Analytical Study of the Behavior of Steel Tubular Columns Filled with Recycled Aggregate Concrete with Normal or High Compressive Strength

The current research starts by modeling experimental test from literature. The influences of different parameters such as recycled aggregates ratios and steel tube thicknesses on the behavior of recycled aggregates concrete (RAC) encased columns under axial loads of minimum eccentricity are studied. The slenderness of the finite element analyzed columns is also quickly looked at. These data along with other data collected from the literature are used to check the validity of the formulas for ultimate capacity of AISC360-22, EC4, SBC304-18, Chinese, and ECP203-2020 codes for such columns. It is found that the increase in the concrete strength results in increase in the column capacity, while the increase in recycled aggregate ratio results in decrease in the column capacity. Keeping all other parameters constant, the increase in the steel tube thickness results in higher column ultimate loads. Slender column supports lesser load and the equation of ECP203-2020 for the lateral deformation when calculating the additional moment needs to be readjusted. The studied equations can still be used for the case of recycled concrete filled steel tube columns. A new equation for the capacity of this type of columns is proposed and proved to be more accurat.