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Mechanical response of shallow foundations - Some experimental/theoretical and numerical issues: monotonic loading Introduction Prof. ing. Claudio di Prisco
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2 Experimental device Max= 712 gal Max= 608 gal Shear stacks
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Prof. ing. Claudio di Prisco 3 Experimental evidence
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Prof. ing. Claudio di Prisco 4 The elasto-perfectly plastic approach
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Prof. ing. Claudio di Prisco 5 Coupled elastoplastic CONSTITUTIVE RELATIONSHIP Defined in quasi static conditions: THE MACRO-ELEMENT CONCEPT Incremental constitutive relationship FOUNDATION NEAR FIELD FAR FIELD
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Prof. ing. Claudio di Prisco 6 The interaction domain for rigid footings Interaction domain for rigid strip footings and elasto-perfectly plastic approach m = M/ψBV MAX, h = H/μV MAX ξ = V/V MAX 1.To each point belonging to the failure locus a distinct failure mechanism corresponds 2.Difficulty in defining the failure locus when loose sand strata are concerned 3.Non-associated flow rule 4.Within the failure locus the mechanical behaviour is assumed to be elastic and uncoupled 5.Extension to rectangular footings MONOTONOUSLY INCREASING LOADING
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Prof. ing. Claudio di Prisco 7 Settlements Centered vertical load Centered inclined load Cyclic inclined loading anisotropic hardening Cremer et al, 2001
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Prof. ing. Claudio di Prisco 8 Hardening Isotropic hardening (Nova and Montrasio, 1991) Swipe tests Butterfield and Gottardi, 2003 H V V M/B c =V c / V MAX Hardening parameter
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Prof. ing. Claudio di Prisco 9 Inclined-eccentric loads Nova and Montrasio, 1991 Inclined and eccentric loading
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Prof. ing. Claudio di Prisco 10 How can R 0 be determined? Some hints about settlement evaluation Homogeneous stratigraphic profiles
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Prof. ing. Claudio di Prisco 11 Settlement evaluation Irreversibility of the material mechanical response Non-linearity Dependency of stiffness on confining pressure
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Prof. ing. Claudio di Prisco 12 The elastic solution Poulos e Davis (1974) Gibson (1973) Winkler (1867) Dependency of stiffness on confining pressure: Eo/λD 1 0 0.5 r/D 0 1 = 0.5
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Prof. ing. Claudio di Prisco 13 Settlement evaluation The elastic solution Linear loading distribution Strip loading distribution Rectangular loading distribution
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Prof. ing. Claudio di Prisco 14 Generalised plasticity
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Prof. ing. Claudio di Prisco 15 Numerical validation
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Prof. ing. Claudio di Prisco 16
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Prof. ing. Claudio di Prisco 17 Cyclic loads Loose sand Dense sand
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Prof. ing. Claudio di Prisco 18 Numerical validation
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Prof. ing. Claudio di Prisco 19 Numerical results
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Prof. ing. Claudio di Prisco 20 Cyclic consequences of the mechanical coupling
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Prof. ing. Claudio di Prisco 23 A dynamic/non seismic problem
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