Estimation of seismic drift and ductility demands in plane regular X-braced steel frames

This paper summarizes the results of an extensive study on the inelastic seismic response of X-braced steel buildings. More than 100 regular multi-storey tension-compression X-braced steel frames are subjected to an ensemble of 30 ordinary (i.e. without near fault effects) ground motions. The records are scaled to different intensities in order to drive the structures to different levels of inelastic deformation. The statistical analysis of the created response databank indicates that the number of stories, period of vibration, brace slenderness ratio and column stiffness strongly influence the amplitude and heightwise distribution of inelastic deformation. Nonlinear regression analysis is employed in order to derive simple formulae which reflect the aforementioned influences and offer a direct estimation of drift and ductility demands. The uncertainty of this estimation due to the record-to-record variability is discussed in detail. More specifically, given the strength (or behaviour) reduction factor, the proposed formulae provide reliable estimates of the maximum roof displacement, the maximum interstorey drift ratio and the maximum cyclic ductility of the diagonals along the height of the structure. The strength reduction factor refers to the point of the first buckling of the diagonals in the building and thus, pushover analysis and estimation of the overstrength factor are not required. This design-oriented feature enables both the rapid seismic assessment of existing structures and the direct deformation-controlled seismic design of new ones. A comparison of the proposed method with the procedures adopted in current seismic design codes reveals the accuracy and efficiency of the former

A construção da visibilidade do Supremo Tribunal Federal: uma análise a partir do julgamento da Ação Penal 470

Submitted by Luciana Ferreira ([email protected]) on 2018-02-21T18:47:07Z No. of bitstreams: 2 Tese - Fernanda da Silva Borges - 2017.pdf: 6338812 bytes, checksum: 152a09d2f11ed2f11ccecee8ec5de379 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5)Approved for entry into archive by Luciana Ferreira ([email protected]) on 2018-02-21T18:47:27Z (GMT) No. of bitstreams: 2 Tese - Fernanda da Silva Borges - 2017.pdf: 6338812 bytes, checksum: 152a09d2f11ed2f11ccecee8ec5de379 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5)Made available in DSpace on 2018-02-21T18:47:27Z (GMT). No. of bitstreams: 2 Tese - Fernanda da Silva Borges - 2017.pdf: 6338812 bytes, checksum: 152a09d2f11ed2f11ccecee8ec5de379 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2017-12-19The main goal of this thesis is to understand the logics involved in the process of building the visibility of the Supreme Federal Court (STF) in the Post-Constitution of 1988, especially in the senses produced from the Criminal Lawsuit nº 470 trial (also known as the “judgment of the big monthly allowance” or “mensalão”) in the formation of the public image of the court and its ministers. In this, it is assumed that the media intersects the conflicts between the judicial sphere and the political sphere, which provokes different outcomes related to the images of the actors and institutions involved in this manner. In this sense, the media’s central role is recognized as it produces the public visibility, since the media functions as a productive device of practices, discourses, events, images and subjectivities. The main hypothesis is that the Supreme Court as a political actor is subjected to the strategies and logic from the media sphere. It is believed that the visibility spaces are managed from the strategies, disputes, interests and negotiations. Thus, the challenge was to analyze the Supreme Court’s institutional changes, especially in the communication sphere, for example the change in the Ministers’ behavior with the Justice TV creation and the live broadcast of the plenary sessions. This research uses the theoretical-methodological contributions to analyze the dynamics, the tensions and the contradictions arising from the Criminal Lawsuit nº 470 trial. The theoreticalmethodological contributions were based on the French Speech Analysis from the work of the philosopher Michel Foucault, in addition with Pierre Bourdieu's Social Theory notion of fields and finally John Thompson’s notions of visibility and political scandal. Therefore, this research worked with a diversified corpus of statements/images extracted from the media field during the trial period (2012-2014). This event was a milestone in the Court’s process of visibility, due to its strong political content and its intense relationship with the media. From a discursive perspective, it has been analyzed the emergency conditions of the statements regarding the ministers' performance, especially the ones from the case’s rapporteur Minister Joaquim Barbosa, and the reviewer, Minister Ricardo Lewandowski. Finally, it is discussed the effects of this major event which confirms our hypothesis about the imbrications of the media for the STF’s public image.A presente tese teve como objetivo central compreender as lógicas envolvidas no processo de construção da visibilidade do Supremo Tribunal Federal (STF) no Pós-Constituição de 1988, em especial, os sentidos produzidos a partir do julgamento da Ação Penal 470 (conhecido como o “julgamento do mensalão”) na formação da imagem pública do tribunal e dos ministros. Partimos do pressuposto que os conflitos vividos entre a esfera judicial e a esfera política estão atravessados pelo campo da mídia, provocando diferentes desdobramentos em relação à imagem dos atores e das instituições. Nesse sentido, reconhecemos o papel de centralidade da mídia na produção das visibilidades públicas, já que ela funciona como um dispositivo produtivo de práticas, discursos, acontecimentos, imagens e subjetividades. A hipótese principal é a de que o STF, como ator político, se submete às estratégias e lógicas da esfera midiática. Acreditamos que os espaços de visibilidade funcionam a partir de estratégias, disputas, interesses e negociações. Deste modo, o desafio proposto foi analisar as transformações institucionais do Supremo, sobretudo na esfera comunicacional, como a mudança no comportamento dos ministros com a criação da TV Justiça e a transmissão ao vivo das sessões plenárias. A pesquisa faz uso das contribuições teórico-metodológicas da Análise do Discurso de linha francesa, como os trabalhos do filósofo Michel Foucault, e das Teoria Sociais, mais precisamente, a noção de campo de Pierre Bourdieu e as noções de visibilidade e de escândalo político de John Thompson, para analisar as dinâmicas, as tensões e as contradições advindas do julgamento da referida Ação Penal. Para isso, trabalhamos com um corpus diversificado de enunciados/imagens que puderam ser extraídos do campo midiático durante o período do julgamento (2012-2014). Em nosso entender, esse acontecimento foi um marco no processo de visibilidade da Corte, tanto pelo forte conteúdo político quanto pela intensa relação com os meios de comunicação. Por meio de uma perspectiva discursiva, analisamos as condições de emergência dos enunciados a respeito da atuação dos ministros, com destaque para o relator do processo, ministro Joaquim Barbosa, e o revisor, ministro Ricardo Lewandowski. Para finalizar, discutimos os efeitos deste acontecimento e confirmamos a nossa hipótese sobre as imbricações da mídia para a imagem pública do STF

Behaviour factor for performance-based seismic design of plane steel moment resisting frames

Simplified expressions to estimate the behavior factor of plane steel moment resisting frames are proposed, based on statistical analysis of the results of thousands of nonlinear dynamic analyses. The influence on this factor of specific structural parameters, such as the number of stories, the number of bays, and the capacity design factor of a steel frame, is studied in detail. The proposed factor describes the seismic strength requirements in order to restrict maximum storey ductility to a predefined value. Interrelation studies between maximum storey ductility and the Park-Ang damage index are also provided for the damage-based interpretation of the performance levels under consideration. Realistic design examples serve to demonstrate the ability of the proposed factor to convert conventional force-based design to a direct performance-based seismic design procedure

Maximum displacement profiles for the performance based seismic design of plane steel moment resisting frames

New relations to estimate maximum seismic displacement profiles of plane steel moment resisting frames are proposed. These expressions associate maximum floor displacements with local member deformation seismic demands and are based on statistical analysis of the results of several hundred nonlinear dynamic analyses of steel frames. The influence of specific parameters, such as the number of stories, the number of bays, the joint capacity design factor and the level of inelastic deformation induced by the seismic excitation, is studied in detail. It is concluded that the main structural characteristic that affects the shape of the displacement pattern is the number of stories. Furthermore, the present study reveals that a differentiation between the profile of a frame in the elastic and the inelastic range of response is necessary. A comparison between the proposed displacement patterns and other existing ones is also made to demonstrate the merits of the former

Extension of the hybrid force/displacement (HFD) seismic design method to 3D steel moment-resisting frame buildings

The hybrid force/displacement (HFD) seismic design method for planar steel frames developed by the authors is extended to 3D steel buildings using moment-resisting frames. HFD combines the advantages of both the displacement-based and the force-based seismic design methods and reduces or eliminates their disadvantages. An extensive response databank is developed through nonlinear dynamic analyses on 38 steel space frames designed according to Eurocodes 3 and 8 and subjected to 42 pairs of earthquake ground motions. This response databank is then utilized for the development of empirical formulae providing the behavior factor as a function of the geometrical and dynamic characteristics of the building, including its accidental eccentricity, as well as the target maximum interstorey drift ratio and local ductility. Thus, the proposed seismic design method, eventhough works as a force-based design one, controls structural and non-structural damage through the use of a behavior factor, which is a function of seismic deformation demands. Numerical examples are presented to illustrate the proposed method and demonstrate its merits over the force-based seismic design method of Eurocode 8