Influence of Internal Steel Mesh on CFT Column Behavior under Steel Tube Damage

Concrete-filled steel tubular (CFT) columns have gained widespread adoption in demanding structural applications, including skyscrapers, bridge piers, and offshore platforms due to their exceptional composite performance. The structural efficiency of CFT columns primarily derives from the confinement effect provided by the steel casing to the encased concrete core. However, this beneficial confinement mechanism becomes compromised when the steel shell sustains damage from extreme events, including seismic actions, fire exposure, or impact loading. This study examines an innovative reinforcement strategy employing internal steel mesh to preserve concrete confinement integrity following partial loss of steel tube functionality. Laboratory investigations were conducted on mesh-reinforced specimens subjected to combined axial compression and reversed cyclic lateral loading. Controlled perforations were introduced in the steel casing to systematically evaluate the mesh’s effectiveness in damaged scenarios. The experimental program comprised thirty specimens—15 intact and 15 with intentionally compromised steel tubes—tested under combined loading conditions. Complementary nonlinear finite element analyses were performed using ANSYS to validate and extend the experimental findings. Both experimental and numerical results demonstrate consistent enhancement in load capacity (29%–62% increase), deformation capability, and energy dissipation characteristics through mesh reinforcement. The performance improvements prove particularly substantial (up to 145% greater energy absorption) in damaged specimens relative to intact counterparts. The findings conclusively establish internal steel mesh as an effective solution for maintaining concrete confinement in compromised CFT columns, offering particular promise for critical structural elements in seismic regions.