Zhuojin Pipe Fitting Co., LtdSeismic Response and Parameter Control of Curved Steel Tube Trusses Under Traveling Wave Effect
Literature Overview
This research investigates the seismic response of curved steel tube trusses, which are commonly used in large-span structures such as stadiums, exhibition halls, and airport terminals. The traveling wave effect, which accounts for the spatial variation of ground motion along the length of a long-span structure, can significantly alter the seismic demand compared to the conventional assumption of uniform ground motion. Understanding this effect is essential for the safe design of curved steel tube trusses, which are particularly sensitive to asymmetric excitation due to their geometric configuration.
Core Technical Methodology
The seismic analysis employs a multi-support excitation framework in which the ground motion at each support point is spatially correlated according to the traveling wave model. The curved steel tube truss is modeled as a three-dimensional frame structure with beam elements that capture the bending, torsional, and axial behavior of the steel tubes. The traveling wave effect is characterized by the wave propagation velocity and the spatial correlation coefficient, both of which depend on the geological conditions and the distance between support points.
| Parameter | Typical Value | Influence on Response |
|---|---|---|
| Truss span | 50–200 m | Longer spans experience greater traveling wave effects |
| Wave propagation velocity | 100–500 m/s | Lower velocities increase spatial variation |
| Spatial correlation coefficient | 0.7–0.95 | Lower values indicate less correlation |
| Ground motion frequency content | 0.5–10 Hz | Higher frequencies reduce traveling wave effects |
| Truss curvature ratio | 1/5 to 1/15 | Shallow curves are more sensitive to asymmetric excitation |
The analysis compares the seismic response under uniform excitation and traveling wave excitation, evaluating key response parameters including displacement, stress, and support reactions. The parametric study varies the truss geometry, material properties, and support conditions to identify the critical design parameters.
Engineering Practice and Key Findings
The study reveals that the traveling wave effect can substantially increase the seismic demand on curved steel tube trusses, with the following key observations:
- The peak displacement under traveling wave excitation can exceed that under uniform excitation by 20–50%, depending on the span length and wave velocity.
- The stress distribution becomes highly asymmetric, with the support closest to the wave source experiencing significantly higher stresses than the far support.
- The torsional response of the truss is amplified under traveling wave excitation, particularly for trusses with shallow curvature ratios, where the geometric asymmetry couples with the spatial variation of ground motion.
Parameter Control Strategies
To mitigate the adverse effects of the traveling wave on curved steel tube trusses, the following design strategies are recommended:
- Increase the stiffness of the truss in the longitudinal direction to reduce the differential displacement between supports.
- Employ base isolation or damping systems at the supports to decouple the truss from the traveling wave excitation.
- Optimize the truss geometry by increasing the curvature ratio to enhance the torsional rigidity and reduce the sensitivity to asymmetric excitation.
Study Insights and Implications
The research on seismic response of curved steel tube trusses under traveling wave effect highlights a critical aspect of seismic design that is often overlooked in practice. For long-span structures, the assumption of uniform ground motion can be non-conservative, and engineers should incorporate the traveling wave effect in the seismic analysis of such structures. The parametric study provides a systematic approach to identifying the critical design parameters and optimizing the structural configuration for seismic performance. Future work should focus on the development of simplified design procedures that account for the traveling wave effect without requiring the computational resources of full multi-support time-history analysis.