Zhuojin Pipe Fitting Co., LtdNumerical Simulation of Bond-Slip Interaction Between Steel Tube and Concrete
Literature Overview
The paper by Hu Bo and Wang Jianguo, published in China Journal of Highway and Transportation in 2009 (Vol. 22, No. 4, pp. 84-91), presents a numerical investigation of the bond-slip interaction between steel tubes and concrete in CFST members. The research was supported by the Anhui Provincial Engineering Technology Research Center for Disaster Prevention and Mitigation in Civil Engineering (Project No. 2007368) and conducted at the College of Civil and Hydraulic Engineering, Hefei University of Technology. The bond-slip interface is a critical mechanism governing load transfer between steel and concrete components, directly influencing the structural behavior of CFST beams and columns under combined loading.
Bond-Slip Model Development
Building upon existing push-out test research, the authors proposed a simplified constitutive model for the bond-slip relationship between steel tubes and concrete. The model captures the essential nonlinear characteristics of the interface behavior, including the initial elastic bond, progressive slip, and ultimate bond degradation. The simplified model was implemented in ANSYS using the nonlinear spring element Combination39, which allows for the definition of arbitrary nonlinear force-displacement relationships.
| Modeling Element | Specification |
|---|---|
| Software | ANSYS |
| Interface element | Combination39 (nonlinear spring) |
| Model type | Simplified bond-slip constitutive relationship |
| Validation basis | Push-out test data |
| Analysis cases | CFST beam mid-span, column mid-section |
Numerical Results and Interface Behavior
The numerical simulation results demonstrated good agreement between the simplified model predictions and experimental curves. The analysis covered two representative cases: CFST beams under flexural loading and CFST columns under axial loading. For the beam case, the mid-span section was analyzed, with separate examination of the steel tube stress distribution on the tension and compression sides. For the column case, the mid-section was analyzed.
The relative slip distribution along the member length at the end of loading revealed important patterns. The bond-slip interaction is not uniform along the member length, with localized regions of high slip corresponding to zones of maximum shear transfer demand. The stress distribution on the tension side and compression side of the steel tube differed significantly, reflecting the asymmetric nature of bond-slip under flexural loading.
Engineering Practice Implications
For finite element modeling of CFST structures, the selection of an appropriate bond-slip interface model is critical for accurate prediction of load-deflection behavior and failure modes. The Combination39 element approach provides a practical implementation strategy that balances computational efficiency with modeling accuracy. Engineers should note that the bond-slip behavior is sensitive to concrete strength, steel tube wall thickness, and section geometry, and these parameters should be calibrated for each specific application.
Study Insights
The research highlights that the bond-slip interface in CFST members is not a passive connection but an active load-transfer mechanism that significantly influences structural performance. The simplified model approach is particularly valuable for parametric studies and design optimization, where computational efficiency is paramount. The observation that slip distribution is non-uniform along the member length has implications for reinforcement detailing, as regions of high slip demand may require additional mechanical interlock or shear connectors. The study demonstrates the value of combining experimental push-out tests with numerical simulation to develop practical interface models, a methodology that remains relevant to contemporary research on steel-concrete composite interfaces.