Numerically evaluate responses of concrete-encased steel tube columns in octal-shaped tall buildings under wind loading

• The CEST column is formed by replacing equal volume reinforcements of RC column. • The stiffness and base moment are closely varied between CEST and RC column. • The deflection and stiffness of CEST and RC columns are evaluated under wind loading. • The CEST shows the lower deflection and higher stiffness compared to the RC column. A unique attachment of the main reinforcements and stirrups in the column is comparatively harder than the placement of the steel tube inside the column. The replacement of reinforcements by the steel tube inside the column is economical if the volume is equal. The present research utilizes an innovative concrete-encased steel tube (CEST) column in an octal-shaped frame-in-frame tall building to evaluate its lateral deflection and stiffness under wind loading. The proposed CEST column is compared to the reinforced concrete (RC) column to obtain close variations of self-weight of 0.12 % and base moment of 0.22 %, which may indicate a good agreement of verification of CEST with RC column. The parametric study is performed by varying height-to-length ratio, wind speed, concrete compressive strength, and longitudinal bar diameter of the column. The CEST shows lower deflection and higher stiffness variations compared to the RC column due to the reason of larger in-plane stiffness of the steel tube compared to the reinforcements of the column. The deflection and stiffness of the CEST column are 22.8 % lower and 34.4 % higher than those of the RC column obtained from the parametric analysis. However, these findings may help professional engineers in practice.