Investigation of Rehabilitation Effects on Fire Damaged High Strength Concrete Beams

Authors: Eun Mi Ryu, Ah Young An, Ji Yeon Kang, Yeong Soo Shin, Hee Sun Kim

Abstract:

When high strength reinforced concrete is exposed to high temperature due to a fire, deteriorations occur such as loss in strength and elastic modulus, cracking and spalling of the concrete. Therefore, it is important to understand risk of structural safety in building structures by studying structural behaviors and rehabilitation of fire damaged high strength concrete structures. This paper aims at investigating rehabilitation effect on fire damaged high strength concrete beams using experimental and analytical methods. In the experiments, flexural specimens with high strength concrete are exposed to high temperatures according to ISO 834 standard time temperature curve. From four-point loading test, results show that maximum loads of the rehabilitated beams are similar to or higher than those of the non-fire damaged RC beam. In addition, structural analyses are performed using ABAQUS 6.10-3 with same conditions as experiments to provide accurate predictions on structural and mechanical behaviors of rehabilitated RC beams. The parameters are the fire cover thickness and strengths of repairing mortar. Analytical results show good rehabilitation effects, when the results predicted from the rehabilitated models are compared to structural behaviors of the non-damaged RC beams. In this study, fire damaged high strength concrete beams are rehabilitated using polymeric cement mortar. The predictions from the finite element (FE) models show good agreements with the experimental results and the modeling approaches can be used to investigate applicability of various rehabilitation methods for further study.

Keywords: Fire, High strength concrete, Rehabilitation, Reinforced concrete beam.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1108901

References:

[1] E.G.Choi, “Performance assessment of high strength concrete members subjected to fire”, Ph.D. thesis, Ewha Womans University, South Korea.
[2] T.Z.Harmathy, Fire Safety Design and Concrete, Scientific & Technical, 1993
[3] Kodur, B.K.R., and Sultan, M.A., “Effect of temperature on thermal properties of high-strength concrete”, J. of Materials in Civil Engineering, vol.15, no.2, pp. 101-107, 2003
[4] Cheng, F., Kodur, V.K.R., and Wang, T., “Stress-strain curves for high strength concrete at elevated temperature.” J. of Materials in Civil Engineering, vol.16, no.1, pp.84-90, 2004
[5] M.K.Shin, “Structural behaviors of fire-damaged reinforced concrete beams with high strength”, Master’s thesis, Ewha Womans University, South Korea.
[6] Haj-Ali RM, Choi J, Kim HS, “Integrated fire dynamics and thermomechanical modeling frame work for steel-concrete composite structures.”, Steel and Composite Structures, vol.10, no.2, pp.129-149, 2010
[7] Choi J, Haj-Ali Rm, Kim HS, “Integrated fire dynamic and thermomechanical modeling of a bridge under fire.”, Structural Engineering and Mechanics, vol.42, no.6, pp.815-829, 2012
[8] E. G. Choi, Y. S. Shin, H. S. Kim, “Structural damage evaluation of reinforced concrete beams exposed to high temperatures.”, Journal of Fire Protection Engineering, vol.23, no.2, pp.135-151, 2013
[9] Lamont, S., Usmani, A.S., Drysdale, D.D., “Heat transfer analysis of the composite slab in Cardington frame fire tests.”, Fire Safety Journal, vol.36, pp.815-839, 2001
[10] C.S Poon, S. Azhar, M. Ason, Y.L. Wong, “Strength and durability recovery of fire-damaged concrete after post-fire-curing”, Cement and Concrete research, vol.31, pp.1307-1318, Sep.2001
[11] Henderson, J. B., Wiebelt, J. A., and Tant, M. A., “A model for the thermal response of polymer composite materials with experimental verification.”, J. of Composite Materials, vol.19, pp.579--595, 1985