Search results for "optimal"

Assessment of the tuned mass damper inerter for seismic response control of base‐isolated structures

2020

In this paper, the hybrid control of structures subjected to seismic excitation by means of tuned mass damper inerter (TMDI) and base-isolation subsystems is studied with the aim of improving the dynamic performance of base-isolated structures by reducing the displacement demand of the isolation subsystem. The seismic performance of TMDI hybrid controlled structures is investigated in a comparative study, considering simple isolated systems and systems equipped with other absorber devices such as the tuned mass damper (TMD) and the tuned liquid column damper (TLCD). The TMDI has been optimized by performing a simplified approach based on minimizing the base-isolation subsystem displacement …

Optimal Design of New Steel Connections

2018

The Limited Resistance Rigid Perfectly Plastic Hinge (LRPH) are special steel connections mainly usable to join beam elements of plane or spatial steel frames. The fundamental characteristics of these devices are the mutual independence of their own resistance and stiffness features as well as the respect of assigned constraints related to the elastic and limit behaviour of the joined elements. Within the frame structural scheme, the device plays the role of a rigid perfectly plastic hinge, constituted by a suitably sized sandwich section. The efficient use of the LRPH in the relevant frame depends on the appropriate design of the device geometry. In the present paper, a new approach devote…

Existence for shape optimization problems in arbitrary dimension

2002

We discuss some existence results for optimal design problems governed by second order elliptic equations with the homogeneous Neumann boundary conditions or with the interior transmission conditions. We show that our continuity hypotheses for the unknown boundaries yield the compactness of the associated characteristic functions, which, in turn, guarantees convergence of any minimizing sequences for the first problem. In the second case, weaker assumptions of measurability type are shown to be sufficient for the existence of the optimal material distribution. We impose no restriction on the dimension of the underlying Euclidean space.

Shakedown optimum design of reinforced concrete framed structures

1994

Structures subjected to variable repeated loads can undergo the shakedown or adaptation phenomenon,-which prevents them from collapse but may cause lack of serviceability, for the plastic deformations developed, although finite, as shakedown occurrence postulates, may exceed some maximum values imposed by external ductility criteria. This paper is devoted to the optimal design of reinforced concrete structures, subjected to variable and repeated loads. For such structures the knowledge of the actual values taken by the plastic deformations, at shakedown occurrence, is a crucial issue. An approximate assessment of such plastic deformations is needed, which is herein provided in the shape of …

On State Constrained Optimal Shape Design Problems

1987

This paper is concerned with the following optimal design problem with constraints both on the state and on the control: $$MinimizeJ(y,u)$$ (P) subject to $$A\left( u \right)y + \partial \varphi \left( y \right) \mathrel\backepsilon Bu + f,$$ (1.1) $$y \in K,$$ (1.2) $$u \in {U_{ad}}.$$ (1.3)

Automatic EMI filter design for power electronic converters oriented to high power density

2018

In this paper, a complete computer aided procedure based on the power density concept and aimed at the automatic design of EMI filters for power electronic converters is presented. It is rule-based, and it uses suitable databases built-up by considering information on passive components available from commercial datasheets. The power density constraint is taken into consideration by imposing the minimization of the filter volume and/or weight; nevertheless, the system in which the automatically designed filter is included satisfies the electromagnetic compatibility standards limits. Experimental validations of the proposed procedure are presented for two real case studies, for which the per…

Analysis and design of elastic plastic structures subjected to dynamic loads

In the last decades, the concept of “optimization” has reached considerable value in many different fields of scientific research and, in particular, it has assumed great importance in the field of structural mechanics. The present study describes and shows the scientific path followed in the three years of doctoral studies. The state of the art concerning the optimization of elastic plastic structures subjected to quasi-static loads was already well established at the beginning of the Ph.D. course. Actually, it was already faced the study of structures subjected to quasi-static cyclic loads able to ensure different structural behaviors in relation to different intensity levels of the appli…

Optimal design of tube hydroforming processes: A fuzzy-logic-based approach

2004

In recent years, tube hydroforming has become an economic and industrially suitable alternative to various traditional stamping processes, in particular for small batch production. In the present paper, an artificial intelligence system based on fuzzy logic was implemented for tube hydroforming process design. The aim was to achieve a process design procedure able to prevent forming defects and guarantee the achievement of the desired final shape of the component. In particular, the process design concerns the internal pressure history and the axial feeding. The fuzzy system is able to provide optimal trajectories for both the controlled parameters, producing a defect-free final part.

OPTIMUM DESIGN OF REINFORCED CONCRETE STRUCTURES UNDER VARIABLE LOADINGS

1987

Abstract This paper presents a method for optimal design of reinforced concrete (RC) structures, subjected to quasi-static variable loads and accounting for cross-sections limited ductility requirements. It consists of a very simple refinement procedure to be applied in the classical Optimal Shakedown Design, (OSD), which leads to a strengthened structure satisfying the requisite that the actual plastic relative rotations, developed at a specified set of critical sections as a result of a variable repeated loading program, do not exceed given upper limits. This strengthened design is a safe but not strictly optimal design and is obtained using the simple rule that the steel reinforcement ar…

Optimal design of elastic plastic frames accounting for seismic protection devices

2013

The optimal design of elastic perfectly plastic steel frames with or without suitable protection devices and subjected to static as well as seismic loadings is studied. Two minimum volume problem formulations are proposed, on the grounds of the so-called statical approach, accounting for three different resistance limits: the purely elastic limit, the (elastic) shakedown limit and the instantaneous collapse limit. The adopted load combinations are characterized by the presence of fixed loads, of quasi-static perfect cyclic loads and dynamic (seismic) loads. The linear elastic effects of the dynamic actions are studied by utilizing a modal technique. The proposed treatment is referred to the…