Engineering Commons^™

Technique And Qualities Of Beams With Expanded Metal Sections, M. Hellsten

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

The rotary expander technique can be used for manufacturing Lattice framework from a single strip of sheet metal by integrating expanded metal with solid sheet. This technique can be used to distribute the material in a tubular, or open profile to where it's best needed. Valuable qualities possible to are: - low weight and optimal strength - low energy transmission (noise and heat) - soft deformation and favorable energy absorbing properties - good fatigue resistance - high flexibility in design and product qualities These qualities are useful in applications like: - light and strong steel framing systems for buildings - …

Behaviour Of Thin G550 Sheet Steel Screwed Connections, Colin A. Rogers, Gregory J. Hancock

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

This paper provides a summary of results detailing the behaviour of screwed connections tested in shear, which were composed of thin G550 and G300 sheet steels (to the 1993 Australian Standard AS 1397). Recommendations concerning the adequacy of current design standards with respect to the design of thin sheet steel screwed connections are made.

Understanding Pullover, Jonathan Sabia Kreiner, Duane S. Ellifritt

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

Self drilling screws are often used for attaching roof and wall panels to structural framing and are subjected to tensile loads caused by negative wind pressures. Pullover failure is often associated with this loading condition, which occurs when It fastener pulls through a metal panel but remains attached to the structural framework underneath. The American lron and Steel Institute (AISI) has developed several standard tests for pullover and has included a design criterion for pullover in their specification. However, previous research at the University of Florida has found one particular test and the AISI Specification Section E4.4.2 to be un-conservative. …

Distortional Buckling Formulae For Thin Walled Channel And Z-Sections With Return Lips, John T. Merrick, Gregory J. Hancock, M. R. Bamach

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

Cold-formed Channel- and Z-sections subject to both flexure and torsion may undergo distortional buckling where the flange and lip rotate about the flange/web junction. This mode of failure is prevalent in purlin sections when lateral deformation of the section is prevented and when the sections are manufactured from high strength steel. In an attempt to prevent distortional buckling, some manufacturers have added additional return lips to the flange lips to produce complex edge stiffeners. The Australian/New Zealand Standard for Cold-Formed Steel Structures includes design rules for determining the distortional buckling strength of cold-formed beam and column sections. These design rules …

Behaviour Of Thin G550 Sheet Steel Bolted Connections, Colin A. Rogers, Gregory J. Hancock

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

This paper provides a summary of results detailing the behaviour of bolted connections tested in shear, which were composed of 0.42 mm G550, 0.60 mm G550 and 0.60 mm G300 sheet steels (to the 1993 Australian Standard AS 1397). Recommendations concerning the adequacy of current design standards with respect to the design of thin sheet steel bolted connections are made, along with the calibration of applicable limit states resistance equations for the three observed modes of failure; end pull-out, bearing, and net section fracture.

Compressional Behaviour Of Stainless Steel Short Struts, M. Macdonald, J. Rhodes, G. T. Taylor

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

The effects of cold forming on both carbon steel and stainless steel structural members has been the subject of extensive research since the early 1940's. Design code specifications for carbon steel members have been published in many countries around the world, including BS 5950, Part 5 in the UK (1) the AlSI Specification in the USA (2), and the new Eurocode 3, Part 1.3 (3). For stainless steel members there are fewer design code specifications available, and those that are available, which include the ANSI/ASCE in the USA (4) and the new Eurocode 3, Part 1.4 (5), do not give …

Bearing Design Of Thin Sheet Steel Screwed Connections, Colin A. Rogers, Gregory J. Hancock

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

The 1996 Australian / New Zealand AS/NZS 4600 and North American; CSA-S136, AISI Cold Formed Steel Design Standards allow for the use of thin (t < 0.9 mm in AS/NZS 4600), high strength (fy = 550 MPa) sheet steels if the yield stress and ultimate strength are reduced to 75% of their minimum specified values. At present, these reduced material properties must be used in the design of screwed connections which undergo bearing and bearing/tilting failure. Previous research has illustrated the need for design standards to include a gradated bearing coefficient method to account for the behaviour of thin high strength sheet steels, instead of a gross reduction in material properties. This paper provides a summary of results detailing the behaviour of screwed connections tested in shear which have failed in the bearing and bearing/tilting modes. Recommendations concerning the adequacy of current design standards with respect to a proposed formulation which can be used to more accurately predict the shear resistance of screwed connections which fail in the bearing and bearing/tilting modes are presented.

A Simplified Model For Distortional Buckling Of Channels And Zees In Flexure, Duane S. Ellifritt, Robert L. Glover, Jonathan D. Hren

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

Certain cold-formed sections like channels and zees, when subjected to bending in the plane of the web, often fail in laboratory tests at a load less than that predicted by standard specification equations. The mode of failure is an upward movement of the compression flange and lip relative to the web, which may remain fairly plane. When bends which were right angles change dramatically under load, the section changes shape, or distorts, resulting in a reduction of the section stiffness followed by buckling of the flange. Such a failure is referred to as "distortional buckling". An analytical solution to the …

Laterally Braced Cold-Formed Steel Flexural Members With Edge Stiffened Flanges, Benjamin W. Schafer, Teoman Pekoz

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

The moment capacity of a laterally braced cold-formed steel flexural member with edge stiffened flanges (e.g., a channel or zee section) may be adversely affected by local or distortional buckling. Traditional design methods recognize the need to explicitly account for local buckling, but not distortional buckling. Experimental data and numerical analyses suggest that proper strength prediction of laterally braced cold-formed steel flexural members requires explicit treatment of distortional buckling. New procedures for hand prediction of the buckling stress in the local and distortional mode are presented. Numerical investigations are employed to highlight post-buckling behavior unique to the distortional mode. A …

Lateral Load Strength Of Screw Connections In 29ga Metal, G. A. Anderson, V. C. Kelley

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

The results of 300 tests on screwed connections in shear are presented. The load capacity of screws in a row is shown to be additive and screws placed in narrow ribs of 29ga steel have the same strength as screws placed in flat sheets. The AISI equation for tilting strength of screw connections under predicts the strength of the screw connections tested. A regression equation is developed for tilting and compared to the AISI tilting equation and a third party test data. The regression equation is more accurate but less precise than the AISI equation.

The Effect Of Cold Forming On Type 3cr12 Square Tubes, Rudolph Laubscher

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

A non linear finite element simulation is conducted which completely simulates the forming of the tube from flat virgin plate to its final shape. The predicted residual stresses and amount of cold forming in the tube sides and comers are then compared to actual experimental data from cold formed tubes where the initial material properties and the material properties after the cold forming process are known. This illustrates the usefulness of the non linear finite element method in predicting how the material properties change during cold forming and gives a useful insight in what the actual condition of the material …

Analysis Of Hat Sections With Multiple Intermediate Longitudinal Stiffeners, V. V. Acharya, R. M. Schuster

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

This paper is the second paper by the authors on the subject of the behavior of cold formed steel hat sections in bending with multiple intermediate longitudinal stiffeners. The first paper, also contained in these Proceedings, deals with the test results only (Acharya and Schuster, 1998). Presented in this paper is the analysis associated with the test program that was conducted at the University of Waterloo. The main objective was to develop a consistently accurate and practical method of predicting the ultimate bending strength of sections that fail in overall plate buckling. Recent testing carried out by previous researchers indicates …

Shear Plus Bending In Lapped Z-Purlins, Keith Almoney, Thomas M. Murray

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

Six two purlin line, three span continuous Z-purlin tests were conducted to show that combined shear plus bending is a possible failure mode immediately outside the lapped portion of the purlin lines. AISI Specification provisions predicted that combined shear plus bending was the controlling limit state. Strain gage data showed that local buckling occurred immediately outside of the lapped portion of the purlins lines prior to failure which caused moment to redistribute to the positive moment region. It is concluded that shear plus bending is a possible controlling limit state for continuous lapped purlins.

Web Crippling Behaviour Of Cold-Formed Unlipped Channels, Ben Young, Gregory J. Hancock

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

An experimental investigation of cold-formed unlipped channels subject to web crippling is described. The tests were carried out under four loading conditions according to the AISI Specification, namely End-One-Flange (EOF), Interior-One-Flange (IOF), End-Two-Flange (ETF), and Interior-Two-Flange (ITF) loading. The concentrated load or reaction forces were applied by means of bearing plates which acted across the full flange widths of the channels. The web crippling test results are compared with the American Iron and Steel Institute (AISI 1996) Specification and the Australian/New Zealand Standard (AS/NZS 4600-1996) for cold-formed steel structures. The design web crippling strength predictions given by the specifications have …

Web Crippling Of Cold Formed Steel Members, K. Prabakaran, R. M. Schuster

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

A new design expression for web crippling of cold formed steel members has been developed. An extensive statistical analysis was performed using published test data from Canada, the United States, Sweden and France to develop new expressions for the web crippling strength of cold formed steel members under four different loading cases, i.e. (1) end one-flange loading (EOF), (2) interior one-flange loading (lOF), (3) end two-flange loading (ETF) and (4) interior two-flange loading (lTF). I-sections made of two channels connected back-to-back, Z-sections, channels and multiple web sections (decks) were considered. Comparisons were made with the web crippling expressions presented in …

Columns Under Loads Of Varying Eccentricity, J. Rhodes

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

A series of tests on small lipped channel section columns is reported in this paper. The columns were loaded with varying degrees of eccentricity. The eccentricity of loading was produced by offsetting the loading line from the neutral axis of the section, and the offset could be set to a different degree at each end of the column. By this means the effect of moment variation along the column could be examined experimentally and the results compared with the predictions of different design codes for this type of loading. The predictions of the 1986 AISI Specification, the British Standard and …

Shift Of The Effective Centroid Of Channel Columns, Ben Young, Kim J. R. Rasmussen

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

In the design of pin-ended channel columns, it is necessary to account for the shift of the effective centroid caused by local buckling. The current American Iron and Steel Institute (AISI 1996) Specification and the Australian/New Zealand Standard (AS/NZS 4600-1996) for cold-formed steel structures calculate the shift by use of effective widths. However, the ability of the effective width rules to accurately predict this shift has not been experimentally assessed. In this paper, recent tests on fixed-ended channel columns are used to obtain values of the shift of the effective centroid, including its variation with the applied load. In the …

Tests Of Cold-Formed Channel Columns, Ben Young, Kim J. R. Rasmussen

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

The paper presents a series of tests on cold-formed plain and lipped channel columns, compressed between fixed and pinned ends. While it is well-known that local buckling of pin-ended channel columns induces overall bending, this phenomenon does not occur in fixed-ended channel columns which remain straight after local buckling and only bend when overall buckling occurs. These fundamentally different effects of local buckling on the behaviour of pin-ended and fixed-ended channel sections lead to inconsistencies in traditional design approaches, which account for full or partial rotational end restraint solely by using effective lengths. A series of tests was performed on …

A European Design Code For Pallet Racking, M. H. R. Godley, J. Michael Davies

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

The work leading to a European design code for pallet racking started almost 25 years ago. Many difficulties were encountered in the early days of this work. Notable were the absence of a consistent safety philosophy between the various countries of Europe and the existence of procedures with which the manufacturers were comfortable but which were potentially unsafe. There were also difficulties in defining acceptable standard. test procedures. The emergence of Eurocode 3, especially Part 1.3 dealing with cold formed sections, provided a new impetus to the work because here was a European code which provided the required basis for …

Deriving Of Single Intensive Picosecond Optical Pulses From A High-Power Gain-Switched Laser Diode By Spectral Filtering, S. N. Vainshtein, Grigory Simin, J. T. Kostamovaara

Faculty Publications

Single 25 ps/16 W optical pulses were achieved by spectral filtering from a multiheterostructure gain-switched laser diode with its quasisteady-state modes suppressed by a factor of 10³ as compared with the peak power. A significant transient spectrum broadening makes this possible provided that a very high dI/dt rate of the pumping current pulse is used. A simple numerical model is suggested which describes adequately both the spectral and transient features of the observed phenomenon. It follows from the model that single picosecond optical pulses can be obtained from any type of high power semiconductor laser.

Extension Of The Generalized Hebbian Algorithm For Principal Component Extraction, Fredric M. Ham, Inho Kim

Electrical Engineering and Computer Science Faculty Publications

Principal component analysis (PCA) plays an important role in various areas. In many applications it is necessary to adaptively compute the principal components of the input data. Over the past several years, there have been numerous neural network approaches to adaptively extract principal components for PCA. One of he most popular learning rules for training a single-layer linear network for principal component extraction is Sanger's generalized Hebbian algorithm (GHA). We have extended the GHA (EGHA) by including a positive-definite symmetric weighting matrix in the representation error-cost function that is used to derive the learning rule to train the network. The …

Investigation Of A Cyclic Laterally Loaded Model Pile Group, Robb E.S. Moss, Joseph A. Caliendo, Loren R. Anderson

Civil and Environmental Engineering

In certain regions of the world, designing deep foundations to withstand seismic loading is a reality. Seismic loading of structures and foundations reaches its most critical state as a cyclic lateral force. The response of soils and foundations to repetitive lateral forces is highly complex, relegating most design methods to be based upon overly conservative rules-of-thumb. The primary objective of this research was to analyze the mechanics of seismic loading on pile groups in clay soils. To achieve this a model testing facility was constructed to house a fully instrumented 1 X 5 model pile group that was subjected to …

Fuzzy Logic Control Of A Model Airplane, Jon C. Ervin, Sema E. Alptekin

Industrial and Manufacturing Engineering

Common uses of fuzzy logic control today are found in relatively simple applications in products. These applications only scratch the surface of the potential of fuzzy logic control in complex mechatronic systems. In order to demonstrate the utility of fuzzy logic in complex device control, a fuzzy logic fly-by-wire system has been developed for a model airplane. The model airplane is a complex system of several critical inputs that require rapid processing and action in order to maintain flight stability. In addition, payload and power constraints severely limit the size, weight and processing power of the hardware to be carried …

Processing Of Hydroxylapatite Coatings On Titanium Alloy Bone Prostheses, Michael A. Nastasi, Timothy E. Levine, James W. Mayer, Vincent B. Pizziconi

Department of Mechanical and Materials Engineering: Faculty Publications

Processing of hydroxylapatite Sol-gel films on titanium alloy bone prostheses. A method utilizing non-line-of-Sight ion beam implantation and/or rapid thermal processing to provide improved bonding of layers of hydroxylapatite to titanium alloy Substrates while encouraging bone ingrowth into the hydroxylapatite layers located away from the substrate, is described for the fabrication of prostheses. The first layer of hydroxylapatite is mixed into the Substrate by the ions or rapidly thermally annealed, while Subsequent layers are heat treated or densified using ion implantation to form layers of decreasing density and larger crystallization, with the outermost layers being Suitable for bone ingrowth.

Method For Improving The Pozzolanic Character Of Fly Ash, John G. Groppo Jr., Thomas L. Robl, Charles J. Mccormick

Center for Applied Energy Research Faculty Patents

A method for improving the pozzolanic character of fly ash includes the steps of first hydraulically classifying and then flotation separating the fly ash in order to reduce particle size distribution and remove carbon. The method also includes the steps of spiral concentrating separated coarse particles to recover iron, pyrite and marcasite and screening the fly ash to remove ultra-light carbon and plant debris.

Acuta Enews October 1998, Vol.27, No. 10

ACUTA Newsletters

In This Issue

FCC Approves Two-Way Digital ITFS and MDS Communications

Recognizing Our Best

Board Report

DC at a Glance

Positions Available

Welcome New Members

Optimum Control Of A Hybrid System For Seismic Excitations With State Observer Technique, Franklin Y. Cheng, Hongping Jiang

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

This paper presents a theoretical study of a hybrid seismic response control system comprising a passive fluid viscous damper and an active control system with a hydraulic actuator and acceleration sensors. The analytical model of this system is derived in the discrete time domain with actuator and clamper dynamics considered. Based on digital control theory, a state observer is established for optimal control strategies of the hybrid system. This study shows that the hybrid system gains the advantages of both active and passive control techniques currently in vogue; and that, with the state observer technique, a seismic response control system …

Microstructures And Mechanical Properties Of Two-Phase Alloys Based On Nbcr2, Katherine C. Chen, Paul G . Kotula, Carl M. Cady, Michael E. Mauro, Dan J. Thoma

Materials Engineering

A two-phase, NbCrTi alloy (bcc + C15 Laves phase) has been developed using several alloy design methodologies. In efforts to understand processing-microstructure-property relationships, different processing routes were employed. The resulting microstructures and mechanical properties are discussed and compared. Plasma arc melted (PAM) samples served to establish baseline, as-cast properties. In addition, a novel processing technique, involving decomposition of a supersaturated and metastable precursor phase during hot isostatic pressing (HIP), was used to produce a refined, equilibrium two-phase microstructure. Quasi-static compression tests as a function of temperature were performed on both alloy types. Different deformation mechanisms were encountered based upon temperature …

Modern Water Control And Management Practices In Irrigation: Impact On Performance, Charles M. Burt, Stuart W. Styles

BioResource and Agricultural Engineering

This research addressed the basic questions of what levels of water delivery service are presently provided by irrigation projects having some aspect of modernization; what hardware and software features impact those levels of service; whether modern water control and management practices in irrigation make a positive difference in performance; and what universal lessons can be learned and applied.

Ole Miss Engineer 1998

Ole Miss Engineer

No abstract provided.