Title: Assessment of Use of Steel Bars with Unintended High Strength in Tied Columns

Author(s): Muhammad Masood Rafi and Muhammad Saad Khan

Publication: Structural Journal

Volume: 121

Issue: 5

Appears on pages(s): 65-76

Keywords: curvature; moment capacity; Monte Carlo simulation; reinforced concrete columns; strength-reduction factor; tensile strain

DOI: 10.14359/51740852

Date: 9/1/2024

Abstract:
This paper presents the details of the analyses which were conducted to study the effects of steel reinforcing bars with unintended high strength on the behaviors of reinforced concrete (RC) columns. The influence of these bars on the column strength and strength-reduction factors were investigated. The former was studied with the help of column axial load-moment interaction diagrams, while a reliability analysis was carried out for the latter. Four different column cross sections reinforced with reinforcement ratios varying from 1 to 4% were included in the analysis. Other variables included concrete compressive and reinforcing bar yield strengths. The effects of the aforementioned variables were also considered on the development length of the reinforcing bars in tension and compression. It was found that the use of reinforcing bars with unintended high strength could change column behavior to compression-controlled at a lesser axial load level, which is accompanied by a reduction in the curvature capacity. Modifications have been suggested to control the negative effects of unintended high strength of bars on the column behavior and bar development length. Strength-reduction factors for RC sections ranging from compression-controlled to tension-controlled regions have also been proposed, which differ from those suggested by the prevalent code of practice.