The global demand for stronger, smarter, and more sustainable infrastructure has placed unprecedented pressure on traditional structural systems. Modern construction must now support ever-taller buildings, longer-span bridges, high-capacity transportation corridors, and resilient lifeline structures capable of withstanding extreme loads and seismic events. While reinforced concrete and bare steel sections have served the engineering community for decades, the evolving complexity of today’s built environment calls for structural solutions that deliver superior performance, efficiency, and durability. In this context, Concrete-Filled Steel Tubes (CFSTs) emerge as a compelling composite system capable of redefining modern infrastructure.

Extensive experimental and analytical research has consistently demonstrated the exceptional behavior of CFST members under combined axial and flexural loading. Experimental studies on high-strength square concrete-filled steel tube beam-columns, involving specimens tested under constant axial load and increasing flexural demand, revealed that ultimate moment capacity is governed by the combined inelastic response of the steel tube and concrete infill, accompanied by local buckling of steel and crushing of concrete [1]. Complementary numerical investigations using nonlinear fiber element analysis (FEA) have successfully captured axial load–moment interaction behavior under biaxial bending, showing excellent agreement with experimental results and validating the suitability of such methods for advanced nonlinear analysis and design of composite columns and frames [2]. Further insight into flexural performance has been provided by mechanics-based unified theory models incorporating confinement effects, which accurately predict the load–deflection behavior of concrete-filled hollow structural section beams across a wide range of section proportions [3]. Parametric studies have also confirmed that flexural capacity increases with sectional area [4], while experimental testing of high-strength concrete-filled CFT beams has demonstrated remarkably ductile failure behavior even for thin-walled steel tubes [5]. Collectively, these findings establish CFSTs as structurally efficient, ductile, and reliable members under both compression and bending. Despite this strong body of evidence and successful global applications, CFSTs remain underutilized in many regions, including India. Their limited adoption is not a reflection of technical inadequacy, but rather a consequence of conservative design practices, incomplete code provisions, and limited practitioner familiarity. This editorial argues that CFSTs must transition from a niche structural option to a mainstream construction system to meet the demands of future infrastructure.

The effectiveness of CFSTs lies in their composite action. A hollow steel tube filled with concrete creates a member in which each material compensates for the weaknesses of the other. The steel tube provides confinement, tensile resistance, and ductility, while the concrete infill enhances compressive strength, stiffness, and stability. This interaction results in a structural system that outperforms conventional reinforced concrete or hollow steel sections used independently.

CFST columns exhibit outstanding axial load capacity due to continuous confinement of the concrete core by the steel tube, which delays cracking and enhances compressive strength. The concrete infill, in turn, prevents inward local buckling of the steel tube, allowing it to reach higher stress levels before instability occurs. This mutual restraint leads to stable post-peak behavior and high energy absorption capacity—critical attributes for seismic-resistant structures. Additionally, CFST columns act as permanent formwork, significantly reducing construction time and labor requirements, particularly in dense urban environments.

Under flexural loading, CFST members demonstrate highly efficient stress distribution. The steel tube resists tensile stresses, while the confined concrete core carries compressive forces, resulting in enhanced flexural strength and stiffness retention. Research has shown that CFST beams and beam-columns exhibit delayed local buckling, smoother post-yield behavior, and superior energy dissipation compared to traditional systems. These characteristics make CFSTs especially suitable for structures subjected to dynamic and cyclic loading, such as bridges, metro systems, and seismic frames.

The slow adoption of CFSTs is primarily driven by non-technical factors. Many design codes lack comprehensive provisions, leading engineers to adopt conservative assumptions that underestimate capacity. Limited exposure during professional training and misconceptions regarding cost and constructability further hinder acceptance. In reality, CFSTs often provide superior lifecycle economy through reduced construction time, lower maintenance, and enhanced durability.

Concrete-Filled Steel Tubes represent a structural system uniquely aligned with the needs of modern infrastructure. Their proven performance in compression and bending, combined with high ductility, constructability, and resilience, positions them as a superior alternative to conventional structural forms. As infrastructure demands continue to escalate, the question is no longer whether CFSTs are effective, but whether the industry is ready to embrace them. To build smarter, safer, and more sustainable structures, CFSTs must become a standard solution rather than an exception.