Stress-Strain Relation for Hybrid Fiber Reinforced Concrete at Elevated Temperature
The performance of concrete structures in fire depends on several factors which include, among others, the change in material properties due to the fire. Today, fiber reinforced concrete (FRC) belongs to materials which have been widely used for various structures and elements. While the knowledge and experience with FRC behavior under ambient temperature is well-known, the effect of elevated temperature on its behavior has to be deeply investigated. This paper deals with an experimental investigation and stress‑strain relations for hybrid fiber reinforced concrete (HFRC) which contains siliceous aggregates, polypropylene and steel fibers. The main objective of the experimental investigation is to enhance a database of mechanical properties of concrete composites with addition of fibers subject to elevated temperature as well as to validate existing stress-strain relations for HFRC. Within the investigation, a unique heat transport test, compressive test and splitting tensile test were performed on 150 mm cubes heated up to 200, 400, and 600 °C with the aim to determine a time period for uniform heat distribution in test specimens and the mechanical properties of the investigated concrete composite, respectively. Both findings obtained from the presented experimental test as well as experimental data collected from scientific papers so far served for validating the computational accuracy of investigated stress-strain relations for HFRC which have been developed during last few years. Owing to the presence of steel and polypropylene fibers, HFRC becomes a unique material whose structural performance differs from conventional plain concrete when exposed to elevated temperature. Polypropylene fibers in HFRC lower the risk of concrete spalling as the fibers burn out shortly with increasing temperature due to low ignition point and as a consequence pore pressure decreases. On the contrary, the increase in the concrete porosity might affect the mechanical properties of the material. To validate this thought requires enhancing the existing result database which is very limited and does not contain enough data. As a result of the poor database, only few stress-strain relations have been developed so far to describe the structural performance of HFRC at elevated temperature. Moreover, many of them are inconsistent and need to be refined. Most of them also do not take into account the effect of both a fiber type and fiber content. Such approach might be vague especially when high amount of polypropylene fibers are used. Therefore, the existing relations should be validated in detail based on other experimental results.
Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1132539Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 592
 Q. Ma, G. Rongxin, Z. Zhiman, L. Zhiwei and H. Kecheng, “Mechanical properties of concrete at high temperature - a review,” Construction and Building Materials, vol. 93, pp. 371–383, June 2015.
 C. S. Poon, Z. H. Shui and L. Lam, “Compressive behavior of fiber reinforced high-performance concrete subjected to elevated temperatures,” Cement and Concrete Research, vol. 34, pp. 2215–2222, February 2004.
 G. Peng, Y. Wen-Wu, J. Zhao, L. Ye-Feng, B. Song-Hua and L. Zhao, “Explosive spalling and residual mechanical properties of fiber-toughened high-performance concrete subjected to high temperatures,” Cement and Concrete Research, vol. 36, pp. 723-727, December 2006.
 Y. Ding, C. Azevedo, J. B. Aguiar and S. Jalali, “Study on residual behaviour and flexural toughness of fibre cocktail reinforced self compacting high performance concrete after exposure to high temperature,” Construction and Building Materials, vol. 26, pp. 21-31, July 2011.
 W. Zheng, H. Li and Y. Wang, “Compressive behaviour of hybrid fiber-reinforced reactive powder concrete after high temperature,” Materials and Design, vol. 41, pp. 403-409, May 2012.
 A. Jameran, S. I. Izni, H. S. S. Yazan and S. N. A. A. Rahim, “Mechanical properties of steel-polypropylene fibre reinforced concrete under elevated temperature,” Procedia Engineering - The 5th International Conference of Euro Asia Civil Engineering Forum (EACEF-5), vol. 125, pp. 818 824, 2015.
 D. Choumanidis, E. Badogiannis, P. Nomikos and A. Sofianos, “The effect of different fibres on the flexural behaviour of concrete exposed to normal and elevated temperatures,” Construction and Building Materials, vol. 129, pp. 266-277, November 2016
 D. Xiangjun, D. Yining and W. Tianfeng, “Spalling and Mechanical Properties of Fiber Reinforced High-performance Concrete Subjected to Fire,” Journal of Wuhan University of Technology-Mater. Sci. Ed, pp. 743-749, October 2008.
 W. Khaliq and V. Kodur, “Thermal and mechanical properties of fiber reinforced high performance self-consolidating concrete at elevated temperatures,” Cement and Concrete Research, vol. 41, pp. 1112-1122, June 2011.
 S. Sanchayan and S. J. Foster, “High temperature behaviour of hybrid steel–PVA fibre reinforced reactive powder concrete,” Materials and Structures, vol. 46, pp. 769-782, January 2016.
 J. Novák and A. Kohoutková, “Fire response of hybrid fiber reinforced concrete to high temperature,” Procedia Engineering vol. 172, pp. 784-790, 2017.
 P. Bamonte and P. G. Gambarova, “Thermal and Mechanical Properties at High Temperature of a Very High-Strength Durable Concrete,” Journal of Material in Civil Engineering, pp. 545 555, June 2010.
 P. Bamonte and P. G. Gambarova, “A study on the mechanical properties of self-compacting concrete at high temperature and after cooling,” Materials and Structures, vol. 45, pp. 1375–1387, February 2012.
 Z. Xing, A. Beaucour, R. Hebert, A. Noumowe and B. Ledesert, “Influence of the nature of aggregates on the behaviour of concrete subjected to elevated temperature,” Cement and Concrete Research, vol. 41, pp. 392-402, January 2011.
 K. K. Sideris, P. Manita and E. Chaniotakis, “Performance of thermally damaged fibre reinforced concretes,” Construction and Building Materials, vol. 23, pp. 1232-1239, September 2009.
 J. Kim, G. P. Lee and D. Y. Moon, “Evaluation of mechanical properties of steel-fibre-reinforced concrete exposed to high temperatures by double-punch test,” Construction and Building materials, vol. 79, pp. 182-191, January 2015.
 F. Aslani and B. Samali, “High Strength Polypropylene Fibre Reinforcement Concrete at High Temperature,” Fire Technology, vol. 50, pp. 1229-1247, 2014.
 F. Aslani and B. Samali, “Constitutive Relationships for Steel Fibre Reinforced Concrete at Elevated Temperatures,” Fire Technology, vol.50, pp. 1249-1268, 2014.
 W. Zheng, H. Li and Y. Wang, “Compressive stress-strain relationship of steel fiber-reinforced reactive powder concrete after exposure to elevated temperatures,” Construction and Building Materials, vol. 35, pp. 931-940, 2012.
 Y. S. Tai, H. H. Pan and Y. N. Kung, “Mechanical properties of steel fiber reinforced reactive powder concrete following exposure to high temperature reaching 800°C,” Nuclear Engineering and Design, pp. 2416-2424, 2011
 L. Y. Li and J. Purkiss, “Stress-strain constitutive equations of concrete material at elevated temperatures,” Fire Safety Journal, vol. 40, pp. 669 686, 2005.
 Y.F. Chang, Y.H.Chen, M.S. Sheu and G.C.Yao,” Residual stress-strain relationship for concrete after exposure to high temperatures,” Cement and Concrete Research, vol.36, pp. 1999-2005, 2006.
 M.A.Youssef and M. Moftah, “General stress-strain relationship for concrete at elevated temperatures,” Engineering Structures, vol. 29, pp. 2618-2634, 2007.
 CSN EN 197-1 Cement - Part 1: Composition, specifications and conformity criteria for common cements, Urad pro technicku normalizaci, metrologii a statni zkusebnictvi (UNMZ), April 2012.
 R. Serrano, A. Cobo, M. I. Prieto and M. de las N. González, “Analysis of fire resistance of concrete with polypropylene or steel fibers,” Construction and Building Materials, vol. 122, pp. 302-309, July 2016.
 CSN EN 12390-3: Testing hardened concrete Part 3: Compressive strength of test specimens, Urad pro technicku normalizaci, metrologii a statni zkusebnictvi (UNMZ), 2009.
 CSN EN 12390-6 Testing hardened concrete: Part 6 – Splitting tensile strength of test specimens, Urad pro technicku normalizaci, metrologii a statni zkusebnictvi (UNMZ), 2010.
 A. Fina, F. Cuttica and Camino, G., “Ignition of polypropylene/montmorillonite nanocomposites,” Polymer Degradation and Stability, vol. 97, pp. 2619-2626, 2012.
 CSN EN 1991-1-2 Eurocode 1: Actions on structures - Part 1-2: General actions - Actions on structures exposed to fire. Urad pro technicku normalizaci, metrologii a statni zkusebnictvi (UNMZ), November 2006.
 International Federation for Structural Concrete (fib),”Fib Model Code for Concrete Structures 2010,” Berlin, Germany: Wilhelm Ernst & Sohn, Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, 2013.