A new macro-element model encapsulating the dynamic moment–rotation behaviour of raft foundations

Abstract

A new macro-element model encapsulating the dynamic moment-rotation behaviour of raft foundations. Geotechnique, 65 (5). pp. 442-451. ISSN 1751-7656 Access from the University of Nottingham repository: http://eprints.nottingham.ac.uk/34863/1/2015%20-%20Heron%20-%20Geotechnique%20-%20A%20new%20macro-element%20model%20encapsulating%20the%20dynamic %20moment-rotation%20behaviour%20of%20raft%20foundations.pdf Copyright and reuse:The Nottingham ePrints service makes this work by researchers of the University of Nottingham available open access under the following conditions. This article is made available under the University of Nottingham End User licence and may be reused according to the conditions of the licence. For more details see: http://eprints.nottingham.ac.uk/end_user_agreement.pdf A note on versions:The version presented here may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the repository url above for details on accessing the published version and note that access may require a subscription. AbstractThe interaction of shallow foundations with the underlying soil during dynamic loading can have both positive and negative effects on the behaviour of the superstructure. Although the negative impacts are generally considered within design codes, seldom is design performed in such a way as to maximise the potential beneficial characteristics. This is, in part due to the complexity of modelling the soil-structure interaction. Using the data from dynamic centrifuge testing of raft foundations on dry sand, a simple moment-rotation macro-element model has been developed which has been calibrated and validated against the experimental data. For the prototype tested, the model is capable of accurately predicting the underlying moment-rotation backbone shape and energy dissipation during cyclic loading. Utilising this model within a finite element model of the structure could potentially allow a coupled analysis of the full soil-foundation-structure system's seismic response in a simplified manner compared to other methods proposed in literature. This permits the beneficial soil-structure interaction characteristics, such as the dissipation of seismic energy, to be reliably included in the design process resulting in more efficient, cost-effective and safe designs.In this paper the derivation of the model will be presented including details of the calibration process. In addition, an appraisal of the likely resultant error of the model prediction will be presented and visual examples of how well the model mimics the experimental data will be

Liquefaction induced displacement and rotation of structures with wide basements

“…The amplitude of rotations presented here for the symmetric structures used in Tests A and B are of the same order of magnitude as those observed for rigid, symmetric structures with shallow foundations on dry sand [36,37,38] and on liquefiable layers [39]. However, the moment transmitted from the structure to the underlying soil was far less for structures on shallow foundations than those with basements presented here.…”

“…Shallow foundations on dry sand have been observed to lift off the soil surface when rocking [37,38]. This was not observed in liquefied soil by Adamidis and Madabhushi [39] using shallow foundations or in the tests presented here using structures with basements.…”

Dynamic rocking response of a rigid planar block on a nonlinear hysteretic Winkler foundation

“…While simplified approximate methods have been presented in a number of recent works [54][55][56][57][58] where soil yielding and foundation uplifting are integrated into a single element, researchers and engineers are more accustomed to nonlinear hysteretic Winkler foundation (NHWF) models because of their capability of explicitly and physically capturing the foundation uplift and inelastic soil deformation, which enabled them to find their way into the current seismic standard ASCE/SEI 41-17. [59] Compared with the aforementioned elastic WF models, the NHWF models consist of distributed nonlinear hysteretic elements that simulate the coupled vertical-rotational foundation response considering yielding of soils.…”

Centrifuge modelling of structures with oil dampers under seismic loading

“…In recent years, there seems to be a general trend among centrifuge SSI researchers to use more intricate superstructure models to capture the full soil‐structure system response: be it material nonlinearities in the soil, geometric nonlinearities at the foundation, and even nonlinearities in the superstructure . Jabary and Madabhushi were among the first researchers to employ dynamic centrifuge testing to investigate the performance of buildings with tuned mass dampers (TMDs) on sand.…”