Ubani Obinna Uzodimma, Okonkwo Victor Odinaka, Osayanmon Osarenkhoe


Thermo Mechanically Treated (TMT) reinforcements from different manufacturers in Nigeria were subjected to tensile strength tests to determine the variability of their yield strength, ultimate tensile strength, and ductility. For the 70 samples tested, 91.5% met the required characteristic strength of 500 MPa, and the percentage elongation at fracture satisfied all the requirements of BS 4449:2005. The probability distribution of the yield strength of the TMT reinforcements were found to conform better to normal distribution with a Chi-Square value (X2 ) of 4.342 against lognormal and Weibull distribution, with Chi-Square values of 4.80 and 6.536 respectively. The mean yield strength of the samples was found to be 532.8 MPa with a standard deviation of 24.926 MPa, and coefficient of variation of 4.678%. The probability of the samples tested falling below the yield strength of 500 MPa was found to be 9.4% with a reliability index of 1.316. The ultimate tensile strength to yield strength ratio (Rm/Re) was found to be averagely high (with a mean of 1.356 and a standard deviation of 0.095) when compared to the requirements of BS 4449:2005 and test results from other parts of the world. This was the major source of non-conformity to the requirements of BS 4449:2005. Read full PDF

Keywords: Thermo Mechanically Treated Steel, Yield strength, Ductility, Ultimate tensile strength


[1] Jibrin M.U. (2012). Characterisation of reinforcing steel bars in the Nigerian construction industry. PhD thesis submitted to the Department of Civil Engineering, Ahmadu Bello University, Zaria

[2] Ede A.N., Egunjobi E.O., Bamigboye G.O., Ogundeji J. (2015). Assessment of quality steel reinforcing bars used in Lagos, Nigeria. International Research Journal of Innovative Engineering Vol 1(3) pp 1-8

[3] Adetoro A.E., Silas O.A. (2017). Assessment of suitability of selected Nigerian reinforcing bars used for construction in Nigeria. Journal of Multidisciplinary Engineering Science and Technology Vol 4(5) pp 7308-7313

[4] Kabir I.R., Islam M.A. (2014). Hardened case properties and tensile behaviour of TMT steel bars. American Journal of Mechanical Engineering Vol 2(1) pp 8-14

[5] Senfuka C., Kirabira J.B., Byaruhanga J.K. (2013): Thermo-mechanically treated steel bars made from recycled steel in Uganda. International Journal of Engineering and Technology Vol 3(2) pp 183-188

[6] BS 4449:1997: Specification for carbon steel bars for the reinforcement of concrete. British Standards Institution

[7] BS 4449:2005 + A2:2009: Steel for reinforcement of concrete – Weldable reinforcing steel bar – Bar, coil and decoiled product – Specification. British Standards Institution Ubani O. Uzodimma et al./ Journal of Science and Technology Research 2(1) 2020 pp. 1-12 12

[8] BS 4449:2005 + A3:2016: Steel for reinforcement of concrete – Weldable reinforcing steel bar – Bar, coil and decoiled product – Specification. British Standards Institution

[9] BS 8110-1:1997: Structural Use of Concrete Part 1: Code of practice for design and construction. British Standards Institution

[10] EN 1992-1-1:2004: Eurocode 2: Design of concrete structures part 1-1: General rules and rules for buildings. European Committee for Standardization

[11] Dergamo E.P., Black J.T., Kohser R.A. (2013). Materials and Processes in Manufacturing (9th Edition). John Wiley and Sons Inc, New York

[12] Shetty A., Venkataramana K., Gogoi I., Praveen B.B. (2012): Performance enhancement of TMT rebars in accelerated corrosion. Journal of Civil Engineering Research Vol 2(1) pp 14-17

[13] Nair S.A.O., Gokul P.R., Sethuraj R., Sarvani N., Pillai R.G. (2015). Variations in microstructure and mechanical properties of thermo-mechanically treated (TMT) steel reinforcement bars. In proceedings to a conference – cited from (assessed on 12th September, 2019)

[14] Rai D.C., Jain S.K., Chakrabati I. (2012). Evaluation of properties of steel reinforcing bars for seismic design. In Proceedings to the 15th World Conference on Earthquake Engineering Lisbon, Portugal

[15] Arum C. (2008). Verification of properties of concrete reinforcing bars: Nigeria as a case study. Journal of Indoors and Built Environment Vol 17(4) pp 370-376

[16] Ejeh S.P., Jibrin M.U. (2012). Tensile strength tests on reinforcing steel bars in the Nigerian construction industry. IOSR Journal of Mechanical and Civil Engineering Vol 4(2) pp 06-12

[17] Awofadeju A.S., Adekigbe A., Akanni A.O., Adeyemo B.G. (2014). Evaluation of locally produced and imported steel rods for structural purpose in Nigerian market. International Journal of Recent Development in Engineering and Technology Vol 3(8) pp 81-84

[18] Osarenmwida J.O., Amuchi E.C. (2013): Quality assessment of commercially available reinforced steel rods in Nigerian market. Journal of Emerging Trends in Engineering and Applied Sciences Vol 4(4) pp 562-564

[19] ASTM Standard, A706 (1990): Metals, Test Methods and Analytical Procedures, Metals – Mechanical Testing; Elevated and Low – Temperature Test; Metallography; Section 03: Volume 01

[20] Oyenuga V.O. (2008). Simplified reinforced concrete design – A Consultant/Computer Based Approach (1st Ed). ASROS Limited, Lagos Nigeria

[21] Brooker O. (2006). How to design structures to Eurocode 2 – Getting started. In (Bond et al) How to Design Concrete Structures to Eurocode 2. The Concrete Centre, UK

[22] EN 10080:2005: Steel for the reinforcement of concrete – Weldable reinforcing steel – General. European Committee for Standardization

[23] UK Cares (2011): The Cares guide to reinforcing steel part 3: Properties of reinforcing steels. UK Certification Authority for Reinforcing Steels

[24] Sorensen J.D. (2004): Structural Reliability 1+2. In Notes in Structural Reliability Theory and Risk Analysis. Aalborg University, Denmark pp 27-48

[25] Holický M., Vrouwenvelder T. (2005): Elementary methods of structural reliability I. In Implementation of Eurocodes (Handbook 2) Reliability Backgrounds. Leonardo Da Vinci Project CZ/02/B/F/PP-134007 pp 1-15

[26] Bachmann H. (2000): Problems relevant to poor ductility properties of European reinforcing steel. In Proceedings to the 12th World Conference on Earthquake Engineering, Auckland New Zealand Vol (2)

[27] Bandara C.S., Jayasinghe J.A.S.C., Dissanayake P.B.R. (2017). Variation of mechanical properties and load carrying capacity of reinforcing steel bars used in Sri Lanka. Sri Lanka Construction Industry Development Authority (CIDA) Journal Vol 15 pp 40-48,

[28] Djavanroodi F., Salmam A. (2017). Variability of mechanical properties and weight for reinforcing bars produced in Saudi Arabia. In Proceedings to IOP Conference series: Materials Science and Engineering 230(2017)012002 Ubani O. Uzodimma et al./ Journal of Science and Technology Research 2(1) 2020 pp. 1-12 13

[29] Allington C., Bull D. (2003). Grade 500 reinforcement design issues with L, N, E, grade reinforcing steel and over-strength factor of pacific steel micro-alloy reinforcement. In Proceedings to the 2003 Pacific Conference on Earthquake Engineering, New Zealand. Paper Number 65 pp 1-8