Development and application of force resultant models describing jack-up foundation behaviour

Cassidy, Mark; Martin, C. M.; Houlsby, G. T.

doi:10.1016/j.marstruc.2004.08.002

Cited by 59 publications

(29 citation statements)

References 24 publications

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“…This expression is similar to that presented in Vlahos et al (2008) and reduces to the form of Martin and Houlsby (2001), Houlsby and Cassidy (2002) and Cassidy et al (2004b), amongst others, when no tensile capacity is assumed (χ¼0). Note that the yield surface is defined in terms of the net compressive vertical capacity V 0 rather than the total capacity.…”

Section: Yield Surfacesupporting

confidence: 56%

Jack-up push-over analyses featuring a new force resultant model for spudcans in soft clay

Bienen

Cassidy

2014

Ocean Engineering

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a b s t r a c tWith the development of the offshore oil and gas industry, mobile jack-up drilling platforms are increasingly utilized in deeper waters and harsher environments. Excessive conservatism in jack-up site specific assessment may result in undue rejection of a unit. In soft clayey seabeds, the spudcan foundations of the jack-up platform penetrate deeply into the soil with partial or complete backflow. Although the deep penetration and associated backflow are widely perceived to increase horizontal and moment foundation bearing capacities in particular, the problem is not well understood. In this paper therefore, a plasticity foundation model is proposed that accounts for the effects of backflow. It has been developed through a combined numerical and experimental study. The model is suitable for performing integrated soil-structure analyses. Results of such analyses of a jackup under quasi-static push-over load are discussed to highlight the impact of the model in the context of site specific assessment of jack-up rigs in soft clay.

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Section: Yield Surfacesupporting

confidence: 56%

Jack-up push-over analyses featuring a new force resultant model for spudcans in soft clay

Bienen

Cassidy

2014

Ocean Engineering

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“…Model B is described extensively by Martin (1994) and Martin & Houlsby (2001), and its application in the analysis of jack-ups with multiple independent footings is discussed by Martin & Houlsby (1999) and Cassidy et al (2004). Therefore, a full description of the various components will not be repeated here.…”

Section: Foundation Modelmentioning

confidence: 99%

Numerical simulation of pushover tests on a model jack-up platform on clay

Vlahos¹,

Cassidy²,

Martin³

2011

Géotechnique

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This paper assesses a method for predicting the ultimate capacity and failure mode of a model jack-up platform subjected to monotonic pushover tests on soft clay. Separate structural and geotechnical analyses are incapable of making such predictions, so in this work integrated structural/geotechnical simulations are evaluated against detailed experimental pushover data. The commercial finite-element program Abaqus is used, with standard beam elements representing the jack-up structure and a user-defined element describing the behaviour of each spudcan footing by means of a force-resultant plasticity model. This model takes a macro-element approach by expressing the foundation behaviour purely in terms of the loads on the spudcan and the corresponding displacements. Although the model has proven ability to simulate the single-footing experiments from which it was derived, the load paths experienced by the spudcans of a threelegged jack-up are significantly different. To investigate this, numerical simulations of three experimental pushover tests on a 1:250 scale model jack-up have been performed. The tests represent jack-ups with different leg lengths and load orientations. The integrated numerical modelling approach successfully predicts three different failure modes, although the predictions of ultimate pushover capacity are consistently conservative. Because previously published parameters were used for the foundation model, these predictions demonstrate the versatility of the spudcan model in the context of a multifooting structure, and confirm the effectiveness of the integrated analysis technique.

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“…(1), (2) D is the footing diameter, N max is the maximum vertical force supported by the footing under vertical centered load, N, V and M are the resultant vertical and horizontal force and moment on the footing, ux, uz are the horizontal and vertical displacement of the footing center respectively and u y is the rotation angle of the footing.…”

Section: A Short Survey Of Existing Macroelement Modelsmentioning

confidence: 99%