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Yan, Zhihao, and 阎志浩. "Nonlinear dynamic analysis and strcutural identification of frames." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2009. http://hub.hku.hk/bib/B43224076.
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Yan, Zhihao. "Nonlinear dynamic analysis and strcutural identification of frames." Click to view the E-thesis via HKUTO, 2009. http://sunzi.lib.hku.hk/hkuto/record/B43224076.
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White, M. J. "Dynamic characteristics of infilled frames." Thesis, University of Bradford, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.355241.
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Hunt, Stephen J. "Semi-active smart-dampers and resetable actuators for multi-level seismic hazard mitigation of steel moment resisting frames." Thesis, University of Canterbury. Mechanical Engineering, 2002. http://hdl.handle.net/10092/1256.
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This thesis explores the creation and assessment of semi-active control algorithms for both squat shear buildings and tall flexible structures. If cost-effective, practicable, semi-active structural control systems can be developed, the potential reduction in loss of both property and lives due to seismic events is significant. Semi-active controllers offer many of the benefits of active systems, but have power requirements orders of magnitude smaller, and do not introduce energy to the structural system. Previous research into semi-active controllers has shown their potential in linear simulations with single earthquake excitations. The distinguishing feature of this investigation is the use of appropriate non-linear modelling techniques and realistic suites of seismic excitations in the statistical assessment of the semi-active control systems developed. Finite element time-history analysis techniques are used in the performance assessment of the control algorithms developed for three and nine story structural models. The models include non-linear effects due to structural plasticity, yielding, hysteretic behaviour, and P-delta effects. Realistic suites of earthquake records, representing seismic excitations with specific return period probability, are utilised, with lognormal statistical analysis used to represent the response distribution. In addition to displacement focused control laws, acceleration and jerk regulation control methods are developed, showing that potential damage reduction benefits can be obtained from these new control approaches. A statistical assessment of control architecture is developed and undertaken, examining the distribution of constant maximum actuator authority for both squat shear buildings, and tall slender structures, highlighting the need to consider non-linear structural response characteristics when implementing semi-active control systems. Finally, statistical analysis of all results and normalised values shows the efficacy of each control law and actuator type relative to different magnitude seismic events. As a result, this research clearly presents, for the first time, explicit tradeoffs between control law, architecture type, non-linear structural effects, and seismic input characteristics for the semi-active control of civil structures.
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Falzon, Christopher. "Pattern solver for the static and dynamic analysis of framework models /." [Hong Kong : University of Hong Kong], 1985. http://sunzi.lib.hku.hk/hkuto/record.jsp?B12315588.
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Clément, Denis Emile. "Seismic analysis of knee elements for steel frames." Thesis, University of Oxford, 2002. http://ora.ox.ac.uk/objects/uuid:c69aee93-4489-486c-a5fe-11685728e903.
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The 1994 Northridge and 1995 Kobe earthquakes, which were moderate in seismological terms, showed that many buildings were subjected to demolition or very expensive repairs because of severe damage in principle members, mainly in the column-beam connections. As a result, the development of dissipative systems was encouraged, which limit the damage parts to easily replaceable elements, in case of moderate earthquakes. One such system is the knee braced frame. Knee braced frames are a modified form of cross bracing in which the brace is cut short and connected to the mid point of a knee element spanning between the adjacent beam and column. The key component is the knee element, which controls both the initial elastic stiffness of the frame, and the onset of yield and subsequent energy dissipation. The knee elements are required to ensure energy absorption through repeated large deformations without suffering collapse or instability. This thesis describes the development of different knee element designs and their performance assessments. It is shown that the dissipative mechanism of the web yielding in shear is advantageous because it is independent of the moment distribution and it does not affect the connections and extends the dissipative zones to all its lengths. Extensive finite element modelling and experimental testing have been undertaken. In the shear yielding mode excellent performance was achieved using standard hot rolled sections, modified by the addition of web stiffeners to prevent localised buckling failure. Weakening of the knee element's webs so that it yields very early in an earthquake has potential benefit, but is shown to be unsafe as it promotes premature failure of the element. A knee element model for non-linear dynamic analysis of an entire building has been developed. Time history analyses showed that knee braced frames with the developed knee element have a large global ductility and an outstanding performance. Results obtained with different pushover analysis methods (Eurocode 8, FEMA-356 and ATC-40) have been compared to those obtained wit the time history analyses. Moreover FEMA-356 method, which includes a more accurate representation of the structure's significant post-yield stiffness, gave the closest agreement with the time history analyses and is recommended for the design of knee braced frames.
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Flint, Eric Michael. "Electro-dynamic analysis of stack actuators and active members integrated within truss structures." Thesis, This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-12042009-020329/.
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Jackson, Karen E. "Scaling effects in the static and dynamic response of graphite- epoxy beam-columns." Diss., This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-08222008-063229/.
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Falzon, Christopher. "Pattern solver for the static and dynamic analysis of frameworkmodels." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1985. http://hub.hku.hk/bib/B31206864.
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Oz̈bek, M. Akif. "Short- and long-term dynamical behavior of beam type structures with computer graphics." Diss., Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/19017.
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Ozcelik, Ramazan. "Seismic Upgrading Of Reinforced Concrete Frames With Structural Steel Elements." Phd thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613450/index.pdf.
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This thesis examines the seismic internal retrofitting of existing deficient reinforced concrete
(RC) structures by using structural steel members. Both experimental and numerical studies
were performed. The strengthening methods utilized with the scope of this work are chevron
braces, internal steel frames (ISFs), X-braces and column with shear plate. For this purpose,
thirteen strengthened and two as built reference one bay one story portal frame specimens
having 1/3 scales were tested under constant gravity load and increasing cyclic lateral
displacement excursions. In addition, two ½scaled three bay-two story frame specimens strengthened with chevron brace and ISF were tested by employing continuous pseudo dynamic testing methods. The test results indicated that the cyclic performance of the Xbrace and column with shear plate assemblage technique were unsatisfactory. On the other hand, both chevron brace and ISF had acceptable cyclic performance and these two techniques were found to be candidate solutions for seismic retrofitting of deficient RC structures. The numerical simulations by conducting nonlinear static and dynamic analysis were used to estimate performance limits of the RC frame and steel members. Suggested strengthening approaches, chevron brace and ISF, were also employed to an existing five story case study RC building to demonstrate the performance efficiency. Finally, design approaches by using existing strengthening guidelines in Turkish Earthquake Code and ASCE/SEI 41 (2007) documents were suggested.
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Akpinar, Ugur. "Nonlinear Analysis Of Rc Frames Retrofitted With Structural Steel Elements." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612380/index.pdf.
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Deficient concrete structures are serious danger in seismic zones. In order to minimize economical and human loss, these structures should be retrofitted. Selecting suitable retrofitting schemes requires detailed investigation of these systems. Considering these facts, this study aims to calibrate analytical models of systems with chevron braces and internal steel framesand evaluate their seismic performances. First, analytical models of the frames with braces and internal steel frames were prepared and then their responses were compared with cyclic responses of experimental studies. Results of these models were used to determine performance limits by the methods proposed by TEC2007 and ASCE/SEI-41. Then, calibrated models were employed for time history analyses with various scales of Duzce ground motion and analytical results were compared with experimental findings. Seismic performance of these systems was also evaluated by using aforementioned codes. Finally, evaluated retrofitting schemes were applied to a 4-story 3-bay reinforced concrete frame that was obtained from an existing deficient structure and effectiveness of applied retrofitting schemes was investigated in detail.
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Juston, John M. "Theoretical and experimental study into the dynamics and control of a flexible beam with a DC-servo motor actuator." Thesis, Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/50029.
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Position and vibration control of a flexible beam is studied analytically and in the laboratory. Two different motor types are compared as actuators throughout the thesis: a standard voltage controlled motor and a torque controlled motor. The experimental beam is controlled with a dc-servo motor at its base and is instrumented with strain gages and a potentiometer. The control law is a form of linear, direct-output feedback. State estimators augment the control law to provide rate information that is not available from the instrumentation. Accurate modeling of the system’s inherent damping characteristics is achieved by analyzing experimental data. Gains were iterated yielding minimum-gain norm and minimum-sensitivity norm solutions to meet imposed eigenvalue placement constraints. Results for the two solutions and the two systems are compared and contrasted. Experimental verification of analytical results is hampered by unmodeled system non-linearities. Several attempts at bypassing these obstacles are shown. Finally, conclusions and recommendations are made.Master of Science
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Xu, Jian. "Development of a general dynamic hysteretic light-frame structure model and study on the torsional behavior of open-front light-frame structures." Online access for everyone, 2006. http://www.dissertations.wsu.edu/Dissertations/Fall2006/j_xu_120606.pdf.
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Kruep, Stephanie Jean. "Using Incremental Dynamic Analysis to Visualize the Effects of Viscous Fluid Dampers on Steel Moment Frame Drift." Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/34122.
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This thesis presents the details of a study regarding both the use of linear viscous fluid dampers in controlling the interstory drift in steel moment frames, and the use of incremental dynamic analysis as a method of visualizing the behavior of these moment frames when subjected to seismic load effects. Models of three story and nine story steel moment frames were designed to meet typical strength requirements for office buildings in Seattle, Washington. These models were intentionally designed to violate seismic interstory drift restrictions to test the ability of the linear viscous fluid dampers to reduce these drifts to the point of code compliance. Dampers were included in one bay of every story in each model. These devices were used to produce total structural damping ratios of 5%, 10%, 20%, and 30% of critical. Undamped, traditional stiffness controlled models of both three stories and nine stories were also created for comparison purposes. Incremental dynamic analysis was used to subject these models to ten ground motions, each scaled to twenty incremental levels. Two new computer applications were written to facilitate this process. The results of these analyses were studied to determine if the linear viscous fluid dampers were able to cause compliance with codified drift limits. Also, incremental dynamic analysis plots were created to examine the effects of the dampers on structural behavior as damping increased from inherent to 30% of critical. It was found that including linear viscous fluid dampers in steel moment frame design can satisfactorily control interstory drift, and incremental dynamic analysis is a beneficial tool in visualizing dynamic structural behavior.Master of Science
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Chen, Chung-Kang. "Applications of substructuring methods to the dynamic finite element analysis of a container refrigeration unit frame structure /." Online version of thesis, 1992. http://hdl.handle.net/1850/11688.
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Abou-Rayan, Ashraf M. "A study of full displacement design of frame structures using displacement sensitivity analysis." Thesis, Virginia Tech, 1985. http://hdl.handle.net/10919/45557.
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The intent of this study is to develop an algorithm for structural design based on allowable displacements for structural members, independent of stresses caused by the configurations imposed. Structural design can be based on displacement constraints applied in the same basic format as stress constraints so that convergence is based on allowable displacements rather than on stresses.
Master of Science
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Means, Daniel Eric. "Identification of Physical Changes to a Steel Frame." DigitalCommons@CalPoly, 2010. https://digitalcommons.calpoly.edu/theses/246.
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The thesis utilized physical testing and computer modeling to determine the feasibility of identifying a change to the mass or stiffness of a steel frame. Physical testing was performed using an accelerometer, linear shaker, and arbitrary function generator. Two methods of laboratory testing were developed: ambient vibration testing (AVT) and forced vibration testing (FVT). AVT was able to preliminarily identify the natural frequencies and mode shapes of the frame. FVT was able to precisely identify four distinct natural frequencies, mode shapes, and damping ratios. The baseline frame then underwent two physical changes: the addition of mass to its roof, and the addition of braces along one of its sides. FVT was used again to determine the natural frequencies, mode shapes, and damping ratios of the newly changed structure.
An ETABS computer model was developed to represent the frame. This baseline model produced natural frequencies and mode shapes that closely matched the values determined by FVT. The mass and stiffness of this baseline model were then changed multiple times through the addition of mass and braces at various locations on the model. The frequencies and mode shapes were recorded for each change.
Two methods were developed to identify the changes to the steel frame. The first method was able to determine which one of the models best represented a single change to the structure (adding mass to its roof). The second method was able to determine the combination of models that best represented the two concurrent changes to the structure (adding mass to its roof and braces to its sides). Both methods utilized the percent differences of each altered computer model relative to the original, and each method satisfactorily identified its respective physical alteration.
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Elbadawy, Mohamed Mohamed Zeinelabdin Mohamed. "Dynamic Strain Measurement Based Damage Identification for Structural Health Monitoring." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/86167.
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Structural Health Monitoring (SHM) is a non-destructive evaluation tool that assesses the functionality of structural systems that are used in the civil, mechanical and aerospace engineering practices. A much desirable objective of a SHM system is to provide a continuous monitoring service at a minimal cost with ability to identify problems even in inaccessible structural components. In this dissertation, several such approaches that utilize the measured dynamic response of structural systems are presented to detect, locate, and quantify the damages that are likely to occur in structures. In this study, the structural damage is identified as a reduction in the stiffness characteristics of the structural elements. The primary focus of this study is on the utilization of measured dynamic strains for damage identification in the framed structures which are composed of interconnected beam elements. Although linear accelerations, being more convenient to measure, are commonly used in most SHM practices, herein the strains being more sensitive to elemental damage are considered. Two different approaches are investigated and proposed to identify the structural element stiffness properties. Both approaches are mode-based, requiring first the identification of system modes from the measured strain responses followed by the identification of the element stiffness coefficients. The first approach utilizes the Eigen equation of the finite element model of the structure, while the second approach utilizes the changes caused by the damage in the structural curvature flexibilities. To reduce size of the system which is primarily determined by the number of sensors deployed for the dynamic data collection, measurement sensitivity-based sensor selection criterion is observed to be effective and thus used. The mean square values of the measurements with respect to the stiffness coefficients of the structural elements are used as the effective measures of the measurement sensitivities at different sensor locations. Numerical simulations are used to evaluate the proposed identification approaches as well as to validate the sensitivity-based optimal sensor deployment approach.Ph. D.
All modern societies depend heavily on civil infrastructure systems such as transportation systems, power generation and transmission systems, and data communication systems for their day-to-day activities and survival. It has become extremely important that these systems are constantly watched and maintained to ensure their functionality. All these infrastructure systems utilize structural systems of different forms such as buildings, bridges, airplanes, data communication towers, etc. that carry the service and environmental loads that are imposed on them. These structural systems deteriorate over time because of natural material degradation. They can also get damaged due to excessive load demands and unknown construction deficiencies. It is necessary that condition of these structural systems is known at all times to maintain their functionality and to avoid sudden breakdowns and associated ensuing problems. This condition assessment of structural systems, now commonly known as structural health monitoring, is commonly done by visual onsite inspections manually performed at pre-decided time intervals such as on monthly and yearly basis. The length of this inspection time interval usually depends on the relative importance of the structure towards the functionality of the larger infrastructure system. This manual inspection can be highly time and resource consuming, and often ineffective in catching structural defects that are inaccessible and those that occur in between the scheduled inspection times and dates. However, the development of new sensors, new instrumentation techniques, and large data transfer and processing methods now make it possible to do this structural health monitoring on a continuous basis. The primary objective of this study is to utilize the measured dynamic or time varying strains on structural components such as beams, columns and other structural members to detect the location and level of a damage in one or more structural elements before they become serious. This detection can be done on a continuous basis by analyzing the available strain response data. This approach is expected to be especially helpful in alerting the owner of a structure by identifying the iv occurrence of a damage, if any, immediately after an unanticipated occurrence of a natural event such as a strong earthquake or a damaging wind storm.
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Sarvghad-Moghadam, Abdoreza. "Seismic torsional response of asymmetrical multi-storey frame buildings." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0003/NQ42874.pdf.
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Mutlu, Mehmet Basar. "Numerical Simulations Of Reinforced Concrete Frames Tested Using Pseudo-dynamic Method." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614460/index.pdf.
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Considering the deficiencies frequently observed in the existing reinforced concrete buildings, detailed assessment and rehabilitation must be conducted to avoid significant life and value loss in seismic zones. In this sense, performance based evaluation methods suggested in the regulations and codes must be examined and revised through experimental and analytical research to provide safe and economical rehabilitation solutions.
In this study, seismic behavior of three reinforced concrete frames built and tested in Middle East Technical University Structural Mechanics Laboratory is examined. The specimens are extracted from a typical interior frame of 3-story 3-bay reinforced concrete structure. One of the specimens has compliant design according to Turkish Earthquake Code (2007) and each of the other two specimens represents different types of deficiencies in terms of material strength and detailing. The test specimens were modeled using different modeling approaches and nonlinear dynamic analyses were conducted on the numerical models. Results of continuous pseudo-dynamic testing of three ground motions are presented and compared with the numerical simulations on models. Calibrated finite element models were used for evaluation of performance assessment procedure of Turkish Earthquake Code (2007) and further investigation on local deformation components in light of experimental findings and observations. Deformation sources of columns and joints were studied in terms of their interaction and contributions to the total drift. Estimated plastic hinge lengths of columns were compared with the experimental observations and the proposed expressions in the literature.
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Prinz, Gary S. "Effect of Beam Splicing on Seismic Response of Buckling-Restrained Braced Frames." Diss., CLICK HERE for online access, 2007. http://contentdm.lib.byu.edu/ETD/image/etd2126.pdf.
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Li, Quanwang. "Mathematical Formulation of Tools for Assessment of Fragility and Vulnerability of Damaged Buildings." Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/10529.
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Performance-Based (PBE) and Consequence-Based (CBE) are new approaches to seismic design, evaluation and risk assessment, in which design criteria are devised to achieve stated performance objectives, and regional losses to civil infrastructure are mitigated through selective interventions for critical components of a civil infrastructure. These new approaches give engineers more flexibility in achieving performance goals but require substantial additional computational resources to fully achieve performance goals. As a step toward making such approaches feasible, this dissertation develops a number of computationally efficient methods for performing finite element-based structural system dynamic response analysis and reliability assessment. The Enhanced Uncoupled Modal Response History Analysis (EUMRHA) procedure developed herein is an efficient response analysis procedure to make the analysis of dynamic structural response to earthquakes in the nonlinear range less time-consuming. This technique is used to investigate the potential for aftershocks to cause additional damage to steel moment frame buildings, utilizing a technique designed to enhance the efficiency of Monte Carlo simulation in estimating low-probability events. Relatively simple probabilistic tools are proposed for purposes of rapid structural evaluation and condition assessment of damaged buildings. Finally, an analysis-based inspection scheme based on an associated probability model of connection damage is proposed for assessing the safety condition of existing buildings, and a procedure to assess the likely performance of an un-repaired building during a future earthquake is developed.
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Li, Xiaohua. "Evaluation of Earthquake-Induced Local Damage in Steel Moment-Resisting Frames Using Wireless Piezoelectric Strain Sensing." 京都大学 (Kyoto University), 2015. http://hdl.handle.net/2433/202704.
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Vargas, Vinicius Athaydes de. "Efeitos da flexibilidade estrutural em simulações de dinâmica lateral de veículo de transporte de carga." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2011. http://hdl.handle.net/10183/34760.
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Este trabalho apresenta uma análise multicorpos de combinação veicular de carga com chassi de semirreboque flexível, para avaliação de dinâmica lateral. O contexto é dado por um breve panorama do transporte rodoviário de cargas no Brasil. No intuito de melhorar seus produtos, os fabricantes de implementos rodoviários têm utilizado metodologias de desenvolvimento baseadas em simulação virtual. Nessas circunstâncias, análises dinâmicas são realizadas, geralmente levando-se em conta a hipótese de corpos rígidos (não deformáveis). Subjetivamente, é sabido que a inclusão da flexibilidade em um modelo numérico o aproxima do fenômeno real, mas são raros os trabalhos que analisam quantitativamente essa diferença. Assim, neste estudo é proposta uma abordagem para consideração da flexibilidade estrutural do chassi de um semirreboque em simulações de tráfego. Procede-se a discretização do quadro do implemento em elementos finitos, para realização de análise de vibração livre, na qual são determinados os modos (autovetores) e as frequências naturais (autovalores) da estrutura. Utilizando metodologia de superposição modal, os modos de vibração são classificados para compor, por combinação linear, a flexibilidade da estrutura nas análises dinâmicas em ferramenta comercial de MBS (sistemas multicorpos). São realizadas, então, simulações de manobras representativas da dinâmica lateral de combinações veiculares, com ênfase à estabilidade em rolagem. Os efeitos globais da inserção de flexibilidade modal no chassi do semirreboque são avaliados por meio de métricas específicas, baseadas em normas ISO de dinâmica lateral para veículos pesados. Os resultados das simulações, apresentados em forma gráfica e tabelas, mostram a grande influência da flexibilidade estrutural do chassi no desempenho dinâmico da combinação veicular analisada. Grandezas relevantes como aceleração lateral (no domínio do tempo e da frequência), ângulo de rolagem e força atuante nos pneus, além de fenômenos físicos como a transferência lateral de carga em curvas, são fortemente afetados pela flexibilidade do quadro. Agrega-se ao trabalho desenvolvido uma forma simplificada de equacionar analiticamente a rolagem de um semirreboque flexível. É realizada também uma análise de sensibilidade da rigidez torcional do chassi quanto ao número de travessas.This work presents a lateral dynamics multibody analysis of a heavy articulated vehicle with a flexible frame for the semi-trailer. The context is given by a short perspective of the load carrying transportation scenery in Brazil. In order to build better products, the trailer manufacturers have been using development methodologies based on virtual simulation. In these circumstances, dynamic analyses are carried out, considering the hypothesis of rigid (non-deformable) bodies. Subjectively, it is known that the inclusion of flexibility in a numerical model brings it closer to reality, but very few studies work on giving numbers to this difference. Thus, this study presents an approach for taking into account the frame structural flexibility of a semi-trailer in traffic simulations. The frame of the semi-trailer is represented by a finite element model, and a free vibration analysis of this structure is carried out. The mode shapes (eigenvectors) and natural frequencies (eigenvalues) are determined. With a mode superposition method, the vibration modes are classified, for the purpose of building the structural flexibility (by linear combination) of the chassis in the dynamic analyses of the MBS software. Typical maneuvers of lateral dynamics are simulated, testing the roll stability of the combined vehicle model. The global effects for considering the mode flexibility in the semitrailer frame are evaluated through specific metrics, based on ISO standards for heavy vehicles lateral dynamics. The strong influence of the frame structural flexibility, when analyzing the articulated vehicle transient behavior, is showed by simulation results, which are presented in graphics and tables. Important measurements, such as lateral acceleration (in time and frequency domains), roll angle and vertical force on tires, besides physical phenomenon like lateral load transfer, are significantly modified by the flexibility of the frame. A simplified approach for writing the analytical equations of the flexible semi-trailer roll dynamics is added to the study. A torsional stiffness sensitivity analysis is also performed, regarding the number of transversal members in the semi-trailer chassis.
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Izzuddin, Bassam Afif. "Nonlinear dynamic analysis of framed structures." Thesis, Imperial College London, 1990. http://hdl.handle.net/10044/1/8080.
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VIANA, EDUARDO ARREGUY. "STRUCTURE-SOIL INTERACTION BY FRAME STRUCTURES UNDER DYNAMIC LOADS DUE TO RECIPROCATING COMPRESSORS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2012. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=21832@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCompressores de gás de grande porte são componentes fundamentais em plantas industriais de refino de petróleo, atuando principalmente como agentes fornecedores de energia mecânica aos processos químicos. Dentre os tipos de compressores, destacam-se os alternativos. Devido a exigências de processo químico e arranjo industrial, é comum a instalação desses equipamentos em estruturas aporticadas, fato que, associado às características do movimento de suas partes mecânicas, não raramente as cargas dinâmicas geradas provocam vibrações inadmissíveis. Neste trabalho é avaliado o comportamento dinâmico de um sistema formado por uma estrutura aporticada, por compressor alternativo, pela fundação em estacas e finalmente pelo próprio solo. O estudo paramétrico realizado se desenvolve a partir de uma análise de modelos simplificados massa-mola, de um modelo em elementos finitos e de medições de campo visando a estabelecer intervalos de valores dos parâmetros do solo local dentro dos quais se identifique as características da resposta dinâmica do sistema. São avaliados os parâmetros coeficiente de mola (km) e a constante do coeficiente de reação horizontal (nh) do solo natural típico da área abrangida pela refinaria REPAR, localizada no município de Araucária, no estado do Paraná, solo esse pertencente à formação geológica denominada Guabirotuba. A avaliação do comportamento dinâmico do sistema através dos modelos desenvolvidos é balizada por valores de medição na estrutura real de velocidades de vibração efetivas, obtidas por instrumentação. Os parâmetros do solo são obtidos por retroanálise de resultados de ensaio de campo, utilizando-se dois modelos amplamente utilizados nos escritórios de projeto: modelo proposto por Miche (1932) e modelo proposto por Hetenyi (1946). O primeiro considera que os parâmetros do solo variam com a profundidade, e o segundo os considera constante com a profundidade. Busca-se avaliar também a influência de parâmetros do solo obtidos através de ensaios de carregamento estático (ABNT NBR 12131, 2006) e obtidos através de ensaios de carregamento estático cíclico, este último se propondo a simular o efeito dinâmico sobre o solo. Finalmente, compara-se os resultados fornecidos pelos modelos simplificados e pelo modelo em elementos finitos em termos das freqüências naturais de vibração.
Gas compressors are key components of industrial plants in oil refining, mainly acting as mechanical energy suppliers to chemical processes. Among the types of compressors, the reciprocating ones is highlighted. Due to mandatory demands of chemical process and industrial arrangement, it is common to install such equipment in framed structures. This condition and the typical movement of mechanical parts of the compressors generate dynamic loads which frequently causes unacceptable vibrations. The aim of the present work is to evaluate the dynamic behavior of a system consisting of a framed structure, a reciprocating compressor, foundation in piles and the soil itself. For this purpose, parametric study is developed from simplified spring-mass models, a finite element model and field measurements. The parametric study is aimed at establish ranges of local soil parameters within which the dynamic behavior of a system can be understood and measured. The parameters so-called spring stiffness (km) and the constant coefficient of horizontal reaction (nh) of natural soil which typically occurs in the area covered by the REPAR refinery, located in Araucaria, Paraná, are then evaluated. This type of natural soils belongs to the geological formation called Guabirotuba. The evaluation of the dynamic behavior of the system through the developed models is benchmarked by field measurements of effective velocity of vibration in the actual structure, obtained by instrumentation. The soil parameters are obtained by back analysis of tests results by using two models widely used in design offices: model proposed by Miche (1932) and model proposed by Hetenyi (1946). The first one takes in account the variation of the soil parameters with depth, and the second one considers soil parameters constant with depth. The aim is also to evaluate the influence of the soil parameters obtained by static and cyclic horizontal loading tests, the latter being proposed to simulate the dynamic effect on the soil. Finally, it is done comparisons of the results provided by simplified models and the finite element model in terms of natural frequencies of vibration.
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Foliente, Greg C. "Stochastic dynamic response of wood structural systems." Diss., This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-05042006-164535/.
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Figueroa, Michael. "Dynamic Analysis of a Light Wood-Framed Structure during Fire Conditions." Digital WPI, 2016. https://digitalcommons.wpi.edu/etd-theses/777.
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The purpose of this project is to create a theoretical dynamic analysis model to assess the dynamic response of light, wood-framed structures before and after fire conditions. This information is useful for predicting the damage to structural integrity due to a fire. The mass and stiffness matrices used for the dynamic model are derived from a standard residential building created for an existing project at WPI funded through the DHS/FEMA/USFA Assistance to Firefighters Grant program. The damping matrix is derived via the Rayleigh Damping Method using the mass and stiffness matrices obtained through SAP. Then, theoretical impact forces are applied to the developed dynamic model, and the acceleration response is estimated using Matlab. Both acceleration time history and frequency responses are used as the evaluation method. Finally, the dynamic model is integrated with a fire simulation model to investigate the impact of fire conditions on dynamic responses of residential buildings. The results show that frequencies can shift due to the structural degradation due to fire.
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Susila, Gede Adi. "Experimental and numerical studies of masonry wall panels and timber frames of low-rise structures under seismic loadings in Indonesia." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/experimental-and-numerical-studies-of-masonry-wall-panels-and-timber-frames-of-lowrise-structures-under-seismic-loadings-in-indonesia(3ceb094b-4e6e-432a-b3de-3d4c306b0551).html.
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Indonesia is a developing country that suffers from earthquakes and windstorms and where at least 60% of houses are non-engineered structures, built by unskilled workers using masonry and timber. The non-engineered housing units developed in urban region are also vulnerable to seismic hazard due to the use of low quality of material and constructions method. Those structures are not resistant to extreme lateral loads or ground movement and their failure during an earthquake or storm can lead to significant loss of life. This thesis is concerned with the structural performance of Indonesian low-rise buildings made of masonry and timber under lateral seismic load. The research presented includes a survey of forms of building structure and experimental, analytical and numerical work to predict the behaviour of masonry wall and traditional timber frame buildings. Experimental testing of both masonry and timber have been carried out in Indonesia to establish the quality of materials and to provide material properties for numerical simulations. The experimental study found that the strength of Indonesia-Bali clay brick masonry are below the minimum standard required for masonry structures built in seismic regions, being at least 50% lower than the requirement specified in British Standard and Eurocode-6 (BS EN 1996-1-1:2005). In contrast, Indonesian timber materials meet the strength classes specified in British Standard/Eurocode- 5 (BS EN 338:2009) in the range of strength grade D35-40 and C35).Structural tests under monotonic and cyclic loading have been conducted on building components in Indonesia, to determine the load-displacement capacity of local hand-made masonry wall panels and timber frames in order to: (1) evaluate the performance of masonry and timber frame structure, (2) investigate the dynamic behaviour of both structures, (3) observe the effect of in-plane stiffness and ductility level, and (4) examine the anchoring joint at the base of timber frame that resists the overturning moment. From these tests, the structural ductility was found to be less than two which is below the requirement of the relevant guidelines from the Federal Emergency Management Agency, USA (FEMA-306). It was also observed that the lateral stiffness of masonry wall is much higher than the equivalent timber frame of the same height and length. The experimental value of stiffness of the masonry wall panel was found to be one-twelfth of the recommended values given in FEMA-356 and the Canadian Building code. The masonry wall provides relatively low displacement compared to the large displacement of the timber frame at the full capacity level of lateral load, with structural framing members of the latter remaining intact. The weak point of the timber frame is the mechanical joint and the capacity of slip joint governs the lateral load capacity of the whole frame. Detailed numerical models of the experimental specimens were setup in Abaqus using three-dimensional solid elements. Cohesive elements were used to simulate the mortar behaviour, exhibiting cracking and the associated physical separation of the elements. Appropriate contact definitions were used where relevant, especially for the timber frame joints. A range of available material plasticity models were reviewed: Drucker-Prager, Crystalline Plasticity, and Cohesive Damage model. It was found that the combination of Crystalline Plasticity model for the brick unit and timber, and the Cohesive Damage model for the mortar is capable of simulating the experimental load-displacement behaviour fairly accurately. The validated numerical models have been used to (1) predict the lateral load capacity, (2) determine the cracking load and patterns, (3) carry out a detailed parametric study by changing the geometric and material properties different to the experimental specimens. The numerical models were used to assess different strengthening measures such as using bamboo as reinforcement in the masonry walls for a complete single storey, and a two-storey houses including openings for doors and windows. The traditional footing of the timber structures was analysed using Abaqus and was found to be an excellent base isolation system which partly explains the survival of those structures in the past earthquakes. The experimental and numerical results have finally been used to develop a design guideline for new construction as well as recommendations for retrofitting of existing structures for improved performance under seismic lateral load.
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Dai, Li. "Design and structural analysis of sofa frames." Diss., Mississippi State : Mississippi State University, 2007. http://library.msstate.edu/etd/show.asp?etd=etd-10262007-100150.
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Liu, Di. "VIBRATION OF STEEL-FRAMED FLOORS SUPPORTING SENSITIVE EQUIPMENT IN HOSPITALS, RESEARCH FACILITIES, AND MANUFACTURING FACILITIES." UKnowledge, 2015. http://uknowledge.uky.edu/ce_etds/34.
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Floors have traditionally been designed only for strength and deflection serviceability. As technological advances have been made in medical, scientific and micro-electronics manufacturing, many types of equipment have become sensitive to vibration of the supporting floor. Thus, vibration serviceability has become a routinely evaluated limit state for floors supporting sensitive equipment. Equipment vibration tolerance limits are sometimes expressed as waveform peak acceleration, and are more often expressed as narrowband spectral acceleration, or one-third octave spectral velocity.
Current floor vibration prediction methods, such as those found in the American Institute of Steel Construction Design Guide 11, Floor Vibrations Due to Human Activity, the British Steel Construction Institute P354, Design of Floors for Vibration: a New Approach and the British Concrete Centre CCIP-016 A Design Guide for Footfall Induced Vibration of Structures, have limitations. It has been observed that non-structural components such as light-weight partitions could significantly change floor dynamic properties. Current prediction methods do not provide a fundamental frequency manual prediction method nor finite element modeling guidance for floors with non-structural components. Current prediction methods only predict waveform peak acceleration and do not provide predictions for frequency domain response including narrowband spectral acceleration or one-third octave spectral velocity. Also, current methods are not calibrated to provide a specific level of conservatism.
This research project provides (1) a fundamental frequency manual prediction method for floors with lightweight partitions; (2) an improved finite element modeling procedure for floors with light-weight partitions; (3) a procedure to predict the vibration response in narrow-band spectrum and one-third octave band spectrum which can be directly compared with vibration tolerance limits; and (4) a simplified experimental procedure to estimate the floor natural frequencies.
An experimental program including four steel-framed building floors and a concrete was completed. Modal tests were performed on two of the steel-framed buildings and the concrete building using an electrodynamic shaker. Experimental modal analysis techniques were used to estimate the modal properties: natural frequencies, mode shapes, and damping ratios. Responses to walking excitation were measured several times in each tested bay for individuals walking at different walking speeds. During each test, the walker crossed the middle of the bay using a metronome to help maintain the intended cadence.
The proposed method was used to predict the modal properties and responses to walking. The measurements are used to assess the precision of the proposed methods and to calibrate the prediction methods to provide a specific probability that the actual response will exceed the predicted response. Comparison of measurements and predictions shows the proposed methods are sufficiently accurate for design usage.
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Wang, Yanchun. "Simplified methods for determining dynamic characteristics of tall wall-frame buildings." Thesis, University of Hertfordshire, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.323652.
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Mohamed, Salah-Eldin A. "Elastic-plastic instability of plane frames." Diss., Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/12092.
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Rudman, Chantal. "Investigation into the structural behaviour of portal frames." Thesis, Stellenbosch : University of Stellenbosch, 2009. http://hdl.handle.net/10019.1/1853.
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Malhotra, Gaurav. "Dynamics of structural priming." Thesis, University of Edinburgh, 2009. http://hdl.handle.net/1842/2751.
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This thesis is about how our syntactic choice changes with linguistic experience. Studies on syntactic priming show that our decisions are influenced by sentences that we have recently heard or recently spoken. They also show that not all sentences have an equal amount of influence; that repetition of verbs increases priming (the lexical-boost effect) and that some verbs are more susceptible to priming than others. This thesis explores how and why syntactic decisions change with time and what these observations tell us about the cognitive mechanism of speaking. Specifically, we set out to develop a theoretical account of syntactic priming. Theoretical accounts require mathematical models and this thesis develops a sequence of mathematical models for understanding various aspects of syntactic priming. Cognitive processes are modelled as dynamical systems that can change their behaviour when they process information. We use these dynamical systems to investigate how each episode of language comprehension or production affects syntactic decisions. We also use these systems to investigate how long priming persists, how groups of consecutive sentences affect structural decisions, why repeating words leads to greater syntactic priming and what this tells us about how words, concepts and syntax are cognitively represented. We obtain two kinds of results by simulating these mathematical models. The first kind of results reveal how syntactic priming evolves over time. We find that structural priming itself shows a gradual decay with time but the lexical enhancement of priming decays catastrophically – a result consistent with experimental observations. We also find that consecutive episodes of language processing add up nonlinearly in memory, which challenges the design of some existing psycholinguistic experiments. The second kind of results reveal how our syntax module might be connected to other cognitive modules. We find that the lexical enhancement of syntactic priming might be a consequence of how the modules of attention and working memory influence syntactic decisions. These models suggest a mechanism of priming that is in contrast to a previous prediction-based account. This prediction-based account proposes that we actively predict what we hear and structural priming is due to error-correction whenever our predictions do not match the stimuli. In contrast, our account embodies syntactic priming in cognitive processes of attention, working memory and long-term memory. It asserts that our linguistic decisions are not based solely on abstract rules but also depend on the cognitive implementation of each module. Our investigations also contribute a novel theoretical framework for studying syntactic priming. Previous studies analyse priming using error-correction or Hebbian learning algorithms. We introduce the formalism of dynamical systems. This formalism allows us to trace the effect of information processing through time. It explains how residual activation from a previous episode might play a role in structural decisions, thereby enriching our understanding of syntactic priming. Since these dynamical systems are also used to model neural processes, this theoretical framework brings our understanding of priming one step closer to its biological implementation, bridging the gap between neural processes and abstract thoughts.
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Sawan, Hassan Tayseer. "NONLINEAR STABILITY OF PORTAL FRAMES WITH ELASTIC END RESTRAINTS." Thesis, The University of Arizona, 1985. http://hdl.handle.net/10150/275410.
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羅征桂 and Ching-quei Lo. "Study of multibay and multistorey infilled frames." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1988. http://hub.hku.hk/bib/B31231640.
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Lo, Ching-quei. "Study of multibay and multistorey infilled frames /." [Hong Kong] : University of Hong Kong, 1988. http://sunzi.lib.hku.hk/hkuto/record.jsp?B12428620.
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Zhou, Qing. "Combined linear/nonlinear stability analysis of plane and space frames." Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-07112009-040327/.
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Hoang, Ha. "Structural Continuity Effects in Steel Frames under Fire Conditions." Digital WPI, 2010. https://digitalcommons.wpi.edu/etd-theses/420.
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Fire has always been one of the most serious threats of collapse to structural building frames. The September 11 incident has stimulated significant interests in analyzing and understanding the behavior of the structures under fire events. The strength of the material decreases due to the elevated temperature caused by fire, and this reduction in strength leads to the failure of the member. Frames that do not have sufficient ductility can suffer progressive collapse of the entire structure if one member fails during a fire event. Such collapse could result in loss of human life and serious economic consequences. The motivation for this thesis is to provide an understanding of the continuity effects in steel frames under fire conditions. The continuity effects of the structure can provide additional strength to the system to sustain the loads under fire event. Different scenarios of the frame and beam structures which include changes to member sizes, fire locations, and bay size, are investigated with the assistance of SAP2000 and ANSYS. These programs can provide the collapse analysis for each scenario at different temperature. The continuity effect was investigated from the strength point of view of the structure. Ultimately, the thesis presents a design tool for aiding member design under fire conditions. The design tool consists of different graphs that maybe use to determine the collapse load capacity of a continuous structure at elevated temperature based on the analysis of a simpler, determinate structure.
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Painter, Christopher D. (Christopher Donald) 1972. "System variation analysis of MIG welded aluminum structural frames." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/9596.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1998.Includes bibliographical references (leaves 73-75).
Variation reduction techniques are developed which explore an entire system for improved quality, rather than a single manufacturing operation. This system-level modeling approach is explored with an example of a complex assembly of aluminum extrusions and castings welded into a structural frame. By making use of modeling techniques such as Finite Element Analysis (FEA) and Design of Experiments (DOE), it can be shown how this method can also be applied to systems that include complex processes such as welding. Modeling the entire system of manufacturing operations allows key sources of variation and difficult output quality characteristics to be identified. In addition, intermediate tolerances can be determined in relation to the final required output tolerances. Determining intermediate tolerances is a two step process. First, a system of block diagrams are created to clearly outline ho-v1· variation propagates forward through the system. These block diagram representations are linearized models that map the transformations between the input variations and the output variations of a particular manufacturing operation. Secondly, using the combined transformation matrix of the system, intermediate tolerances, at a particular manufacturing operation can be determined by back-propagating final output tolerances. This provides a means by which design tolerances on the final product can be used in determining the allowable tolerances on Work-In-Progress (WIP) at intermediate manufacturing processes.
by Christopher D. Painter.
S.M.
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Hafeez, Ghazanfarah. "Dynamic Characteristics of Light-frame Wood Buildings." Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/36223.
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This research project deals with dynamic field testing of light-frame wood buildings with wood based shear walls. The primary objective of the investigation is to evaluate the code formula for estimating light wood frame building’s fundamental period, through intensive field testing and numerical modelling. The project also aims to propose an alternative simplified rational approach where applicable. The thesis provides insight to the ambient vibration testing procedures of light-frame wood buildings and explains the protocol adopted for the current research program.
Ambient vibration (AV) field tests were conducted on several multi-storey wood and beam-and-post buildings in Canada. Modal parameters of measured buildings, such as natural frequency, mode shapes and equivalent structural damping were obtained from Frequency Domain (FD) analysis of ambient motion records.
Experimental and numerical investigations were performed to evaluate the effect of non-structural components, and the connectivity between firewall-separated buildings, on dynamic properties of light-frame wood buildings. The study provides a reliable expression for building period estimate based on field testing and numerical modeling.
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Edwards, William. "Structural Dynamics in Novel Electrolytes." Thesis, University of Kent, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.499827.
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Balmés, Etienne. "Modelling structural dynamics for control." Thesis, Massachusetts Institute of Technology, 1991. http://hdl.handle.net/1721.1/42519.
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Yoo, Jung Han. "Analytical investigation on the seismic performance of special concentrically braced frames /." Thesis, Connect to this title online; UW restricted, 2006. http://hdl.handle.net/1773/10115.
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Bourahla, Nouredine. "Knee bracing system for earthquake resisting steel frames." Thesis, University of Bristol, 1990. http://hdl.handle.net/1983/d4ba97ab-0a65-4469-8a69-776a009514d9.
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Creamer, Nelson Glenn. "Identification of linear structural models." Diss., Virginia Polytechnic Institute and State University, 1987. http://hdl.handle.net/10919/53631.
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With a great amount of research currently being aimed towards dynamic analysis and control of very large, flexible structures, the need for accurate knowledge of the properties of a structure in terms of the mass, damping, and stiffness matrices is of extreme importance. Typical problems associated with existing structural model identification methods are: (i) non-unique solutions may be obtained when utilizing only free-response measurements (unless some parameters are fixed at their nominal values), (ii) convergence may be difficult to achieve if the initial estimate of the parameters is not "close" to the truth, (iii) physically unrealistic coupling in the system matrices may occur as a consequence of the identification process, (iv) large, highly redundant parameter sets may be required to characterize the system, and (v) large measurement sets may be required. To overcome these problems, a novel identification technique is developed in this dissertation to determine the mass, damping, and stiffness matrices of an undamped, lightly damped, or significantly damped structure from a small set of measurements of both free-response data (natural frequencies, damping factors) and forced-response data (frequency response functions).
The identification method is first developed for undamped structures. Through use of the spectral decomposition of the frequency response matrix and the orthogonality properties of the mode shapes, a unique identification of the mass and stiffness matrices is obtained. The method is also shown to be easily incorporated into a substructure synthesis package for identifying high-order systems. The method is then extended to include viscous damped structures. A matrix perturbation approach is developed for lightly damped structures, in which the mass and stiffness matrices are identified using the imaginary components of the measured eigenvalues and, as a post-processor, the damping matrix is obtained from the real components of the measured eigenvalues. For significantly damped structures, the mass, dauping, and stiffness matrices are identified simultaneously.
A simple, practical method is also developed for identification of the time-varying relaxation modulus associated with a viscoelastic structure. By assuming time-localized elastic behavior, the relaxation modulus is determined from a series of identification tests performed at various times throughout the response history.
Many interesting examples are presented throughout the dissertation to illustrate the applicability and potential of the identification method. It is observed from the numerical results that the uniquely identified structure agrees with simulated measurements of both free and forced·response records.Ph. D.
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Kaveh, Mohammad. "Topological optimization of rigidly jointed space frames." Thesis, Cardiff University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.238227.
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van, Beerschoten Wouter Adrian. "Structural Performance of Post-tensioned Timber Frames under Gravity Loading." Thesis, University of Canterbury. Department of Civil and Natural Resources engineering, 2013. http://hdl.handle.net/10092/8735.
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A new structural system for multi-storey timber buildings has been developed over the last seven years at the University of Canterbury. The system incorporates large timber structural frames, whereby semi-rigid beam-column connections are created using post-tensioning steel tendons. This system can create large open floor plans required for office and commercial buildings.
Several material properties of the engineered timber used were determined based on small-scale experimental testing. Full-scale testing of beams, connections and frames resulted in a more comprehensive understanding of the behaviour of such systems. Numerical, analytical and framework models also led to the development of design equations and procedures which were validated with the acquired experimental data.