Journal of Constructional Steel Research 192 (2022) 107229 0143-974X/© 2022 Elsevier Ltd. All rights reserved. Experimental behavior of circular composite columns with different weld arrangements Said Boulaares a, b, * , Djamel Boutagouga a, b , Abdelkader Houam a a Civil Engineering department, Larbi Tebessi University, Tebessa, Algeria b Laboratoire de G´ enie Civil Appliqu´ ee, Larbi Tebessi University, Tebessa, Algeria A R T I C L E INFO Keywords: Lateral welds Longitudinal welds Concrete-flled Waste metal plates Composite columns Load bearing capacity ABSTRACT Eighteen (18) circular short composite columns including 9 concrete-flled steel columns and 9 concrete-flled stainless steel columns, were experimentally studied in this paper. All composite columns have the same di- mensions: D= 160 mm, H= 300 mm and t= 2 mm. The objective of this study is to shed light on the effect of the number and arrangement of lateral and longitudinal welds on the resistance and behavior of concrete-flled composite columns. Based on the results obtained, it was confrmed that weld joints have slight effect on the bearing capacity and instability modes of the studied composite columns. Lateral and longitudinal welds were very successful in conveying compression and bending efforts. The experimentally measured load-bearing ca- pacities of the composite columns were compared to those predicted by Eurocode 4, AISC 360–16 and the equation proposed by Giakoumelis and Lam. All the results predicted by the AISC 360–16 code showed a good concordance with the experimental test results. However, the predictions calculated by the EC4 and the equation proposed by Giakoumelis and Lam were not conservative. This investigation shows that the use of lateral and longitudinal welds in composite columns applications would result in a reliable and economical design. This encourages designers to build their confdence in the use of this type of waste metal plates as structural com- ponents of locally produced materials. 1. Introduction Concrete-flled steel tubular (CFST) columns have been widely used in large buildings and bridges [1–3] due to their excellent structural performance characteristics. By combining the benefcial characteristics of steel and concrete, economical and high-performance designs can be achieved. Composite columns offer high strength, high ductility, high rigidity and high fre resistance [3–5]. In addition, steel tubes serve as a permanent formwork for concrete which, effectively reduces construc- tion time and costs [6,7]. In recent years, concerns about environment protection have been rapidly increased in various countries; therefore, researchers in the feld of construction and civil engineering have motivated for the reuse of waste material of factories and constructions. Among these waste ma- terials are steel and stainless steel sheet plates. Using these waste ma- terials in civil engineering can help preserve the environment and reduces construction costs. We have thus, developed the idea that the offcuts of steel and stainless steel sheets welded together can form a hollow column. The mechanical behavior of CFST composite columns has attracted the attention of many researchers and have been the subject of numerous studies in different countries. For instance, Sakino et al. [8] explained the underlying mechanisms for developing circum- ferential tensile stress in the steel tube. In the initial stages of loading circular columns subjected to axial load, since Poisson ratio of concrete is lower than that of steel, the steel tube wall tends to separate from the concrete core. As the load increases, the longitudinal and lateral strains increase until the concrete transverse deformation catches up with that of the steel tube. When the load is further increased, a circumferential tensile stress expand in the steel tube, and the concrete core is subjected to a tri-axial stress state. Giakoumelis and Lam [1] studied the effect of the concrete compressive strength, circular wall thickness and square steel tubes on the concrete-flled steel tubes behavior. Although, there are a few studies that are related to longitudinal welding in composite columns. Ekmekyapar [4], experimentally studied 18 composite col- umns to evaluate the performance of lateral and longitudinal welded columns. The studied parameters are the ratio L/D (short, medium and long columns), the ratio D/t, and the lateral welding position. Guo et al [9] performed an experimental work on longitudinally welded box * Corresponding author at: Civil Engineering department, Larbi Tebessi University, Tebessa, Algeria. E-mail address: said.boulaares@univ-tebessa.dz (S. Boulaares). Contents lists available at ScienceDirect Journal of Constructional Steel Research journal homepage: www.elsevier.com/locate/jcsr https://doi.org/10.1016/j.jcsr.2022.107229 Received 30 September 2021; Received in revised form 26 February 2022; Accepted 2 March 2022