Zhuojin Pipe Fitting Co., LtdComprehensive Analysis of Progressive Collapse Resistance and Seismic Performance of Steel Tube Concrete Joints with Different Connection Types
Literature Overview
This paper by Wang Jingxuan and Wang Wenqi from the School of Civil Engineering at Lanzhou University of Technology, published in Progress in Steel Building Structures (2022, Vol. 24, No. 9, pp. 25-35), presents a comprehensive finite element analysis of steel tube concrete (STC) joints with six different connection types. Funded by the National Natural Science Foundation of China (Grants 52068047 and 51708270), the Gansu Provincial Youth Science and Technology Foundation (Grant 20JR5RA437), and the Gansu Provincial Construction Department Science and Technology Project (Grant JK2021-16), this study addresses the dual challenge of progressive collapse resistance and seismic performance in STC structures. The research is particularly significant given the increasing use of STC structures in high-rise buildings and the growing recognition of progressive collapse as a critical structural safety concern.
Finite Element Modeling Approach
The study employed ABAQUS finite element software to establish detailed models of six different STC joint connection types. The modeling approach included:
| Modeling Aspect | Description |
|---|---|
| Software | ABAQUS (explicit and implicit dynamic analysis) |
| Joint Types Analyzed | Six different connection configurations |
| Steel Material Model | Bilinear or multilinear kinematic hardening plasticity model |
| Concrete Material Model | Concrete damage plasticity model (CDP) |
| Load Cases | Vertical progressive collapse loading and horizontal cyclic seismic loading |
| Performance Metrics | Collapse resistance capacity, ductility, energy dissipation, stiffness degradation |
The six connection types analyzed included variations of bolted, welded, and hybrid bolted-welded connections with different diaphragm plate configurations. The specific connection types examined were:
- Bolted external ring plate joint
- Bolted internal diaphragm plate joint
- Welded external ring plate joint
- Welded internal diaphragm plate joint
- Hybrid bolted-welded external ring plate joint
- Hybrid bolted-welded internal diaphragm through joint
Progressive Collapse Resistance Analysis
Under vertical progressive collapse loading, the study evaluated the collapse resistance capacity and failure characteristics of each joint type. The key findings include:
| Connection Type | Collapse Resistance Rating | Failure Mode |
|---|---|---|
| Hybrid bolted-welded external ring plate | High | Progressive yielding of ring plate with bolt slippage |
| Internal diaphragm plate | High | Diaphragm plate yielding with concrete confinement |
| Bolted external ring plate | Moderate | Bolt fracture or plate yielding |
| Welded external ring plate | Moderate | Weld failure or plate buckling |
| Bolted internal diaphragm | Moderate | Bolt shear failure |
| Welded internal diaphragm | Moderate | Weld cracking |
The hybrid bolted-welded external ring plate joint and the internal diaphragm plate joint demonstrated the best progressive collapse resistance. The hybrid connection benefits from the ductility of welded components combined with the redundancy of bolted connections, while the internal diaphragm plate joint benefits from the direct load path through the diaphragm plate into the concrete core.
Seismic Performance Analysis
Under horizontal low-cycle reversed loading, the study evaluated the seismic performance of each joint type through hysteresis analysis. The key seismic performance indicators included:
- Bearing capacity — The peak lateral load resistance of each joint type.
- Stiffness degradation — The reduction in stiffness with increasing displacement amplitude.
- Ductility — The ratio of ultimate displacement to yield displacement.
- Energy dissipation — The area enclosed by hysteresis loops, representing energy absorption capacity.
The hybrid bolted-welded external ring plate joint and the hybrid bolted-welded internal diaphragm through joint exhibited the best seismic performance. These connections demonstrated stable hysteresis loops with minimal pinching, indicating good energy dissipation and damage tolerance under cyclic loading.
Comprehensive Performance Comparison and Recommendations
The study's primary contribution is the comprehensive comparison of progressive collapse resistance and seismic performance for each connection type. The following table summarizes the overall assessment:
| Connection Type | Progressive Collapse Resistance | Seismic Performance | Comprehensive Rating |
|---|---|---|---|
| Hybrid bolted-welded external ring plate | Excellent | Excellent | Recommended |
| Internal diaphragm plate | Excellent | Good | Acceptable |
| Hybrid bolted-welded internal diaphragm through | Good | Excellent | Acceptable |
| Bolted external ring plate | Moderate | Good | Limited |
| Welded external ring plate | Moderate | Moderate | Limited |
| Bolted internal diaphragm | Moderate | Moderate | Limited |
| Welded internal diaphragm | Moderate | Moderate | Limited |
Based on the comprehensive analysis, the authors recommend the hybrid bolted-welded external ring plate joint for engineering design and application, as it provides the best balance of progressive collapse resistance and seismic performance. This recommendation is significant for the design of STC structures in regions with both high seismic hazard and progressive collapse risk.
Study Insights and Reflections
This paper makes a valuable contribution to the understanding of STC joint behavior under combined progressive collapse and seismic loading scenarios. The use of finite element analysis to evaluate multiple connection types under different loading conditions provides a systematic comparison framework that can guide engineering design decisions. The recommendation of the hybrid bolted-welded external ring plate joint is well-supported by the analytical results and aligns with the general principle that hybrid connections offer superior ductility and redundancy compared to purely bolted or purely welded connections. However, the study is limited to numerical analysis and does not include experimental validation. Future research should include full-scale or large-scale model tests to verify the numerical predictions and to investigate the actual failure modes and damage evolution under combined loading conditions.