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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Development and Validation of a Twelve Bolt Extended Stiffened End-Plate Moment Connection

Szabo, Trevor Alexander 20 June 2017 (has links)
Three end-plate moment connection configurations are prequalified for special moment frames for seismic applications in AISC 358-10. The eight bolt extended stiffened connection is the strongest of the three configurations, but it can only develop approximately 30 percent of currently available hot-rolled beam sections. The strength of this configuration is limited by bolt strength. There is a need for a stronger end-plate moment connection, hence the reason for the development and validation of a twelve bolt configuration. Equations were developed for the design procedure using various analytical methods, which included yield line analysis and an effective tee stub model. An experimental program was conducted, which consisted of the full-scale cyclic testing of four end-plate moment connections. The intention of the testing was to develop and validate the design procedure, and prequalify a new twelve bolt configuration. A displacement-controlled loading protocol was applied according to AISC 341-10. The experimental results showed that the model for thick end-plate behavior is conservative by 6.7%, the model for end-plate yielding is conservative by 8.8%, and the model for bolt tension rupture with prying conservatively predicts by 18.5%. The specimens that were designed to form a plastic hinge in the beam fractured in a brittle manner. The deep beam specimen fractured in the first 2% story drift cycle, and the shallow beam specimen fractured in the second 3% story drift cycle. The fracture of the prequalification specimens was determined to have been caused by stiffeners of high yield stress relative to the beam yield stress. / Master of Science / End-plate moment connections are a common way to create a rigid joint between beams and columns. Before using a moment connection in a steel building to resist horizontal earthquake loads, each connection configuration must be tested at full-scale and meet performance criteria prescribed in the applicable building code (in this case, the Seismic Provisions for Structural Steel Buildings published by the American Institute of Steel Construction). Three end-plate moment connection configurations have been previously “prequalified” for high seismic regions, which means that sufficient previous testing has shown adequate performance. The eight bolt end-plate moment connection is the strongest of the three configurations, but it can only develop approximately 30 percent of currently available hot-rolled steel beam sections. The strength of this configuration is limited by bolt strength. There is a need for stronger end-plate moment connections, which motivated the development and validation of a twelve bolt configuration in this thesis. Equations were developed for the design of the twelve-bolt end-plate moment connection including equations to predict when the bolts would fracture and when the end-plate would yield. An experimental program was conducted, which consisted of the full-scale cyclic testing of four end-plate moment connections. The intention of the testing was to validate the design procedure and demonstrate that the connection could withstand significant inelastic rotation. The connection assembly was cycled back and forth according to a displacement protocol prescribed in the Seismic Provisions for Steel Buildings. The experimental results showed that the equations were able to predict bolt rupture within 6.7% of the applied moment at fracture, the equation for end-plate yielding was conservative by 8.8%, and the equation for bolt fracture with prying action was conservative by 18.5%. The specimens that were intended to show the connection could withstand significant inelasticity fractured in an unexpected brittle manner. The deep beam iv specimen fractured in the first 2% story drift cycle, and the shallow beam specimen fractured in the second 3% story drift cycle, neither of which reach the target of 4% story drift. The fractures were determined to have been caused by stiffeners that had too high a yield stress relative to the beam yield stress.
22

The Effect of Masonry Infill On The Seismic Behaviour of Reinforced Concrete Moment Resisting Frames

Basiouny, Wael January 2009 (has links)
<p> A moment resisting frame is one of the most commonly used lateral load resisting system in modem structures because it is suitable for low and medium rise buildings and industrial structures. It can be designed to behave in a ductile manner under seismic loads. </p> <p> Masonry infills have traditionally been used in buildings as partitions and for architectural or aesthetic reasons. They are normally considered as non-structural elements, and their effect on the structural system has been ignored in the design. However, even though they are considered non-structural elements, there is mounting evidence that they interact with the frame when the structures are subjected to lateral loads Infill walls have been identified as a contributing factor to catastrophic structural failures during earthquakes. Frame-infill interaction can induce brittle shear failures of reinforced concrete columns by creating a short column. Furthermore, infills can over-strengthen the upper stories of a structure and when they fail a soft first storey is created, which is highly undesirable from the earthquake resistance standpoint. </p> <p> There is a need for an efficient and accurate computational model to simulate the nonlinear hysteretic force-deformation behaviour of masonry infills, which is also suitable for implementation in time-history analysis of large structures. The aim is to develop a simplified advanced and cost-effective model for nonlinear time history analysis and seismic design of masonry infill frame structures. </p> <p> The objective of this research was to develop a practical and economical technique applicable for global analysis of general three-dimensional reinforced concrete infilled frames under lateral loads. Novel finite element model for the infill and the surrounding frame was developed using a special finite element configuration to represent the masonry panel. Some prescribed failure planes in different directions were defined depending on the common failure mode of masonry panels. Moreover, some of contact elements were used on the failure planes to connect among the panel elements, and between the panel elements and the boundary reinforced concrete frame. Different material models were used to represent the behaviour of concrete, reinforcing steel, mortar joints and inclined saw-tooth cracks in the infill panel. Different material models were used to describe the behaviour through and perpendicular to the prescribed failure planes. The proposed model and the used material models were described in details in the first part of this research. </p> <p> The proposed finite element model was verified against experimental and analytical results previously published by others. Different frames configurations, reinforcing details, boundary conditions and material properties were consider in that section to verify the capability of the proposed model to simulate the behaviour of different frames. The overall behaviour "Load-deflection relationship", failure point and failure mode were compared with the experimental and analytical results. Satisfactory agreement with the previously published results was obtained. </p> <p> The study investigates the capability of the proposed model to simulate the behaviour of infilled frames subjected to cyclic loads. Hysteretic loops obtained by using the new model were verified against experimental and analytical results and good correlation were obtained. The failure modes and crack patterns were compared with the experimental results and good agreements were obtained. The proposed model failed to capture some shear cracks in the RC frames as per the experimental results. </p> / Thesis / Doctor of Philosophy (PhD)
23

Design comparison of ordinary concentric brace frames and special concentric brace frames for seismic lateral force resistance for low rise buildings

Grusenmeyer, Eric January 1900 (has links)
Master of Science / Department of Architectural Engineering / Kimberly Waggle Kramer / Braced frames are a common seismic lateral force resisting system used in steel structures. Ordinary concentric braced frames (OCBFs) and special concentric braced frames (SCBFs) are two major types of frames. Brace layouts vary for both OCBFs and SCBFs. This report examines the inverted-V brace layout which is one common arrangement. OCBFs are designed to remain in the elastic range during the design extreme seismic event. As a result, OCBFs have relatively few special requirements for design. SCBFs are designed to enter the inelastic range during the design extreme seismic event while remaining elastic during minor earthquakes and in resisting wind loads. To achieve this, SCBFs must meet a variety of stringent design and detailing requirements to ensure robust seismic performance characterized by high levels of ductility. The design of steel seismic force resisting systems must comply with the requirements of the American Institute of Steel Construction’s (AISC) Seismic Provisions for Structural Steel Buildings. Seismic loads are determined in accordance with the American Society of Engineers Minimum Design Loads for Buildings and Other Structures. Seismic loads are very difficult to predict as is the behavior of structures during a large seismic event. However, a properly designed and detailed steel structure can safely withstand the effects of an earthquake. This report examines a two-story office building in a region of moderately high seismic activity. The building is designed using OCBFs and SCBFs. This report presents the designs of both systems including the calculation of loads, the design of frame members, and the design and detailing of the connections. The purpose of this report is to examine the differences in design and detailing for the two braced frame systems.
24

Eccentrically braced steel frames as a seismic force resisting system

Hague, Samuel Dalton January 1900 (has links)
Master of Science / Department of Architectural Engineering / Kimberly Waggle Kramer / Braced frames are a common seismic lateral force resisting system used in steel structure. Eccentrically braced frames (EBFs) are a relatively new lateral force resisting system developed to resist seismic events in a predictable manner. Properly designed and detailed EBFs behave in a ductile manner through shear or flexural yielding of a link element. The link is created through brace eccentricity with either the column centerlines or the beam midpoint. The ductile yielding produces wide, balanced hysteresis loops, indicating excellent energy dissipation, which is required for high seismic events. This report explains the underlying research of the behavior of EBFs and details the seismic specification used in design. The design process of an EBF is described in detail with design calculations for a 2- and 5-story structure. The design process is from the AISC 341-10 Seismic Provisions for Structural Steel Buildings with the gravity and lateral loads calculated according to ASCE 7-10 Minimum Design Loads for Buildings and Other Structures. Seismic loads are calculated using the Equivalent Lateral Force Procedure. The final member sizes of the 2-story EBF are compared to the results of a study by Eric Grusenmeyer (2012). The results of the parametric study are discussed in detail.
25

Upgrade of Seismically Deficient Steel Frame Structures Built in Canada Between the 1960s and 1980s Using Passive Supplemental Damping

Kyriakopoulos, Nikolas 20 November 2012 (has links)
A typical 1960s Type 2 Construction steel MRF hospital structure in Quebec, representative of a prevalent construction philosophy of the time, was investigated and modelled in OpenSees using an advanced strength degradation model. The structure was then subjected to a nonlinear time-history analysis (NLTHA) for Montreal (MTL) and Vancouver (VAN) ground motions and was found to be deficient under the design hazard levels. Retrofits were proposed for the two orthogonal frames at both sites using a performance-based approach. An experimental program determined that the connections had less ductility than expected and began deteriorating around 2.0% interstorey drift. The OpenSees model was updated according to the experimental connection behaviour and the predicted NLTHA performance of the structure worsened. The proposed retrofit designs for both orthogonal frames in both MTL and VAN were updated with the new connection behaviour and final retrofit designs were proposed.
26

Upgrade of Seismically Deficient Steel Frame Structures Built in Canada Between the 1960s and 1980s Using Passive Supplemental Damping

Kyriakopoulos, Nikolas 20 November 2012 (has links)
A typical 1960s Type 2 Construction steel MRF hospital structure in Quebec, representative of a prevalent construction philosophy of the time, was investigated and modelled in OpenSees using an advanced strength degradation model. The structure was then subjected to a nonlinear time-history analysis (NLTHA) for Montreal (MTL) and Vancouver (VAN) ground motions and was found to be deficient under the design hazard levels. Retrofits were proposed for the two orthogonal frames at both sites using a performance-based approach. An experimental program determined that the connections had less ductility than expected and began deteriorating around 2.0% interstorey drift. The OpenSees model was updated according to the experimental connection behaviour and the predicted NLTHA performance of the structure worsened. The proposed retrofit designs for both orthogonal frames in both MTL and VAN were updated with the new connection behaviour and final retrofit designs were proposed.
27

Design And Manufacturing Of Impact Resisting Structures (Aluminium Foam)

Shankar, C Uma 02 1900 (has links)
Metal foams have found increasing applications in a wide range of structural and functional products, due to their exceptional mechanical, thermal, acoustic and electrical properties and offer great potential for lightweight structures for energy absorption in packaging during impact at high velocities. Metal foam structures have densities only fractions of that of a solid structure and have high specific strength and higher stiffness than other contemporary packaging materials. Therefore, the metal foam in particular “Aluminium Foam” has an important application as packaging material for transportation of Reactor fuels and Radioactive samples. Nuclear materials are transported in packages which should meet stringent safety standards like impact resistance, thermal shock etc. Therefore, in the transportation of the above materials, aluminium foam can play a key role in providing a cushion for absorption of shock and impact. The aim of this work is to develop a process for fabrication of aluminum foam. Two methods are experimented to manufacture metal foams. The first method involves mixing of a foaming agent in a liquid aluminium pool and the subsequent cooling of the melt while hydrogen is released from the foaming agent. The second method of metal foaming process is based on a procedure consisting of a base metal and a foaming agent, which are milled for homogeneous mixing and then pre-compacted by cold isostatic pressing. This is followed by cold/warm extrusion. The extruded piece is then heated up to a certain foaming temperature. The heating process leads to partial metal melting as well as to the release of the hydrogen gas and consequently to the formation of metal foam in the semi-solid state. In this thesis, the technology for fabrication of Al foam having a density of around 0.2-0.3 g/cm3 has been made & discussed in detail. The effects of various fabrication parameters like compaction pressure, extrusion ratio and foaming temperature on the formation of the Al foam are discussed. The quality of fabricated Al foams is characterized in terms of density, microstructure, porosity content etc. The various mechanical properties like yield strength, tensile strength and impact energy of the Al foams are evaluated in order to understand their behavior under different conditions. The typical values of Young’s modulus, plateau stress, densification strain and energy absorbed for the foam tested are tabulated. The observations, which are made from the data, can be briefly quoted as under: a) As the length of the specimen increases, plateau stress increases which increases the energy absorption. b) The energy absorption for Al-20% Mg alloy has been found to be minimum. The foam exhibited brittle behaviour and crumbled under load application. c) Young’s modulus varies in the range of 0.057 – 0.13 GPa for the foam. d) As density increases, Young’s modulus also increases and correspondingly the energy absorption value increases for Al-foam. It is found that the variation in the plateau stress with density is marginal. But the strain value was found to be dependent on the alloy composition and the density. The strain obtained for all cases was found to be very near to 75-90%. Al-20%Mg alloy showed an inferior behaviour compared to pure Al. It showed a lesser plateau stress and crumbled while testing. This shows that this alloy is highly brittle in nature. Also, the Al-Mg foam obtained did not exhibited good luster.
28

A comparison of Reduced Beam Section moment connection and Kaiser Bolted Bracket® moment connections in steel Special Moment Frames

Johnson, Curtis Mathias January 1900 (has links)
Master of Science / Department of Architectural Engineering and Construction Science / Kimberly W. Kramer / Of seismic steel lateral force resisting systems in practice today, the Moment Frame has most diverse connection types. Special Moment frames resist lateral loads through energy dissipation of the inelastic deformation of the beam members. The 1994 Northridge earthquake proved that the standard for welded beam-column connections were not sufficient to prevent damage to the connection or failure of the connection. Through numerous studies, new methods and standards for Special Moment Frame connections are presented in the Seismic Design Manual 2nd Edition to promote energy dissipation away from the beam-column connection. A common type of SMF is the Reduce Beams Section (RBS). To encourage inelastic deformation away from the beam-column connection, the beam flange’s dimensions are reduced a distance away from the beam-column connection; making the member “weaker” at that specific location dictating where the plastic hinging will occur during a seismic event. The reduction is usually taken in a semi-circular pattern. Another type of SMF connection is the Kaiser Bolted Bracket® (KBB) which consists of brackets that stiffen the beam-column connection. KBB connections are similar to RBS connections as the stiffness is higher near the connection and lower away from the connection. Instead of reducing the beam’s sectional properties, KBB uses a bracket to stiffen the connection. The building used in this parametric study is a 4-story office building. This thesis reports the results of the parametric study by comparing two SMF connections: Reduced Beam Section and Kaiser Bolted Brackets. This parametric study includes results from three Seismic Design Categories; B, C, and D, and the use of two different foundation connections; fixed and pinned. The purpose of this parametric study is to compare member sizes, member forces, and story drift. The results of Seismic Design Category D are discussed in depth in this thesis, while the results of Seismic Design Category B and C are provided in the Appendices.
29

Svařování žárupevných ocelí metodou 121 do úzké mezery. / Welding of heat - resistent steels by narrow gap SMAW method.

Lukosz, Ondřej January 2010 (has links)
LUKOSZ Ondřej: Welding of heat - resistent steels by method SMAW into the narrow gap. The project elaborated in frame of engineering studies branch 2307. The project is submitting design of technology production of the weld procedure creep metal. It uses in manufactory power equipment. The power equipment, the type of steam turbine, uses steel 30CrMoNiV 5-11. The welding into the narrow gap has its specifics. The most important parameter is the choice of flux and filler metal. We must decide appropriate flux for convenient disposing of slag. Based on the literature study these problems were proposed the specified welding procedure, appropriate flux and appropriate additional material. For the experiment was selected appropriate temperature of preheating.
30

Genderová analýza vybraných románů Miloše Urbana / Gender analysis of chosen novels of Miloš Urban

Husáková, Martina January 2014 (has links)
This diploma thesis A Gender Analysis of Selected Novels of Miloš Urban researches two concrete literary texts, novels Sedmikostelí and Lord Mord, which are analysed from gender perspective. By using two methods, feminist "resisting reading" and discursive analysis, there are uncovered various ways of female's characters construction, which are put in the social and cultural context. Theoretically the work is patterned on Judith Fetterley's concept, which was created during second wave of feminism, and it is connected to new poststructuralist and deconstructivist approaches. In this theses literature is perceived as space of impressing and encountering different discourses. Senses, categories and relations, incuding gender relations, are deconstructed in this space. This theses's core is the analysis of different categories and forms of femininity, which are reproduced in Urban's texts. It tries to show the possibility to read literary text "against the hair" and to not succumb to its interpellations. In this way it stresses personality of reading individual and his/her ability to complete/reshape text during every single process of reading and to produce new senses and categories. Keywords: feminism, gender analysis, Lord Mord, Sedmikostelí, Urban Miloš, resisting reading, women characters

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