0000000000030813
AUTHOR
Roberto Spallino
Numerical analysis of masonry structures via interface models
The present paper is devoted to the theoretical formulation and numerical implementation of an interface model suitable to simulate the behavior of mortar joints in masonry structures. The interface laws are formulated in the framework of elasto-plasticity for non-standard materials in order to simulate the softening response which occurs along the decohesion process in presence of shear and tension tractions. A variable material dilatancy parameter is introduced together with a further geometrical dilatancy related to the roughness of contact surfaces after joint fracture. An asperity model is adopted with the aim to describe the evolution of the contact surface shape during the loss of co…
Thermal buckling optimization of composite laminates by evolution strategies
Abstract Thermal buckling optimization of laminated composite plates subject to a temperature rise is presented in this paper. Aerospace structures require such components that are able to withstand the external environment loads without loss of stability. The discrete optimal design problem, formulated under strain and ply contiguity constraints is solved using evolution strategies, a guided random-search method. Two different constraint handling methods are investigated and compared: the disregarding infeasible solutions and the classical penalty function approach. The results are also compared with an exact enumerative study conducted on the problem, showing the effectiveness and perform…
A design algorithm for the optimization of laminated composite structures
This paper is devoted to the optimal design of laminated composite structures. The goal of the study is to assess the quality and the performance of an algorithm based on the directional derivative method. Particular attention is paid to the one‐dimensional search, a critical step of the process, performed by cubic splines approximation. The optimization problem is formulated as weight minimization, under constraints on the mechanical behavior of the structure. The assumed design variables are the ply thicknesses, treated as continuous design variables, constrained by technological requirements. The structural analysis is performed making use of quadrilateral four‐node composite elements, b…
Shakedown optimal design of reinforced concrete structures by evolution strategies
Approaches the shakedown optimal design of reinforced concrete (RC) structures, subjected to variable and repeated external quasi‐static actions which may generate the well‐known shakedown or adaptation phenomenon, when constraints are imposed on deflection and/or deformation parameters, in order to simulate the limited flexural ductility of the material, in the presence of combined axial stress and bending. Within this context, the classical shakedown optimal design problem is revisited, using a weak upper bound theorem on the effective plastic deformations. For this problem a new computational algorithm, termed evolution strategy, is herein presented. This algorithm, derived from analogy …