill and grid-systems

8. outcome

- place the façade components with framework in the vertical support frames; - place the precast infill and grid-system on the steel brackets; - connect infills with infrastructure; - place the inner, outer and uniform building grid layers; - supply and installation of fit-out (interior, etc).

- outcome ‘here and now’; - completion and final check of total building and users wishes; - if necessary, adjustment and replacement of infill and grid- system in relationship with the space plan.

SECTION OF THE SYSTEM

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SCOPE AND POSSIBILITIES

The users can choose their own square meters (and thus the price), location and orientation on the floor plan. The faรงade can be programmed with functions according to different requirements and wishes. The infills and configuration of the system can be chosen by the user or other involved parties. The possibilities are ordered in a catalog.

SCENARIO

An example of the changeability could be the gentrification of neighbourhoods which will be transformed from deprived areas (low budget) to luxury districts (high budget). The deprived areas have no ´strong´ context, so the main decision-maker could be the user.

A case study building is required to project the theory and outcomes. The building must meet some constraints that have emerged from the transformation analysis. Each ‘potential’ building and location must be analyzed so that the supporting structure and infrastructure can be mapped.

Because of the low incomes, the users have chosen for the standard package. During a certain time period, the gentrification will strike and suddenly the building does not fit anymore in the new ´strong´ context. The old users cannot pay the rent and are forced to relocate to make room for new users.

The new users are demanding a modernization of the building with larger living spaces and beautiful, delicate and smooth new materials. Therefor, their choice would be the deluxe package. Due to the ‘strong’ context the user is not the main decision-maker anymore but the professionals and government (for instance the architect and municipality).

Conclusions the methodology and faรงade system provide an uniform approach for the transformation of vacant office buildings from 1960 till 1980; extra square meters are created by using a horizontal frame as extension for the floor area. This makes the system feasible and will encourage investors and stakeholders to cooperate; the existing structure stays intact and interference with the structure is avoided, this will lead to less problems and a higher flexibility compared to other transformation systems. Interference is avoided with the use of clamped consoles and the placement of infrastructure shafts outside the floor field of the existing structure; all system elements are prefabricated which will lead to a more efficient process and a reduction of construction time; the separation of the different layers makes the system upgradable and future proof. The latest energy performance requirements and user wishes can be achieved with the upgrading and changing of system elements; parcellation and clustering of apartments is possible in horizontal and vertical direction, almost every floor area and space plan can be created; the system can be used for temporary transformation. Nothing is mounted monumental to the existing structure and all system elements are demountable; the structure of the transformation system is only using 23% of its load capacity. This makes transformation to other functions than dwellings possible, like offices, commercial buildings, etc. The principle of the system can be used in other fields on the transformation market; single buildings can be transformed or complete office areas. With one system different appearance can be created and new neighborhoods can arise.

Peter van Luijn & Willem Kok Education: Building Technology [ Faรงade Master ] Graduated ( mark: 9 ) January 27th 2012 Main mentor BT: Second mentor AE: Second mentor BT: Consultant:

Marcel Bilow Ype Cuperus John van der Vliet Thaleia Konstantinou

Contact information: Willem Kok: +31 (0)6 408 86 989 kok_willem@hotmail.com Peter van Luijn +31 (0)6 287 88 855 plvanluijn@hotmail.com