Challenging Glass 2

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<p>Challenging Glass 2</p> <p>I</p> <p>Conference on Architectural and Structural Applications of Glass Faculty of Architecture, Delft University of Technology May 2010</p> <p>1</p> <p>Bos, Louter, Veer (Eds.)</p> <p>Challenging Glass 2 Contents</p> <p>Challenging Glass 2 Conference on Architectural and Structural Applications of Glass Faculty of Architecture, Delft University of Technology vmw.bk.tudelft.nl/challengingglass challengingglass-bk@tudelft.nl</p> <p>ForewordDear reader. Proudly, we present the proceedings of the second Challenging Glass Conference (CGC2). Obviously, the economic difficulties of recent years have not thwarted the development of glass as an architectural and structural material. Almost 70 papers from around the globe show that efforts in both research and practice to fiilly utilize the possibilities of this material are relentless. These proceedings stait with four key-note papers. Three of them present the latest advances in architectural design, fafade and structural engineering with glass. The fourth takes us outside the usual scope of the building industry, right into the heait of the material and its propeities. The session papers cover a wide range of subjects related to the use of glass in buildings, from the fundamental questions of glass strength to the practical problems of construction. The authors constitute a mix of established names and young professionals. We trust this will spark lively discussion and an exchange of ideas that will help the progression of glass in buildings in the coming years. We have done our utmost to provide the right setting. Challenging Glass 2 owes its success to all its contributors. We would like to express our gratitude to the key-note speakers as well as to the other presenters and authors. Furthermore, we thank the Scientific and Organizing Committees, the supporting organizations, the advertisers and, off course, all participants. Welcoine to Challenging Glass!</p> <p>Support Challenging Glass 2 is supported by the Delft Centre of Materials (DCMAT), the Research School Structural Engineering, CUR Bouw &amp; Infra, Kenniscentrum Glas (KCG), and the Dutch group of lABSE. Cover credits Background: Front Inc. Photo ribbon, from back left to front right: JCDA Inc. (2x), Front Inc., Pascal Richet (2x), Werner Sobek, JCDA Inc., Werner Sobek, JCDA Inc., Werner Sobek. Editors Bos, Louter, Veer Organizing Committee Freek Bos Christian Louter Fred Veer Scientific Committee Jan Rots, chair (NL) Fred Veer, secretary (NL) Jan Belis (B) Paulo Cruz (PT) Ulrich Knaack (NL) Rob Nijsse (NL) Mauro Overend (UK) Tanguy Rouxel (F) Jens Schneider (D) Geralt Siebert (D) Holger Techen (D) Bemhard Weller (D)</p> <p>Wishing you an inspiring and enjoyable conference,</p> <p>ISBN 978-90-8570-524-6 Printed by Whrmann Print Service, Zutphen, the Netherlands Copyriglit with the authors. All rights reserved. No part of this publication may be reproduced in any fonn, by print, copy, or in any other way, without prior written pennission from the respective author(s). The editors and authors are not responsible for the use which might be made of the following information.ii iii</p> <p>Freek Bos, Christian Louter Organizing Committee Jan Rots, Fred Veer Chairman and Secretary of the Scientific Committee</p> <p>Challenging</p> <p>Glass 2</p> <p>^ TUDelft</p> <p>Challenging</p> <p>7. References[I] [2] [3] [4] [5] [6] [7] [8] [9] Ngo, T.; Gupra, A.; Ramsay, J., Blast Loading and Blast Effects on Structures. Electronic Journal of Structural Engineering (Special Issue: Loading on Structures), 2007, pp. 76-91 Beveridge, A., Foreni;c/;7vei//ga/;'o q/'iLvp/o^/on^, Taylor and Francis, London, 1998 Baker, W., Explosions in Air, University o f Texas Press, Austin, 1973 Springer - Verlag, New York, 1991 Model, ASCE Journal of Structural Engineering, 110 Scholze, H., Glass: Nature, Structure and Properties, Beason, L.; Morgan, J., Glass Failure Prediction (2), 2007, pp. 197-212 Amstock, J., Glass in Construction, McGraw Hill, New York, 1997 of PVB Interlayer Used in Laminated Glass, Vallabhan, C ; Das, Y.; Ramasamudra, M . , Properties</p> <p>Glass 2 - Conference on Archileclural and Structural Applications of Glass, Bos, Louter, Veer (Eds.). TUDelft, May 20IO Copyright with the authors. All rights reserved.</p> <p>Corrosion effects on soda lime glassFred Veer Faculty of Architecture, Delft University of Technology f.a.veer@tudelft.nl, www.glass.bk.tiidelft.nl Yurii Rodichev 70.5". Pisarenko Institute for Problems of Strength ofNASU, Kiev, Ukraine, rym@ipp. Iciev. ua</p> <p>Journal of Materials in Civil Engineering, 4 (1), 1992, pp. 71-76 Du Bois, P.; Kolling, S.; Fassnacht, W., Modelling of Safety Glass for Crash Simulation, Computational Material Science, 28, 2003, pp. 675-683 Wei, J.; Dharani, L., Fracture Mechanics of Laminated Applied Fracture Mechanics, 44, 2005, pp. 157-167 [10] Vallabhan, C , Iterative Analysis of Glass Plates, Journal o f Structural Engineering, 109 (2), 1983, pp. 489-502 [ I I ] Vallabhan, C ; Das, Y.; Magdi, M . ; Asik, M . ; Baily, J., Analysis Structural Engineering, 1 19 (5), 1993, pp. 1572-1585 [12] Wei, J.; Shetty, M . ; Dharani, L., Failure Analysis of Architectural Engineering Failure Analysis, 13,2006, pp. 1029-1043 [13] Wei, J.; Shetty, M . ; Dharani, L . , Stress Characteristics of a Laminated Architectural Glazing Subjected to Blast Loading, Computers and Structures, 84, 2006, pp. 699-707 [14] Weggel, D.; Zapata, B.; Kiefer, M . , Properties and Dynamic Behavior of Glass Curtain Walls with Split Screw Spline Mullions, Journal of Structural Engineering, 133 (10), 2007, pp. 1415-1425 [15] Weggel, D.; Zapata, B., Laminated [16] GSA, TS0F2003 Overpressure [17] DoD, Structures Standard Glass Curtain Walls and Laminated for Glazing and Window G/O.M Lites Subjected Systems Subject to to LowDynamic Level Blast Loading, Journal of Structural Engineering, 134 (3), 2008, pp. 466-477. Test Method Loadings, General Services Administration, Washington, 2003 lo Resist the Effects of Accidental Explosions. UFC 3-340-02, Unified Facilities Design Glazing Subjected lo Blast Loading, of Laminated Glass Units, Journal of Glass Subject to Blast Loading, Theoretical and</p> <p>Although soda lime glass is the most common used transparent material in architecture, little is known about the corrosion effects on long term strength and the interaction between corrosion and defects. Extensive testing on soda lime bars under different environmental conditions and different degrees of damage has resulted in a inore clear picture of the stress-conosion luechanisms involved. The effects of these on long tenn strength are discussed. Keywords: Glass strength, stress corrosion</p> <p>1. Introduction Soda lime glass is coinmonly used as it is a durable material. It is however susceptible to stress con-osion. A review of this is given by Haldimann et al. in [1,2]. Although there is considerable previous research, such as [3,4], there are still inany questions. One of them i f only the pH of the water is critical. A ftindamental problem is the complex series of flaws that exist in cut and cut, ground and polished float glass. These significantly complicate the analysis of the results. Some of this is covered by Veer et al. in [5,6]. I f it is difficult to determine the basic strength, determining the added corrosion product is an added difficulty. To avoid some of these problems it was decided to use Schott AR glass rods. These have the same chemical composition as fioat glass, but as there are not cut, ground and polished; the results from these tests should be more easy to interpret. Initial results by Veer and Rodichev are given in [7]. These initial results gave some indications about the corrosion mechanism but as the scatter in test data was still significant additional tests were deemed necessary. This includes tests on glass bars with quantifiable damage created using a diamond indenter. 2. Methodology Standard Schott Ar glass rods are cut down in to 250 mm long segments. These are tested in four point bending in a custom made rig on a Zwick ZlOO universal testing machine equipped with climate chamber. Distance between the bottom supports was 200 mm, distance between the loading rollers was 100 mm. Test speeds of 50 mm/min and 0.5 mm/min were used. A l l specimens were conditioned for the environment where385</p> <p>Criteria, U.S. Army Corps of Engineers, Department of Defence, United States o f America, 2008 [18] A S T M , ASTM F 2248-03 Standard Practice for Specifying Loading for Blast Resistant Conshohocken, 2003 [19] Zienkiewicz, O.; Taylor, R., Finite Element Method for Solid and Structural Elsevier, 2005 [20] Pica, A.; Wood, R.; Hinton, E., Finite Element Analysis of Geometrically Computers and Structures, 11, 1980, pp. 203-215 [21 ] Reddy, J., Mechanics of Laminated [22] Pica, A . ; Hinton, E., Efficient Composite Plates and Shells, CRC Press, Boca Raton, USA, 2004 Dynamic Plate Bending Analysis with Mindlin Elements, Transient Nonlinear Plate Behaviour, Mechanics (6''' Edition), Glazing Fabricated an Equivalent 3-Second Duration with Laminated Glass, A S T M International, West</p> <p>Earthquake Engineering and Structural Dynainics, 9, 1980, pp. 23-31 [23] Vallabhan, C ; Asik, M , ; Kandil, K., Analysis of Structural 65 (2), 1997, pp. 231-239 [24] McLellan, G.; Shand, E., Glass Engineering Handbook, McGraw H i l l , New York, 1984 Modelling of Architectural Glazing Subject to [25] Seica, M . ; Krynski, M . ; Packer, J.A., Explicit Dynamic [26] SJ Software, SJ Mepla v 3.0, Aachen, Germany, 2007 [27] Krynski M . , Dynamic Response of Architectural Glazing Subject lo Blast Loading, M.A.Sc. Thesis, University of Toronto, Toronto, Canada, 2008 [28] Nicholas, T., Tesile Testing of Materials 177-185 384 at High Rales of Strain, Experimental Mechanics, 1980, pp. Glazing Systems, Computers and Structures,</p> <p>Blast Loading, Proceedings of ISIEMS13, Cologne, Germany, 2009</p> <p>Corrosion effects on soda lime glass Challenging Glass 2</p> <p>One series of specimens was pre-con-oded (water strengthened) by corroding them in water at 80C for 24 hours. The specimens were then dried, left to lie m air foi 24 hours and 4 point bend tested in air at room temperature. Fracture surfaces were examined using optical microscopy techniques. The results of this will be published later due to space constraints. 3. Results There are four sets of resuhs. The first deals with one set of experiments comparing tes in a r with tests ,n demmeralised water. The second set compares tests m air with n salt water and tests on pre-coiToded (water soaked) specimens. The third set eompares tests on undamaged bars in air with tests on bars with indenter dattrage m a,^ ThT fourth set compares tests on undamaged bars m water with tests on bars with indenter damage in water.Table 1: Tests in air and demineralised water. Specimen number 1 Air fast (MPa) 141.0 139.9 164.1 129.2 128.2 112.1 113.6 90.1 68.4 90.4 117.7 24.3% Air slow (MPa) 61.9 125.7 81.2 107.9 83.3 110.7 95.0 115.0 109.3 64.1 95.4 23.0% Demineralised water fast (MPa) 117.5 107.9 80.5 116.4 113.9 87.9 103.2 73.0 92.2 121.0 101.4 16.7% Deiuineralised water slow (MPa) 70.8 90.1 86.9 82.6 79.0 100.1 46.6 71.9 98.3 75.1 80.1 19.5%</p> <p>Some specimens were indented using a Knoop indenter with the length axis of the indenter perpendicular to the length axis of the specimen. The Knoop indenter was mounted in a Zwick zlO. The loading pattern is given in figure 2, and consists of four steps of 50,100,150 and 200 N respectively. Each held for 30 seconds with slow loading and unloading. This was done to create beach marker trails on the fracture surface to better study the initiation and growth of the crack. After indenting the specimens were kept at room temperature for one week before the four point bending tests.</p> <p>2 3 4 5 6 7 8</p> <p>oell</p> <p>9 10 Average Standard deviation /average</p> <p>y-</p> <p>320.527</p> <p>Figure 2: Load sequence for glass indentation.</p> <p>387386</p> <p>Corrosion effects on soda lime glass Challenging Glass 2 Table 4: Comparison of undamaged and indented bars in water at 20C Table 2: Tests in air, salt water and pre-corroded specimens Specimen number 1 2 3 4 5 6 7 8 9 10 Average Standard deviation / average A i r fast (MPa) 118.9 84.7 115.0 91.5 94.7 157.4 122.5 108.6 98.6 131.7 112.4 19.4% Air slow (MPa) 91.1 107.2 62.7 76.2 75.1 118.5 82.2 82.6 110.4 66.2 87.2 21.9% Precorroded slow (MPa) 117.1 88.6 94.7 100,4 66,2 90,8 101.5 74,8 91.5 104.0 93.0 15,7% Precorroded fast (MPa) 81,2 113,6 89,0 104,3 115,3 150,6 119,3 80,8 91,1 60,9 100,6 25,3% Salt water slow (MPa) 77,3 89,7 62,3 57,7 94,0 68,7 66,2 63,0 69,4 53,4 70,2 18,8% Test series Air fast 1 Air fast 2 Air fast 3 Air slow 1 Table 3: Comparison of undamaged and indented bars in air Specimen number 1 2 3 4 5 6 7 8 9 10 Average Standard deviation /average Air fast (MPa) 95.7 119.0 94.0 96.1 110.7 115.6 112.3 118.1 104.4 95.7 106.2 9.5% Air slow (MPa) 98.2 110.8 89.9 84.0 75,7 95.7 95.9 84.4 91.5 115.2 94.1 12.8% Indented fast (MPa) 37,6 31,4 26,5 27,9 30,6 35,5 29,7 25,4 30,5 28,7 30,4 12,5% Indented slow (MPa) 31,4 27,1 27,2 33,2 23,7 28,8 26,2 26,7 29,4 32.5 28,6 10,6% Air slow 2 Air slow 3 Demi water fast Demi water slow Salt water slow Pre-corroded fast Pre-corroded slow Air indented fast Air indented slow Water fast Water slow Water indented fas;t Water indented slo w Table 5: summary of results Mean failure stress 117.7 112.4 106,2 95,4 87,2 94.1 101.4 80.1 70.2 100.6 93,0 30,4 28,6 80,7 75,9 28,2 22,2 Standard deviation/mean 24.3% 19,4% 9.5% 23,0% 21.9% 12,8% 16,7% 19,5% 18,8% 25,3% 15.7% 12,5% 10.6% 5.0% 17.3% 9,0% 20,6% Number of tests 10 10 10 10 10 10 10 10 10 10 10 10 10 5 5 5 5 Speciinen number 1 2 3 4 5 Average Standard deviation / qvp.rape Water fast (MPa) 77,4 85,3 78,2 77,8 84,9 80,7 5.0% Water slow (MPa) 67,8 76,5 65,7 71.1 98,2 75,9 17,3% Indented fast in water (MPa) 30,2 25,2 26,8 27,4 31,4 28,2 9,0% Indented slow in water (MPa) 30,2 20,1 18,6 21,3 20,9 22,2 20,6%</p> <p>4. Discussion The resuhs are summarized in table 5. I f we look at the results it becoines obvious that the three fast and slow series in air, which were done with about a month between each successive series due to limited machine availability, do not coincide. Figure 3 shows a Weibull plots for the three fast series separately. In figure 4 the data is combined to give a single Weibull plot. There is no clear reason for the differences. It does make it clear389</p> <p>388</p> <p>Challenging Glass 2</p> <p>Corrosion effects on soda lime glass</p> <p>that considerable care must be taken in comparing data from different time periods. As all glass specimens were prepared beforehand and all specimens were cut in a single session an aging phenomenon could be responsible but there is no logical basis for this and this is discounter for now. The data does however give a lot of useftil information. Figure 5 shows Weibull plots for the slow tests in sah and demineralised water. The salt water is clearly more con-osive. Normal water seems to be in t...</p>

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