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A new modular steel floor system, named FastFloor, is proposed for commercial buildings. The system is conceptualized to be prefabricated at the shop and ready to be installed on a previously erected skeleton frame structure consisting of girders and columns or connected to core shear walls. The system configuration aims to increase the speed of design, fabrication, and erection of a steel project by eliminating concrete pouring and curing times. Other advantages include reducing the weight of the building and its carbon footprint. Several module configurations were considered and evaluated based on a series of interviews with experts in steel fabrication and erection engineering. The selection relied not only on addressing the issues related to fabrication, transportation, and erection but also on satisfying floor vibrations, as it was determined to be the governing limit state of the plate thickness, section sizes, and beam spacing due to the presence of an unstiffened bare plate acting as a slab. Observations were performed regarding fabrication sequence and transportation on the chosen configuration. The dynamic properties of the module are particularly important because DG11 was developed for composite concrete-steel floor systems, and its applicability to all steel-floor systems needs to be evaluated. In parallel, a vibration testing program was conducted to determine the dynamic properties of the module, including natural frequencies and mode shapes. Lastly, the acceptability of the modular system for floor vibrations was evaluated by both a calculation method and a modeling approach. The analysis results suggest that the module will not satisfy floor vibrations criteria, but a modified module with added stiffeners is shown to be acceptable. Upcoming tests, by others, on specimens with a raised access floor will be necessary to refine the predictions and determine if the stiffeners are actually required. / Master of Science / FastFloor is an innovative modular all-steel floor system that aims to revolutionize the construction of commercial buildings, with benefits including enhanced efficiency in design, fabrication, and erection, as well as reduced environmental impact, by eliminating the need for concrete pouring and curing and full prefabrication in shops. Several module configurations were evaluated based on insights from industry experts in steel fabrication and erection engineering. It was observed that the main challenge in the early phases was to address issues related to fabrication, transportation, and erection while ensuring optimal performance in terms of floor vibrations. This thesis project focused on a preliminary assessment of the vibration behavior of the system by conducting dynamic tests and evaluating the compatibility with the analytical and computational procedures in Design Guide 11, which is not calibrated for an all-steel system like FastFloor. Based on the results, it was concluded that the initial configuration did not fully satisfy the floor vibrations criteria. However, through further computational evaluation, a modified module, based on the initial configuration with added stiffeners, was predicted to be satisfactory. Thus, future research will continue to refine the system behavior and predictions and evaluate the contributions of Raised Access Floor to the vibration performance.

This thesis is comprised of two studies. The objective of the first study was to find the frequency response and stiffness of the biceps brachii muscle group during recovery from exercise induced damage and to determine whether these data could be used to track muscle recovery by correlating changes in the frequency response with changes in muscle stiffness. Stiffness moduli were collected using Shear Wave Elastography (SWE) which were then applied to a proportional first mode frequency analysis. Data were collected for the muscle stiffness and frequency response for fifteen subjects (25.6 +- 4.5). By comparing the proportion of the square root of the SWE results, the variation in stiffness showed a less than 2 Hz change in first mode resonance for the control group. Frequency response results for the control group agreed with the modified SWE results and the proportion analysis. SWE results for the damage protocol group showed an average increase of 4 Hz. Frequency response results for the damage protocol group were sorted into three categories: three subjects had a change in frequency of peaks of at least 4 Hz in the positive direction; four subjects had an increase in amplitude, but no change in frequency of peaks; three subjects showed mixed responses like fewer resonance peaks, variable amplitudes, changes in peak bandwidth. This research allowed for the documentation of the in-vivo frequency response of the biceps brachii muscle. We believe that the frequency response of a muscle group may be used in the future to evaluate recovery from exercise induced damage. Lessons learned were also recorded for helping future studies in their efforts using an SLDV with human body testing.The second study focused on finding the effects on the surface velocity of tissue above and below a region of the lower leg wrapped in an elastic band when excited by an external source. Ten male subjects between the ages of 18-25 were seated in a chair with one foot placed on a vibrating platform. Two excitation frequencies were separately applied while three points along the leg were measured. A repeatability analysis, using results without the leg wrap, showed a 6.5%, 2.5%, and 10.5% variance in the x-, y-, and z-directions respectively, applying a 20 Hz frequency. With a 40 Hz frequency, the variations were 24%, 23.8%, and 28.4% respectively. A change in displacement of +38% and +10% occurred above the knee in the x-direction with 40 Hz and in the y-direction with 20 Hz, respectively. A change in displacement of -20% occurred below the knee in the x-direction with 20 Hz. A change in displacement of -24% occurred below the wrap location in the y-direction with 40Hz. With a confidence interval of 93%, surface velocity of the tissue located above the wrap increased, while the surface velocity of the tissue below the wrap decreased.

No description available.

No description available.

The typical construction of a stator coil includes the use of end corona protection (ECP)coating, which is made of semi-conductive materials like silicon carbide (SiC). Thepurpose of ECP is to smooth the electric stress distribution near the slot exit, limitingthe electric field and partial discharge (PD) activity within the insulation system. Thisthesis investigates how ECP affects the dielectric response of a stator coil in highvoltagemeasurements, both in the time-domain and frequency-domain. It also studieshow well time-domain results transformed to the frequency-domain correspond to directmeasurements. As a further point, the effect of the ECP on PD activity was demonstrated.Measurements of dielectric response and PD were made on new coil-halves producedin the usual way in a production run for a motor. The results show that applying theECP design significantly reduces the PD activity and increases the inception voltage. Inaddition, the dielectric response of the coil with ECP tape has shown to have a nonlinearvoltage dependent characteristic due to the presence of ECP. As the voltage goes higher,this causes a shift of the loss peak toward higher frequency. A distributed-element modelof the end section of a stator coil was used to model the nonlinear effect due to ECP, andits results are compared to the measured results. Lastly, FEM simulation of a stator coilend section is presented, showing the contribution of ECP tape in evenly distributing theelectric stress near the slot exit. / Den typiska konstruktionen av en statorhärva använder ändglimmskydd (ECP), somär tillverkad av halvledande material som kiselkarbid (SiC). Syftet med ECP är attjämna ut det elektriska fältet vidövergången från spåret tilländlindningen, för attundvika högpåkänning och partiell urladdningsaktivitet (PD). Arbetet som presenteras här undersöker hur ECP påverkar den dielektriska responsen hos en statorspole, vid tidsdomänoch frekvensdomänmätningar vid höga spänningar. Den studerar också hur väl tidsdomänresultat som omvandlas till frekvensdomänen motsvarar direkta mätningar. Som en annan punkt visades ECP:s inverkan på PD-aktivitet. Mätningar av dielektrisk respons och PD gjordes på nya statorhärvor som tillverkades för en stor motor. Resultaten visar att tillämpningen av ECP-konstruktionen avsevärt minskar PD-aktiviteten och ökar inceptionsspänningen. Dessutom har spolens dielektriska respons med ECP-tejp visat sig ha en ickelinjär spänningsberoende egenskap på grund av närvaron av ECP. Ö kad spänning orsakar en förskjutning av förlusttoppen mot högre frekvens. En modell för ECP användeseteendet, och dess resultat jämförs med mätningarna.utligen presenteras FEM-simulering som visar hur ECP gör fältet jämnare.

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.

published_or_final_version / Electrical and Electronic Engineering / Doctoral / Doctor of Philosophy

In this thesis, partial discharge (PD) phenomenon in oil-impregnated paper (OIP) is investigated under accelerated electrical stress. The thesis is mainly focused on the characteristic of PD activity and the influence it has on the insulation properties of OIP. PD source was created by introducing an air filled cavity embedded between layers of OIP. PD activity is investigated from the initiation up to final puncture breakdown of the OIP. The time-evolution of number, maximum magnitude and average magnitude of PD is investigated for cavities with different diameter and height. It was found that time to breakdown is shorter if the cavity diameter is larger and cavities with higher depth produce larger PDs. Comparison between PD activity in three cases, i.e. unaged OIP, thermally aged OIP and OIP samples with higher moisture content is performed. In general, it is found that for all cases the number and the maximum magnitude of PD follows a similar trend versus ageing time. During the very beginning of the experiment large discharges occur and they disappear after a short ageing time. Number and maximum magnitude of PD increase with time until reaching a peak value. Finally both parameters decrease with time and puncture breakdown occurs in the sample. Even though PD activity in thermally aged OIP is higher compared to the unaged OIP samples, the time to breakdown for new and thermally aged OIP samples is similar while it is shorter for OIP samples with higher moisture content. In this thesis, partial discharge (PD) phenomenon in oil-impregnated paper (OIP) is investigated under accelerated electrical stress. The thesis is mainly focused on the characteristic of PD activity and the influence it has on the insulation properties of OIP. PD source was created by introducing an air filled cavity embedded between layers of OIP. PD activity is investigated from the initiation up to final puncture breakdown of the OIP. The time-evolution of number, maximum magnitude and average magnitude of PD is investigated for cavities with different diameter and height. It was found that time to breakdown is shorter if the cavity diameter is larger and cavities with higher depth produce larger PDs. Comparison between PD activity in three cases, i.e. unaged OIP, thermally aged OIP and OIP samples with higher moisture content is performed. In general, it is found that for all cases the number and the maximum magnitude of PD follows a similar trend versus ageing time. During the very beginning of the experiment large discharges occur and they disappear after a short ageing time. Number and maximum magnitude of PD increase with time until reaching a peak value. Finally both parameters decrease with time and puncture breakdown occurs in the sample. Even though PD activity in thermally aged OIP is higher compared to the unaged OIP samples, the time to breakdown for new and thermally aged OIP samples is similar while it is shorter for OIP samples with higher moisture content. Breakdown strength of OIP samples is measured before and after ageing with PDs. It is found that the breakdown strength of OIP samples decreases by around 40% after the sample is exposed to accelerated electrical ageing. Furthermore a thermal model was developed to investigate the possible transition of breakdown mechanism from erosion to thermal breakdown in OIP dielectrics. It was found that PD activity can lower the thermal breakdown voltage of OIP up to four times. / <p>QC 20150206</p>

Esta dissertação tem como objetivo principal o estudo das técnicas de cancelamento de massa, bem como suas aplicações em análise modal experimental. Estas técnicas são utilizadas na redução de determinados erros nos dados de resposta em frequência da estrutura sob estudo. Estes erros são por sua vez causados por fontes adicionais de inércia, tais como acelerômetros e transdutores de força, que são frequentemente utilizados nos ensaios para o levantamento das características dinâmicas da estrutura. As técnicas de cancelamento de massa estudadas neste trabalho são desenvolvidas a partir de uma modelagem das relações de entrada e saída no domínio da frequência, utilizando-se para tanto as Funções de Resposta em Frequência (FRF), bem como conceitos de subestruturação. Os modelos analíticos utilizados no problema de cancelamento de massa são também aplicados na geração de FRFs desconhecidas para a estrutura sob estudo, a partir de um subconjunto de FRFs medidas com massas adicionais acopladas à estrutura. Os métodos estudados são aplicados a dados obtidos através de simulações numéricas em sistemas discretos, bem como a dados experimentais provenientes de ensaios em estruturas simples. Resultados satisfatórios foram obtidos tanto a partir das simulações numéricas quanto na análise experimental para o problema de cancelamento de massa. Na obtenção de FRFs desconhecidas, verificou-se que os modelos teóricos conduzem a resultados satisfatórios em determinadas situações, e que o ruído encontrado em dados experimentais representa um fator detrimental na utilização das técnicas de cancelamento de massa para o propósito de gerar-se FRF desconhecidas a partir de FRF efetivamente medidas na estrutura sob estudo. / The goal of this dissertation is to develop a study on mass cancellation techniques and their applications in experimental modal analysis. These techniques are commonly employed in the reduction of experimental errors on the structure\'s measured frequency response data. Such errors are in turn caused by extra masses such as accelerometer and force transducers, that are utilized on the measurement of the system\'s Frequency Response Functions (FRF). The mass cancellation techniques studied here are developed through frequency domain input and output relationships as well as substructuring concepts. The analytical models employed in the mass cancellation problem are also applied in obtaining unknown FRF from a subset of measured FRF that are measured with extra masses attached to the structure. The methods studied are applied to numerically simulated data from discrete systems, as well as to experimental data coming from modal tests performed on simple structures. Reasonably good results are obtained in either the numerical and experimental analysis for the mass cancellation problem. In obtaining unknown FRF data, it was verified that the models generated reasonable results in some circumstances, and that experimental noise is a major source of error in using these mass cancellation techniques for the purpose of obtaining unmeasured data from a subset of measured FRF.