Bio: Melina Bosco is an academic researcher from University of Catania. The author has contributed to research in topics: Braced frame & Structural engineering. The author has an hindex of 16, co-authored 51 publications receiving 688 citations. Previous affiliations of Melina Bosco include Concordia University Wisconsin & Concordia University.
TL;DR: In this article, a new parameter, called damage distribution capacity factor, is defined to evaluate the effect of premature yielding of links on the ability of structures to develop significant inelastic behaviour of all links prior to link failure.
Abstract: In the past, the analysis of the seismic behaviour of eccentrically braced frames designed in fulfilment of capacity design principles has highlighted the significant role of the link overstrength factor. The link overstrength factor is, however, unable to explain many seismic responses because it is defined on the basis of the sole elastic behaviour of structures. To achieve thorough comprehension of the seismic behaviour of eccentrically braced systems, a new parameter, called damage distribution capacity factor, is defined here. The proposed parameter is calculated on the basis of the inelastic structural behaviour and is intended to evaluate the effect of premature yielding of links on the ability of structures to develop significant inelastic behaviour of all links prior to link failure. The paper discusses the distribution of the damage distribution capacity factor in eccentrically braced structures designed in accordance with capacity design principles and the influence of this parameter on the seismic response of structures. Finally, an analytical relation is defined between overstrength factor of links, damage distribution capacity factor and plastic rotation of links to obtain quantitative evaluation of the structural damage of eccentrically braced structures upon first failure of links.
TL;DR: In this paper, an operative approach that provides the same accuracy as the N2 method without requiring the evaluation of an equivalent single degree-of-freedom (SDOF) system equivalent to the examined structure is proposed.
Abstract: In the most recent seismic codes, the assessment of the seismic response of structures may be carried out by comparing the displacement capacity, provided by nonlinear static analysis, with the displacement demand. In many cases the code approach is based on the N2 method proposed by Fajfar, which evaluates the displacement demand by defining, as an intermediate step, a single degree-of-freedom (SDOF) system equivalent to the examined structure. Other codes suggest simpler approaches, which do not require equivalent SDOF systems, but they give slightly different estimation of the seismic displacement demand. The paper points out the differences between the methods and suggests an operative approach that provides the same accuracy as the N2 method without requiring the evaluation of an equivalent SDOF system. A wide parametric investigation allows an accurate comparison of the different methods and demonstrates the effectiveness of the proposed operative approach. Copyright © 2009 John Wiley & Sons, Ltd.
TL;DR: In this article, the authors present some of the oral discussion by the author and others at the 2005 Annual Meeting of the Los Angeles Tall Buildings Structural Design Council on the development of a new building code for tall buildings.
Abstract: This paper presents some of the oral discussion by the author and others at the 2005 Annual Meeting of the Los Angeles Tall Buildings Structural Design Council. It also includes additional opinions added by the author after the annual meeting. These opinions address the development of a new building code for tall buildings and where the non-structural engineering decision makers can and must make contributions. It also addresses the very important topic of quality control. Copyright © 2005 John Wiley & Sons, Ltd.
TL;DR: In this paper, the authors present new findings that can explain long lasting controversies in this area and at the same time may raise questions about the adequacy of code provisions based on results from questionable models.
Abstract: The problem of earthquake induced torsion in buildings is quite old and although it has received a lot of attention in the past several decades, it is still open. This is evident not only from the variability of the pertinent provisions in various modern codes but also from conflicting results debated in the literature. Most of the conducted research on this problem has been based on very simplified, highly idealized models of eccentric one-story systems, with single or double eccentricity and with load bearing elements of the shear beam type, sized only for earthquake action. Initially, elastic models were used but were gradually replaced by inelastic models, since building response under design level earthquakes is expected to be inelastic. Code provisions till today have been based mostly on results from one-story inelastic models or on results from elastic multistory idealizations. In the past decade, however, more accurate multi story inelastic building response has been studied using the well-known and far more accurate plastic hinge model for flexural members. On the basis of such research some interesting conclusions have been drawn, revising older views about the inelastic response of buildings based on one-story simplified model results. The present paper traces these developments and presents new findings that can explain long lasting controversies in this area and at the same time may raise questions about the adequacy of code provisions based on results from questionable models. To organize this review better it was necessary to group the various publications into a number of subtopics and within each subtopic to separate them into smaller groups according to the basic assumptions and/or limitations used. Capacity assessment of irregular buildings and new technologies to control torsional motion have also been included.
TL;DR: In this paper, the results of experimental and numerical studies on strength, rotation capacity, and overstrength of links of steel eccentrically braced frames (EBFs) are discussed.
Abstract: This paper reviews the research conducted on steel eccentrically braced frames (EBFs). Both component level and system level responses for such braced frames are treated and discussed. For the component level response, a thorough review of the investigations on links, which are the primary sources of energy dissipation in EBFs, has been presented. The results of experimental and numerical studies on strength, rotation capacity, and overstrength of links are discussed. Furthermore, studies on the effects of axial force, the presence of a concrete slab, the loading history, compactness, link detailing, and the lateral bracing on link behavior are summarized. Relevant available research on link-to-column connections is revisited. Different approaches for the numerical modeling of links are also given. For the system level response, characteristics of EBF systems are discussed in light of the capacity design approach. Findings of numerical studies on the seismic performance of EBFs are discussed to provide insight into suitable response factors utilized in the design of these systems. Additionally, special topics and emerging applications of EBFs, such as replaceable links, are provided. The impact of research findings on the design of EBF systems is demonstrated considering the AISC Seismic Provisions for Structural Steel Buildings. Finally, future research needs for improvement of EBF design and application are identified and presented.
TL;DR: In this paper, a buckling restrained shear panel damper (BRSPD) is proposed to restrain the out-of-plane buckling of an energy dissipation plate.
Abstract: Steel shear panel dampers (SPDs) have been widely used in structural seismic design. The low cycle fatigue damage for SPD often occurs close to the welded stiffener, significantly weakening the fatigue performance of the damper. A novel steel shear panel damper called a buckling restrained shear panel damper (BRSPD) is proposed in this paper. A BRSPD has two main parts, an energy dissipation plate and two restraining plates. No stiffener is welded to the energy dissipation plate. The two restraining plates clamp the energy dissipation plate with bolts on both sides to prevent out-of-plane buckling. Quasi-static tests of five specimens were carried out to investigate the performance of the BRSPDs. The test focused on the stiffness and strength of the restraining plates and the gaps between them and the energy dissipation plate. The tests showed that the restraining plates with adequate stiffness and strength can effectively restrain the out-of-plane buckling of the energy dissipation plate. Numerical analysis of the BRSPD was conducted using the general finite element program, ABAQUS, to supplement the test results. A design method for the restraining plates and the bolts is suggested based on the test and analysis results.
TL;DR: In this article, a detailed analysis of an existing triple-arched bridge is performed by means of a comparison with a comprehensive set of 84 nonlinear dynamic analyses, and the choice of the control node on the finite element structural model is investigated, in order to understand its influence on the prediction of seismic capacity.
Abstract: This work delves into the seismic assessment of masonry bridges through a detailed analysis of an existing triple-arched bridge. Firstly, the effectiveness of the nonlinear static analysis is evaluated by means of a comparison with a comprehensive set of 84 nonlinear dynamic analyses. Secondly, the choice of the control node on the finite element structural model is investigated, in order to understand its influence on the prediction of seismic capacity. Although the node located at the top level is usually considered to characterize the force–displacement response of common structures, such a choice is not suitable for the considered case-study. The node located at the level of the bridge’s centre of mass proves to be a better choice since it ensures a more reliable estimation of the seismic capacity. The critical discussion of the numerical analyses results gives useful indications towards an improved procedure for the seismic assessment of the considered structural typology.