Abstract
Ambient and forced vibration tests are proposed to evaluate dynamic characteristics of a caisson-type breakwater, including natural frequencies and modal damping ratios. The feasibility of a numerical analysis model with fluid-structure-soil interaction effects, which play an important role in evaluating structural performance and safety, was investigated by comparing the numerical results with experimental results. The Oryukdo breakwater in Busan, Republic of Korea, was employed as the target structure. This breakwater was once heightened by installing additional parapet structures of about 4 m tall to improve the harbor tranquility in 2005. Vibration tests were carried out in 2000 (before heightening) and in 2011 (after heightening). Most caissons were tested in the first test, while only one caisson was tested in 2011. It was found that natural frequencies were reduced by 1.7%–4.3% after heightening, and similar results were observed from the numerical analysis. It was also found that forced vibration tests can yield more reasonable results than ambient vibration tests. Even though there is some discrepancy between experimental and numerical results, numerical analysis can be carried out to analyze dynamic characteristics and evaluate structural performance and safety.
Highlights
In the recent years, strong typhoons (e.g., Typhoon Maemi in 2003 and Typhoon Bolaven in 2012) have slammed into the Korean Peninsula
To protect harbor infrastructures and facilities from future typhoons and storms, design specifications for breakwaters should be revised to take into account gradually increasing extreme wind speed and wave height during typhoons due to climate change in the northeast Asian region [1]
The dynamic characteristics were analyzed using numerical models of the structure before and after parapet installation, and the results were compared with experimentally evaluated natural frequencies
Summary
Strong typhoons (e.g., Typhoon Maemi in 2003 and Typhoon Bolaven in 2012) have slammed into the Korean Peninsula. It is possible to evaluate existing structures by carrying out numerical analysis with simulation models based on design drawings It would be very difficult or infeasible to quantitatively evaluate structural performance when design drawings are unclear or when the structure is modified without documentation. Visual inspection is a practical and widely applied means of inspecting caisson-type breakwaters and can be supplemented with nondestructive evaluation when necessary Loading tests such as static and dynamic tests allow for loading conditions similar to service loading states and can more accurately evaluate structural performance. Boroschek et al carried out similar vibration tests on a pile-supported breakwater in Ventanas Port, Chile, through pull-back tests (a type of FVTs) and AVTs. It was reported that clearer and more distinct peaks were observed from FVTs than AVTs, and the first and second natural frequencies were estimated to be around 1.6 Hz and 2.7 Hz, respectively. The practicality of the numerical analysis model was investigated by comparing the analysis results with experimental results
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
