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Journal of Control Science and Engineering
Volume 2017, Article ID 7208241, 17 pages
https://doi.org/10.1155/2017/7208241
Research Article

Investigation and Control of VIVs with Multi-Lock-in Regions on Wide Flat Box Girders

1Key Laboratory of New Technology for Construction of Cities in Mountain Area, Chongqing 400045, China
2School of Civil Engineering, Chongqing University, Chongqing 400045, China
3Department of Highway Engineering, Chongqing Construction Science Research Institute, Chongqing 400017, China

Correspondence should be addressed to Liangliang Zhang; moc.621@015002llz and Yang Yang; moc.361@01725002yy

Received 19 December 2016; Revised 10 February 2017; Accepted 20 February 2017; Published 14 March 2017

Academic Editor: Seiichiro Katsura

Copyright © 2017 Bo Wu et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

On the preliminary designing of a wide flat box girder with the slenderness ratio 12, vertical and torsional vortex-induced vibrations (VIV) are observed in wind tunnel tests. More than one lock-in region, which are defined as “multi-lock-in regions,” are recorded. Therefore, suspicions should be aroused regarding the viewpoint that wide box girders are aerodynamic friendly. As the three nascent vortexes originating at the pedestrian guardrails and inspection rails shed to near-wake through different pathways with different frequencies, the mechanisms of VIVs and multi-lock-in regions are analyzed to be determined by the inappropriate subsidiary structures. A hybrid method combining Large Eddy Simulation (LES) with experimental results is introduced to study the flow-structure interactions (FSI) when undergoing VIVs; the vortex mode of torsional VIV on wide flat box girders is defined as “4/2S,” which is different from any other known ones. Based on the mechanism of VIV, a new approach by increasing ventilation rate of the pedestrian guardrails is proved to be effective in suppressing vertical and torsional VIVs, and it is more feasible than other control schemes. Then, the control mechanisms are deeper investigated by analyzing the evolution of vortex mode and FSI using Hybrid-LES method.