DBPapers
DOI: 10.5593/sgem2017/14/S05.038

ON SITE CONDITIONS EFFECT IN DISPLACEMENT AND STRAIN STATE MONITORING FOR OFFSHORE STRUCTURES

R. Joavina, M. Popa, S. Zagan
Monday 11 September 2017 by Libadmin2017

References: 17th International Multidisciplinary Scientific GeoConference SGEM 2017, www.sgem.org, SGEM2017 Conference Proceedings, ISBN 978-619-7408-00-3 / ISSN 1314-2704, 29 June - 5 July, 2017, Vol. 17, Issue 14, 303-310 pp, DOI: 10.5593/sgem2017/14/S05.038

ABSTRACT

Design of a structure together with monitoring the structural response to dynamic loads (seismic and hydrodynamic), fatigue aging, the possibility of successive degradation, resilience respective vulnerability are strongly influenced by the chosen calculus model, and a laborious probabilistic calculation. For particular case of offshore structures this implies the connection between the actions of the environment: wave histograms, wind action, foundation collapse, structure, technological activities and so on. Also history response study of the same type platforms (or type near) is important (although it is unlikely that two platforms to be used in similar conditions) the behavior of a structure in specific conditions could give valuable information to the design engineer. The present article tries to assess the responses in displacements and deformations of a marine self erecting platform structure at the return in shipyard for maintenance operations after 8 years service period using a finite element method - FEM model. Analyze is done using the hydro meteorological data on the site during the service period (wave histograms and wind speed on cardinal directions and sea spectrum) and also by considering the effects of structural corrosion. The wave and wind forces used for loading the model were calculated using two computational programs developed by authors: MIRAF and MIRAV programs based on probabilistic calculus. Analyzes goes for the modeling influence of nodal connections in evaluating the structural response in displacements but focused on displacement differences between new and corroded structure. Results shows about 15% increase of displacement for corroded structure. Also the first 5 fundamental free vibration period for the structure are obtained, data that can be used in evaluating the dynamic resonance.

Keywords: displacement, offshore structure, onsite condition, structural model