Response of an offshore structure to random ice forces

Reddy, D. V.; Cheema, P. S.

doi:10.1109/oceans.1974.1161393

Cited by 3 publications

(1 citation statement)

References 3 publications

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“…The dynamic response, determined for a “saw-tooth” type of deterministic loading simulated by the model, showed good agreement with earlier field measurements of Peyton (1968[a]). Sundararajan and Reddy ([1974]) used spectral techniques to study the stochastic response of a single-degree-of-freedom (SDOF) model subjected to ice-loading obtained by field measurements (Blenkarn, 1970) at Cook Inlet, Alaska. They noted that the system responded to excitation for ω ≤ ω 0 (the fundamental frequency of vibration of the structure), but filtered out the excitations for ω » ω 0 .…”

Section: Introduction and Review Of Literaturementioning

confidence: 99%

Ice-Structure Interaction with Artificially Generated Force Records

1977

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The paper describes the dynamic ice-structure interaction study of monopod platforms (fixed type) which are of considerable interest to the off-shore oil industry in cold regions. In view of the scantiness of continuous ice-force records, artificial-force records are generated from available small-scale field ice-force records using stochastic concepts. The method, based on the similarity between the fluctuating parts of randomly varying ice-force records and the seismic records uses a non-stationary random process obtained from filtering a shot noise through a second-order filter. The dynamic response analysis of a monopod structure located at Cook Inlet, Alaska, is carried out by hybridizing the relevant sub-routines of the computer programmes, SAP IV (Structural Analysis Programme) and EA TSW (Earthquake response of Axisymmetric Tower Structures surrounded by Water) . The work includes a study of the influence of soil properties on the frequencies and responses, and a comparison between the responses of fixed and elastically supported (by the soil foundation) monopod platforms. REsuME. Enregistrements de l'interaction entre la structure de la glace et des forces produites artificiellement. Cet article decrit I'etude dynamique de I'action sur la structure de la glace de plates-formes monopodes (d'un type fixe) qui sont d'un interc~t considerable dans I'industrie petroliere des regions froides. En raison du petit nombre d'enregistrements continus des efforts dans la glace, on engendre artificiellement des efforts distribues de maniere aleatoire 11 partir des enregistrements disponibles des efforts constates sur le terrain 11 petite echelle. La methode basee sur la similitude entre les parties f1uctuantes des enregistrements d'efforts dans la glace variant au hasard, et les enregistrements sismiques utilise une succession aleatoire non stationnaire obtenue en filtrant un bruit de detonation 11 travers un filtre du second ordre. L'analyse de la reponse dynamique d'une structure monopode, situee 11 Cook Inlet, Alaska, est conduite en combinant les boucles utilisables des programmes d'ordinateurs SAP IV (Programme d'Analyse Structural e) et EATSW (Reponse aux Tremblements de Terre de Tours en Beton Asymetriques Entourees d'Eau). Le travail inclut une etude de I'influence des proprietes du sol sur les frequences et les reponses et une comparaison entre les reponses des plates-formes monopodes fixes et 11 support elastique (par la fondation sur le sol ). ZUSAMMENFASSUNG. Wechselwirkungm zwischen Eis und Bauwerken mit simulierten Kraften. Die Arbeit handelt von der Untersuchung der dynamischen Wechselwirkung zwischen Eis und Bauwerk fur einstutzige Plaltformen (ortsfester Typ), die von betrachtlichem Interesse fur die kustennahe Olsuche in kalten Gebieten is!. Wegen des Mangels an kontinuierlichen Aufzeichnungen der Eiskrafte werden kunstliche Kraftaufzeichnungen aus verfugbaren Daten von Eiskraftfeldern kleinen Massstabs unter Verwendung stochastischer Konzepte erzeugt. Die Methode beruht auf der Ahnlichkeit zwischen ...

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Section: Introduction and Review Of Literaturementioning

confidence: 99%

Ice-Structure Interaction with Artificially Generated Force Records

1977

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Response of Offshore Towers to Nonstationary Ice Excitation

Reddy

Arockiasamy

Cheema³

1987

Lecture Notes in Engineering

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Probabilistic analysis of ice – offshore structure interaction using enveloping step function power spectral densities

Sundararajan¹,

Reddy²

1977

Can. J. Civ. Eng.

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A probabilistic analysis is presented for the response of offshore structures subjected to random forces due to ice floe movement. Analysis based on the averaged power spectral density of the ice force fluctuations is shown to result in unreliable designs in certain cases, owing to sensitivity to even small errors in the calculated natural frequencies of the structure. To overcome this drawback, an ‘enveloping, step function power spectral density’ is proposed. A single-degree-of-freedom system and a three-dimensional offshore tower are solved as examples.

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Response of an offshore structure to random ice forces

Cited by 3 publications

References 3 publications

Ice-Structure Interaction with Artificially Generated Force Records

Ice-Structure Interaction with Artificially Generated Force Records

Response of Offshore Towers to Nonstationary Ice Excitation

Probabilistic analysis of ice – offshore structure interaction using enveloping step function power spectral densities

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