1,721,167 research outputs found
Input-State Feedback Linearization of a Boost DC/DC Converter
No full textThe paper presents a procedure to achieve an input-state feedback linearization on a bidirectional Boost DC/DC converter connected to a passive load. The system linearization is achieved by a proper state-space/output transformation performed on a non-dimensional form of the analytical model. The resulting system is then controlled through a standard linear regulator. An online load estimation technique is also provided to overcome the transformations parameter dependency. The proposed approach has been numerically tested and compared with a standard two-loop controller
Structural Survey and Empirical Seismic Vulnerability Assessment of Churches in the Historical Center of Cusco
No full textThe seismic vulnerability assessment of buildings represents a fundamental step for seismic risk prevention and mitigation, especially in seismic-prone areas where severe damage scenarios are expected or where valuable assets are present. The city of Cusco, whose historic center has been a UNESCO World Heritage site since 1983, has a long list of seismic events that caused extensive damage. Being part of the international heritage, churches are characterized by great architectural and cultural value, and their preservation is crucial. In this paper, the seismic vulnerability assessment of churches within the historic center of Cusco is presented. The assessment is made through a two-step process. First, data on churches are collected with a structural survey at the urban scale. Second, collected data are used to determine the seismic vulnerability with an empirical method that combines field observations and engineering judgments. The most vulnerable churches in the city center are identified, and their primary structural deficiencies are determined through this process
Buckling resistance of perforated steel angle members
No full textThe detrimental effect due to perforations on the buckling resistance of perforated hot-rolled steel L-shaped members in compression is evaluated in the current paper. FEM numerical models are used in order to carry out buckling and non linear analyses with the aim of detecting both the critical and the collapse load of the studied elements in case of one or more holes. The obtained results show that, although the critical load is not strongly influenced by the presence of holes, the load bearing capacity, when members are characterized by middle-low slenderness, could be significantly diminished when drillings of common sizes are applied on one of the two section legs, meaning that current methods given by the codes are not fully conservative. As a consequence, specific stability curves are determined and proposed as useful alternative design procedure
Metal shear panels for seismic protection of buildings: Recent findings and perspectives
No full textThis paper describes recent experimental researches carried out on metal shear panels to be employed as dampers for seismic protection of new and existing buildings. Three typologies of shear panels are presented, which have been conceived with different strategies to mitigate the detrimental effects provoked by buckling phenomena. For each solution, experimental results are provided together with design issues. Also, some remarks on the technological aspects of the devices are highlighted in order to limit the adoption of bad details that could jeopardize the structural performance of the system. In the whole, the obtained outcomes provide interesting information opening new frontiers in the field of research on dissipative metal shear panels
Experimental and numerical analysis of a multi-stiffened pure aluminium shear panel
No full textThe current paper deals with a detailed numerical study carried out on a pure aluminium shear panel and implemented through a FEM numerical model calibrated on the results obtained by an experimental test. The comparison between experimental and numerical data, in terms of dissipative capacity, maximum hardening ratio, secant shear stiffness and equivalent viscous damping factor, is carried out in order to show that the proposed model is reliable enough to well interpret the actual behaviour of the specimen, which exhibits many buckling phenomena and large plastic deformations. The proposed model is therefore profitably used to detect the exact displacement levels corresponding to the activation of the main buckling phenomena, as well as the stresses acting on the boundary bolted connections, which may result the weak point of the system. Moreover, the main outcomes of a parametrical study, which are implemented on the basis of the calibrated numerical model, are critically discussed and properly analysed, in order to define the erosion factor of the shear strength due to buckling
Buckling Inhibited Shear Panel as a New Damper Based on the Development of the Brb Concept in the 2D Space
No full textIn the current paper, an innovative dissipative shear panel for seismic protection of steel and reinforced concrete buildings is dealt with. It represents an extension of the Buckling Restrained Brace concept in the bi-dimensional space, as it is based on the use of a metal plate, made of aluminum or steel, representing the core of a damper whose hysteretic response could be properly controlled by an external jacket able to inhibit either the most important or, even, all the buckling phenomena under shear forces. The main results of an experimental campaign carried out under cyclic loads on both partially and totally Buckling Inhibited Shear Panels, made of different metallic materials and thicknesses, are analyzed and presented. Two different solutions are analyzed. The former is conceived in order that the buckling inhibition system restrains the out-of-plane displacements of the plate portions centered around the two diagonals, which are more sensible to the firsts and most important critical modes. The latter is based on devices able to restrain the out-of-plane displacements of the whole system. The obtained results allow to observe the significant improvement of dissipative capacity that the buckling inhibition devices are able to provide. Nevertheless, it is pointed out that for reduced thicknesses of the base plate, the system performance could be jeopardized due to the gap between the inhibiting and the inhibited parts within which buckling phenomena could develop
Design of low strength-high hardening metal multi-stiffened shear plates
No full textIn this paper design curves for low strength-high hardening metal multi-stiffened shear plates are provided, based on both experimental tests and parametric numerical analyses. To this aim, an almost pure aluminum is considered as base material, it being characterized by a yielding stress point of about 20. MPa and a hardening ratio higher than 4.An "initial stability" curve, which is useful to determine service limit conditions for metal plates in shear, is outlined with the aim of establishing the early buckling phenomena. Then, design curves providing the reduction factor of the ultimate strength of the plate in shear duly accounting for buckling phenomena are proposed as a design tool for system dimensioning.Finally, the issue related to the design of stiffeners, which are applied to delay shear buckling and to improve the plate hysteretic performance, is investigated. The current study represents an extension of the outcomes provided in a previous paper [4] (Brando and De Matteis, 2011), where the above design curves have been provided for hardening aluminum shear plates without stiffeners
A Design Formulation for Dissipative Metal Shear Panels
No full textThis paper proposes an analytical formulation for designing dissipative metal shear panels for the seismic protection of buildings. In particular, two types of dissipative shear panels are analyzed. The first is based on the adoption of a material characterized by a low yield strength with the application of transversal stiffeners. The latter is a steel shear plate that is properly weakened by perforations. Both the studied typologies are conceived in order to obtain a low shear elastic strength, so that their dissipative function is activated when the other members of the structure are still in the elastic field, even for high intensity earthquakes. Moreover, they are usually designed in order to postpone the trigger of potential buckling phenomena to the field of high shear inelastic demands. The proposed design formulations put in relation demanded shear stresses and strains. In particular, a unique expression, characterized by different coefficients for the two panel typologies, is given. The validity of the proposed expression is corroborated on the basis of the results of several numerical and experimental analysis
Analysis of aluminium beam-to-column joints by the component method: Existing studies and research needs
No full textThis paper aims at providing an overview on the current state of the art and on possible future developments concerning the component method implementation for the classification of beam-to-column joints belonging to aluminum moment resisting frames. After a brief discussion on the component method theoretical bases, developed in the past to give a feasible calculation procedure for steel joints, recent experimental and numerical studies, carried out for investigating some aluminum components, are presented and discussed. In particular strengths and weaknesses of the current knowledge are put into evidence, also in light of the peculiarities that make aluminum alloys different from steel. The launch of new research fields, aimed at pursuing an update of the current codes dealing with aluminum structures, is therefore proposed
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