Issue 57

M. T. Nawar et alii, Frattura ed Integrità Strutturale, 57 (2021) 259-280; DOI: 10.3221/IGF-ESIS.57.19

Enhancement of blast resistance of R.C beams using micro/nano silica in the presence of steel fibers

Mahmoud T. Nawar, Kareem A. El-Awady, Hamdy K. Shehab, Ahmed S. Eisa Zagazig University, Department of Structural Engineering, Egypt. Mn6w8@mail.missouri.edu, k_ahmed2012@hotmail.com

A BSTRACT . The study investigates the effect of Micro/Nano silica and steel fibers on improving the dynamic response of R.C beams, using the ABAQUS/Explicit dynamic analysis. According to the results of Magnusson and Hallgren's experimental investigation, the FE model has been well- verified and calibrated. The FE test program has further been extended to study the effect of tensile reinforcement ratios of 0.5%, 0.78%, and 1.13%, in comparison with the enhancement of concrete’s material properties, on the behavior of tested beams under blast loading. The results were compared in terms of changes in the max deflection at mid-span and flexural toughness values. The results showed that the flexural toughness of beams decreases when the tensile reinforcement ratio increases due to an increase in the moment of inertia (I effective ).R.C beams incorporating SMCs (10%MS+1%NS) with different volume fractions (0%, 1%, 2%) of steel fibers showed that the concrete mixes with higher compressive strength values lead to an increase in the last beam deflection, producing a considerable rise in the flexural toughness by 18.2%, 27% and 31.8% for (0.50%) and 15%, 19.9% and 23.6% for (0.78%) and 6.6%, 13.7% and 19.6% for (1.13%) respectively in comparison with the reference beam. K EYWORDS . Reinforced concrete; Micro silica; Nano silica; Blast load; Flexural toughness; Steel fibers.

Citation: Nawar, M., El-Awady, K., Shehab, H., Eisa, A., Enhancement of blast resistance of R.C beams using micro/nano silica in the presence of steel fibers , Frattura ed Integrità Strutturale, 57 (2021) 259-280.

Received: 20.04.2021 Accepted: 10.06.2021 Published: 01.07.2021

Copyright: © 2021 This is an open access article under the terms of the CC-BY 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

I NTRODUCTION

last loads are considered one of the severe loads impacting structures, and even a small amount of blast may cause significant damage to the structure, Baker et al. [1].Enhancement of the ductility and flexural toughness of concrete material plays an important role in absorbing much more energy of R.C structural elements, not only under static loads but also dynamic loads such as "blast" . Ductility refers to the ability of material to undergo plastic deformation without failure. On the other hand, toughness refers to the energy required to deform a material to failure. Tough materials tend to have both high strength and significant deformation before failure. In case of a blast pressure B

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