Investigating Optimal Confinement Behaviour of Low-Strength Concrete through Quantitative and Analytical Approaches

Mujahid Ali; Sheraz Abbas; Bashir Salah; Javed Akhter; Waqas Saleem; Sani Haruna; Shah Room; Isyaka Abdulkadir

doi:10.3390/ma14164675

Investigating Optimal Confinement Behaviour of Low-Strength Concrete through Quantitative and Analytical Approaches

Materials (Basel). 2021 Aug 19;14(16):4675. doi: 10.3390/ma14164675.

Authors

Mujahid Ali^{1

2}, Sheraz Abbas², Bashir Salah³, Javed Akhter⁴, Waqas Saleem⁵, Sani Haruna⁶, Shah Room⁷, Isyaka Abdulkadir⁶

Affiliations

¹ Civil and Environmental Engineering Department, Universiti Teknologi PETRONAS, Perak 31750, Malaysia.
² Civil and Architecture Engineering Department, City University of Science and Information Technology, Peshawar 25000, Pakistan.
³ Department of Industrial Engineering, College of Engineering, King Saud University, P.O. Box 800, Riyadh 11421, Saudi Arabia.
⁴ Department of Mechanical Engineering, University of Engineering and Technology Taxila, Rawalpindi 47080, Pakistan.
⁵ Department of Mechanical and Manufacturing Engineering, Institute of Technology, F91 YW50 Sligo, Ireland.
⁶ Civil Engineering Department, Bayero University Kano, Kano 700241, Nigeria.
⁷ Department of Civil Engineering Technology, University of Technology, Nowshera 24100, Pakistan.

Abstract

Reinforced concrete is used worldwide in the construction industry. In past eras, extensive research has been conducted and has clearly shown the performance of stress-strain behaviour and ductility design for high-, standard-, and normal-strength concrete (NSC) in axial compression. Limited research has been conducted on the experimental and analytical investigation of low-strength concrete (LSC) confinement behaviour under axial compression and relative ductility. Meanwhile, analytical equations are not investigated experimentally for the confinement behaviour of LSC by transverse reinforcement. The current study experimentally investigates the concrete confinement behaviour under axial compression and relative ductility of NSC and LSC using volumetric transverse reinforcement (VTR), and comparison with several analytical models such as Mander, Kent, and Park, and Saatcioglu. In this study, a total of 44 reinforced-column specimens at a length of 18 in with a cross-section of 7 in × 7 in were used for uniaxial monotonic loading of NSC and LSC. Three columns of each set were confined with 2 in, 4 in, 6 in, and 8 in c/c lateral ties spacing. The experimental results show that the central concrete stresses are significantly affected by decreasing the spacing between the transverse steel. In the case of the LSC, the core stresses are double the central stress of NSC. However, increasing the VTR, the capacity and the ductility of NSC and LSC increases. Reducing the spacing between the ties from 8 in to 2 in center to center can affect the concrete column's strength by 60% in LSC, but 25% in the NSC. The VTR and the spacing between the ties greatly affected the LSC compared to NSC. It was found that the relative ductility of the confined column samples was almost twice that of the unrestrained column samples. Regarding different models, the Manders model best represents the performance before the ultimate strength, whereas Kent and Park represents post-peak behaviour.

Keywords: axial compression; confinement behaviour; low strength concrete; numerical modeling; quantitative analysis; stress–strain.

Grants and funding

RSP-2021/145/Basheer Salah, Kind Saud University, Riyadh Saudi Arabia