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- Title
Safety Evaluation of a Long-Span Steel Trestle with an Extended Service Term Age in a Coastal Port Based on Identification of Modal Parameters.
- Authors
Hongbiao Liu; Ying Li
- Abstract
Combining vibration testing and safety evaluation improves the understanding of structural vibration behavior, aids in the future design of similar structures, and provides key information for the design of remedial measures. This paper investigates the safety of a unique full-scale 40 year old steel trestle structure of an oil wharf based on the identification of modal parameters. This structure is a typical simply-supported through-type parabolic vierendeel steel truss (SSTTPVST) structure with a span of 106m in an extended service term age. Steel trestle vibration responses were measured using state-of-the-art methods, such as ambient vibration survey, initial velocity excitation method, and initial displacement excitation method. The natural frequencies, mode shapes, and damping ratios of the trestles located in land and in the sea were obtained in both the vertical and horizontal lateral directions. Test results showed that the vibration parameters identified by the three excitation methods were almost identical despite the differences in excitation levels between methods. It was also demonstrated that properly planned testing can be performed successfully even in limited conditions, such as low-level excitation. In addition, finite element (FE) modeling of this trestle and model consistency with both experimental results of natural frequencies and mode shapes were described. A mode shape node was found in the first vertical mode shape of this kind of trestle, which was proven in the time history and Fourier spectrum of the trestle vibration response. This result was considerably different than that of normal simply-supported concrete bridges on highways. The safety evaluation of the trestles located in land and in the sea was carried out using the natural frequency changes based on the frequencies obtained in three different years, including the years 2000, 2002, and 2014. The evaluation results indicated that the damage of the trestle located in the sea was more severe than that of the trestle in land, which paralleled with the visual inspection result of the trestle.
- Subjects
TRESTLES; STEEL girders; STRUCTURAL frames; VIBRATION tests; TRUSSES; WHARVES
- Publication
Engineering Letters, 2016, Vol 24, Issue 1, p84
- ISSN
1816-093X
- Publication type
Article