0000000001081890
AUTHOR
A. Caffarelli
Bòvedas tabicadas: experimental and numerical analysis
A class of thin vaults, the so-called “bovedas tabicadas”, which represent one of the most common Spanish traditional building techniques at the end of XIX century are studied here, treating the relevant analysis problem through a numerical, as well as an experimental, approach. At first the problem is studied by searching for the behaviour of the material effecting suitable experiments. Once the constitutive behaviour of the materials and the structural elements are experimentally characterized, a semi inverse method for the identification of the optimum mechanical parameters to assign to an equivalent homogeneous ideal material through analysis reproducing the executed experimental tests …
Minimum volume design of structures with constraints on ductility and stability
Abstract A minimum volume design problem of elastic perfectly plastic frame structures subjected to different combinations of fixed and seismic loads is presented, in which the design variables are considered as appertaining alternatively to a continuous assigned range as well as to appropriate discrete sets. The structure is designed so as to behave elastically for the applied fixed loads, to shakedown in presence of serviceability seismic conditions and to prevent the instantaneous collapse for suitably chosen combinations of fixed and high seismic loadings. In order to avoid further undesired collapse modes, the P-Delta effects are considered and the structure is also constrained to prev…
MULTICRITERIA OPTIMAL DESIGN OF CONTINUOUS CIRCULAR PLATES
The paper is devoted to a quite general version of the multicriteria optimal (minimum volume) design of axisymmetric circular plates. The constitutive material is considered as elastic perfectly plastic without any ductility limit and the actions are assumed as quasi-statically variable within a given load domain. In the design problem formulation different resistance criteria are considered, in order to investigate all the possible structural limit responses, and for each one a suitably chosen safety factor is chosen. The optimal design problem is formulated as the search for the minimum structure volume according with a statical approach. The features of the optimal structures will be stu…
Computational procedures for plastic shakedown design of structures
The minimum volume design problem of elastic perfectly plastic finite element structures subjected to a combination of fixed and perfect cyclic loads is studied. The design problem is formulated in such a way that incremental collapse is certainly prevented. The search for the structural design with the required limit behaviour is effected following two different formulations, both developed on the grounds of a statical approach: the first one operates below the elastic shakedown limit and is able to provide a suboptimal design; the second one operates above the elastic shakedown limit and is able to provide the/an optimal design. The Kuhn–Tucker conditions of the two problems provide usefu…
Bounds on plastic strains for elastic plastic structures in plastic shakedown conditions
The problem related to the computation of bounds on plastic deformations for structures in plastic shakedown condition (alternating plasticity) is studied. In particular, reference is made to structures discretized by finite elements constituted by elastic perfectly plastic material and subjected to a special combination of fixed and cyclic loads. The load history is known during the steady-state phase, but it is unknown during the previous transient phase; so, as a consequence, it is not possible to know the complete elastic plastic structural response. The interest is therefore focused on the computation of bounds on suitable measures of the plastic strain which characterizes just the fir…
On the modern use of the bòvedas tabicadas
The paper concerns the study of the so-called “bòvedas tabicadas” (i.e. thin vaults constituted by layers of “rasillas” suitably superimposed) based on the results obtained by specific experimental investigations effected on the material of which they are constituted as well as on a vault that is still working. In particular, aim of the present research is the implementation of a first analysis of the structure in its present configuration (often unusable), with the purpose to evaluate the real structure serviceability related to the prescribed intensity of the acting loads, and moreover the execution of a new second analysis of the same structure but suitably reinforced by placing further …
Optimal shakedown design of base isolated structures
The optimal design problem of finite element discretized elastic perfectly plastic structures is studied. In particular, a minimum volume formulation is developed, based on a statical approach, and two different resistance limits are considered: the elastic shakedown limit and the instantaneous collapse limit, imposing for each a suitably chosen safety factor. The structure is thought as subjected to quasi-static loads as well as to dynamic actions. The dynamic features of the relevant structure are determined taking also into account an appropriate base isolation system in order to reduce the seismic effects. According with the Italian code related to the structural analysis and design, th…