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 Department: Department of Engineering Technology
Analytical Model of Cold-formed Steel Framed Shear Wall with Steel Sheet and Wood-based Sheathing

Analytical Model of Cold-formed Steel Framed Shear Wall with Steel Sheet and Wood-based Sheathing

Date: May 2013
Creator: Yanagi, Noritsugu
Description: The cold-formed steel framed shear walls with steel sheets and wood-based sheathing are both code approved lateral force resisting system in light-framed construction. In the United States, the current design approach for cold-formed steel shear walls is capacity-based and developed from full-scale tests. The available design provisions provide nominal shear strength for only limited wall configurations. This research focused on the development of analytical models of cold-formed steel framed shear walls with steel sheet and wood-based sheathing to predict the nominal shear strength of the walls at their ultimate capacity level. Effective strip model was developed to predict the nominal shear strength of cold-formed steel framed steel sheet shear walls. The proposed design approach is based on a tension field action of the sheathing, shear capacity of sheathing-to-framing fastener connections, fastener spacing, wall aspect ratio, and material properties. A total of 142 full scale test data was used to verify the proposed design method and the supporting design equations. The proposed design approach shows consistent agreement with the test results and the AISI published nominal strength values. Simplified nominal strength model was developed to predict the nominal shear strength of cold-formed steel framed wood-based panel shear walls. The nominal shear ...
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Cold-formed Steel Framed Shear Wall Sheathed with Corrugated Sheet Steel

Cold-formed Steel Framed Shear Wall Sheathed with Corrugated Sheet Steel

Date: May 2013
Creator: Yu, Guowang
Description: Incombustibility is one important advantage of the sheet steel sheathed shear wall over wood panel sheathed shear wall. Compared to shear wall sheathed with plywood and OSB panel, shear wall sheathed with flat sheet steel behaved lower shear strength. Although shear wall sheathed with corrugated sheet steel exhibited high nominal strength and high stiffness, the shear wall usually behaved lower ductility resulting from brittle failure at the connection between the sheathing to frames. This research is aimed at developing modifications on the corrugated sheathing to improve the ductility of the shear wall as well as derive practical response modification factor by establishing correct relationship between ductility factor ? and response modification factor R. Totally 21 monotonic and cyclic full-scale shear wall tests were conducted during the winter break in 2012 by the author in NUCONSTEEL Materials Testing Laboratory in the University of North Texas. The research investigated nineteen 8 ft. × 4 ft. shear walls with 68 mil frames and 27 mil corrugation sheet steel in 11 configurations and two more shear walls sheathed with 6/17-in.OSB and 15/32-in. plywood respectively for comparison. The shear walls, which were in some special cutting arrangement patterns, performed better under lateral load conditions according ...
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Corrosion Protection of Low Carbon Steel By Cation Substituted Magnetite (Fe3o4)

Corrosion Protection of Low Carbon Steel By Cation Substituted Magnetite (Fe3o4)

Date: May 2013
Creator: Phadnis, Ameya
Description: Surfaces of low carbon steel sheet were modified by exposure to highly caustic aqueous solutions containing either chromium or aluminum cations. Corrosion resistances of such surfaces were compared with that of steel surfaces exposed to plain caustic aqueous solution. In all cases a highly uniform, black coating having a spinel structure similar to magnetite (Fe3O4) was obtained. The coated steel surfaces were characterized using X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and Fourier transform infrared spectrophotometry (FTIR). Polarization resistances (Rp) of modified steel surfaces were measured and compared with that of bare steel surfaces. Results indicate that chromium (Fe2+ Fe3+x Cr3+1-x) or aluminum (Fe2+ Fe3+x Al3+1-x) substituted spinel phases formed on steel surfaces showed higher Rp values compared to only magnetite (Fe2+ 2Fe3+O4) phase formed in the absence of either chromium or aluminum cations. Average Rp values for steel surfaces with chromium containing spinel phase were much higher (21.8 k?) as compared to 1.7 k? for bare steel surfaces. Steel surfaces with aluminum containing spinel phase and steels with plain magnetite coated samples showed average Rp values of 3.3 k? and 2.5 k? respectively. XPS and EDS analysis confirmed presence of cations of chromium and ...
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Direct Strength Method for Web Crippling of Cold-formed Steel C-sections

Direct Strength Method for Web Crippling of Cold-formed Steel C-sections

Date: May 2013
Creator: Seelam, Praveen Kumar Reddy
Description: Web crippling is a form of localized buckling that occurs at points of transverse concentrated loading or supports of thin-walled structural members. The theoretical computation of web crippling strength is quite complex as it involves a large number of factors such as initial imperfections, local yielding at load application and instability of web. The existing design provision in North American specification for cold-formed steel C-sections (AISI S100, 2007) to calculate the web-crippling strength is based on the experimental investigation. The objective of this research is to extend the direct strength method to the web crippling strength of cold-formed steel C-sections. ABAQUS is used as a main tool to apply finite element analysis and is used to do the elastic buckling analysis. The work was carried out on C-sections under interior two flange (ITF) loading, end two flange (ETF) loading cases. Total of 128 (58 ITF, 70 ETF) sections were analyzed. Sections with various heights (3.5 in.to 6 in.) and various lengths (21 in. to 36 in.) were considered. Data is collected from the tests conducted in laboratory and the data from the previous researches is used, to extend the direct strength method to cold formed steel sections. Proposing a new ...
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Effects of Processing Techniques on Mechanical Properties of Selected Polymers

Effects of Processing Techniques on Mechanical Properties of Selected Polymers

Date: May 2013
Creator: Dong, Yao
Description: The mechanical properties of a polymer represent the critical characteristics to be considered when determining the applications for it. The same polymer processed with different methods can exhibit different mechanical properties. The purpose of this study is to investigate the difference in mechanical properties of the selected polymers caused by different processing techniques and conditions. Three polymers were studied, including low density polyethylene (LDPE), polypropylene (PP), and NEXPRENE® 1287A. Samples were processed with injection molding and compression molding under different processing condition. Tensile and DMA tests were performed on these samples. The acquired data of strain at break from the tensile tests and storage modulus from the DMA were utilized to calculate brittleness. Calculated brittleness values were used to perform analysis of variance (ANOVA) to investigate the statistical significance of the processing technique and condition. It was found that different processing techniques affect the brittleness significantly. The processing technique is the major factor affecting brittleness of PP and NEXPRENE, and the processing temperature is the major factor affecting brittleness of LDPE.
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Drive Level Dependence of Advanced Piezoelectric Resonators

Drive Level Dependence of Advanced Piezoelectric Resonators

Date: August 2012
Creator: Xie, Yuan
Description: Resonators are one of the most important parts of electronic products. They provide a stable reference frequency to ensure the operation of these products. Recently, the electronic products have the trend of miniaturization, which rendered the size reduction of the resonators as well [1]. Better design of the resonators relies on a better understanding of the crystals' nonlinear behavior [2]. The nonlinearities affect the quality factor and acoustic behavior of MEMS (Micro-Electro-Mechanical-System) and nano-structured resonators and filters [3]. Among these nonlinear effects, Drivel Level Dependence (DLD), which describes the instability of the resonator frequency due to voltage level and/or power density, is an urgent problem for miniaturized resonators [2]. Langasite and GaPO4 are new promising piezoelectric material. Resonators made from these new materials have superior performance such as good frequency-temperature characteristics, and low acoustic loss [2]. In this thesis, experimental measurements of drive level dependence of langasite resonators with different configurations (plano-plano, single bevel, and double bevel) are reported. The drive level dependence of GaPO4 resonators are reported as well for the purpose of comparison. The results show that the resonator configuration affects the DLD of the langasite resonator. Experiments for DLD at elevated temperature are also performed, and it ...
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Effects of Minimum Quantity Lubrication (Mql) on Tool Life in Drilling Aisi 1018 Steel

Effects of Minimum Quantity Lubrication (Mql) on Tool Life in Drilling Aisi 1018 Steel

Date: August 2012
Creator: Maru, Tejas
Description: It has been reported that minimum quantity lubrication (MQL) provides better tool life compared to flood cooling under some drilling conditions. In this study, I evaluate the performance of uncoated HSS twist drill when machining AISI 1018 steel using a newly developed lubricant designed for MQL (EQO-Kut 718 by QualiChem Inc.). A randomized factorial design was used in the experiment. The results show that a tool life of 1110 holes with a corresponding flank wear of 0.058 mm was realized.
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Mist Characterization in Drilling 1018 Steel

Mist Characterization in Drilling 1018 Steel

Date: August 2012
Creator: Cole, Ian
Description: Minimum quantity lubrication replaces the traditional method of flood cooling with small amounts of high-efficient lubrication. Limited studies have been performed to determine the characteristics of mist produced during MQL. This study investigated the mist concentration levels produced while drilling 1018 steel using a vegetable based lubricant. ANOVA was performed to determine whether speed and feed rates or their interactions have a significant effect on mist concentration levels and particle diameter. It was observed that the concentration levels obtained under all four speed and feed rate combinations studied exceeded the current OSHA and NIOSH standards.
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Wireless In-home Ecg Monitoring System with Remote Access

Wireless In-home Ecg Monitoring System with Remote Access

Date: August 2012
Creator: Porter, Logan
Description: The thesis work details the design and testing of a wireless electrocardiogram (ECG) system. This system includes a wireless ECG device, as well as software packages to visually display the waveform locally on a computer and remotely on a web page. The remote viewing capability also extends to using an Android phone application. The purpose of the system is to serve as a means for a doctor or physician to check up on a patient away from a hospital setting. This system allows for a patient to be in their home environment while giving health vital information, primarily being the heart’s activity through the ECG, to medical personnel.
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Bearing Strength of Cold Formed Steel Bolted Connections in Trusses

Bearing Strength of Cold Formed Steel Bolted Connections in Trusses

Date: May 2012
Creator: Panyanouvong, Mark
Description: The existing design provision in North American Specification for Cold- Formed Steel Structural Member (AISI S100) for the bearing strength of bolted connections were developed from tests on bolted connected sheets which were restrained by bolt nut and head with or without washers. However, in the cold-formed assemblies, particularly in trusses, the single bolt goes through both sides of the connected sections, making the connected sheets on each side unrestrained. the warping of the unrestrained sheet may reduce the bearing strength of the bolted connection. This research investigates the behavior and strength of bearing failure in bolted connections in cold-formed steel trusses. Tensile tests were conducted on trusses connections with various material thicknesses. It was found that the AISI S100 works well for thick connections but provides unconservative predictions for thin materials. Based on the experimental results, a modified bearing strength method is proposed for calculating the bearing strength of bolted truss connections. the proposed method can be used for any cold-formed steel connections with unrestrained sheet.
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