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2012

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Articles 1111 - 1140 of 6303

Full-Text Articles in Engineering

Preparation And Performance Of Sn-Co-M-C（M = Zn, Fe）Composites As An Anode Material, Guo-Qing Fang, Wei-Wei Liu, Shi-Ci He, Qian Zhang, Jun-Wei Zheng, De-Cheng Li Aug 2012

Preparation And Performance Of Sn-Co-M-C（M = Zn, Fe）Composites As An Anode Material, Guo-Qing Fang, Wei-Wei Liu, Shi-Ci He, Qian Zhang, Jun-Wei Zheng, De-Cheng Li

Journal of Electrochemistry

The anode materials of Sn-Co-M-C (M = Zn, Fe) composites were prepared by carbothermal reduction method from metal oxides and sucrose in N2 atmosphere. Their structural and electrochemical properties were studied by XRD, SEM and charge-discharge test. Among them, the Sn-Co-Zn-C composite showed higher specific capacity and good cycle performance. The initial specific discharge capacity of 571 mAh·g-1 could be obtained, while 369 mAh·g-1 was still kept after 45 cycles.

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H3Po4-Imbibed Three-Dimensional Polyacrylamide/Polyacrylamide Hydrogel As A High-Temperature Proton Exchange Membrane With Excellent Acid Retention, Qunwei Tang, Guoging Qian, Kevin Huang Aug 2012

H3Po4-Imbibed Three-Dimensional Polyacrylamide/Polyacrylamide Hydrogel As A High-Temperature Proton Exchange Membrane With Excellent Acid Retention, Qunwei Tang, Guoging Qian, Kevin Huang

Faculty Publications

We herein report the use of polyacrylamide/polyacrylamide interpenetrating polymer network (PAM/PAM IPN) hydrogel as a matrix to imbibe proton conducting H3PO4, forming a robust proton exchange membrane (PEM) suitable for high-temperature PEM fuel cells by combining excellent acid retention, simple synthesis, and low cost. Its extraordinary ability to absorb large quantity of aqueous solution is fully utilized to achieve high H3PO4 loading, showing a proton conductivity of 0.0833 S cm−1 at 183 °C in dry air. The synthesized membrane also shows excellent acid retention even under mechanical load and high humidity. These profound …

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Methods Of Cellular Integration And Techniques For Improving Encapsulated Cell Viability For The Purpose Of Developing Living Materials And Cell Based Bio-Sensing Materials, Travis J. Savage Aug 2012

Methods Of Cellular Integration And Techniques For Improving Encapsulated Cell Viability For The Purpose Of Developing Living Materials And Cell Based Bio-Sensing Materials, Travis J. Savage

Chemical and Biological Engineering ETDs

Living materials offer the potential for detection-reporter systems based on living cells that are genetically tailored to sense target analytes with high levels of specificity and accuracy. A biotic or living material would allow the development of simple, hand held devices that could be utilized for many applications including industrial process monitoring, environmental remediation, military and defense applications and drug delivery. Many living materials have been developed and characterized but they still lack heightened and prolonged encapsulated cell viability necessary to make the material a candidate for widespread use. One particular material offers several advantages to increase yeast cell viability …

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Electrochemical Sensing Of Guanine And Adenine Based On The Boron-Doped Carbon Nanotubes Modified Electrode, Ya-Lin Xia, Chun-Yan Deng, Juan Xiang Aug 2012

Electrochemical Sensing Of Guanine And Adenine Based On The Boron-Doped Carbon Nanotubes Modified Electrode, Ya-Lin Xia, Chun-Yan Deng, Juan Xiang

Journal of Electrochemistry

In this work, the boron-doped carbon nanotubes (BCNTs) modified glassy carbon (GC) electrode was simply fabricated, and the electrochemical oxidation behaviors of guanine and adenine at the BCNTs/GC electrode were investigated. Compared with the bare GC and CNTs/GC electrodes, the BCNTs-modified electrode exhibited extraordinary electrocatalytic activity towards the oxidations of guanine and adenine as indicated by the obvious increase in current responses. Moreover, the peak separation between guanine and adenine was large enough for their potential recognition in mixture without any separation or pretreatment. Therefore, the simultaneous determination of guanine and adenine was successfully achieved. The BCNTs/GC electrode showed high …

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Naf-M (M = Fe, Cu) Nanocomposites As Conversion Cathode Materials For Sodium Ion Batteries, Ting Li, Zhong-Xue Chen, Yu-Liang Cao, Han-Xi Yang Aug 2012

Naf-M (M = Fe, Cu) Nanocomposites As Conversion Cathode Materials For Sodium Ion Batteries, Ting Li, Zhong-Xue Chen, Yu-Liang Cao, Han-Xi Yang

Journal of Electrochemistry

The NaF-M (M = Fe, Cu) nanocomposites were prepared by high-energy ball milling using TiN grinding nanoparticles and investigated as cathode materials for sodium ion batteries. The experimental results demonstrated that NaF-Fe and NaF-Cu nanocomposites can go through electrochemical conversion reaction with Na+ uptake or removal, delivering a reversible capacity of ~ 150 mAh·g-1, even through a reversed conversion from initial discharged state to a charged state. These results reveal the possibility to realize a conversion reaction as long as NaF and elemental metal particles are intimately contacted to form active nanocomposites at nanodomain, which suggests a …

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Synthesis And Electrochemical Properties Of High-Capacity Cathode Material 0.08lico0.75Al0.25O2-0.92linio2, Ru-Ying Wang, Tian Qiu, Chong Mao, Wen-Sheng Yang Aug 2012

Synthesis And Electrochemical Properties Of High-Capacity Cathode Material 0.08lico0.75Al0.25O2-0.92linio2, Ru-Ying Wang, Tian Qiu, Chong Mao, Wen-Sheng Yang

Journal of Electrochemistry

CoAl-LDH or Co(OH)2 coated spherical Ni(OH)2 precursors were obtained via a co-precipitation method at a constant pH. The mixtures of the precursors and LiOH·H2O were annealed at high temperature in O2 atmosphere, and then the cathode materials of 0.08LiCo0.75Al0.25O2-0.92LiNiO2, 0.08LiCoO2-0.92LiNiO2 and LiNiO2 were synthesized. Effects of the coating layer were also studied. The results showed that the 0.08LiCo0.75Al0.25O2-0.92LiNiO2 material possessed the best rate and cycle life performance. The discharging capacities at 0.1C, 0.5C and 3C were …

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Preparation And Modification Of Li4Ti5O12 As Anode Materials For Lithium-Ion Batteries, Jin-Long Liu, Zhou-Guang Lu, Yang Ren, Ya-Jie Zhu, Shan-Shan Hu, Zhong Peng, Dong Qian, You-Gen Tang Aug 2012

Preparation And Modification Of Li4Ti5O12 As Anode Materials For Lithium-Ion Batteries, Jin-Long Liu, Zhou-Guang Lu, Yang Ren, Ya-Jie Zhu, Shan-Shan Hu, Zhong Peng, Dong Qian, You-Gen Tang

Journal of Electrochemistry

Anode Material Li4Ti5O12 for lithium-ion batteries was successfully prepared using half-solid-state method. Furthermore, carbon coating modification of Li4Ti5O12 was also carried out. The phase structure and morphology were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM). The electrochemical properties were investigated by constant current discharge-charge tests, cyclic voltammetry and electrochemical impedance techniques. The results indicated that the electrochemical performance of Li4Ti5O12 without modification declined seriously due to the aggregation of Li4Ti …

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Preparation And Electrochemical Performance Of Nanostructured Mno2 Materials, Wen Wu, Dan-Dan Zhou, Meng-Yan Hou, Yong-Yao Xia Aug 2012

Preparation And Electrochemical Performance Of Nanostructured Mno2 Materials, Wen Wu, Dan-Dan Zhou, Meng-Yan Hou, Yong-Yao Xia

Journal of Electrochemistry

Nanostructured MnO2 materials were prepared in a micro-emulsion medium using sodium dodecyl sulfate (SDS）as a surfactant by a redox reaction between potassium permanganate and aniline. The morphologies of the obtained MnO2 were critically dependent on the concentrations of SDS. The particle sizes varied with the change in the micro-emulsion medium. The optimized properties of MnO2 material obtained with the surfactant concentration of 0.2 mol.L-1 had a specific surface area of 228.2 m2.g-1, and delivered a specific capacitance of 237 F.g -1 in 1 mol.L-1 Li2SO4. Additionally, a …

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Carbon Nanotubes With Ni2P Nanoparticles As A Counter Electrode In Dye-Sensitized Solar Cells, Yan-Ye Dou, Nan-Fu Yan, Guo-Ran Li, Xue-Ping Gao Aug 2012

Carbon Nanotubes With Ni2P Nanoparticles As A Counter Electrode In Dye-Sensitized Solar Cells, Yan-Ye Dou, Nan-Fu Yan, Guo-Ran Li, Xue-Ping Gao

Journal of Electrochemistry

Carbon nanotubes (CNTs) supported by Ni2P nanoparticles are prepared and used as a counter electrode in dye-sensitized solar cells (DSSCs) for the first time. The CNTs-Ni2P composite was prepared by the heat treatment of a mixed precursor including nickel chloride, sodium hypophosphite and CNTs in argon atmosphere. The X-Ray diffraction (XRD) results indicate that the as-prepared sample consists of hexagonal Ni2P and carbon nanotubes. No peaks of other nickel phosphides are observed in the XRD pattern. Microstructure of the Ni2P-CNTs composite was investigated using transmission electron microscopy (TEM). It is shown that the Ni …

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Synthesis And Electrochemical Characterization Of Li3V2(Po4)3/C Cathode Material By Ball-Milling Assisted Microwave Method, Zhi-Yuan Tang, Wen-Feng Mao, Ji Yan, Wei Yuan, Xin-He Zhang Aug 2012

Synthesis And Electrochemical Characterization Of Li3V2(Po4)3/C Cathode Material By Ball-Milling Assisted Microwave Method, Zhi-Yuan Tang, Wen-Feng Mao, Ji Yan, Wei Yuan, Xin-He Zhang

Journal of Electrochemistry

The cathode materials of Li3V2(PO4)3/C were successfully synthesized by ball-milling assisted microwave method and the microwave irradiation time was also optimized. It is found that the Li3V2(PO4)3/C material obtained at a microwave power of 640 W for 18 min showed the best electrochemical performance with the initial reversible capacity of 101.3 mAh·g-1 and the remained 100.8 mAh·g-1 at 5C rate after 300 cycles. This excellent electrochemical capability may be resulted from good crystallinity, smaller and uniform particle size of the material, showing …

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Electrochemical Performance Of Yf3-Coated Li(Li0.22Ni0.17Mn0.61)O2 Cathode Material For Li-Ion Batteries, Xin Feng, Guo-Ran Li, Shi-Hai Ye, Xue-Ping Gao Aug 2012

Electrochemical Performance Of Yf3-Coated Li(Li0.22Ni0.17Mn0.61)O2 Cathode Material For Li-Ion Batteries, Xin Feng, Guo-Ran Li, Shi-Hai Ye, Xue-Ping Gao

Journal of Electrochemistry

The Li(Li0.22Ni0.17Mn0.61)O2 was prepared with oxalic co-precipitation and coated with an YF3 layer by a chemical deposition method. The as-prepared and YF3-coated Li-rich materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). The results demonstrate that the as-prepared and YF3-coated Li(Li0.22Ni0.17Mn0.61)O2 materials have a typical layered structure and are composed of sphere-like particles with a diameter of 100~200 nm. Galvanostatic charge-discharge tests show that the discharge capacity of the YF3-coated Li(Li0.22 …

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A Facile Approach To Prepare Lifepo4/C Composite With High-Rate Performance, Peng Zhang, Ling-Bin Kong, Yong-Chun Luo, Long Kang Aug 2012

A Facile Approach To Prepare Lifepo4/C Composite With High-Rate Performance, Peng Zhang, Ling-Bin Kong, Yong-Chun Luo, Long Kang

Journal of Electrochemistry

The LiFePO4/C composite electrode material was synthesized by a moderate in situ carbothermal reduction method at 600 °C using FeCl3·6H2O, LiOH·H2O, and NH4H2PO4 as starting materials, soluble starch sol as a carbon source and a reducing agent. This method is readily reproducible and possibly feasible to carry out large-scale synthesis. The structure and morphology of the LiFePO4/C samples were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The synthesized LiFePO4/C composite was in pure phase of olivine-type, …

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Electrochemical Performances Of Layered Polypyrrole/Chemically Reduced Graphene Oxide Nanocomposites As Supercapacitor Electrodes, Si-Zhe Xu, Xue-Jiao Zhou, Kun Wu, Yong-Qiang Yang, Hai-Xia Wu Aug 2012

Electrochemical Performances Of Layered Polypyrrole/Chemically Reduced Graphene Oxide Nanocomposites As Supercapacitor Electrodes, Si-Zhe Xu, Xue-Jiao Zhou, Kun Wu, Yong-Qiang Yang, Hai-Xia Wu

Journal of Electrochemistry

Nanocomposites of polypyrrole (Ppy) and chemically reduced graphene oxide (CRGO), Ppy/CRGO, have been fabricated through in-situ polymerization of pyrrole on graphene oxide (GO) sheets. The as-synthesized Ppy/CRGO composites were characterized complementarily using scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and Fourier transformed infrared spectroscopy (FT-IR). By controlling the initial ratio of the GO to pyrrole, the layered composites could be obtained and their thickness could be tuned properly. The Ppy/CRGO electrodes were prepared using a mechanical compressing technique and their electrical conductivity and electrochemical properties were characterized systematically. We demonstrated that as electrodes for supercapacitor, the Ppy/CRGO composites with Ppy …

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Electrochemical Corrosion And Protection Of Copper Foil Treated By Surface Siloxane Filming, Wei-Jun Miao, Yu-Bao Zhang, Ning-Yu Gu, Feng Liu Aug 2012

Electrochemical Corrosion And Protection Of Copper Foil Treated By Surface Siloxane Filming, Wei-Jun Miao, Yu-Bao Zhang, Ning-Yu Gu, Feng Liu

Journal of Electrochemistry

Copper foil specimens were immersed in hydro-alcoholic solution of 3-amino-propyl-trimethoxy-silane (γ-APS) to prepare a protective self-assembled siloxane membrane on the surface. Potentiodynamic polarization and electrochemical impedance spectroscopic tests were performed in 0.1 mol.L-1 NaCl to evaluate the effects of the self-assembled siloxane membranes prepared at different pH of γ-APS on corrosion of copper foil. The surface morphology of siloxane membrane was studied by SEM. Experimental results revealed that the γ-APS self-assembled siloxane membranes effectively inhibited the corrosion of copper foil and the optimum anti-corrosion effect was found when the pH value of the silane solution was 7.

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Electrochemical Immunosensor Based On Polycalconcarboxylic Acid Modified Electrode For The Determination Of Alpha-Fetoprotein, Xiao Lin, Shao-Huang Weng, Jian-Zhang Zhou, Ai-Lin Liu, Xin-Hua Lin, Yong-Ji You Aug 2012

Electrochemical Immunosensor Based On Polycalconcarboxylic Acid Modified Electrode For The Determination Of Alpha-Fetoprotein, Xiao Lin, Shao-Huang Weng, Jian-Zhang Zhou, Ai-Lin Liu, Xin-Hua Lin, Yong-Ji You

Journal of Electrochemistry

A highly sensitive electrochemical immunosensor based on novel electropolymerized polycalconcarboxylic acid modified electrode (poly-CCA/GC) has been fabricated for the detection of alpha-fetoprotein (AFP). The differences of the poly-CCA/GC electrodes before and after the immobilization of AFP antibody were characterized via scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). The immobilization of antibody/antigen/antibody-HRP sandwich was formed on the poly-CCA modified electrode for the determination of special AFP concentrations. The electrochemical signals generated from the HRP which catalyzed the TMB substrate were measured. Experiment results indicated that the developed immunosensor showed a good sensitivity and precision.

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Electrocatalytic Activities Of Mb/Aunps/Mwnts/Gc Electrode For Hydrogen Peroxide Reduction, Zheng-Juan Huang, Hua-Ping Peng, Dai-Jun Cha, Ai-Lin Liu, Wei Chen, Xin-Hua Lin, Yong-Ji You Aug 2012

Electrocatalytic Activities Of Mb/Aunps/Mwnts/Gc Electrode For Hydrogen Peroxide Reduction, Zheng-Juan Huang, Hua-Ping Peng, Dai-Jun Cha, Ai-Lin Liu, Wei Chen, Xin-Hua Lin, Yong-Ji You

Journal of Electrochemistry

A novel matrix, multiwalled carbon nanotubes supported Au nanoparticles composite nanomaterial (AuNPs/MWNTs), for immobilization of protein and biosensing was designed using a simple and effective one-step in situ synthesis route. Using myoglobin (Mb) as a model, the direct electrochemistry of the immobilized proteins on the AuNPs/MWNTs composite was studied. The results showed that the AuNPs/MWNTs composite can maintain the bioactivity and facilitate the direct electrochemistry of Mb in the Mb/AuNPs/MWNTs/GC electrode. Based on the direct electron transfer of the immobilized Mb, the protein electrode exhibited excellent electrocatalytic activity to the reduction of H2O2 with a linear range …

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Direct Writing Of Au Nanoneedles Array On Glass By Confined Laser Spinning, Yingling Yang, Dong Lin, Gary J. Cheng Aug 2012

Direct Writing Of Au Nanoneedles Array On Glass By Confined Laser Spinning, Yingling Yang, Dong Lin, Gary J. Cheng

Birck and NCN Publications

Generation of gold nanoneedles on glass by confined laser spinning was explored by using a nanosecond pulsed laser. When the coated Au thin film was irradiated under the confinement of glass, gold nanoneedles were formed by spreading the molten liquid of gold under high pressure. The mechanism of the confined laser spinning process is studied. The maximum velocity and instability of molten liquid during confined laser spinning were estimated. The diameter of nanoneedles can be controlled by changing the thickness of coated gold thin film. Large scale of gold nanoneedles can be formed by this direct writing method and collected …

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Control Of Reflectance And Transmittance In Scattering And Curvilinear Hyperbolic Metamaterials, T. U. Tumkur, J. K. Kitur, B. Chu, Lei Gu, V. A. Podolskiy, Evgenii E. Narimanov, M. A. Noginov Aug 2012

Control Of Reflectance And Transmittance In Scattering And Curvilinear Hyperbolic Metamaterials, T. U. Tumkur, J. K. Kitur, B. Chu, Lei Gu, V. A. Podolskiy, Evgenii E. Narimanov, M. A. Noginov

Birck and NCN Publications

We demonstrate reduced reflectance in curvilinear lamellar hyperbolic metamaterials as well as planar hyperbolic metamaterials consisting of metal/dielectric multilayers, with scatterers deposited on the top. The reduced reflectance is accompanied by a significant enhancement in transmission along with non-reciprocity of transmittance in forward and backward propagating directions. The observed experimental behavior is qualitatively similar to the results of numerical solutions of Maxwell equations. The findings of this study pave the way to a variety of important applications, including broadband enhancement of light trapping in photovoltaic devices. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4746387]

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Study On Spontaneous Emission In Complex Multilayered Plasmonic System Via Surface Integral Equation Approach With Layered Medium Green's Function, Yongpin P. Chen, Wei E.I. Sha, Wallace C.H. Choy, Lijun Jiang, Weng Cho Chew Aug 2012

Study On Spontaneous Emission In Complex Multilayered Plasmonic System Via Surface Integral Equation Approach With Layered Medium Green's Function, Yongpin P. Chen, Wei E.I. Sha, Wallace C.H. Choy, Lijun Jiang, Weng Cho Chew

Electrical and Computer Engineering Faculty Research & Creative Works

A rigorous surface integral equation approach is proposed to study the spontaneous emission of a quantum emitter embedded in a multi-layered plasmonic structure with the presence of arbitrarily shaped metallic nanoscatterers. With the aid of the Fermi's golden rule, the spontaneous emission of the emitter can be calculated from the local density of states, which can be further expressed by the imaginary part of the dyadic Green's function of the whole electromagnetic system. To obtain this Green's function numerically, a surface integral equation is established taking into account the scattering from the metallic nanoscatterers. Particularly, the modeling of the planar …

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Rigid Finite Element Model Of A Cracked Rotor, Zbigniew Kulesza, Jerzy T. Sawicki Aug 2012

Rigid Finite Element Model Of A Cracked Rotor, Zbigniew Kulesza, Jerzy T. Sawicki

Mechanical Engineering Faculty Publications

The article introduces a new mathematical model for the cracked rotating shaft. The model is based on the rigid finite element (RFE) method, which has previously been successfully applied for the dynamic analysis of many complicated, mechanical structures. In this article, the RFE method is extended and adopted for the modeling of rotating machines. An original concept of crack modeling utilizing the RFE method is developed. The crack is presented as a set of spring–damping elements of variable stiffness connecting two sections of the shaft. An alternative approach for approximating the breathing mechanism of the crack is introduced. The approach …

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Sbx7 Flow Rate Measurement Compliance For Agricultural Irrigation Districts, Charles M. Burt, Evan Geer Aug 2012

Sbx7 Flow Rate Measurement Compliance For Agricultural Irrigation Districts, Charles M. Burt, Evan Geer

BioResource and Agricultural Engineering

Senate Bill x7-7 (SBx7-7) requires documented volumetric accounting to individual turnouts for water deliveries. Section 597.3 of the bill lists two very different requirements for devices. This document examines the requirements of SBx7 and the implications for agricultural irrigation districts. The definitions and impacts of flow rate and volumetric accuracy are defined. Example scenarios and solutions are offered, as well as descriptions of applicable devices.

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Definition Of Common Conventions For Education Of Cfs System Design, Semih Göksel Yıldırım Aug 2012

Definition Of Common Conventions For Education Of Cfs System Design, Semih Göksel Yıldırım

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

CFS system of which can be used in the field of low rise residentials, are included in industrialised building systems due to installation principles of the system. Widespreading of the usage of an industrialised building system depends on the widespreading of the system design datum. Therefore, education of CFS system design is required in order to increase the system usage. Also, awareness of CFS system in the levels of public authorities and technical staff can be increased by education. The aim of this paper is to develop an education model for CFS system design by using open building concept. The …

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Numerical And Experimental Investigation Of Cold-Formed Steel Double Angle Members Under Compression, W. F. Maia, L. C. M. Vieira Jr., B. W. Schafer, M. Malite Aug 2012

Numerical And Experimental Investigation Of Cold-Formed Steel Double Angle Members Under Compression, W. F. Maia, L. C. M. Vieira Jr., B. W. Schafer, M. Malite

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

This paper presents a numerical and experimental study of double angle members connected by batten plates under concentric and eccentric axial compression. The number of batten plates is varied to study the influence on the nominal axial strength. Numerical analyses are able to accurately predict the behavior and strength found in the experiments, except for long columns under eccentric axial compression where the composite section failed in major-axis flexural buckling. Two design hypotheses are compared to the results obtained: (i) non-composite action (no interaction between angles), with only local, flexural, and flexural-torsional buckling considered; (ii) composite action (full interaction between …

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The 1st Student Competition On Cold-Formed Steel Design, Cheng Yu, Cristopher Moen Aug 2012

The 1st Student Competition On Cold-Formed Steel Design, Cheng Yu, Cristopher Moen

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

The first Student Competition on Cold-Formed Steel Design (CFS Competition) was held at the University of North Texas in 2011. The CFS Competition was initiated by Cheng Yu through a National Science Foundation CAREER award. The objective of the CFS Competition is to promote higher education in coldformed steel structural design and to encourage students to use creative thinking skills to solve engineering problems. The subject of the first CFS Competition is to design an optimal thin-walled cold-formed steel cross section under several pre-defined restrictions. The CFS Completion received total 78 entries from students in 5 different countries. The judging …

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Compression-Tension Hysteretic Response Of Cold-Formed Steel C-Stection Framing Members, D. Padilla-Llano, C. D. Moen, M. Eatherton, L. Mcanallen, T. Bruce Aug 2012

Compression-Tension Hysteretic Response Of Cold-Formed Steel C-Stection Framing Members, D. Padilla-Llano, C. D. Moen, M. Eatherton, L. Mcanallen, T. Bruce

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

This paper summarizes results from an experimental program designed to evaluate the tension-compression cyclic axial response of cold-formed steel C-section structural framing members. A new cyclic loading protocol for cold formed steel members is presented that defines the target axial displacement based on elastic buckling parameters. The protocol is used to explore the cyclic response of members experiencing local buckling, distortional buckling, and global buckling deformation. In the experiments, post-bucking energy dissipation was observed along with tension stretching and softening. The quantity of dissipated energy per cycle increased as cross-section and global slenderness decreased. Specimens experiencing local and distortional buckling …

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Towards The Design Of Cold-Formed Steel Foam Sandwich Columns, S. Szyniszewski, B. H. Smith, V. M. Zeinoddini, J. F. Hajjar, S. R. Arwade, B. W. Schafer Aug 2012

Towards The Design Of Cold-Formed Steel Foam Sandwich Columns, S. Szyniszewski, B. H. Smith, V. M. Zeinoddini, J. F. Hajjar, S. R. Arwade, B. W. Schafer

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

In this paper a design method for the compressive capacity of sandwich panels comprised of steel face sheets and foamed steel cores is derived and verified. Foamed steel, literally steel with internal voids, provides the potential to mitigate many local stability issues through increasing the effective width-to thickness of the component for the same amount of material. Winter’s classical effective width expression was generalized to the case of steel foam sandwich panels. The provided analytical expressions are verified with finite element simulations employing brick elements that explicitly model the steel face sheets and steel foam cores. The closed-form design expressions …

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Dynamic Time-History Analysis On Wind-Induced Response Of Light-Weight Roof System, X. K. Jing, Y. Q. Li, D. J. Gong Aug 2012

Dynamic Time-History Analysis On Wind-Induced Response Of Light-Weight Roof System, X. K. Jing, Y. Q. Li, D. J. Gong

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

Severe damage to light-weight roof system occur when exposed to strong wind loading. Damage investigations and wind load-bearing capacity tests of light-weight roof system reveal that the connection damage of roof sheeting and fastener is the most serious. Wind pressure distributions on the roof of gabled steel frame measured in a wind tunnel are described. Secondly, illustrated by the example of the classic standing-lock roof system, the wind-induced forces for the concealed clips estimated by the building code and time-history analysis based on wind tunnel test, respectively, are compared. The results indicate that the uniform gust factor used in the …

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Experimental Analysis Of Beam-To-Upright Connections In Cold-Formed Steel Storage Pallet Racks, Tuo Wang, Xianzhong Zhao, Yiyi Chen Aug 2012

Experimental Analysis Of Beam-To-Upright Connections In Cold-Formed Steel Storage Pallet Racks, Tuo Wang, Xianzhong Zhao, Yiyi Chen

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

A research program is currently in progress at Department of Building Engineering of Tongji University with the aim of investigating the behavior of cold-formed steel storage pallet racks under static and dynamic loading. This paper presents preliminary experimental analysis on the monotonic behavior of beam-to-upright connections. In the experimentation, the set-up was specially designed to accommodate precise requirement of boundary conditions and the measurement method was refined from the general ones used in rack design codes. It is shown that deformation modes of the connections were similar before failure while the failure modes were different depending on the specific constructional …

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Experimental And Numerical Investigations Of High Strength Cold-Formed Lapped Z Purlins Under Combined Bending And Shear, Cao Hung Pham, Annabel F. Davis, Bonney R. Emmett Aug 2012

Experimental And Numerical Investigations Of High Strength Cold-Formed Lapped Z Purlins Under Combined Bending And Shear, Cao Hung Pham, Annabel F. Davis, Bonney R. Emmett

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

Plain C or Z- sections are two of the most common cold-formed steel purlins in use for roof systems throughout the world. Especially for Z- sections, their lapping ability provides continuity and double thickness material at the support regions results in greater performance and more economical designs. At the region just outside the end of the lap, the purlin may fail under a combination of high bending and shear. Design methods for these sections are normally specified in the Australian/New Zealand Standard for Cold-Formed Steel Structures (AS/NZS 4600:2005) or the North American Specification for Cold- Formed Steel Structural Members (2007). …

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Mechanisms Of Block Shear Failure Of Bolted Connections, Lip H. Teh, Drew D. A. Clements Aug 2012

Mechanisms Of Block Shear Failure Of Bolted Connections, Lip H. Teh, Drew D. A. Clements

CCFSS Proceedings of International Specialty Conference on Cold-Formed Steel Structures (1971 - 2018)

This paper examines the mechanisms for block shear failure postulated in the design provisions specified in the North American Specification for the Design of Cold-formed Steel Structural Members 2007 and AS/NZS 4600:2005 Coldformed Steel Structures. It explains that there is only one feasible mechanism for the limit state of conventional block shear failure, that which involves shear yielding and tensile rupture. It proposes an equation that provides more accurate results compared to the code equations in predicting the block shear capacities of bolted connections in steels having minimal strain hardening. A resistance factor of 0.8 for the proposed equation is …

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