Interfacial Bond Strength of Concrete-Filled Galvanized Steel Tubes: Push-Out Experiments, Geometry-Grouped Machine Learning, and Multi-Criteria Optimization
Year: 2026
Type: preprint
Abstract: Interfacial load transfer governs composite action in concrete-filled steel tubes, yet the combined effects of concrete strength and tube geometry remain difficult to quantify when experiments are limited. This study evaluates the push-out bond strength of concrete-filled galvanized steel tubes using 27 reported observations arranged as three concrete grades (nominal M40, M50, and M70) across a Taguchi L9 geometry matrix comprising tube diameters of 33.7–48.3 mm, wall thicknesses of 2.6-4.0 mm, and length-to-diameter ratios of 12–16. The measured bond strength ranged from 0.830 to 2.062 MPa. Main-effect analysis and analysis of variance identified L/D as the dominant factor (33.13% contribution, p < 0.001), followed by wall thickness (19.43%, p = 0.003), concrete strength (17.44%, p = 0.004), and diameter (8.86%, p = 0.043). To avoid optimistic model assessment, machine-learning models were evaluated by nested, geometry-grouped cross-validation, in which all concrete grades sharing one L9 geometry were withheld together. Support vector regression provided the best generalization (R² = 0.719, RMSE = 0.193 MPa, MAE = 0.157 MPa, and MAPE = 10.87%), whereas tree ensembles were less reliable for this small structured dataset. Entropy-weighted MOORA and COPRAS analyses, together with the Taguchi larger-the-better criterion, consistently selected D = 42.2 mm, t = 4.0 mm, and L/D = 12 as the robust optimum; the corresponding bond strengths were 1.899, 1.915, and 1.802 MPa. The results show that a short, thick-walled tube geometry provides the most stable interfacial resistance within the investigated domain, while grouped validation is essential for credible data-driven prediction from compact experimental designs.
Source: Research Square
Institution: B.M.S. College of Engineering
Language: English
Subfield: Civil and Structural Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7213530396