This study aims to present the load-carrying capacity and its most influential parameters for concrete-filled steel built-up columns (CFSBC) under axial compression. A novel analytical model has been proposed and validated to estimate the ultimate inelastic buckling strength of the CFSBC. The research also explores the effects of column length, plate thickness and carbon fibre-reinforced polymer (CFRP) confinement through finite element analysis (FEA).
The model has been proposed based on the column’s inelastic buckling. The proposed model has also been verified with the experimental database of 96 CFSBC. The parametric study is carried out using the finite element (FE)-based ABAQUS software for various parameters, such as the length of CFSBC, the plate thickness and the number of confining CFRP layers.
It is observed that while increasing the length of the column, the load-carrying capacity is reduced to about 12% for per metre of length increment and the reduction in the width-to-thickness ratio (b/t) reduces the load-carrying capacity to the extent of 10% to 15% for each 2 mm of thickness reduction. Owing to the change of CFRP layers from 0 to 3, there is no significant change in the results, which concludes that CFRP has a less effective role in the case of CFSBC.
This study primarily focuses on the axial compression behaviour of CFSBC without considering lateral or seismic loading effects. The analytical model is validated against 96 experimental results, but further verification with larger data sets is needed for broader applicability. The FEA is conducted using ABAQUS, which may have limitations in capturing many complex real-world conditions. Additionally, CFRP confinement is analysed for up to three layers only, and its effectiveness beyond this limit remains uncertain.
This study provides a robust framework for designing CFSBC with optimised load-carrying capacity. Engineers can use the validated analytical model to estimate inelastic buckling strength, reducing reliance on costly experimental testing. The findings emphasise controlling column length and plate thickness to maximise strength, ensuring safer and more efficient structural designs. As CFRP confinement has minimal impact, its usage can be minimised, leading to cost savings. These insights are crucial for high-rise buildings and bridge applications, promoting sustainable construction by improving material efficiency, reducing waste and enhancing the overall performance of composite structural elements.
The study contributes to safer and more efficient infrastructure by improving the design of CFSBC, leading to durable and cost-effective construction. Enhanced structural performance reduces the risk of failures, ensuring public safety in high-rise buildings and bridges. The optimised use of materials, especially reduced reliance on CFRP, lowers construction costs, making housing and infrastructure development more affordable. Additionally, promoting sustainable construction through efficient material use aligns with environmental conservation efforts. The findings support infrastructure resilience, benefiting communities by ensuring long-term structural reliability, reducing maintenance needs and fostering economic growth through optimised engineering solutions.
This study proposes a novel analytical model for predicting the inelastic buckling strength of CFSBC, validated with experiments and simulations, offering insights into key design factors while optimising material use and structural efficiency.
