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In this thesis, free vibration of beam structures with initial load is analyzed. It is based on the theory of elasticity and the formulation is derived by finite element method. The present method is different from traditions beam theories and is able to simulate beam vibration more precisely. The free vibration frequencies of beams under initial axial loading and different boundary conditions and geometrical aspect ratios are solved first and compared with those of Timoshenko beam theory. Vibration of beams with initial lateral loading is then analyzed, considering only the initial stresses and both the initial stresses and the initial displacements induced by the initial loading, to reveal the effect of initial stresses and initial displacement on vibration of beams with initial loading.

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Full-scale structural deflection tests were conducted on floor sections with 2"x4" , 2"x6", and 2"x8" joists at four different stages of construction. Stage A was joist alone; stage B joists plus 1/2" plywood subflooring; stage C, stage B plus 25/32" oak strip flooring laid parallel to the joists; and stage D, stage B plus oak strip flooring laid perpendicular to joists. Results show substantial decreases in deflection due to stages B, C, and D. Stage C resulted in the stiffest floor for all sizes of joists followed by stage D and stage B in that order. Decreases in deflection also varied by size of joist, showing that as the size of the joist increases, the effects of the added construction components decreases. Average decreases in deflection are shown in Table 11. / Master of Science

Despite advancements in automotive safety, motor vehicle collisions remain the leading cause of unintentional death for children ages 5 to 14. Enhancement of child occupant protection depends on the ability to accurately assess the effectiveness of restraint systems. Booster seat design and proper belt fit require evaluation using child anthropomorphic test devices, yet biofidelity of the abdomen and pelvis of the current anthropomorphic test device, the Hybrid III 6-year-old, needs improvement. Further, measurement of abdominal deflection is needed for quantification of the degree of submarining and associated potential injury risk. A biofidelic abdomen for the Hybrid III 6-year-old dummy is being developed by the Ford Motor Company. A practical measurement system for the biofidelic abdominal insert has been developed and demonstrated for three dimensional determination of abdominal deflection. Quantification of insert deflection is achieved via differential signal measurement using electrodes mounted within a conductive medium. Signal amplitude is proportional to the distance between the electrodes. A microcontroller is used to calculate distances between ventral electrodes and a dorsal electrode in three dimensions. This system has been calibrated statically, as well as evaluated dynamically. Its performance has also been demonstrated in a series of sled tests. Deflection measurements from the instrumented abdominal insert showed clear differences between two booster seat designs, yielding an average peak anterior to posterior displacement of the abdomen of 1.0 ± 3.4 mm and 31.2 ± 7.2 mm for the seats, respectively. Implementation of a 6-year-old abdominal insert with the ability to evaluate submarining potential will likely advance the effectiveness of booster seat design and restraint performance, and help mitigate child occupant injury severity in automobile collisions. / Master of Science

This thesis studies the present methods used to predict the ultimate tripping strength of stiffened panels under compressive axial stress. The current methods involve the use of a bifurcation, or eigenvalue, approach to predicting failure stress. The effects of initial transverse eccentricity of the stiffener are ignored using such a method. Six panels were modeled and tested with ABAQUS, a finite element software package, and the results were compared to output from ULSAP, a closed-form ultimate strength analysis program. The ultimate strengths predicted by ABAQUS changed with the influence of initial deflection of the stiffener flange, while the results from ULSAP did not change. This thesis attempts to use beam-column analysis on the imperfect stiffener flange to predict the tripping strength. It was determined that the procedure presented in this thesis does not accurately model the true failure mode of stiffeners in tripping. The resulting ultimate strengths are extremely conservative and neglect the importance of the stiffener web's role in tripping. Future work is recommended to expand on these findings and to incorporate the influence of the stiffener web into a beam-column solution. / Master of Science

In any infrastructure project, monitoring and managing the built assets is an important task. Structural Health Monitoring (SHM) is meant for continuous assessment of safety and serviceability of a structure and its elements. SHM has taken a leading role in the field of structural engineering and has become very popular in recent age. Bridge deflection is the basic evaluation index to examine the health status of a bridge structure. The existing bridge monitoring systems have several drawbacks. Hence, a new methodological approach has been proposed to overcome the limitations of traditional contact-based bridge deflection monitoring system and other non-contact based system. This study developed a non-contact linear feature based Deflection Monitoring System (DMS) using Terrestrial Laser Scanning (TLS) and cameras for timber railroad bridges. The process and detailed workflow of building the DMS, its components and sensors involved are discussed here. The efficiency of this DMS is validated against a deflectometer. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2018. / FAU Electronic Theses and Dissertations Collection

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This dissertation analyzes the trading effects and the politics of antidumping. The first essay empirically examines the influence of partisanship on antidumping. I show that an increase in the leftist orientation of the government makes labor intensive industries less likely to file an antidumping petition. I also demonstrate that the increase in the leftist orientation of the government is associated with an increase in the likelihood of an affirmative antidumping outcome for the petitions of labor intensive industries. The second essay investigates the effect of past exporting relationships of the firms, whose products are targeted by antidumping duties, on their export flows to alternative markets. My estimations show that facing an antidumping duty on a product leads to a 18% increase in the exports of the firm for that product to the alternative countries where the firms previously exported the same product and a 8% increase to the countries where the firms exported another product. On the contrary, I fail to find a significant effect of antidumping duties on the exports of the particular product to third countries to which the firm did not export before. Further, I show that a firm’s probability to start exporting the duty imposed product in a different destination increases by 8-10% if the firm already exported another product to that destination. However, I find no such evidence for the countries to which the firm did not export before. The third essay empirically analyzes the effect of potential antidumping claims, resulting from an antidumping investigation in the domestic market, on the quality of exported products to the target countries. My findings suggest that retaliation threats increase the quality of firms’ shipments for the named industries’ products to the target countries by 11%. This effect is also significantly increasing in the share of the exports of the named industries’ products shipped to the target country in the firms’ total exports. Further, I show that this effect is 4 % higher for the exporters serving the developed countries and 3% higher for ones serving the heavy antidumping users.

Glue laminated wood deck systems are commonly used for bridge decks on girder bridge systems. These decks are usually covered with a hot-mix asphalt wearing surface in conjunction with a bituminized fabric sheet waterproofing membrane. Often cracks occur in the asphalt at the intersection of two adjacent deck panels which limits the useful life of the wear surface, provides a poor riding surface and potentially allows moisture to flow to wooden bridge components. The purpose of this study was to investigate the structural behavior of asphalt/wood/membrane deck systems. This was accomplished experimentally by determining the deflection of bridge deck panels with respect to each other under simulated truck loading. A classical linear analysis model and a finite element analysis model were developed for the deck panel deflections. These analytical results were compared to the experimental results and a value of approximately 0.05 in for the interpanel differential deflection was determined to be a reasonable, conservative value for the typical configuration considered. This deflection was then used to load various asphalt/membrane/ wood configurations to investigate the effectiveness of the arrangement with regards to resisting hot-mix asphalt cracking. It was found that when subjected to repeated deflections of 0.05 in, the following experimental composite bridge deck performed best in terms of reduced cracking: 1) hot-mix asphalt base layer applied directly onto the glulam deck panel; 2) waterproofing membrane placed on the base layer of asphalt; 3) hot-mix asphalt surface layer placed on the waterproofing membrane. / Master of Science