Composite Columns made of Concrete‐filled Hollow Section with embedded Steel Cores using High‐Strength Steel

Abstract In recent years, steel composite columns have lost significant market share compared to prefabricated reinforced concrete columns due to rising material costs and competitive pricing. The use of high‐strength steel (HSS) in composite columns presents an opportunity to revitalize the market for these columns. HSS offers improved strength‐to‐weight ratios, which can enhance the performance of composite columns, but its application in this context faces challenges. One of the primary issues when using HSS in composite columns is the impact due to welding. Welding HSS can lead to cold and hot cracking as well as high residual stresses, both of which can negatively impact the load‐bearing capacity of the columns. To address these challenges, concrete‐filled hollow steel sections with embedded steel cores using HSS may provide a promising solution. This design avoids the need for welding, thereby reducing the risk of cracks and residual stresses. So far, research has primarily focused on round hollow sections with embedded solid cores, but these studies have only considered steel grades up to S460. There is limited research on the use of higher steel grades in this configuration. As part of a research project, this gap is to be closed by investigating the behavior of hollow sections with embedded solid cores as composite columns made of HSS. A test setup was developed to study these columns under axial loading conditions. The experiments were conducted to validate a novel design concept for the composite columns made of concrete‐filled hollow steel sections with embedded steel cores using high‐strength steel under different loading conditions (i.e., eccentrical load introduction). The novel design concept is presented within the scope of this paper and is compared to experimental results.