On the mechanics of “false vaults”: new analytical and computational approaches

The aim of this paper is to present new analytical and computational approaches for assessing the structural safety of “false vaults” structures like Trulli, and more generally for corbelled structures. In particular, the proposed procedure is capable of taking into account the three-dimensional behavior of such complex masonry structures

A New Ultrasonic Immersion Technique for the Evaluation of Damage Induced Anisotropy in Composite Materials

We present a theoretical and experimental approach for the characterization of the damage induced anisotropy superimposed to the constitutive anisotropy of fiber-reinforced composite materials. The proposed theoretical model has been developed in the framework of the Continuum Damage Mechanics theory and allows for determining a tensorial damage measure based on the change of the elastic moduli of the composite material. Moreover, the model is general since it is applicable independently of the fibers reinforcement nature, of the presence of cracks, interlaminar voids and delamination, of the geometry of this cracks, and from of failure mechanisms of the composite materials. We perform damage experiments by employing an innovative goniometric device designed and built at our laboratory (Laboratorio “M. Salvati”), and aimed at the mechanical characterization of materials. In particular, by rotating the sample into a water tank, we measure the ultrasonic “natural” velocities of the undamaged composite material along suitable propagation directions. This allow us for classifying the degree of symmetry of the material and for determining the elastic constants, also in highly anisotropic materials. Then we measure the ultrasonic velocities of the artificially damaged composite and we determine again the elastic moduli. The comparison between the elastic moduli of the damaged and the undamaged composite allows us for the characterization of the anisotropic tensorial damage measure

Self-Equilibrium state of V-Expander Tensegrity Beam

In this paper, we study an innovative class of tensegrity beams, obtained by a suitable assembly of elementary V-Expander tensegrity cells along a longitudinal axis in the three-dimensional space. Tensegrity structures, made by struts in compression and cables in tension, are an innovative structures by itself: they are similar only in appearance to conventional pin-joint structures (trusses), and their mechanics is strongly related to initial feasible self-stress states induced in absence of external loads. In particular, from a kinematical point of view these self-stress states avoid the activation of possible infinitesimal mechanisms. By a numerical study, we analyze the feasible self-stress states for lightweight tensegrity beams made by a suitable assembly of V-Expander elementary cells. Moreover, we analyze the influence on the feasible self-stress states of the addition of struts or cables starting from the simplest V-Expander configuration