جستجو در تالارهای گفتگو

Frequency Domain Long-Term Efficiency of Viscous Damper in Jacket Platforms Under Random Wave Load Mohammad Reza Tabeshpour1 · Hossein Janbazi Rokni2 Abstract Various types of controlling mechanisms have been investigated to decrease vibrations of different structures, and in many cases, the reliability has been increased with respect to conventional methods of structural optimization. Among them, using passive viscous damper is one of the useful methods to control structure response due to environmental loads. Hence, in this study, the effect of viscous damper on vibration control of jacket platform (case study oil platform SPD2 and Resalat) exposed to wave loads is investigated, and with the sea state, long-term performance of damper to reduce the structural response is introduced for the first time the more suitable than the responses in an especial case. To keep up this purpose, the platform is modeled by finite element method, and wave spectra are radiated to it. Spectral analysis is adopted to investigate the structural response of the jacket platform equipped with viscous dampers, and also, conventional arrangements of dampers are analyzed to acquire optimal one. Then, the economically optimal arrangement of damper is determined. The novelty of this paper is that the results based on the sea states recorded in the long term help one find the optimal arrangement of damper. Keywords Jacket · Long term · Viscous damper · Wave منبع دانلود Tabeshpour_Janbazi_Frequency Domain Long-Term Efficiency.pdf

Hydrodynamic damped pitch motion of tension leg platforms 1M. R. Tabeshpour; 2B. Ataie Ashtiani; 3M. S. Seif; 2A. A. Golafshani 1 Center of Excellence in Hydrodynamics and Dynamics of Marine Vehicles, Mechanical Engineering Department, Sharif University of Technology, Tehran, Iran 2 Civil Engineering Department, Sharif University of Technology, Tehran, Iran 3 Mechanical Engineering Department, Sharif University of Technology, Tehran, Iran Received 5 February 2013; revised 2 March 2013; accepted 27 March 2013 ABSTRACT: Because of fluctuation in leg tension, pitch motion is very effective fatigue and life safety of leg elements in tension leg structures (TLSs). In this paper an exact solution for pitch vibration of a TLS interacting with ocean wave is presented. The legs of TLP are considered as elastic springs. The flow is assumed to be irrotational and single-valued velocity potentials are defined. The effects of radiation and scattering are considered in the boundary value problem. Because of linear behavior of legs during wave excitation, ignoring coupling effects with other degrees of freedom, the analytical solution of pitch response has good agreement with the real behavior of the structure. Keywords:Hydrodynamic; Tension Leg Structure (TLS); Pitch; Wave; Radiation; Scattering دانلود Tabeshpour_..._Hydrodynamic-damped_2013.pdf