Comparative Analysis of Distorted Froudian and Equivalent Single Degree of Freedom Models in Offshore Jacket Platform Seismic Simulation

Mohasel, Mohamadhosein; Mostafa Gharabaghi, Ahmad Reza; Chenaghlou, Mohamad Reza

doi:10.22034/ijcoe.2024.457741.1083

Comparative Analysis of Distorted Froudian and Equivalent Single Degree of Freedom Models in Offshore Jacket Platform Seismic Simulation

Document Type : Original Research Article

Authors

Mohamadhosein Mohasel ¹^{, 2}

Ahmad Reza Mostafa Gharabaghi ³

Mohamad Reza Chenaghlou ⁴

¹ Department of Civil Engineering, Sahand University of Technology, Tabriz, Iran.

² Pars Oil and Gas Company (POGC), Tehran, Iran.

³ Professor, Department of Coasts, Ports and Marine Structures, Sahand University of Technology, Tabriz, Iran

⁴ Professor, Faculty of Civil Engineering, Sahand University of Technology, Tabriz, Iran

10.22034/ijcoe.2024.457741.1083

Abstract

The techniques of modeling are a very powerful way to simulate offshore platforms. For situations where the numerical modelling of structure process is very complex, these methods are preferred, and the model cannot be expressed in precise mathematical formulas. Dynamic characteristics of the structure shall be taken into account in order to determine simulation specifications. In this article, two methods of distorted Froudian models and an equivalent single degree of freedom system were used to model the platform. In the distorted Froudian method, by allocating different scale coefficients for geometric features and other specifications, the problem of modeling members that suffer from problems such as unreality due to applying some scale coefficients (such as the thickness of tubular members) is solved. In the second method, due to the more significant effect of the first mode on the vibration of the system (more than 90% mass participation), the structure becomes an equivalent single degree of freedom model and the construction of the platform in the laboratory becomes very simple. The obtained results showed the excellent accuracy of both methods and the excellent efficiency of the equivalent system with an equivalent single degree of freedom in the specific conditions in this research.

Keywords

Offshore jacket platform

Physical modeling

Distorted Froudian model

Equivalent single degree of freedom

Time history response

Subjects