Zhuojin Pipe Fitting Co., LtdEnd-Strengthened Steel Tube Double Steel Plate Concrete Composite Shear Wall Seismic Performance Research
Literature Overview
This paper by Dai Xiaohui, Yuan Chaoqing, Song Shuang, Li Guoyang, and Fang Kuanguang, published in the Journal of Hebei Engineering University (Natural Science Edition, 2021, Vol. 38, No. 4), investigates the seismic performance of double steel plate concrete composite shear walls with end-strengthened steel tubes. The research is supported by the Heilongjiang Provincial Natural Science Foundation Joint Guidance Project.
The fundamental innovation in this work is the introduction of I-shaped steel sections within the steel tube columns at the ends of the double steel plate concrete composite shear wall. This end-strengthening measure is specifically designed to suppress local buckling at the critical end regions of the shear wall, which is a common failure mode in conventional steel tube shear wall systems under seismic loading.
Core Technical Content and Finite Element Model Design
The authors designed 18 finite element models of double steel plate concrete composite shear walls using ABAQUS software, with the primary parameters being the steel tube cross-section form, the I-shaped steel section dimensions, and the shear span ratio. The finite element models were used to evaluate the hysteresis performance, load-bearing capacity, energy dissipation capacity, deformation and ductility, and stiffness degradation of the end-strengthened shear walls.
The finite element model accounts for the nonlinear material behavior of all structural components, including the steel tubes, I-shaped steel sections, steel plates, and concrete core. The interaction between the steel plates and the concrete core is modeled using appropriate contact algorithms to capture the bond-slip behavior and the confinement effect. The material models for the steel components follow the von Mises yield criterion with isotropic hardening, while the concrete model accounts for cracking, crushing, and confinement effects.
Comparative Seismic Performance Analysis
The 18 finite element models allow for a comprehensive comparison of the seismic performance of end-strengthened steel tube double steel plate concrete composite shear walls against conventional steel tube double steel plate concrete composite shear walls. The results demonstrate significant improvements in all key performance indicators.
| Performance Indicator | End-Strengthened Wall | Conventional Wall | Improvement |
|---|---|---|---|
| Peak load capacity | Higher | Baseline | Significant |
| Yield load | Higher | Baseline | Significant |
| Ductility coefficient | Higher | Baseline | Significant |
| Initial stiffness | Higher | Baseline | Moderate |
| Equivalent viscous damping coefficient | Higher | Baseline | Significant |
| Stiffness degradation rate | Slower | Baseline | Improved |
The end-strengthened steel tube double steel plate concrete composite shear walls exhibit substantially improved load-bearing capacity, ductility, stiffness degradation characteristics, and energy dissipation capacity compared to conventional steel tube double steel plate concrete composite shear walls. The I-shaped steel sections within the end steel tubes effectively suppress local buckling, allowing the steel tube columns to maintain their structural integrity under large inelastic deformations.
Influence of Shear Span Ratio
The shear span ratio (the ratio of the shear span to the wall height) is a critical parameter that significantly influences the failure mode and seismic performance of shear walls. The analysis reveals that as the shear span ratio increases, the peak load, yield load, ductility, initial stiffness, and peak equivalent viscous damping coefficient of the end-strengthened specimens all increase substantially.
This trend is consistent with the well-established understanding that higher shear span ratios promote bending-dominated failure modes over shear-dominated failure modes. Bending failure is generally more ductile and provides better energy dissipation capacity than shear failure, which is typically brittle. The end-strengthening measure enhances this beneficial effect by preventing premature local buckling that would otherwise reduce the ductility advantage of bending-dominated failure.
Influence of Steel Tube Cross-Section Form and I-Steel Dimensions
The analysis also investigates the influence of the steel tube cross-section form and the I-shaped steel section dimensions on the seismic performance of the end-strengthened shear walls. The results indicate that these parameters have a relatively insignificant effect on the overall seismic performance of the specimens.
This finding is somewhat counterintuitive but can be explained by the fact that the primary contribution of the end-strengthening measure is the suppression of local buckling, which is achieved effectively by the presence of the I-shaped steel section regardless of its specific dimensions. The overall seismic performance is more strongly influenced by the shear span ratio and the interaction between the steel tube columns and the steel plate-concrete wall panel.
Among the 18 specimens, the specimen designated AZ22-2.0 exhibits the most superior seismic performance, suggesting an optimal combination of parameters that engineers should consider in practical design.
Engineering Practice Considerations
For engineers considering the application of end-strengthened steel tube double steel plate concrete composite shear walls in practice, several important considerations must be addressed:
- The welding of I-shaped steel sections within the steel tube columns is a critical construction activity that requires careful planning and execution. The I-shaped steel must be precisely positioned within the steel tube, and full-penetration groove welds should be used at the top and bottom connections to ensure structural integrity.
- The preheating requirements for welding within the confined space of the steel tube column may be challenging. The thick steel sections at the weld locations may require preheating temperatures of 100-150°C to prevent cold cracking, particularly for higher-strength steels.
- The concrete placement within the steel plate-concrete wall panel must be carefully controlled to ensure proper compaction and bonding with the steel plates. The use of self-compacting concrete is recommended to achieve uniform concrete quality throughout the wall panel.
- The shear span ratio should be selected to promote bending-dominated failure, with a target value of 2.0 or higher to maximize ductility and energy dissipation capacity.
- Post-weld inspection using ultrasonic testing (UT) or magnetic particle inspection (MT) is mandatory for all critical welds, including the connections between the I-shaped steel sections and the steel tube columns.
Key Questions and Reflections
The research raises several important questions for further investigation. First, the long-term durability of the steel plate-concrete interface under cyclic loading is a concern, particularly regarding the potential for delamination or bond degradation over time. Second, the fire resistance of the end-strengthened steel tube double steel plate concrete composite shear wall has not been investigated, which is a critical consideration for practical application.
From a welding perspective, the confined welding environment within the steel tube columns presents significant challenges. The limited access for welding equipment and the restricted ventilation can lead to poor weld quality and increased residual stresses. The use of advanced welding techniques such as robotic welding or narrow-gap welding may be necessary to achieve consistent weld quality in these confined spaces. Additionally, the residual stresses from the welding of the I-shaped steel sections within the steel tube columns may affect the buckling behavior of the steel tube, which should be considered in the structural design.
Summary and Study Insights
This paper provides valuable insights into the seismic performance of end-strengthened steel tube double steel plate concrete composite shear walls. The finite element analysis clearly demonstrates that the introduction of I-shaped steel sections within the end steel tubes significantly improves the load-bearing capacity, ductility, stiffness degradation, and energy dissipation capacity of the shear walls. The shear span ratio emerges as the most influential parameter, with higher ratios promoting more ductile bending-dominated failure modes. The findings offer practical guidance for engineers designing composite shear walls with enhanced seismic performance, emphasizing the effectiveness of end-strengthening measures in suppressing local buckling and improving overall structural resilience.