The scope of this study is divided into three topics. To begin, more accurate methods for estimating the fundamental natural frequencies of floors were explored. Improvements for predicting the behavior of floor systems using several criteria were also investigated. The final topic compared the AISC and SCI methods for analyzing vibrations acceptability. Natural frequency prediction was studied by examining 103 case studies involving floor systems of various framing occupied or being constructed in the United States and Europe. Based on the results from these comparisons, it was reasonably concluded that the predicted bay frequency using Dunkerly's estimate (fn2) is not the most accurate method for predicting the system frequency using the AISC Design Guide for all types of framing analyzed. The predicted beam frequency using AISC methods provided sound correlations with the measured bay frequencies. On the other hand, with the exception of floor systems with joist girders and joists, the results showed that the SCI methods provided more accurate predictions of bay frequency despite a fair amount of data scatter. Evaluations based on the AISC Design Guide 11, the SCI criteria Murray Criterion, and Modified Reiher-Meister scale were compared with subjective field analyses for each case study in the second part of this study. The AISC Design Guide criterion is the most consistent method for predicting floor behavior. The SCI criterion is the next most consistent method for floor acceptability, followed by the Murray Criterion then the Modified Reiher-Meister scale. In the final part of this study, predicted accelerations and floor behavior tolerability for 78 case studies were evaluated using the AISC and the SCI criteria. The two prediction methods are in agreement for 82 % (64 of 78) of the case studies, and strongly disagree for only 12 % (9 of 78) of the case studies. / Master of Science

The research presented herein is an analysis of acceleration measurements of the head during helmet-helmet impacts, where a player's helmet impacts another player's helmet, and with a youth population in football. This research is aimed at advancing current understanding of impact biomechanics for two specialized groups. The first study is an observational analysis focusing on helmet-helmet impacts, and the difference in effective mass and head acceleration measurements between the striking player and the struck player. The study involved working with football players outfitted with a sensor integrated into their helmets containing a 6 accelerometer array, capable of measuring linear accelerations and estimating angular accelerations. To evaluate helmet-helmet impacts, video analysis of past NCAA football competitions between Virginia Tech and University of North Carolina (UNC) were utilized to identify these impacts between instrumented players. A force balance was then carried out for the observed impacts and their respective acceleration measurements to compute the effective mass of the players. It was determined that the total mass recruited by the striking player was 28% to 77% more than that of the struck player. The second study focused on documenting the head impact biomechanics of a youth population. To accomplish this objective, unique accelerometer arrays, capable of measuring linear and angular accelerations, were integrated into existing youth football helmets for 7 players on a local team. Acceleration data were collected for every practice and game during the 2011 season to amass a total of 748 impacts. No instrumented player sustained a concussion during the 2011 season. Results of the study indicated impacts of greater magnitudes were more likely to occur in practices, and can be minimized by augmenting practice activities. / Master of Science

The possibility of using a commercially available structural analysis program to predict the response of a floor system due to walking excitation as given in AISC Design Guide 11, Floor Vibrations Due to Human Activity (Murray, et al., 1997) was explored. This research included ideal floors that did not have measured values as well as several case study floors that do have measured values for the fundamental frequency. First, multiple model set-ups and loading protocols are applied to the ideal floors and the results compared to results from the Design Guide procedure. A recommendation of the best combination of a model set-up and loading protocol that best matches the Design Guide procedure results is made. Then, case study floors are modeled with the recommended model set-up and loading protocol, and the results compared to the results from the Design Guide procedure and to measured fundamental frequencies. The peak accelerations are also compared to subjective evaluations as to the acceptability of the system. Next, multiple systems were analyzed using five different modeling techniques, including the Design Guide Method, an alteration of the Design Guide Method, the Rayleigh Method, the Analytical Method, and the structural analysis program method, in an attempt to determine the source of discrepancies between the structural analysis program method and the Design Guide method. Finally, conclusions are drawn regarding the structural analysis program procedure as well as possible sources of differences. In general, the structural analysis program procedure reliably predicts the fundamental frequency of a floor system, but does not predict the Design Guide peak acceleration under dynamic loading. The difference in the effective mass of a system between the two methods is a source of discrepancy. / Master of Science

The information presented herein attempts to quantify the conditions surrounding concussive impacts from foul tips to the masks of catchers and umpires in baseball. Media reports of such occasions were researched on video and pitch speed data from the Pitch F/X system recorded to suggest speeds and locations at which impacts occur. To evaluate mask performance, a pneumatic-wheel, electric-motor driven pitching machine was utilized to shoot baseballs at the instrumented head of a Hybrid III dummy. Head accelerations were calculated from a 3-2-2-2 accelerometer array to allow for comparisons of linear and angular kinematics. 6 common masks (2-piece traditional-style and 1-piece hockey-style) were tested at 7 locations at 60 mph to determine the severity of each location. The center-eyebrow and chin locations were further tested at 84 mph. Speed and location data were used to evaluate a large sample of 25 masks to explore possible performance differences between manufacturer models, mask types and cage styles. The results of this study showed no significant difference between hockey-style and traditional-style mask performance. Titanium caged masks, although lighter than their steel counterparts, experienced higher linear accelerations. However, all masks experienced linear and angular accelerations well below commonly accepted injury thresholds. Yet, concussive injury has still occurred in the players and umpires that wear these masks. The work presented here can be used to help better understand these thresholds and influence the design, construction and evaluation of a new generation of masks that decrease the risk of concussions to the wearer. / Master of Science

Experimental and analytical research was conducted to address the vibration properties of Long Span Deck Floor Systems (LSDFS). The research comprised three stages. In the first part, experimental in-situ tests were conducted on thirteen bays of buildings under construction. The natural frequencies and acceleration responses were captured to observe the vibration behavior of the tested floors. In the second part, a laboratory footbridge was constructed to determine the fixity level attained at the supports when a LSDFS is supported by CMU walls. For this purpose, the footbridge was tested with three support conditions, and a number of experiments were carried out to determine the dynamic properties of the structure. Static tests using both point and distributed loadings were conducted to measure the deflections at the footbridge midspan. The static test results were compared to the theoretical deflections for a pinned-end beam and a fixed-end beam. Dynamic tests using experimental modal analysis techniques were conducted to determine the natural frequencies and mode shapes of the structure. The measured fundamental natural frequency of the footbridge was compared to the frequencies calculated for a simply supported beam and a beam with fixed ends, to determine the degree of fixity attained in the connection between the LSDFS and the supporting walls. In the last part of the research, three analytical procedures to predict modal characteristics of long span deck floor systems are studied. Floor frequencies are calculated using finite element analyses. Two design guides for floor vibration analysis were used to calculate natural frequencies and response accelerations. The predicted results obtained from the analytical methods are compared to the experimental results to determine their accuracy. Recommendations for the use of the analytical methods are provided. / Master of Science

Mätning av fotbollsspelares fysiska kapacitet har blivit allt vanligare och viktigare för att optimera spelarnas återhämtning och kapacitet, speciellt i slutet av matcherna i den så kallade kritiska fasen av en match. I dagens elitfotboll mäts spelarnas fysiska prestation med hjälp av global positioning systems (GPS). GPSerna har utvecklats enormt de senaste åren och kan i dag ta fram hundratals parametrar för tränare och spelare att analysera. På lägre nivåer finns inte samma möjligthet att använda GPSer, ofta på grund av eknomiska skäl, och fystester av olika sorter, bland annat agility T-test, används ofta för att mäta spelarnas fysiska kapacitet. Syftet med denna studie var att undersöka om ett enkelt fystest, ett modifierat agility T-test (T3-test) korrelerar med fysiska matchparametrar inom fotbollen. Totalt i studien deltog 8 stycken manliga elitfotbollsspelare från ett svenskt seniorfotbollslag. Deltagarna bar STATSport Apex GPS-system en hel säsong, av vilket fem parametrars (total distans, höghastighetslöpningar, sprints, accelerationer och decelerationer) procentuella värde sista 15 minuterna i ordinarie matchtid (minut 75-90) i förhållande till hela matchens genomsnitt mättes och jämfördes sedan med deras prestation på T3-test. T3-testet utfördes i säsongens sista kvartal. Korrelationen analyerades genom Spearman’s rho korrelationsanalys. Resultatet från denna studie visade inga signifikanta korrelationer mellan de nämnda fysiska matchparametrarna och prestationen på T3-testet. Då studiens statistiska power var lågt på grund av otillräckligtdeltagarantalet, bör inga säkra slutsatser dras utifrån studiens resultat. Mer forskning av T3-test eller liknanden enkla fystester som prediktorer av fysisk matchkapacitet inom fotbollen krävs innan eventuell tillämpning i elitfotbollen bör säkerställas eller avvisas. / Measuring the physical capacity of football players has become more important in optimizing players' recovery and capacity, especially at the end of matches in the so-called critical phase of a match. In today's elite football, players' physical performance is measured using global positioning systems (GPS). The GPSs have developed enormously in recent years and can today produce hundreds of parameters for coaches and players to analyze. At lower levels, there is not the same possibility to use GPSs, often due to economic reasons, and fitness tests of various kinds, including agility T-test, are often used to measure players' physical capacity. The purpose of this study was to investigate whether a simple fitness test, a modified agility T-test (T3-test) correlates with physical match parameters in football. A total of 8 male elite football players from a Swedish senior football team participated in the study. Participants wore the STATSport Apex GPS system for an entire season, of which five parameters (total distance, high-speed runs, sprints, accelerations and decelerations) percentage value in the last 15 minutes of regular match time (minutes 75-90) in relation to the entire match average were measured and compared with their performance on T3-test. The T3-test was performed in the last quarter of the season. The correlation was analyzed by Spearman's rho correlation analysis. The results from this study showed no significant correlations between the mentioned physical match parameters and the performance on the T3-test. As the statistical power of the study was low, due to insufficient number of participants, no definite conclusions should be drawn based on the results of the study.

The purpose of this master thesis was to study the dynamic response of the bridge Västerbron. The bridge is situated in Stockholm and is considered being of critical significance for the infrastructure. The thesis consists of both field measurements and analyses of a finite element model. A stochastic load model was created that is intended to simulate different realistic traffic situations based on parameters as velocity, vehicle type and amount of traffic. The traffic load model was implemented in a finite element model to study if the response was similar to the measurements. With comparisons of the dynamic properties the validity of the model can be assessed. Parameters as stiffness, mass and boundary conditions also often needs to be updated to describe the real behaviour of the bridge. With these updates a model can be created that could better predict problematic behaviour as fatigue. The field measurements were made with accelerometers and analysed in Matlab. The stochastic load model is also scripted in this environment. The FE-model was created using Python scripts that were implemented in BRIGADE/Plus. No conclusive results regarding the mode shapes of Västerbron could be found, however possible eigenfrequencies were identified and presented. The load model was implemented in the FE-model and the influence of different parameters were discussed. The results were consistent with structural dynamics theory and in the same order of magnitude as the measurements. This implies that the traffic load model can be used for further studies regarding dynamic analyses.

The introduction of calculation methods for motion induced interruptions (MII) in 1984 introduced a new way to quantify human factors in addition to the motion sickness index (MSI). The 1990 Graham method for calculating MII uses a combination of a vessel's acceleration and roll to determine a "tipping" factor to calculate MII per minute. The Applebee-Baitis (AB) method considered that the motions are implicitly considered in accelerations, and therefore did not require roll to calculate MII. This thesis examines and analyzes the differences between the AB and Graham methods and compares their results for a unique hull form shape, a cylindrical capsule, in rough seas to determine which method is preferred. Two tests were performed by the Naval Surface Warfare Center, Carderock Division (NSWCCD) for the National Aeronautics and Space Administration (NASA) on the Orion Crew Exploration Vehicle (CEV) in post-splashdown conditions. A one-quarter scale model of the CEV was tested at the Aberdeen Test Center in Aberdeen, Maryland. Direct comparison of the analyzed data, MII sensitivity to location, and scaling analyses are examined and future work to further the application of MII calculation methods are proposed. The symmetry of the capsule leads to the assumption that roll and pitch-dominant MII calculations should be on the same order of magnitude. They are not because both MII methods only take roll-motions into account. The inclusion of both pitch and roll motions for the MII calculations is proposed as future work. The Graham method was found to be the more appropriate calculation because it is more conservative, and therefore preferred in the context of crew safety. / Master of Science

The Thesis of the dissertation work present results of the accelerometer test operation on board of the Russian small spacecraft Universat – 2. This technical experiment was performed in the frame of the project TEASER (Technological Experiment And Space Environmental Resistance) financed by Ministry of Industry and Trade of the Czech Republic. The principal aim of the project was development and application of end-to-end tests procedures for MAC04TS. Generally, End-to-end Testing is intended for verification of the new product comprehensive operational sequence. In the context of the accelerometer this process includes following aspects: On-Ground Qualification of the instrument flight model and its integration with space platform, operation in orbit to verify the device functionality and performances. The MAC04TS is the new modification of the triaxial electrostatic high sensitive microaccelerometer MAC (or MACEK) designed for measurement of non-gravitational accelerations acting to orbiting spacecraft. Mentioned non-conservative perturbations are primary constraint for theoretical predictions of the spacecrafts orbit evolution. Problem of the precise orbit determination is important not only for ballistic mission analysis and support but at planning and realization of the science researches in Geophysics, Geodesy or in Space Physics branches… Presented text to examination is devoted to partial task of the MAC04TS end-to-end testing, especially, measurement and analysis of the micro-gravitational accelerations in the instrument position on board of the spacecraft. Solution of the problem is based on two methods. The first method was based on the calculation of the accelerations by telemetry information about satellite attitude motion. The second method consisted in direct measuring the accelerations by the triaxial low frequency accelerometer MAC04TS and subsequent smoothing measurement data. Comparison of the acceleration values, obtained by different ways, was carried out as a result of constructing the approximation of the measured acceleration values by their calculated values. The approximation was constructed by the least squares method. Both methods gave similar results. The received estimations of the accelerometer measurements can be used for the analysis of the accelerometer verification.

During the months I have been at Virginia Tech, I have experienced the most exciting time of my life. There are many persons who helped me to pursue my Master's degree. I would like to take this opportunity to express my appreciations to them. I would like to thank my advisor and committee chairman, Dr Finley A. Charney. He has supported me for the entire duration of this project with all of his efforts. Without his assistance, it would have been very difficult for me to learn so many concepts in the field of nonlinear dynamic analysis and practical earthquake engineering. I would also like to acknowledge my other committee members, Dr. Raymond Plaut and Dr. W. Samuel Easterling, for taking the time to review the thesis and providing valuable insights and feedback on this thesis. I would like to thank my father, Chan Kwok Fung, who encouraged me to pursue my Master Degree, and my mother, Yu Yuk Ping, who brought me to life. I would like to thank my sister, Doris Chan, and my girlfriend, Ka Man Chan, for supporting and encouraging me during the past two years at Virginia Tech. Finally, I would like to give thanks to the rest of my family, friends, professors, and fellow graduate students for their help and encouragement during my stay at Virginia Tech. / Master of Science