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A contact interface model for nonlinear cyclic moment-rotation behavior of shallow foundations

TL;DR: In this paper, a contact interface model was developed to provide nonlinear constitutive relations between cyclic loads and dis placements of the footing-soil system during combined loading.
Abstract: It has been recognized that the ductility demands o n super structure might be reduced by allowing rocking behavior and mobilization of the ultimate c apacity of shallow foundation, particularly for shear wall structures. However, the absence of prac tical reliable foundation modeling techniques and the uncertainty in soil properties have hindered th e use of nonlinear soil-foundation-structure interaction as a designed mechanism for improving performance of a soil-foundation-building system. This paper presents a new “contact interface model” that has been developed to provide nonlinear constitutive relations between cyclic loads and dis placements of the footing-soil system during combined loading. The rigid footing and the soil be neath the footing in the zone of influence, considered as a macro-element, were modeled by keeping track of the geometry of the soil surface beneath the footing along with the kinematics of th e footing-soil system. The coupling between forces is incorporated in the model through tracking the g eometry of the contact interface, interaction diagrams, and the critical contact length ratio; th e ratio of the minimum length of the footing requir ed to support the vertical and horizontal loads. Sever al contact interface model simulations were carried out and the model predictions are compared with centrifuge experimental results that have a wide range of initial static vertical factor of safety. It is shown that the footing-soil contact interface model captures the essential features of the cyclic load- deformation behavior that were observed in the centrifuge experiments. The contact interface model predictions for moment capacity, rotational stiffness, energy dissipation, and permanent deform ations compare reasonably well with the centrifuge experimental results.

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Citations
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Journal ArticleDOI
TL;DR: In this article, the authors present guidelines for characterization of soil-structure interaction (SSI) effects for shallow foundations based on representing foundation-soil interaction in terms of viscoelasti...
Abstract: Practical guidelines for characterization of soil-structure interaction (SSI) effects for shallow foundations are typically based on representing foundation-soil interaction in terms of viscoelasti...

79 citations

Journal ArticleDOI
TL;DR: In this paper, a macroelement model for shallow foundations encompassing the majority of combinations of soil and foundation-soil interface conditions that are interesting for practical applications is presented. But the model is not explicitly used in the formulation of the model, the obtained force states by the model are always contained within it.
Abstract: The scope of this paper is to present a macroelement model for shallow foundations encompassing the majority of combinations of soil and foundation–soil interface conditions that are interesting for practical applications. The basic idea of the formulation is to raise the common assumption that the surface of ultimate loads of the foundation is identified as a yield surface in the space of force parameters which the footing is subjected to. Instead, each non-linear mechanism participating in the global response of the system is modelled independently and the surface of ultimate loads is retrieved as the combined result of all active mechanisms. This allows formulating each mechanism by respecting its particular characteristics and offers the possibility of activating, modifying or deactivating each mechanism according to the context of application. The model comprises three non-linear mechanisms: (a) the mechanism of sliding at the soil–footing interface, (b) the mechanism of soil yielding in the vicinity of the footing and (c) the mechanism of uplift as the footing may get detached from the soil. The first two are irreversible and dissipative and are combined within a multi-mechanism plasticity formulation. The third mechanism is reversible and non-dissipative. It is reproduced with a phenomenological non-linear hyperelastic model. The model is validated with respect to the existing results for shallow foundations under quasi-static loading tests. It is shown that although the ultimate surface of the foundation is not explicitly used in the formulation of the model, the obtained force states by the model are always contained within it. Copyright © 2010 John Wiley & Sons, Ltd.

59 citations


Cites methods from "A contact interface model for nonli..."

  • ...It has been confronted with a ‘damage mechanics’-inspired model in [52] and with a geometric model (simplified keeping track of the actual contact area of the footing during loading) in [53]....

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01 Jan 2010
TL;DR: It is concluded that it may be preferable to develop criteria that describe performance aspects and system responses that should be considered, rather than prescribe firm quantitative criteria, for the yielding foundation design approach.
Abstract: Current practice for earthquake-resistant shallow foundation design does not allow the foundation to fail in bearing, and does not consider the interaction of non-linear responses of the soil, foundation, and superstructure. Design tools exist that allow this interaction to be considered, and with the use of these tools, an alternative design approach that allows shallow foundations to yield during an earthquake becomes available. This paper uses examples to demonstrate the benefits of this alternative design approach. The approach enables the performance of the foundation to be balanced against that of the superstructure. Foundation and superstructure actions may be reduced significantly, whilst incurring only modest permanent foundation displacements. Broad suggestions of the type of criteria that might be required for the yielding foundation design approach are made. It is concluded that it may be preferable to develop criteria that describe performance aspects and system responses that should be considered, rather than prescribe firm quantitative criteria. The traditional design approach can result in foundations being significantly larger than would be required under static loading only, especially for tall slender structures that can impose large eccentric loadings on foundations. Larger foundations are stiffer than smaller ones, and have a shorter natural period. This affects the dynamic response of the soilfoundation-structure system. 2.2 No reserve of bearing strength during design earthquake (seismic factor of safety of unity) One alternative to the traditional design approach is to size the foundation so that bearing failure is only just prevented from occurring during the design earthquake. Under a LRFD framework, this would correspond to both the earthquake loading demands on the foundation and the available vertical bearing strength being unfactored (a seismic factor of safety of one). Possible advantages to this design approach are a smaller, presumably cheaper foundation, and a less stiff soil-foundation-structure system (which may have benefits for structural performance). A disadvantage to this design approach is that although in theory no yielding will occur during the design earthquake, there is no margin for error. Thus the approach may not be acceptable if it is critical to prevent bearing failure occurring, given the uncertainty that is usually present in assessing soil strength. However, as will be demonstrated, minor instances of bearing failure during an earthquake may not have significant consequences. 2.3 Design based on static LRFD requirements only (seismic yielding allowed) A second alternative to the traditional design approach, and the one that is the focus of this paper, is to size the foundation based only on static considerations (bearing capacity and settlement). Under this approach, brief instances of foundation yielding (bearing failure) might occur during an earthquake, resulting in the accumulation of permanent displacements. This is referred to herein as the ‘yielding foundation’ approach. A major advantage to this approach would be the ability to consider and balance the performance of the foundation and the superstructure, without having the prerequisite requirement that the foundation is not permitted to yield. In many cases, allowing the foundation to yield may have beneficial effects for the superstructure performance or for the system as a whole, and under this approach, these benefits could be obtained. Si ng le de gr ee of fre ed om su pe rs tru ct ur e m od el R ig id fo un da tio n

5 citations

Journal ArticleDOI
TL;DR: In this paper, the authors demonstrate the utility of macroelement modeling of shallow foundations in performance-based design, focusing on the settlements, horizontal displacements and rotations of a bridge pier founded on a rigid circular foundation on a relatively soft cohesive soil.

5 citations

References
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01 Jan 1970

615 citations


"A contact interface model for nonli..." refers background or methods in this paper

  • ...The ultimate vertical load, for pure vertical loading (VULT), is calculated using conventional bearing capacity equations (Hansen, 1970 and Hanna and Meyerhof, 1981)....

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  • ...This minimum contact length is defined as the critical contact length (Lc), which can be calculated from bearing capacity equations proposed by Hansen (1970) and Hanna and Meyerhof (1981)....

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Journal ArticleDOI
TL;DR: In this article, a method to evaluate settlements and rotations of rigid shallow foundations on sand under the combined action of inclined and eccentric loads is presented, based on the hypotheses that the foundation and the soil can be considered as a macro-element for which the loadings act as generalized stress variables while the displacements and rotation of the foundation are the corresponding generalized strain variables.
Abstract: A method to evaluate settlements and rotations of rigid shallow foundations on sand under the combined action of inclined and eccentric loads is presented. Experimental results obtained on a model strip foundation are shown first. Next, a mathematical model is formulated which is based on the hypotheses that (a) the foundation and the soil can be considered as a macro-element for which the loadings act as generalized stress variables while the displacements and rotation of the foundation are the corresponding generalized strain variables; and (b) the constitutive law of the macro-element, that is the relationship between generalized stress and strain rates, is rigid-plastic strain-hardening with a non-associated flow rule. Constitutive functions and parameters are determined by means of simple calibration tests. Predictions of the theory are then compared with experimental results in tests where loadings vary in a complex way up to foundation failure. It is shown that experimental evidence is well matched...

345 citations


Additional excerpts

  • ...Other researchers have used macro-element concepts to model the load-displacement behavior of structural elements and shallow foundations (Nova and Montrasio, 1991, Cremer et al., 2001, Houlsby and Cassidy, 2002)....

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Journal ArticleDOI
TL;DR: In this paper, a series of tests on a large centrifuge, including 40 models of shear wall footings, were performed to study the nonlinear load-deformation characteristics during cyclic and earthquake loading.

199 citations


"A contact interface model for nonli..." refers background in this paper

  • ...Geotechnical components of the foundation are known to have a significant effect on the building response to seismic shaking (Taylor et al., 1981, Faccioli et al., 2001, and Gajan et al., 2005)....

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  • ...When a footing is subjected to cyclic moment loading, due to the repeated rocking of the footing, and the formation of a gap under the unloaded portion of the footing, the soil surface beneath the footing becomes curved (Gajan et al., 2005)....

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Journal ArticleDOI
TL;DR: In this article, a non-linear soil-structure interaction (SSI) macro-element for shallow foundation on cohesive soil is presented. The macro element consists of a nonlinear joint element, expressed in generalised variables, i.e. in forces applied to the foundation and in corresponding displacements.
Abstract: This paper presents a non-linear soil–structure interaction (SSI) macro-element for shallow foundation on cohesive soil. The element describes the behaviour in the near field of the foundation under cyclic loading, reproducing the material non-linearities of the soil under the foundation (yielding) as well as the geometrical non-linearities (uplift) at the soil–structure interface. The overall behaviour in the soil and at the interface is reduced to its action on the foundation. The macro-element consists of a non-linear joint element, expressed in generalised variables, i.e. in forces applied to the foundation and in the corresponding displacements. Failure is described by the interaction diagram of the ultimate bearing capacity of the foundation under combined loads. Mechanisms of yielding and uplift are modelled through a global, coupled plasticity–uplift model. The cyclic model is dedicated to modelling the dynamic response of structures subjected to seismic action. Thus, it is especially suited to combined loading developed during this kind of motion. Comparisons of cyclic results obtained from the macro-element and from a FE modelization are shown in order to demonstrate the relevance of the proposed model and its predictive ability. Copyright © 2001 John Wiley & Sons, Ltd.

188 citations


"A contact interface model for nonli..." refers background in this paper

  • ...12 (for H = 0) and the bounding surface proposed by Cremer et al., 2001 (for M/(H....

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  • ...Other researchers have used macro-element concepts to model the load-displacement behavior of structural elements and shallow foundations (Nova and Montrasio, 1991, Cremer et al., 2001, Houlsby and Cassidy, 2002)....

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Journal ArticleDOI
TL;DR: In this article, a complete theoretical model for the behavior of rigid circular footings on sand, when subjected to combined vertical, horizontal and moment loading, is described, which is expressed in terms of work-hardening plasticity theory, based on a series of tests specifically designed to allow evaluation of various components of the theory.
Abstract: A complete theoretical model is described for the behaviour of rigid circular footings on sand, when subjected to combined vertical, horizontal and moment loading. The model, which is expressed in terms of work-hardening plasticity theory, is based on a series of tests specifically designed to allow evaluation of the various components of the theory. The model makes use of the force resultants and the corresponding displacements of the footing, and allows predictions of response to be made for any load or displacement combination. It is verified by comparison with the database of tests. The use of the model is then illustrated by some demonstration calculations for the response of a jack-up unit on sand. This example illustrates the principal purpose of the development, which is to allow a realistic modelling of foundation behaviour to be included as an integral part of a structural analysis.

151 citations


Additional excerpts

  • ...Other researchers have used macro-element concepts to model the load-displacement behavior of structural elements and shallow foundations (Nova and Montrasio, 1991, Cremer et al., 2001, Houlsby and Cassidy, 2002)....

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