Model Tests of Gravity Platforms. II: Interpretation

Foundation design of structures subjected to cyclic loading, including stability, cyclic and permanent displacements, soil stiffness for use in dynamic analyses, and soil reactions, requires that effect of cyclic loading is accounted for in the soil parameters. A primary goal of this paper is to provide correlations of these parameters with index parameters for use in practical design. The contour diagram framework for interpretation and presentation of cyclic soil behavior is summarized, as well as pore pressure and cyclic strain accumulation procedures to establish equivalent number of maximum loads, N eq , that gives the same degradation as the irregular cyclic load history. Guidance is given on how the soil parameters can be applied in design, and calculated and measured prototype observations and model test results are used to validate the soil parameter framework. Focus is given to foundation design of structures, but a procedure to analyze the stability of slopes subjected to cyclic loading is also included.

show abstract

“…• Five 1 g laboratory model tests of an offshore gravity base structure with monotonic and cyclic loading on a soft clay (Andersen et al 1989).…”

Section: Verification By Prototype Observations and Model Testsmentioning

confidence: 99%

Rock-steel interface testing and considerations for gravity foundations for tidal energy generators

Ziogos¹,

Brown²,

Ivanović³

et al. 2015

Frontiers in Offshore Geotechnics III

View full text Add to dashboard Cite

show abstract

“…Andersen 1976, Andersen 2015. The accumulation procedure has been developed and verified for the foundation design of gravity-based fixed platforms that are subjected to waves and wind of high amplitude and frequency (Andersen et al 1989),but is now also used for the foundation design of a range of offshore structures (Andersen et al 1993, Andersen et al 2013, including anchors and subsea structures that are subjected to different cyclic loading regimes to fixed platforms.…”

mentioning

confidence: 99%

Response of normally consolidated kaolin clay under irregular cyclic loading and comparison with predictions from the accumulation procedure

2019

View full text Add to dashboard Cite

The accumulation procedure on contour diagrams of shear strain is used in geotechnical design to account for the effect of cyclic loading on offshore foundations. In this paper, contour diagrams of maximum shear strain are presented based on a series of stress-controlled, symmetrical and non-symmetrical, cyclic direct simple shear tests on normally consolidated kaolin clay that can be used to re-examine the extensive database of model testing in kaolin clay. It is shown that the failure under non-symmetrical cyclic loading can be defined at a higher maximum shear strain than under symmetrical loading, offering potential opportunities for reducing foundation sizes for structures that are less sensitive to displacement. Staged tests with parcels of uniform amplitudes have been also performed to compare the measured shear strains with the values predicted by the accumulation procedure. It is shown that the accumulation procedure predicts the strain measured in the symmetrical staged tests well but overpredicts shear strains measured in the non-symmetrical staged tests. KeywordsCyclic loading; normally consolidated clay; direct simple shear test List of notation a fitting parameter for contour diagram of γmax b fitting parameter for contour diagram of γmax c fitting parameter for contour diagram of γmax CSR cyclic stress ratio DSS direct simple shear e0 void ratio (as extruded) f frequency Gcyc cyclic shear modulus Gs specific gravity Published in Géotechnique https://doi.

show abstract

“…21. 87,88 Excellent agreement was found between the calculated and measured sliding capacities, and there was reasonably good agreement between the calculated and measured displacements. As noted by Andersen, et al, the calculated displacements are very sensitive to some of the assessments that must be integrated into the analyses.…”

Section: Measured and Predicted Gbs Motionsmentioning

confidence: 75%

“…80,86 The best information presently available to evaluate the bias and uncertainty associated with analyses of GBS foundation performance have been provided by data from 1-g and centrifuge model tests. [87][88][89][90][91][92] In the preceding and following developments on GBS sliding characteristics, the unique aspects associated with calcareous soils will not be addressed. 91,92 Results from the test series published by Andersen, et al, on cyclic loading tests on mats supported by cohesive soils are summarized in Fig.…”

Section: Measured and Predicted Gbs Motionsmentioning

confidence: 99%

Developments in Proposed ISO Guidelines for Design of Offshore Platforms to Resist Earthquakes

Bea

Craig²,

Gudmestad

et al. 1999

All Days

View full text Add to dashboard Cite

This paper summarizes current developments in the International Standards Organization (ISO) proposed guidelines for design of offshore platforms to resist earthquakes. These developments include updated evaluations of seismic exposures in the U.K. and Norwegian Sectors of the North Sea, offshore Japan and Indonesia, and in the Bay of Campeche Mexico. Guidelines have been developed to permit design analyses based on either 100-year or 200 year bases. Recent results from measurements and analyses of the effects of local soil and geologic conditions are used to update the proposed ISO guidelines. Updated developments also address steel and concrete elements in offshore platforms. Both 'fixed' and 'information sensitive' load and resistance factors for steel and concrete elements have been developed to increase the ease of use of these guidelines. The updated guidelines in this paper provide important improvements in development of reliability based criteria for design and requalification of fixed offshore platforms. These improvements are in characterizations of seismic exposure, effects of local soil and geologic conditions on ground motions, performance characteristics of steel and concrete elements and pile and mat foundations subjected to earthquake loading effects, and in characterization of dynamic loading effects in fixed offshore platforms subjected to ultimate limit state earthquakes.

show abstract

Model Tests of Gravity Platforms. II: Interpretation

Cited by 22 publications

References 4 publications

Rock-steel interface testing and considerations for gravity foundations for tidal energy generators

Rock-steel interface testing and considerations for gravity foundations for tidal energy generators

Response of normally consolidated kaolin clay under irregular cyclic loading and comparison with predictions from the accumulation procedure

Developments in Proposed ISO Guidelines for Design of Offshore Platforms to Resist Earthquakes

Contact Info

Product

Resources

About