Zhuojin Pipe Fitting Co., LtdVehicle-Bridge Coupled Vibration Analysis of Large-Span CFST Arch Bridges
Literature Overview
This paper by Yao Dunrong and Deng Nianchun from Guangxi University addresses the vehicle-bridge coupled vibration response of large-span highway CFST arch bridges. Published in the "Journal of Rail and Transportation Engineering" in 2022, the study focuses on the Pingnan No. 3 Bridge, a representative large-span CFST arch bridge in southern China. The research is supported by multiple National Natural Science Foundation grants (51738004, 51868006, 52268048). The work employs a combined approach using ANSYS finite element analysis and the Universal Mechanism (UM) multi-body dynamics software to achieve computationally efficient coupled vibration simulations.
Methodology and Computational Framework
The authors establish a finite element model of the Pingnan No. 3 Bridge using ANSYS, then export sub-models at different truncation frequencies to the Universal Mechanism platform. A 20-degree-of-freedom KAMAZ-55111 truck model is coupled with the bridge sub-models to simulate the vehicle-bridge interaction. This hybrid approach significantly improves computational speed compared to fully coupled finite element models, making it practical for parametric studies involving multiple vehicle-bridge configurations.
The study investigates the influence of several key factors on the coupled vibration response:
| Factor | Effect on Bridge Response | Effect on Vehicle Response |
|---|---|---|
| Road surface roughness grade | Dominant factor; lower roughness grade leads to larger response | Significant amplification with lower roughness grade |
| Vehicle spacing | Larger spacing reduces bridge response through "peak-shaving" and "warping" effects | Moderate influence |
| Bridge damping ratio | Small effect on mid-span displacement; noticeable effect on mid-span acceleration | Minimal effect |
| Vehicle-bridge frequency proximity | Amplifies bridge dynamic response when frequencies approach | Vehicle response changes are governed by its own spring-damper suspension system |
Key Findings and Technical Implications
The most striking finding is that road surface roughness grade is the most influential factor on both vehicle and bridge dynamic responses. This has direct implications for bridge maintenance and pavement management: maintaining good road surface conditions is more effective at controlling dynamic responses than modifying structural parameters. The study also reveals that moderate vehicle spacing has a beneficial "peak-shaving" effect on displacement peaks, which suggests that traffic flow management could be used as a supplementary measure to reduce dynamic loading on CFST arch bridges.
The frequency coupling analysis reveals that two scenarios of vehicle-bridge same-frequency resonance were examined. In both cases, the bridge dynamic response was amplified, but the amplification was not dramatic when the truncation frequency was set to 12, as the vehicle and bridge frequencies did not approach closely enough to produce significant resonance. The vehicle dynamic response, on the other hand, was primarily governed by its own suspension system rather than the bridge response.
Engineering Practice Integration
From a steel pipe manufacturing and welding perspective, the dynamic loading conditions identified in this study have direct implications for the design and quality control of CFST arch ribs. The arch rib steel tubes in large-span CFST arch bridges are typically fabricated from high-strength steel tubes (such as Q345q or Q370q grade per Chinese standards) that are rolled or cold-bent into the required cross-sectional shape. The welding connections between steel tube segments, as well as the welding of internal stiffeners and diaphragms, must withstand cyclic dynamic loading in addition to static loads.
The study's finding that road surface roughness is the dominant factor suggests that engineers should pay particular attention to the fatigue performance of welded joints in the arch rib and hanger connections. Fatigue assessment in accordance with standards such as ISO 15614 or GB/T 3485 should be conducted for critical weld details, and weld quality inspection—particularly ultrasonic testing (UT) and phased array ultrasonic testing (PAUT)—should be emphasized for these connections. The "peak-shaving" effect of moderate vehicle spacing also suggests that traffic management measures, such as speed limits and vehicle spacing regulations, can serve as practical measures to extend the service life of CFST arch bridges.
Study Insights and Outlook
This paper makes a valuable contribution to the understanding of dynamic behavior in large-span CFST arch bridges. The hybrid ANSYS-UM approach is a practical and efficient methodology that can be adapted for other bridge types and vehicle configurations. The study's recommendations for maintaining good road surface conditions, controlling vehicle spacing, and avoiding vehicle-bridge frequency proximity are practical and actionable. However, the study could be extended to include the effect of wind loading on the coupled vibration response, which is particularly relevant for long-span arch bridges in coastal or high-altitude regions where wind speeds can be significant.
The implications for steel pipe manufacturing are clear: the steel tubes used in CFST arch ribs must be manufactured with high geometric accuracy to minimize vibration-induced dynamic amplification, and the welding quality of all structural connections must meet stringent standards to ensure fatigue resistance under the dynamic loading conditions identified in this study.