Vehicle-Bridge Coupled Vibration Analysis of Large-Span Steel Tube Flange Composite Beam Bridges

Literature Overview

The paper by Wang Xiuli, Zhu Wujun, and Zhang Yu, published in "Science Technology and Engineering" (Vol. 22, No. 28, 2022, pp. 12525-12534), presents a comprehensive investigation into the dynamic performance of large-span composite beam bridges incorporating steel tube concrete flanges. Funded by the National Key R&D Program (2019YFD) and Gansu Provincial Department of Housing and Urban-Rural Development (JK2018-17), the study employs three-dimensional vehicle-bridge coupled vibration analysis using ABAQUS with implicit dynamic methods to evaluate the influence of various parameters on bridge dynamic response.

Core Technical Content and Key Points

Structural Configuration and Design Rationale

The steel tube flange composite beam (STF composite beam) is a hybrid structural system that combines:

• Upper flange: Steel tube filled with concrete, providing high compressive capacity and corrosion resistance
• Lower flange: Steel section (typically I-beam or H-beam), providing tensile capacity
• Web: Steel plate connecting upper and lower flanges, resisting shear

This configuration leverages the advantages of both steel (lightweight, high tensile strength) and concrete (high compressive strength, fire resistance) in their most efficient roles. For large-span applications (typically 50–200 m), this system offers a compelling alternative to conventional steel I-beams or prestressed concrete girders.

Dynamic Analysis Methodology

The vehicle-bridge coupled vibration model incorporates:

Key Dynamic Response Findings

Effect of Road Surface Roughness:

The dynamic response of the STF composite beam bridge increases geometrically with increasing road surface irregularity. The dynamic impact factor (DIF) calculated from the simulation results aligns with the formula in JTG D60-2015 only when the road class is B. For smoother roads (Class A), the code formula overestimates the DIF; for rougher roads (Class C and D), the code formula underestimates the actual dynamic response.

Effect of Vehicle Load and Speed:

• Vehicle load has a linear relationship with mid-span deflection
• Speed effects are complex: below 60 km/h, the dynamic response increases moderately with speed; above 60 km/h, the response increases nonlinearly, suggesting resonance or lock-in phenomena
• The nonlinear speed effect above 60 km/h is attributed to the coupling between vehicle suspension frequency and bridge natural frequency

Effect of Upper Flange Concrete Properties:

• Concrete grade and steel ratio in the upper flange have minimal influence on dynamic performance
• This is because the dynamic response is governed primarily by the overall structural stiffness and mass, and the upper flange concrete contributes relatively little to the flexural stiffness of the composite section

Comparison with Conventional Beams:

Engineering Practice Integration

Fabrication Considerations for Steel Tube Flange Beams

The manufacturing of steel tube flange composite beams involves several critical processes:

1. Steel tube fabrication: The upper flange steel tube is typically fabricated from rolled plates with longitudinal and transverse welds. Weld quality is paramount, as the tube must maintain structural integrity under cyclic loading. SAW or FCAW processes are preferred for full-penetration welds, with 100% ultrasonic testing (UT) per GB/T 11345.
2. Concrete filling: The concrete must be placed with adequate compaction to ensure full filling of the steel tube. For large-span bridges, the tube dimensions can be substantial (e.g., 600 mm × 300 mm), making complete filling challenging. Pumping methods with appropriate slump (160–220 mm) and vibration are essential.
3. Welding of flange-web connections: The connection between the steel tube flange and the web plate is typically a full-penetration groove weld. This weld must accommodate the differential thermal expansion between steel and concrete during service, requiring careful weld design and potentially flexible weld configurations.

Design Implications

The finding that the dynamic response increases nonlinearly above 60 km/h has direct implications for bridge design speed limits and vibration control measures. For bridges in high-speed traffic corridors, additional damping devices or tuned mass dampers may be warranted. The road surface roughness sensitivity suggests that bridge maintenance programs should prioritize road surface quality to minimize dynamic loading on the structure.

Study Insights and Reflections

This research provides valuable technical guidance for the development of STF composite beam bridges, a structural system that bridges the gap between traditional steel and concrete bridge design. The finding that concrete properties in the upper flange have minimal dynamic influence is somewhat counterintuitive but physically reasonable: the dynamic response is dominated by the overall structural flexibility, which is primarily governed by the web and lower flange steel components.

The nonlinear speed effect above 60 km/h warrants further investigation, as it may represent a critical threshold for operational safety. Engineers should consider implementing speed monitoring and vibration control systems for STF composite beam bridges in high-speed applications. The alignment of simulation results with JTG D60-2015 only for Class B roads suggests that the current code formula may need revision to better capture the dynamic behavior of hybrid structural systems.

The study also highlights the importance of considering vehicle-bridge interaction in the design of composite beam bridges, particularly for long-span applications where the natural frequencies of the bridge may fall within the range of vehicle-induced excitation frequencies. Future work should explore the long-term dynamic performance under fatigue loading, considering the progressive degradation of weld connections and concrete-steel interface bonding over the design life of the bridge.