Zhuojin Pipe Fitting Co., LtdConstruction Stability Analysis of Reinforced Concrete-Filled Steel Tube Arch Bridge with Lateral Inclination and Deviation
Literature Overview
Authored by Niu Hong, Yang Bingcheng, and Yang Ping from Chang'an University and CCCC First Highway Engineering Survey and Design Institute, this paper was published in the Journal of Architecture and Civil Engineering in 2008 (Vol. 25, No. 4, pp. 111–115). The study investigates the structural stability during the reinforcement construction process of a concrete-filled steel tube (CFST) arch bridge that exhibited lateral inclination and deviation, using finite element buckling analysis.
Core Technical Content
Problem Background
Concrete-filled steel tube arch bridges are increasingly used in highway and railway engineering due to their high load-bearing capacity, aesthetic appeal, and rapid construction. However, during the service life, some bridges develop lateral inclination and deviation due to:
- Asymmetric loading from one-sided traffic
- Foundation settlement on one side
- Thermal asymmetry between sunlit and shaded sides
- Construction tolerances and accumulated errors
- Soil pressure asymmetry on abutments
When such defects develop, reinforcement and restoration become necessary. The reinforcement construction process itself introduces temporary structural conditions that may compromise stability.
Finite Element Analysis Methodology
| Analysis Parameter | Specification |
|---|---|
| Model type | Three-dimensional spatial model |
| Analysis type | Buckling (eigenvalue) analysis |
| Loading conditions | Multiple construction stages |
| Structural elements | CFST arch ribs, transverse beams, temporary supports |
| Failure criterion | Critical buckling load factor |
The analysis covered various construction conditions including:
- Removal of temporary supports
- Installation of reinforcement members
- Application of temporary loads
- Sequential loading/unloading during construction
Reinforcement Measures Evaluated
The study proposed and analyzed the following reinforcement measures:
- Temporary lateral restraint steel longitudinal beams: Added to constrain lateral movement during construction
- K-brace welding on arch ribs: Triangular bracing pattern providing geometric stability
- Additional transverse connection beams: Enhancing the overall structural stiffness
- Sequential loading protocols: Controlling the order of reinforcement installation
Stability Improvement Results
| Reinforcement Measure | Stability Improvement | Construction Feasibility |
|---|---|---|
| Temporary lateral restraint beams | Significant (high) | Moderate |
| K-brace welding on arch ribs | Very significant (very high) | Moderate |
| Combined measures | Maximum stability margin | Requires coordination |
Engineering Practice Integration
Construction Stability Management
The study demonstrates that the reinforcement construction of an already-deflected CFST arch bridge presents unique challenges:
- The existing lateral inclination creates an initial eccentricity that reduces the buckling resistance
- Removal of existing temporary supports during reinforcement introduces transient instability
- The asymmetric geometry of the deflected bridge requires modified analysis assumptions compared to a symmetric bridge
- Wind loads during construction may trigger lateral instability in the already-deviated structure
Practical Construction Sequencing
Based on the buckling analysis results, the following construction sequence was recommended:
- Install temporary lateral restraint beams to stabilize the existing deflected structure
- Weld K-braces to arch ribs in a symmetric pattern to restore geometric stability
- Gradually transfer loads from temporary to permanent reinforcement members
- Remove temporary supports only after confirming that the permanent reinforcement system has adequate stability margin
Key Reflections and Study Insights
This paper addresses a practical engineering challenge that is often encountered in bridge maintenance and rehabilitation projects. The use of eigenvalue buckling analysis for construction stage stability assessment is appropriate because it provides a clear safety margin indicator (buckling load factor) that can be directly compared with applied loads.
The study highlights an important principle: reinforcement of a damaged or deflected structure is not simply a matter of adding material—it requires careful consideration of the construction sequence and temporary structural conditions. A reinforcement scheme that is adequate in the final state may be inadequate during the transition phase.
The K-brace configuration is particularly effective because it converts the arch rib from a single curved member into a series of triangular sub-structures, which are inherently stable against lateral deformation. This is consistent with classical structural stability theory where triangulation provides geometric invariability.
For engineers involved in bridge rehabilitation projects, this study reinforces the importance of conducting construction stage stability analysis rather than focusing solely on the final structural performance. The temporary conditions during reinforcement construction often represent the critical design state, and overlooking them can lead to catastrophic failures during construction.
The collaboration between academic researchers (Chang'an University) and design institutes (CCCC First Highway) exemplifies the productive integration of theoretical analysis with practical engineering knowledge that is essential for solving complex rehabilitation problems.