73,717 research outputs found
Macroelement modeling of shallow foundations
The paper presents a new macroelement model for shallow foundations. The
model is defined through a non-linear constitutive law written in terms of some
generalized force and displacement parameters. The linear part of this
constitutive law comes from the dynamic impedances of the foundation. The
non-linear part comprises two mechanisms. One is due to the irreversible
elastoplastic soil behavior: it is described with a bounding surface
hypoplastic model, adapted for the description of the cyclic soil response. An
original feature of the formulation is that the bounding surface is considered
independently of the surface of ultimate loads of the system. The second
mechanism is the detachment that can take place at the soil-footing interface
(foundation uplift). It is totally reversible and non-dissipative and can thus
be described by a phenomenological non-linear elastic model. The macroelement
is qualitatively validated by application to soil-structure interaction
analyses of simple real structures
Bootstrapped Newtonian stars and black holes
We study equilibrium configurations of a homogenous ball of matter in a
bootstrapped description of gravity which includes a gravitational
self-interaction term beyond the Newtonian coupling. Both matter density and
pressure are accounted for as sources of the gravitational potential for test
particles. Unlike the general relativistic case, no Buchdahl limit is found and
the pressure can in principle support a star of arbitrarily large compactness.
By defining the horizon as the location where the escape velocity of test
particles equals the speed of light, like in Newtonian gravity, we find a
minimum value of the compactness for which this occurs. The solutions for the
gravitational potential here found could effectively describe the interior of
macroscopic black holes in the quantum theory, as well as predict consequent
deviations from general relativity in the strong field regime of very compact
objects.Comment: 27 pages, 17 figures. Version accepted for publication in EPJ
Similarity rules for nonlinear Kerr-like slab optical waveguides
It is shown that the stationary waveguiding properties of TE guided waves in a slab optical waveguide with a nonlinear Kerr-like bounding medium can be described in a compact way by means of the usual normalized effective modal index (b) and a set of only four independent normalized parameters: the well-known normalized thickness (V) and asymmetry measure (a) of the waveguide, the generalized aspect ratio between film and substrate refractive indexes, and a guided power measure. From an analysis starting on Buckingham's II-theorem, the similarity rules existing between the above waveguiding structures have been investigated. Allowed and forbidden regions in (b,V,a)-space in order that a guided solution exists have been recognized and classified, with the marginal loci separating different regions being a function of only V and a.Peer ReviewedPostprint (published version
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