A. Contento

Comparison between the seismic response of 2D and 3D models of rigid blocks

A three-dimensional rigid body on the shape of a parallelepiped is modelled in order to rock on a side or a vertex of the base, in order to evaluate the seismic response of rigid blocks lying on a horizontal support. The center of mass of the body is considered as eccentric with respect to its geometric center. As seismic input, three Italian recorded accelerograms, with different spectral content, are used. The study is mainly conducted to highlight the differences between the seismic response of 2D and 3D models of rigid blocks, with the aim to understand if, in some cases, the use of the 3D model of rigid block is required to obtain safer results. In fact, the outcomes show that in some ranges of the geometrical and mechanical parameters that characterize the excitation and the body, a two-dimensional model, which is not able to consider the 3D rocking on a vertex, can provide unsafe results. In particular, it is found that the overturning process of the three-dimensional block can occur under excitations which are lower than those which overturn a corresponding two-dimensional block.

Dynamics of a Soft Contractile Body on a Hard Support

The motion of a soft and contractile body on a hard support is described by fields of short range contact forces. Besides repulsion these forces are able to describe also viscous friction, damping and adhesion allowing the body to have complex motions which look rather realistic. The contractility is used to make the body behave like a living body with some basic locomotion capabilities. The simulated motions, showing jumping or crawling, are driven either by a contraction or by a contractile couple. Although only homogeneous deformations are allowed, the model arises from a general theory of remodeling in finite elasticity. The body is made of a viscoelastic incompressible neo-Hookean material.