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Response Spectrum Method for Extreme Wave Loading With Higher Order Components of Drag Force Tabeshpour Mohammad Reza1*, Fatemi Dezfouli Mani2, Dastan Diznab Mohammad Ali1, Mohajernasab Saied1 and Seif Mohammad Saied1 1. Center of Excellence in Hydrodynamics and Dynamics of Marine Vehicles, Mechanical Engineering Department, Sharif University of Technology, Tehran, Iran 2. Department of Marine Industries, Science and Research Branch, Islamic Azad University, Tehran, Iran Abstract: Response spectra of fixed offshore structures impacted by extreme waves are investigated based on the higher order components of the nonlinear drag force. In this way, steel jacket platforms are simplified as a mass attached to a light cantilever cylinder and their corresponding deformation response spectra are estimated by utilizing a generalized single degree of freedom system. Based on the wave data recorded in the Persian Gulf region, extreme wave loading conditions corresponding to different return periods are exerted on the offshore structures. Accordingly, the effect of the higher order components of the drag force is considered and compared to the linearized state for different sea surface levels. When the fundamental period of the offshore structure is about one third of the main period of wave loading, the results indicate the linearized drag term is not capable of achieving a reliable deformation response spectrum. Keywords: offshore structure design, response spectrum method, wave analysis, Morison equation, higher order components, drag force, wave loading, extreme wave منبع دانلود Tabeshpour_Response Spectrum Method for Extreme Wave.pdf

Simplified analysis for estimation of the behavior of a submerged floating tunnel in waves and experimental verification Sung-il Seo a, *, Hyung-suk Mun a, 1, Jin-ho Lee a, 2, Jin-ha Kim b, 3 a New Transportation System Research Center, Korea Railroad Research Institute, 176, Cheoldo bangmulgwan-ro, Uiwang-City, Gyeonggi-Do, 16105, South Korea b Offshore Plant Research Division, KRISO [Korea Research Institute of Ships & Ocean Engineering], 171 Jangdong, Yusong, Daejeon, 305-343, South Korea a r t i c l e i n f o Article history: Received 3 December 2014 Received in revised form 2 September 2015 Accepted 3 September 2015 Available online xxx Keywords: Inertia force Morison's equation Physical model Linear wave theory Wave load Drag force Submerged floating tunnel a b s t r a c t To achieve rational design in waves for a submerged floating tunnel which has emerged as a new offshore transportation infrastructure, it's necessary to understand its hydrodynamic behavior. For simple but accurate estimation of hydrodynamic forces, a theoretical method is proposed and the tests with physical models in a wave flume were carried out for verification. Morison's equation was used to estimate wave loads composed of inertia force and drag force. Forces calculated by applying the linear wave theory to Morison's equation coincided well with those measured by the tests. The test results showed that mooring systems played a significant role in the movement of the submerged floating tunnel in waves. A pendulum model could be used to describe the motion of the submerged floating tunnel with a single vertical mooring. Based on the verified relations, a simple slack condition which causes the submerged floating tunnel to be unstable was also proposed. The simplified approach proposed by 10.1016_J.MARSTRUC.2015.09.002-Simplified-analysis-for-estimation-of-the-behavior-of-a-submerged-floating-tunnel-in-waves-and-experimental-verification.rar