Seismic Analysis of Square CFST Frame-Steel Plate Shear Wall Structure

Literature Overview

This research by Jin Shuangshuang, Guo Lanhui, Rong Qin, and Zhang Sumei from Harbin Institute of Technology investigates the seismic performance of a hybrid structural system combining square concrete-filled steel tube (CFST) frames with unstiffened thin steel plate shear walls (SPSW). Published in the Journal of Applied Mechanics and Engineering Sciences in 2013, the study was supported by the National Natural Science Foundation of China (50808053) and the China Postdoctoral Science Foundation. The research addresses the need for efficient lateral force-resisting systems that combine high strength, good ductility, and economic efficiency.

Core Technical Methodology

The study employs the OpenSees finite element software to develop a detailed nonlinear analysis model of the CFST frame-SPSW structural system. The model is calibrated against experimental data to ensure accuracy before being used for parametric studies. The Pushover analysis method is employed to trace the elastic-plastic development of the structure, revealing the distribution of inter-story drifts and inter-story shears under monotonically increasing lateral loading. Complementary time-history dynamic analysis is conducted under different ground motion records to evaluate the dynamic response and derive structural influence coefficients and displacement amplification factors.

Structural System Components

The unstiffened thin steel plate shear wall is selected for its advantages of high load-bearing capacity, strong energy dissipation capability, and economic efficiency compared to stiffened SPSW systems. The steel plate is designed to yield in shear under seismic loading, dissipating energy through inelastic deformation. The CFST frame provides the necessary lateral stiffness and gravity load capacity, while the SPSW serves as the primary lateral force-resisting and energy-dissipating element.

Core Technical Findings

The Pushover analysis reveals that the CFST frame and the steel plate shear wall coordinate effectively in resisting lateral loads. The structural system exhibits good ductility, with a well-defined yield plateau and gradual post-yield strength degradation. The inter-story drift distribution is relatively uniform, indicating that the system does not develop a pronounced soft-story mechanism. The inter-story shear distribution confirms that the SPSW attracts a significant portion of the lateral shear forces, as intended in the design concept.

Seismic Performance Indicators

The time-history dynamic analysis under different ground motion records provides the structural influence coefficients and displacement amplification factors, which are essential parameters for performance-based seismic design. These coefficients account for the nonlinear behavior of the structural system and provide more realistic design values than the elastic response spectrum coefficients used in conventional design procedures. The analysis confirms that the hybrid system can achieve performance objectives of life safety or immediate occupancy under moderate to severe seismic events, depending on the specific design parameters.

Engineering Practice Implications

For structural engineers designing seismic-resistant buildings, this study provides quantitative data for the design and detailing of CFST frame-SPSW systems. The structural influence coefficients and displacement amplification factors derived from the analysis can be directly applied in performance-based design procedures, providing a more rational alternative to the simplified procedures in current seismic design codes. The study also demonstrates that the combination of CFST frames and unstiffened SPSW is a viable structural system that offers advantages over conventional moment-resisting frames in terms of lateral stiffness, energy dissipation, and economic efficiency.

The OpenSees modeling approach provides a practical tool for engineers to evaluate alternative design configurations without the expense of physical testing. The calibrated model can be adapted to different building configurations by modifying geometric and material parameters, making it a valuable design verification tool for project-specific applications.

Study Insights and Reflections

The most significant contribution of this study is the comprehensive evaluation of the seismic performance of the CFST frame-SPSW hybrid system through both Pushover and time-history dynamic analyses. The derivation of structural influence coefficients and displacement amplification factors provides practical design data that can be directly incorporated into performance-based seismic design procedures. The finding that the system exhibits good ductility and effective coordination between the frame and shear wall components confirms the viability of this structural system for seismic regions.

One area for further investigation would be the behavior of the frame-SPSW connection under cyclic loading, as the connection details are critical for ensuring the intended load path and preventing premature connection failure. The current study focuses on the overall structural response but does not provide detailed analysis of the connection behavior. Additionally, the effect of floor diaphragm flexibility on the force distribution between the frame and SPSW should be examined, as rigid diaphragm assumptions may not be valid for all building configurations. Nevertheless, the study provides a solid foundation for the design and application of CFST frame-SPSW systems in seismic regions, and the analytical methodology can be extended to address these additional aspects in future research.