buildings Article Experimental Study on Performance of Steel Fiber-Reinforced Concrete V-Shaped Columns Rafea F. Hassan 1 , Nabeel H. Al-Salim 1 , Nisreen S. Mohammed 2 and Husam H. Hussein 3, *   Citation: Hassan, R.F.; Al-Salim, N.H.; Mohammed, N.S.; Hussein, H.H. Experimental Study on Performance of Steel Fiber-Reinforced Concrete V-Shaped Columns. Buildings 2021, 11, 648. https://doi.org/10.3390/buildings 11120648 Academic Editors: Gaochuang Cai, Amir Si Larbi and Konstantinos Daniel Tsavdaridis Received: 2 October 2021 Accepted: 9 December 2021 Published: 14 December 2021 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). 1 Civil Engineering Department, College of Engineering, University of Babylon, Babylon, Iraq; eng.rafea.flaih@uobabylon.edu.iq (R.F.H.); eng.nabeel.hasan@uobabylon.edu.iq (N.H.A.-S.) 2 Civil Engineering Department, University of Technology, Baghdad, Iraq; 40055@uotechnology.edu.iq 3 Department of Civil Engineering, Ohio University, Athens, OH 45701, USA * Correspondence: hh236310@ohio.edu Abstract: Structural engineers have used V-shaped columns based on technical requirements. The inclination of the V-shaped column underlines the individual purpose of the base floor. However, there is no any specification or guidance on the design of V-shaped columns to date. The aim of this study is to investigate the behavior of V-shaped reinforced concrete columns with three angles between columns (30 ◦ , 60 ◦ , and 90 ◦ ) in order for the results to be used in the design and analysis of the V-shaped column. The impact of using a 1.5% dosage of micro-straight-steel fiber (MSSF) in the concrete mixture was also studied. The results showed that the V-shaped column with 30 ◦ , regardless of the concrete type (with and without MSSFs), exhibited crushing at legends when the sample reached the ultimate load, while no cracks occurred at the legends during the test for the other V-shaped columns. Upon increasing the angle of inclination of the V-shaped columns, the ultimate load capacity was decreased by 24%, 23%, and 20% for V-shaped columns with 30 ◦ , 60 ◦ , and 90 ◦ angles of inclination, respectively. The addition of MSSFs in the concrete significantly improved the ultimate axial load and the bending moment compared to the reference specimens with the normal reinforced concrete (NRC). The steel-fiber-reinforced concrete (SFRC) vertical column specimen demonstrated the highest increase in axial load, and the other SFRC V-shaped and flexural specimens showed a minor increase compared to the NRC specimens. Keywords: V-shaped column; steel fiber reinforced concrete; P–M diagram; reinforced concrete; column 1. Introduction In recent years, the intensity in the design of buildings and bridges has been vast, and several new types of structures have appeared and were utilized. One of the new structure types is V-shaped columns [1–4]. The main advantages of the V-shaped column are that the middle span is short, and the three spans are supported by the assemblage two columns at one foundation. The V-shaped column design generally requires more steel reinforcement than the equivalent straight column, so it is very significant to improve the tensile strength of concrete. The concrete tensile strength of structural members may also be enhanced by utilizing additional steel-reinforced rebar and mixing fibers with concrete materials [5–7]. Fiber-reinforced concrete (FRC) is defined as concrete that includes short and discontinuous fibers and traditional components. Using steel fibers in concrete elements delays crack propagation, improving concrete strength and post-cracking performance [5]. This use enhances the behavior of steel-fiber-reinforced concrete (SFRC) beams in terms of load- bearing capacity, energy dissipation ability, deformation, residual stiffness, and cracking performance. Another study shows that steel-fiber-reinforced concrete beams significantly improved after cracking [6]. On the other hand, the inclusion of steel fibers in concrete components may improve the ductility rather than the concrete strengths [7]. Structural engineers used V-shaped columns based on technical requirements. The inclination of the V-shaped column underlines the individual purpose of the base floor. Two Buildings 2021, 11, 648. https://doi.org/10.3390/buildings11120648 https://www.mdpi.com/journal/buildings