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Civil-Comp Proceedings
ISSN 1759-3433
CCP: 93
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Paper 113

Vibration Analysis of a Production Platform induced by Mechanical Equipment

B.D. Rimola1, J.G.S. da Silva2, A.C.C.F. Sieira2, L.R.O. de Lima2 and L.F. da C. Neves3

1Civil Engineering Post-graduate Programme, PGECIV, State University of Rio de Janeiro, UERJ, Brazil
2Structural Engineering Department, State University of Rio de Janeiro, UERJ, Brazil
3ISISE, Civil Engineering Department, University of Coimbra, Portugal

Full Bibliographic Reference for this paper
B.D. Rimola, J.G.S. da Silva, A.C.C.F. Sieira, L.R.O. de Lima, L.F. da C. Neves, "Vibration Analysis of a Production Platform induced by Mechanical Equipment", in , (Editors), "Proceedings of the Tenth International Conference on Computational Structures Technology", Civil-Comp Press, Stirlingshire, UK, Paper 113, 2010. doi:10.4203/ccp.93.113
Keywords: dynamic analysis, steel structures, production platforms, human comfort, structural behaviour, computational modelling.

The competitive trends of the world market have long been forcing structural engineers to develop minimum weight and labour cost solutions. A direct consequence of this new design trend is a considerable increase in problems related to unwanted floor vibrations. For this reason, the structural floors systems can become vulnerable to excessive vibrations, for example those produced by impacts such as mechanical equipment (rotating machinery) [1].

In this way, the present paper investigates the dynamic behaviour of a production platform made of steel and located in Santos Bay (Merluza field), São Paulo, Brazil. The structural model consists of two steel decks with a total area of 1915 m2 (upper deck: 445 m2 and lower deck: 1470 m2), supported by piles. Mechanical equipment is located on the steel decks of the structural model, related to electrical generators and compressors.

The representation of the soil was based on Winkler's theory. This theory simulates the soil behaviour as a group of independent springs, governed by the linear-elastic model. In the Winkler's model, the soil stiffness was considered as the necessary pressure to produce a unitary displacement.

The proposed computational model, developed for the steel platform dynamic analysis, adopted the usual mesh refinement techniques present in finite element simulations implemented in the GTSTRUDL program. In this computational model, floor steel girders and columns were represented by three-dimensional beam elements, where flexural and torsion effects are considered. The steel decks were represented by shell finite elements. In this investigation, it was considered that the steel has an elastic behaviour.

The structural model dynamic response was determined through an analysis of its natural frequencies and peak accelerations. The results of the dynamic analysis were obtained from an extensive numeric study, based on the finite element method utilising the GTSTRUDL program. In this investigation, dynamic loadings coming from the rotating machinery (electrical generators and compressors) were applied to the steel decks of the structural system (production platform).

A numerical analysis was made, in order to assess the dynamic impact on the deck structure coming from the electrical generators and compressors. Based on the peak acceleration values, obtained for the structure steady-state response, it was possible to evaluate the structural model performance in terms of human comfort, maximum tolerance of the mechanical equipment and vibration serviceability limit states of the structural system, based on the design code recommendations.

B.D. Rimola, "Análise Dinâmica de Plataformas de Aço a partir da Consideração do Efeito da Interação Solo-Estrutura", MSc Dissertation (In Portuguese), Civil Engineering Post-graduate Programme, PGECIV, State University of Rio de Janeiro, UERJ, Rio de Janeiro, RJ, Brazil, 2010.

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