Zhuojin Pipe Fitting Co., LtdSeismic Performance of Steel Tube Concrete Frame with Integral Prefabricated Infill Walls
Literature Overview
This paper by Zhou, Xu, Tian, Wang, Li, and Feng (2021), published in the Journal of Harbin Institute of Technology (Vol. 53, No. 4), presents a full-scale low-cycle reversed loading test on a single-bay, two-span, two-story steel tube concrete (STC) column frame with integral prefabricated infill walls. The research addresses the long-standing challenge of infill wall-frame interaction, where rigid connections between infill walls and frames can induce brittle failure modes and compromise the ductile behavior of the primary structural system.
Construction Details and Connection Strategy
The authors implemented a dual construction strategy to decouple infill wall behavior from the primary frame:
- Gap provision between STC columns and infill walls to prevent direct load transfer during seismic events.
- Flexible connections between infill wall panels and steel beams to allow controlled relative displacement.
This approach preserves the superior deformation capacity and ductility of the STC frame while maintaining the architectural function of infill walls.
Experimental Results and Seismic Performance
| Performance Indicator | Test Result | Assessment |
|---|---|---|
| Hysteresis loop shape | Full and stable | Excellent energy dissipation |
| Ultimate drift ratio | 1/41 | Good ductility |
| Post-peak load stability | Stable residual capacity | Adequate safety reserve |
| Infill wall damage progression | Delayed and mitigated | Flexible connection effective |
| Overall connection reliability | High | Integral connection performs well |
The test demonstrated that the flexible connection effectively reduces the load transferred from the frame to the infill wall panels, thereby delaying and reducing overall damage to the prefabricated panels. The STC frame retained stable load-bearing capacity even at large drift ratios, confirming the effectiveness of the proposed construction approach.
Engineering Practice Integration
For steel pipe and structural steel fabrication engineers, this study highlights the importance of connection design in prefabricated structural systems. The flexible connection details between infill walls and steel beams represent a critical interface that must be carefully designed and fabricated to accommodate seismic displacements without failure. Key fabrication considerations include:
- Precise dimensional tolerances at connection interfaces to ensure proper gap accommodation.
- Selection of appropriate fastener types and materials that can withstand cyclic loading without fatigue failure.
- Quality control of weld connections at beam-to-column joints, which must maintain their full ductile capacity throughout the seismic event.
From a welding quality control perspective, the STC column fabrication involves critical weld joints that must maintain their integrity under cyclic deformation. Non-destructive testing (NDT) protocols including ultrasonic testing (UT) and magnetic particle testing (MT) should be applied to all structural welds in such systems, with particular attention to the weld metal chemistry and heat-affected zone (HAZ) toughness properties.
Study Insights and Reflections
The paper convincingly demonstrates that the combination of STC columns—which inherently possess superior energy dissipation and ductility compared to reinforced concrete columns—with properly detailed prefabricated infill walls creates a structural system with excellent seismic resilience. The finding that the overall structure maintains stable load-bearing capacity at a drift ratio of 1/41 is particularly significant for performance-based seismic design, as it indicates substantial safety margins beyond typical code requirements. However, engineers should recognize that the test specimen was a single-bay, two-story model, and the behavior of multi-story systems with more complex loading patterns may differ, particularly regarding the distribution of inter-story drifts and the cumulative effects of connection damage over multiple seismic cycles.