Behaviour of concrete at elevated temperatures with respect to shear failure

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17/42

Témavezető neve:

Dr. Balázs L. György

Témavezető e-mail címe:

balazs.gyorgy@epito.bme.hu

A témavezető teljes publikációs listája az MTMT-ben:

MTMT

A téma rövid leírása, a kidolgozandó feladat részletezése:

Concrete can be exposed to elevated temperatures during fire in accidental situations or in service.

Behaviour of concrete structural members exposed to elevated temperature is dependent on physical,

especially thermal and mechanical properties of concrete. Therefore, understanding of the influence of high

temperatures to every component is important. Then preventative measures such as choosing the right

materials should be taken to minimize the harmful effects of high temperature.

Fire resistance of concrete can be influenced by the concrete composition. In order to evaluate the behaviour

of concrete at elevated temperatures we need to know the range of modifications of all constituents and their

interaction. Chemical and mechanical changes in concrete may produce considerable modifications of

properties at elevated temperatures. One of the most crucial question is the modification of shear capacity of

concrete.

The main objectives of my research are to study and specify the behaviour of concrete at elevated

temperatures in terms of possible ways of shear deteriorations. Therefore, in my PhD work two main fields

are being addressed:

(i) the way and extent of reduction of shear capacity of concrete as a structural material at elevated

temperatures depending on the composition and max. temperature, as well as

(ii) the way and extent of reduction of interactions between concrete and reinforcement.

Experiments are being prepared related to these two fields including several parameters. Experiments will

be followed by modelling.

Push-off specimens have been chosen to be our experimental model for investigations on shear capacity at

high temperatures. The second group of experiments is directed to the determination of bond-slip behaviour

and force transfer of prestressing tendons at high temperatures.

The bond-slip relationship is of a vital importance when studying failure mode in hollow core slabs. Many

researches have been particularly conducted to study the above mentioned issue, however, a lack of

knowledge does exist in case of high temperatures. Since the shear failure mode is mainly the dominant over

hollow core slabs which are, the latter, the most types of structural elements used around the world, the

significance of the research is unquestionably obvious.

A téma meghatározó irodalma:

ACI SP-180, "Bond and Developmnet of Reinforcement - A tribute to Dr. Péter Gergely" (ed. R. Leon),ISBN: 98-86927, ACI - American Concrete Institute, 1998, (Balázs, G. L., "Bond Under Repeated Loading", pp. 125-143.)

CEB (Editor: Balázs, G. L.), "Behaviour and modelling in serviceability limit states including repeated and sustained loads", CEB Bulletin d' Information No. 235 - ISBN 0378-9489, April 1997, 265 p. (Balázs, G. L. et al., "Development of crack widths and deflections in elements subject to repeated and sustained loads" , Chapter 1 - CEB Bulletin d' Information No. 235, "Behaviour and modelling in serviceability limit states including repeated and sustained loads", April 1997, pp. 1-46.)

fib (Editor: Balázs, G. L.), "Structural Concrete Textbook on Behaviour, Design and Perfomance” Vol 1 fib bulletin 51, Vol 2 fib bulletin 52, Vol 3 fib bulletin 53, Lausanne, ISBN 978-2-88394-091-8, -092-5, -093-2, p. 294, p. 338, p. 376, Nov-Dec. 2009-Febr 2010.

Beeby, A.W. (1978). Cracking: what are crack width limits for?, Concrete, July 1978, 31-33.

Beeby, A.W. (1979). The prediction of crack width in hardened concrete, The Structural Engineer, Vol.57A, No.1, January, pp.9-17.

Beeby, A.W. (2004). The influence of the parameter φ/reff on crack widths, Stuctural concrete No 2, 71-83.

Beeby, A.W. (2005). The influence of the parameter φ/reff on crack widths, Discussion, Stuctural concrete No 4, 155-165.

Borosnyói, A, Balázs G.L.(2005). Models for flexural cracking in concrete: the state of art, Stuctural Concrete Journal, No 2, 53-62.

Broms, B.B., Lutz, L.A. (1965). Effects of Arrangement of Reinforcement on Crack Width and Spacing of Reinforced Concrete Members, ACI Journal, Proceedings V. 62, No. 11, Nov. 1965, pp. 1395-1410.

CEB (1984). CEB Design Manual Cracking and Deformations, CEB Bulletin d'Information No.158, Lausanne 1985

Eckfeldt, L., (2005a). Möglichkeiten und Grenzen der Berechnung von Rissbreiten in Veraederlichen Verbundsituationen, PhD Dissertation, Technical University Dresden

Ferry-Borges, J. (1966). Cracking and deformability of Reinforced Cocrete Beams, IABSE Publication, Zürich, Vol.26, pp.75-79.

Gergely, P., Lutz, L.A. (1968). Maximum Crack Width in Reinforced Flexural Members, Causes, Mechanism and Control of Cracking in Concrete, ACI SP-20, 87-117.

Goto, Y., Otsuka, K. (1971). Studies on Internal Cracks Formed in Concrete Around Deformed Tension Bars, ACI Journal, Vol.68. No.4, April 1971, 244-251.

König, G., Fehling, E. (1988). Zur Rißbreitenbeschränkung im Stahlbetonbau", Beton-und Stahlbetonbau No.6/1988, 161-167. + No.7/1988, 199-204.

Leonhardt, F. (1988). Cracks and Crack Control in Concrete Structures, PCI Journal, July-August 1988, 124-145.

Lutz, L.A., Gergely,P. (1967). Mechanics of Bond and Slip of Deformed Bars in Concrete, ACI Journal, 64(11) 1967, 711-721.

Noakowski, P. (1985), Verbundorientierte, kontinuierliche Theorie zur Ermittlung der Rissbreite, Beton- und Stahlbetonbau No.7/1985, 185-190. und No.8/1985, 215-221.

Oh, B.H., Kang,Y.H. (1987). New Formulas for Maximum Crack Width and Crack Spacing in Reinforced Concrete Flexural Member, ACI Structural Journal March-April, pp.103-112.

Schießl, P. (1989). Grundlagen der Neuregelung zur Beschränkung der Rißbreite, Deutscher Ausschuß für Stahlbeton, Heft 400, pp.158-175.

A téma hazai és nemzetközi folyóiratai:

- ACI Journal

- Structural Concrete Journal

- Materials and Structures Journal

- Magazin of Concrete Research

- Key Engineering Materials Journal

- Beton und Stahlbetonbau

- Concrete Structures Journal

- Vasbetonépítés folyóirat

A témavezető utóbbi tíz évben megjelent 5 legfontosabb publikációja:

Balázs, G. L., Lublóy, É., “Post heating strength of fibre-reinforced concretes”, Fire Safety Journal 49, pp. 100-106. (2012) DOI: 10.1016/j.firesaf.2012.01.002, Q1: 1.021, IF 1.222

Balázs, G. L., et al. “Design for SLS according to fib Model Code 2010”, Structural Concrete Journal, Vol. 14, June 2013, pp. 99-123, E&S Wiley ISSN 1751-7648, DOI: 10.1002/suco.201200042; Q2 0.746, IF 0,857

Walraven, J., Balázs, G. L., “fib Model Code for Concrete Structures 2010: a landmark in an ongoing development”, Structural Concrete Journal Vol. 14, March 2013, pp. 1-2., E&S Wiley ISSN 1751-7648, DOI: 10.1002/suco.201390005, Q2 0.746, IF 0.857

Balázs, G. L.: “Material and Structural Properties for Creating High Performance Concrete”, Key Engineering Materials Journal Vols. 629-630 (2015) pp 21-27 Online available since 2014/Oct/01 at www.scietific.net Trans Tech Publications, Switzerland, Doi: 10.4028/www.scientific.net/KEM.629-630.21 IF: 0.190

Bilotta, A., Ceroni, F., Joaquim A. O. Barros, J.A.O., Costa, I., Palmieri, A., Szabó, K.Zs., Nigro, E., Matthys, S., Balázs, G. L., Pecce, M.: “Bond of NSM FRP-Strengthened Concrete: Round Robin Test Initiative” ASCE Journal of Composites for Construction, June 2015, DOI: 10.1061/(ASCE)CC.1943-5614.0000579, Q1: 1.957, IF: 2.48

A témavezető fenti folyóiratokban megjelent 5 közleménye:

Balázs G. L., "Cracking Analysis Based on Slips and Bond Stresses", ACI Materials Journal, Vol. 90, No. 4, July-August 1993, pp. 86-93, IF 0.462

Balázs G. L., "Fatigue of Bond", ACI Materials Journal, Nov-Dec. 1991, pp. 620-629, IF 0.378

Koch, R., Balázs, G. L., "Verbund unter nicht ruhender Belastung", - Teil 1, Vol.93, 1998/7, pp.177-181; - Teil 2, Vol.93, 1998/8, pp.220-223, Beton- und Stahlbetonbau

Balázs, G. L., Grosse, C.U., Koch, R., Reinhardt, H.W., "Damage accumulation on deformed steel bar to concrete interaction detected by acoustic emission technique", Magazin of Concrete Research, Vol. 48, No. 177, Dec. 1996, pp. 311-320, IF 0.444

Vandewalle, L., Nemegeer, D., Balázs, L.G., Barr, B., Bartos, P., Banthia, N., Brandt, A., Criswell, M., Denarie, E., Prosco, M. Di, Falkner, H., Gettu, R., Gopalaratnam, V., Groth, P., Häusler, V., Katsaragakis, E., Kooiman, A., Kovler, K., Lehtonen, J., Massicotte, B., Mindess, S., Reinhardt, H-W., Rossi, P., Schaerlaekens, S., Schnütgen, Shah, S., Skarendahl, A., Stang, H., Stroven, P., Swamy, R., Tatnall, P., Teutsch, M., Walraven, J., Wubs, A, “RILEM TC162-TDF: Test and Design Methods for Steel Fibre Reinforced Concrete, Ϭ-w- Design Method, Principles and Applications, Marerials and Structures Journal, Vol. 33, Jan-February 2002, pp, Q2 0.631, IF 0.363

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