Numerical Simulation and Sensitivity Analysis of Lateral Bearing Capacity of Square Steel Tube Recycled Concrete Columns

Literature Overview

The research by Wang Chenggang and colleagues from Hefei University of Technology, published in Industrial Construction (2018, Vol. 48, No. 1, pp. 172-178), presents a comprehensive numerical simulation and sensitivity analysis of the lateral bearing capacity of square steel tube recycled concrete columns. Funded by the Ministry of Housing and Urban-Rural Development Science and Technology Program (2013-K4-46) and the Anhui Provincial Housing and Urban-Rural Construction Science and Technology Program (2016YF-12), this study builds upon experimental work conducted under low-cycle reversed loading conditions. The use of ABAQUS finite element software for simulation, combined with sensitivity analysis methodology, provides a systematic approach to identifying the most influential design parameters.

Core Technical Findings

The study established several key relationships governing the lateral bearing capacity of square steel tube recycled concrete columns. The lateral capacity increases with steel yield strength, steel ratio, and recycled concrete compressive strength, though the rate of increase varies significantly among these parameters. The steel ratio emerged as the most impactful factor, producing substantial gains in lateral capacity, while increases in recycled concrete compressive strength yielded only marginal improvements that could be considered negligible for practical design purposes.

The slenderness ratio demonstrated the highest sensitivity to lateral bearing capacity changes, followed by the steel ratio. Steel yield strength, axial compression ratio, and recycled concrete compressive strength showed progressively lower sensitivity. This hierarchy of sensitivity is critical for design optimization, as it directs engineering attention toward the parameters that offer the greatest return on design effort.

Material and Manufacturing Perspectives

The use of recycled concrete in steel tube concrete columns represents an important sustainability initiative that reduces the demand for virgin aggregates and diverts construction and demolition waste from landfills. From a materials science perspective, recycled aggregate concrete typically exhibits lower compressive strength, higher water absorption, and greater variability compared to natural aggregate concrete. These material characteristics directly influence the confining effect provided by the steel tube and the overall composite action of the column.

The square steel tube geometry introduces additional manufacturing considerations compared to circular sections. Square tubes are typically produced through ERW or HFW welding processes, where the corner radius and weld seam placement significantly affect the local buckling behavior under lateral loading. The welding quality at the tube corners and the longitudinal weld seam becomes particularly important, as these locations represent potential weak points under cyclic loading conditions.

The interaction between the steel tube and recycled concrete is governed by the bond strength at the interface, which is influenced by the surface texture of the steel tube, the concrete mix design, and the casting process. For recycled aggregate concrete, the presence of adhered old mortar on recycled aggregates may reduce the interfacial bond strength, potentially affecting the composite action that contributes to lateral load resistance.

Sensitivity Analysis Methodology and Engineering Application

The sensitivity analysis approach employed in this study follows a systematic framework that identifies which design variables warrant the most careful control during fabrication and which can be relaxed without significant performance penalty. For engineers involved in the design of steel tube concrete columns using recycled concrete, the key takeaway is that controlling slenderness ratio and steel ratio should be prioritized over maximizing recycled concrete strength.

In practice, this means that the tube-to-flange ratio and the overall geometric proportions of the column should be carefully designed to minimize slenderness effects. The steel ratio, determined by the tube wall thickness relative to the cross-sectional area, should be optimized to provide adequate confinement and lateral resistance. The relatively low sensitivity of lateral capacity to recycled concrete compressive strength suggests that the full range of recycled concrete grades available in practice can be utilized without significant structural penalty, which is encouraging for sustainable construction initiatives.

This research provides valuable guidance for engineers seeking to incorporate recycled materials into structural systems without compromising safety or performance. The sensitivity analysis framework can be extended to other composite column configurations and loading scenarios, offering a transferable methodology for design optimization. The emphasis on slenderness ratio and steel ratio as primary design drivers aligns with fundamental structural mechanics principles and provides a clear, actionable framework for engineering practice.