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Behavior of thermo-mechanically treated rebar exposed to elevated temperatures

Bishwajeet Choubey (DRDO, Hyderabad, India)
Virendra Kumar (Department of Civil Engineering, National Institute of Technology Jamshedpur, Jamshedpur, India)
Sekhar Chandra Dutta (Civil Engineering, Indian Institute of Technology (ISM) Dhanbad, Dhanbad, India)
Saurav Kumar Saikia (Department of Civil Engineering, National Institute of Technology Jamshedpur, Jamshedpur, India)

Journal of Structural Fire Engineering

ISSN: 2040-2317

Article publication date: 6 January 2022

Issue publication date: 22 September 2022




The purpose of the paper is to mathematically model and predict the characteristics of thermo-mechanically treated (TMT) rebar when subjected to elevated temperatures.


Data were collected from a few selected studies for developing the constitutive relations. Using the exposed temperature and the duration of heating as independent variables, the empirical relations were developed for determining the changes in mechanical properties of TMT rebars at elevated temperatures.


Recrystallization of TMT rebar crystals took place around 500 °C, which led to a decrease in the dislocation density along with the increase of large-sized grains, resulting in the degradation of strength. Up to a temperature range of 500 °C, the normalized fracture strength was higher, while the normalized fracture strain is not so high. This indicated a failure of brittle nature.


This is an original work done by others as a study to theoretically predict the mechanical behavior of TMT rebars when exposed to elevated temperature.


  1. The TMT bars showed brittleness characteristics up to 500 °C and showed ductility characteristics after that on account of its recrystallization and extensive tempering of the outer martensitic rim around that temperature.

  2. The comparison between the super ductile (SD) TMT and the regular TMT exhibit shows that the SD-TMT bars were about 1.5 times more ductile than the normal ones.



The authors greatly acknowledge the experimental investigation done by Kumar et al. (2013), Raj et al. (2015) and Tariq and Bhargava (2018), whose experimental data made it possible to conduct this study. Furthermore, the authors are highly grateful to the Microsoft Excel program and its Solver Add-in in particular, which allowed them to model and understand the mechanical behavior of TMT rebars at elevated temperatures and predict the empirical equations accordingly.

Statement of informed consent in studies with human and animal subjects: There are no human and animal subjects in this article, and informed consent is not applicable.

Statement on consent to publication: All the authors have given their consent to publish this research manuscript in the Journal of Structural Fire Engineering.

Data availability statement: All the data, representative models, constitutive relations and empirical equations generated or used during the study appear in the published article.

Statement on author and co-author contribution: Col Biswajeet Choubey and Dr Virendra Kumar gave the guidance, motivation and numerical work for performing this study. Dr Kumar is the corresponding author. The literature survey, data collection and the initial drafting of the paper was done by Saurav Kumar Saikia. The editing, correction, modification and conversion of the paper into a standard manuscript, including final revision, was done by Dr Sekhar Chandra Dutta.

Statement on conflict of interest: The authors declared that there is no conflict of interest.

Statement on funding sources: The authors received no funding from any external agency for performing this investigation.


Choubey, B., Kumar, V., Dutta, S.C. and Saikia, S.K. (2022), "Behavior of thermo-mechanically treated rebar exposed to elevated temperatures", Journal of Structural Fire Engineering, Vol. 13 No. 4, pp. 470-490.



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