Thesis (Ph. D.)--State University of New York at Binghamton, Thomas J. Watson School of Engineering and Applied Science, Department of Mechanical Engineering, 2008. / Includes bibliographical references.

The main topic of the thesis is the role of timber in the seismic resilience of unreinforced masonry (URM) buildings. The research addressed both existing timber components that can be encountered in URM buildings and timber-based retrofit solutions. The work presented herein can be split into two main phases. In the first part of the research, the in-plane behavior of traditional wooden floors was analyzed by means of numerical static and dynamic simulations. Modelling strategies with different refinement levels were proposed and implemented to assess diaphragm in-plane strength and flexibility. Modelling was undertaken considering as-built diaphragms first and was then extended to diaphragms retrofitted by means of timber-based techniques. The influence of diaphragm construction details on their in-plane response was evaluated and timber-based retrofitting solutions were observed to be effective in mitigating in-plane diaphragm flexibility and in increasing in-plane diaphragm strength. The second part of the PhD work was dedicated to investigate new retrofit solutions for URM buildings based on the use of engineered timber panels mechanically connected to the masonry. The first step saw the experimental testing of different types of timber-to-masonry connections considering both screw-type fasteners and adhesive anchors. In the second stage, full-scale masonry walls were tested in the as-built, retrofitted and repaired configurations, highlighting the benefits of the proposed technique on the in-plane response of the masonry walls.

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Thesis (PhD) -- University of South Australia, 1998

Thesis (Ph. D.)--State University of New York at Binghamton, Thomas J. Watson School of Engineering and Applied Science, Department of Mechanical Engineering, 2009. / Includes bibliographical references.

Thesis (Ph. D.)--University of Texas at Austin, 2006. / Vita. Includes bibliographical references.

This study was initiated to quantify the effect of different degrees of irregularity on structures designed for earthquake using simplified analysis. The types of irregularity considered were: (a) Vertical Irregularity • Mass • Stiffness -Strength (b) Horizontal (Plan) Irregularity • Diaphragm Flexibility Simple models were used to allow many analyses to be conducted in a relatively short time. For vertical irregularity studies, simple shear-type structures were designed according to the New Zealand design Standard, NZS1170.5, firstly as regular structures, and then they were redesigned as irregular structures to the same target drift. Both regular and irregular structures were then subjected to a suite of records, and vertical irregularity effects evaluated from the difference in response. For the flexible diaphragm effect study, simple models of structures were developed with: (a) a rigid diaphragm assumption; and (b) a flexible diaphragm assumption. Flexible diaphragm effects were evaluated by conducting time-history analyses and comparing the responses of structures with rigid and flexible diaphragms. A mechanics based approach was developed to quantify flexible diaphragm effects, which was shown to produce consistent results with those from time-history analyses. Relationships between the degree of irregularity and the change in behaviour were developed. This information facilitates designers and plan checkers to rapidly evaluate the likely effect of irregularity on structures. It provides guidance as to: (a) when the effect of structural irregularity can be ignored, and (b) the change in demands for different degrees of structural irregularity. The relations developed also provide a rigorous technical basis for future regularity provisions in the NZS1170.5 and other world-wide seismic design codes.

Recent research has identified that current code level seismic demands used for diaphragm design are considerably lower than demands in real structures during a seismic event. However, historical data has shown that steel deck diaphragms, common to steel framed buildings, perform exceptionally well during earthquake events. A new alternative diaphragm design procedure in ASCE 7-16 increases diaphragm seismic demand to better represent expected demands. The resulting elastic design forces from this method are reduced by a diaphragm design force reduction factor, Rs, to account for the ductility of the diaphragm system. Currently, there exist no provisions for Rs factors for steel deck diaphragms. This research was therefore initiated to understand inelastic steel deck diaphragm behavior and calculate Rs factors. A review of the literature showed that a large number of experimental programs have been performed to obtain the in-plane load-deformation behavior of steel deck diaphragms. To unify review of these diaphragm tests and their relevant results, a database of over 750 tested specimens was created. A subset of 108 specimens with post-peak, inelastic behavior was identified for the characterization of diaphragm behavior and ductility. A new recommended method for predicting shear strength and stiffness for steel deck diaphragms with structural concrete fill is proposed along with an appropriate resistance factor. Diaphragm system level ductility and overstrength are estimated based on subassemblage test results and Rs factors are then calculated based on these parameters. The effects of certain variables such as deck thickness and fastener spacing on diaphragm ductility are explored. / Master of Science

O atrativo estético proporcionado pela forma arredondada é o fator que na maioria das vezes determina a utilização de estruturas tubulares circulares. É crescente a concepção de pórticos formados por colunas tubulares e as tradicionais vigas de seção I. Esse tipo de ligação ainda é pouco estudado no Brasil, e esse trabalho busca avançar no entendimento do comportamento estrutural dessas ligações. Foram realizados estudos analíticos, numéricos e experimentais em quatro configurações de ligação, com diafragmas externos transversais, chapa de alma, soldas, parafusos e enrijecedor. Avaliou-se a relação M-\'fi\' (momento-rotação) das ligações estudadas e os parâmetros envolvidos como resistência, rigidez e ductilidade, evidenciando-se o modo de colapso das ligações. O estudo analítico foi desenvolvido baseado nas recomendações do Eurocode 3 (2005), com a utilização do Método das Componentes. A análise numérica, através do Método dos Elementos Finitos, foi realizada por meio dos programas computacionais TRUEGRID® e ANSYS®. Os modelos numéricos consideram as características mecânicas do aço, como plastificação, encruamento e não-linearidades geométricas e de contato. As formulações do Eurocode 3 (2005), adaptadas para a determinação da resistência das ligações viga-coluna, apresentaram resultados coerentes e a análise numérica foi representativa frente aos resultados experimentais. A utilização de diafragmas externos conectados à viga apresentou boa funcionalidade, ajudando na distribuição das tensões na região da ligação, melhorando o comportamento da coluna. / The aesthetic appeal provided by the round shape is the factor that mostly determines the use of circular tubular structures. There is an increasing conception of structures formed by hollow columns and traditional beams of section I. This type of connection hasn\' t been sufficiently studied in Brazil, and this paper tries to advance the comprehension of the structural behavior of these connections. Analytical, numerical, and experimental study were performed in four connections configurations, with transverse external diaphragms, web plate, welds, bolts and stiffener. The relation M-\'fi\' (moment-rotation) of the studied connections and the parameters involved such as strength, stiffness and ductility were evaluated, evidencing the failure mode of connections. The analytical study was developed based on recommendations of Eurocode 3 (2005) using the Method of Components. The numerical analysis using the Finite Element Method was performed with the computer programs TRUEGRID® and ANSYS®. The numerical models consider the mechanical characteristics of steel, such as yielding and hardening, and also the geometric and contact nonlinearity. The formulations of Eurocode 3 (2005), adapted for determining the strength of beam-column connections, showed coherent results and the numerical analysis was representative compared to experimental results. The use of external diaphragm connected to the beam showed good functionality, helping in the distribution of stress in the region of connection, improving the behavior of the column.