Civil and Environmental Engineering Commons^™

Self-Shape Optimisation Of Cold-Formed Steel Columns, Benoit P. Gilbert, Timothee J-M Savoyat, Lip H. The

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

This paper presents the optimisation of cold-formed steel open columns using the recently developed self-shape optimisation method that aims to discover new profile shapes. The strength of the cold-formed steel sections is calculated using the Direct Strength Method, and the rules developed in the present work to automatically determine the local and distortional elastic buckling stresses from the Finite Strip and constrained Finite Strip Methods are discussed. The rules are verified against conventional and optimum sections yielded in this research, and found to accurately predict the elastic buckling stresses. The principles behind the self-shape optimisation method are summarised herein and …

Innovative Cross-Section Shapes For Built-Up Cfs Columns. Experimental Investigation, Iveta Georgieva, Luc Schueremans, Lincy Pyl, Lucie Vandewalle

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

Innovative cross-section shapes for built-up columns from cold-formed steel (CFS) profiles are evaluated experimentally. The goal is to obtain highly stable members with reduced sensitivity to bucking effects and initial imperfections, and therefore, higher strength-to-weight ratios. The columns have been designed following the principles of the direct strength method [1], with the ambition to exclude (or reduce) various buckling effects from the column response to compressive loads. Cross-section proportions and bolt spacing have been adapted, in order to interfere with the distortion of individual profiles and the overall buckling of the columns. Experiments show that, through proper design and insight …

Compressive Strength Tests And Design Of Cold-Formed Plain And Dimpled Steel Columns, V. B. Nquyen, C. J. Wang, D. J. Mynors, M. A. English, M. A. Castellucci

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

This paper presents the experiments and design formulae of cold-formed plain and dimpled steel columns. A series of compression tests on plain and dimpled channel columns were conducted over a range of different geometries and the strength of the columns were investigated. The change in strength of the dimpled columns resulting from the cold working associated with the dimpling process was considered. The results showed that the buckling and ultimate strengths of dimpled steel columns were up to 33% and 26% greater than plain steel columns, respectively. The test results were evaluated by comparing buckling and ultimate loads of plain …

Steel Deck Institute Standards For Composite Steel Floor Deck-Slabs, Thomas Sputo

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

As an ANSI accredited standards developer, the Steel Deck Institute (SDI) has developed an updated and expanded version of its “Standard for Composite Steel Floor Deck-Slabs”, ANSI/SDI C-2011 and a new standard, “Test Standard for Composite Steel Deck-Slabs”, ANSI/SDI T-CD-2011. These two standards reflect the current state-of-the-art for the design and testing of composite steel deck-slabs where the steel deck provides the tensile reinforcement for the slab. Substantial changes in the ANSI/SDI-C-2011 Standard include increased information regarding the use of fibers for concrete crack control purposes and concrete serviceability, consideration of moving and concentrated loads, and use of updated shear …

Aisi Standards Update, Helen Chen, Roger Brockenbrough, Richard Haws

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

Since the publication of the 2007 editions, changes and additions have been made to AISI design and construction standards. Accordingly, new editions of the standards, or supplements to existing standards, will be published to formalize these changes. This paper provides an overview of the major changes and additions to those standards.

Direct Strength Method Of Design For Shear Of Cold-Formed Channels Based On A Shear Signature Curve, Gregory J. Hancock, Cao Hung Pham

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

Thin-walled sections in compression and/or bending may undergo one of the three modes of local, distortional or overall (Euler) buckling, or combinations of these. The Semi-Analytical Finite Strip Method (SAFSM) developed by YK Cheung has been widely used in computer software (THIN-WALL, CUFSM) to develop the signature curve of the buckling stress versus buckling half wavelength for a thin-walled section under compression or bending to allow identification of these modes. The minimum points on the signature curve are now used in the Direct Strength Method (DSM) of design of cold-formed sections in the American Specification and Australian/New Zealand Standard for …

Shear Strength Of Hollow Flange Channel Beams With Stiffened Web Openings, P. Keerthan, M. Mahendran

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

This LiteSteel beam (LSB) is a new cold-formed steel hollow flange channel section produced using a patented manufacturing process involving simultaneous cold-forming and dual electric resistance welding. The LSBs are commonly used as floor joists and bearers with web openings in buildings. Their shear strengths are considerably reduced when web openings are included for the purpose of locating building services. Shear tests of LSBs with web openings have shown that there is up to 60% reduction in the shear capacity. Hence there is a need to improve the shear capacity of LSBs with web openings. A cost effective way to …

The Effects Of Web Holes On Web Crippling Strength Of Cold-Formed Steel Channels Under End-Two-Flange Loading Condition, Asraf Uzzaman, James B. P. Lim, David Nash, Jim Rhodes, Ben Young

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

Cold-formed steel sections are often used as wall studs or floor joists; such sections often include web holes for ease of installation of the services. Web crippling at points of concentrated, or localised, load or reaction in thin-walled beams is well known to be a significant problem, particularly in the case of beams with slender webs, and is of high importance in the field of cold-formed steel members, as such members are generally not stiffened against this type of loading. In this paper, a combination of experimental tests and non-linear elastoplastic finite element analyses are used to investigate the effect …

Push Tests On Innovative Shear Connector For Composite Beam With Cold-Formed Steel Section, S. O. Bamaga, M. M. Tahir, C. S. Tan

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

In this study, experimental tests were conducted to investigate the ductility and strength capacity of new shear connector. Push test specimens were prepared and tested according to EN1994-1-1 standard. The push test specimen consists of two cold-formed steel lipped channel sections oriented back-to-back to form an I-section beam, transverse metal deck and normal concrete slabs grade C25/30. Angle brackets were obtained from the same section of the beam and fastened to the web of steel beam to provide the shear connection. Two shear connectors were tested namely; “SC1” and “SC2” shear connectors. Both shear connectors showed a ductile behavior and …

Direct Strength Design Of Metal Building Wall And Roof Systems - Through-Fastened Simple Span Girts And Purlins With Laterally Unbraced Compression Flanges, Tian Gao, Cristopher D. Moen

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

A Direct Strength Method (DSM) prediction approach is introduced and validated for metal building wall and roof systems constructed with steel panels through-fastened with screws to girts or purlins. The focus is capacity prediction for simple spans under wind uplift or suction, however the DSM framework is generally formulated to accommodate gravity loads, continuous spans, standing seam roofs, and insulated roof and wall systems in the future. System flexural capacity is calculated with the usual DSM approach – global buckling, local global buckling interaction, and distortional buckling strengths are determined with a finite strip eigen-buckling analysis including a rotational spring …

An Explicit, Dynamic Finite Element Model For The Local Failure Of Cold-Formed Trapezoidal Sheeting, Hèrm Hofmeyer

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

Trapezoidal sheeting, made of cold-formed, thin-walled steel, is widely used for the construction of cladding and roofs. At an interior support, the sheeting is subject to bending moments and a concentrated load, which leads to possible failure followed by two post-failure modes: the yield-arc and yield-eye modes. Until recently, it was not fully understood why a specific post-failure mode occurs and it was suggested that mode-jumping of the compressed sheeting flange may influence the mode occurring. This paper presents new research, in which both the compressed flange in isolation and the sheeting are modeled by using an explicit, dynamic finite …

Design Of Perforated Industrial Storage Rack Columns For Distortional Buckling, Teoman Peköz, Güven Kıymaz, Miquel Casafont, Maria Magdalena Pastor, Jordi Bonada

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

The results of an on-going research program to develop a design procedure for perforated industrial storage rack columns are presented. The design procedure includes the effects of distortional buckling. The types of columns studied include those commonly used in Europe and some that are used in the US. The design procedure is being developed based on finite element studies verified by physical testing. The design procedure involves the use of the current US rack column design approach with an extension to distortional buckling with Finite Strip Method (FSM) solutions and Direct Strength Method (DSM) approaches. The approach originally developed for …

Advanced Design Optimization Of Cold-Formed Steel Portal Frame Buildings, Duoc T. Phan, James B. P. Lim, Tiku T. Tanyimboh, Wei Sha

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

The design optimization of cold-formed steel portal frame buildings is considered in this paper. The objective function is based on the cost of the members for the main frame and secondary members (i.e., purlins, girts, and cladding for walls and roofs) per unit area on the plan of the building. A realcoded niching genetic algorithm is used to minimize the cost of the frame and secondary members that are designed on the basis of ultimate limit state. It is shown that the proposed algorithm shows effective and robust capacity in generating the optimal solution, owing to the population’s diversity being …

Using Generalized Beam Theory (Gbt) To Assess The Buckling Behavior Of Cold-Formed Steel Structural Systems, Cilmar Basaglia, Dinar Camotim

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

This paper deals with the application of beam finite element models based on Generalized Beam Theory (GBT) to analyze the buckling behavior of three cold-formed steel structural systems, namely (i) beams belonging to storage rack systems, (ii) portal frames built from rectangular hollow section (RHS) profiles and (iii) roof-supporting trusses, exhibiting different support conditions and subjected to various loadings. In particular, taking advantage of the GBT unique and structurally clarifying modal features, it is possible to assess how different geometries and/or bracing arrangements affect (improve) the local, distortional and/or global buckling behavior of the above structural systems. The accuracy of …

Investigation Of Behavior Of Cold-Formed Steel Sheeting Systems In Fire Using Finite Element Modeling, W. Lu, P. Mäkeläinen, J. Outinen, Z. Ma

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

A 3D Finite Element (FE) model of steel sheeting, which includes the screw connector and support plate, is created to investigate the behavior of both steel sheeting and connections at elevated temperatures. The created model considers the material nonlinearity, large deformation and contact behavior. The material damage model for sheeting steel is defined so that the FE model is analyzed through the elastic and plastic ranges up to failure. The FE model is used to predict the ultimate resistance and deformation. The current FE model captures the main behavior of steel roof systems well up to around 20 minutes according …

Active Shear Planes In Block Shear Failure Of Bolted Connections, Drew D. A. Clements, Lip H. Teh

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

In the AISI Specification for the Design of Cold-formed Steel Structural Members 2007, there are two types of shear planes used to determine the resistance of a bolted connection to block shear failure. When the block shear failure occurs by shear yielding and tensile rupture, the shear failure plane is taken to be the gross shear plane. Conversely, when the block shear failure is deemed to occur by simultaneous shear and tensile ruptures, the shear failure plane is assumed to be the net shear plane. Such an approach is not logical since the shear failure planes should be unique irrespective …

In-Plane Shear Lag Of Bolted Connections, Lip H. Teh, Benoit P. Gilbert

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

This paper points out that the shear lag factors embedded in the design equations specified in the North American, European and Australasian cold-formed steel structures codes for determining the net section tension capacity of bolted connections in flat steel sheets either yield “anomalous” results or become irrelevant when they exceed unity. The anomaly is demonstrated through laboratory tests and is explained using simple calculus. A proper mathematical expression for the in-plane shear lag factor, which does not suffer from the anomaly of the code equations and never implies shear lag factors greater than unity for any configuration, is presented and …

Prediction Of Joint Temperatures In Shot-Nailed Cold-Formed Steel Sheeting With Finite Element Modelling, Z. Ma, W. Lu, P. Mäkeläinen, J. Outinen

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

This paper investigates the 3D temperature fields of the shot-nailed steel roof sheeting joints in fire using commercial Finite Element (FE) software ABAQUS when the connected members and connections are protected by either intumescent paint or rockwool panels. Numerical models and parameters used in the models are briefly introduced. When expanded in fire, both thickness and thermal conductivity are varied with increased temperatures. The simplified representation of intumescent paint is described. Parametric analyses are performed in order to investigate the sensitivity of the parameters of thermal contacts. When the joints are protected with rockwool panels, the approximate cavity radiation method …

Modal Identification Of Cold-Formed Steel Members In Shell Finite Element Models, Z. Li, S. Ádány, B. W. Schafer

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

This paper illustrates new capabilities for modal identification of shell Finite Element Method (FEM) models of thin-walled cold-formed steel members. The separation of general deformations into fundamental buckling deformation classes: local, distortional, global, shear, and transverse extension, originated with the constrained Finite Strip Method (cFSM) and is extended here to shell element based FEM analysis. The cFSM base vectors for general end boundary conditions, previously developed by the authors, provide a series of general base functions capable of separating displacements into classes. FEM displacements are identified by minimizing error between the actual FEM displacements and those predicted by the cFSM …

Analytical Model For Cold-Formed Steel Framed Shear Wall With Steel Sheet Sheathing, Noritsugu Yanagi, Cheng Yu

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

The cold-formed steel framed shear wall sheathed with steel sheet sheathing (CFS-SSSW) is a code approved lateral force resisting system for light framed construction. The AISI Steel Framing Standards – Lateral Design (AISI S213-07) provides design provisions for CFS-SSSW. The development of the nominal strength of CFS-SSSW in AISI S213 was based on full-scale experiments which were subjected to limitations in both wall configurations and material properties. This paper presents an analytical model – the Effective Strip Model developed for predicting the nominal strength of CFS-SSSWs. The proposed analytical model and supporting design equations are further verified by experimental results. …

Using Nwp Analysis In Satellite Rainfall Estimation Of Heavy Precipitation Events Over Complex Terrain, Xinxuan Zhang

Master's Theses

This study investigates the use of Weather Research and Forecasting (WRF) high-resolution storm analysis in satellite rainfall estimation over complex terrains. Rainfall estimation here is based on the NOAA-Climate Prediction Center morphing (CMORPH) product. Specifically, CMORPH rainfall is adjusted by applying a power-law function whose parameter values are obtained from the comparison between WRF and CMORPH hourly rain rates. Results are presented based on the analyses of five storm cases that induced catastrophic floods in southern Europe. The WRF-based adjusted CMORPH rain rates exhibited improved error statistics against independent radar-rainfall estimates. We show that the adjustment reduces the underestimation of …

Network- Level Pavement Performance And Management Study In Connecticut, Ramandeep S. Josen

Master's Theses

This thesis presents the analysis of asphalt pavement cracking data on the network level in Connecticut. Pavement performance indicators including longitudinal and transverse cracking as well as roughness are investigated with respect to numerous distinct factors that can be grouped into three categories, i.e. climatic-, pavement structure-, and traffic-related. High-quality climatic data was obtained from the national weather stations in Connecticut. Maintenance and construction data was used to determine the pavement age and structure amongst several other factors. Traffic data was acquired from the state records and accumulated traffic loading was estimated for all segments based on their age. High …

The Effects Of Bolt Pretension, In-Plane Eccentricity, And Friction On The Ductility Of Block Shear Connections, Kevin M. Zmetra

Master's Theses

Block shear is a complex failure mechanism in bolted and welded steel components such as gusset plates, webs of coped beams, angles and tees. It presumes a combination of tension rupture and shear yield. Multiple variables affect the block shear capacity and ductility of a connection. This study investigates the effects of bolt pretension, connection eccentricity and friction force transfer through a series of destructive experiments followed by refined finite element simulation. Clamping forces create a complex triaxial stress field compounded by the stress concentration at the bolt holes. In-plane load eccentricity with respect to the centerline of the connection …

Safety Stock Estimation Of Unit Load Devices For International Airline Operations, Hua-An Lu, Chien-Yi Chen

Journal of Marine Science and Technology–Taiwan

Unit load devices (ULDs) are used to load air cargo and passengers’ checked baggage for wide-bodied aircraft operations. Since ULDs are reusable at the destination, airlines can invest in an appropriate fleet size for their requirements. The estimation of safety stock levels for every operating airport is a premeditated task because airlines must prepare enough devices for the outbound consignments of each flight. The variance of the number of used devices for each arrival and departure flight will influence the stock level of an airport. For scheduled international services, this study proposes an analytic method based on a cyclically time-sequenced …

A Proposal On Standard Rudder Device Design Procedure By Investigation Of Rudder Design Process At Major Korean Shipyards, Hyun-Jun Kim, Sang-Hyun Kim, Jung-Keun Oh, Dae-Won Seo

Journal of Marine Science and Technology–Taiwan

Recently, a very large vessel’s maneuvering performance, rudder performance and rudder design’s importance are considered to be an important subject. However, there have been few studies on the design process of rudder device before. The aim of this paper is to investigate a design process of rudder device and to propose a generalized design process of rudder device. Firstly, we investigated the rudder device design process of Korean major shipyards. And the differences of a torque calculation method, rudder section design, maneuvering performance examination method, etc. were analyzed theoretically. Secondly, the design process of rudder device was divided into concept …

Lateral Resistance Of Piles Near Vertical Mse Abutment Walls, Jacob S. Price

Theses and Dissertations

Full scale lateral load tests were performed on five piles located at various distances behind MSE walls. Three of the five test piles were production piles used to support bridges, and the other two piles were located behind a MSE wing walls adjacent to the bridge abutment. The objective of the testing was to determine the effect of spacing from the wall on the lateral resistance of the piles and on the force resisted by the MSE reinforcement. Tentative curves have been developed showing p-multiplier vs. normalized spacing behind wall for a length to height ratio of 1.1 and 1.6. …

Impact Of Salt On Denitrification Potential In Roadside Environments, Nakita A. Lancaster

Master's Theses

Urban systems are impacted by changes in hydrology and water chemistry, altering their ability to mitigate detrimental impacts to coastal water bodies, particularly those that result from high volumes of stormwater runoff. The elevated level of impervious cover increases not only runoff but also contaminant loading of nutrients, metals, and road salt used for deicing in cold weather climates. Current stormwater management strategies, while focused on managing the changes in hydrology associated with urbanization, also are designed to mitigate the pollutant loading. Here we investigate the impact that road salt will have on nitrogen removal in roadside environments. Sediments were …

Creek And Lake Water Analysis Of The Little Calumet East Branch Watershed, Nicholas H. Feller, Melissa Dorton

Symposium on Research and Creative Expression (SORCE)

The overall goal of this project is to collect and analyze baseline water quality data in the Little Calumet East Branch (LCEB) watershed. This watershed spans portions of Porter and LaPorte counties in northwest Indiana and drains into Lake Michigan. The LCEB currently has impaired water quality. The Indiana Department of Environmental Management (IDEM) has awarded Save the Dunes Conservancy Foundation a two year grant to develop and implement a Watershed Management Plan to improve water quality. During the summer of 2012, the following water quality parameters were collected weekly from 15 sites spread throughout the watershed: 1) pH, 2) …

Municipal Wastewater Disinfection With Electromagnetic Waves Using Escherichia Coli Concentration As Measurement Of Quantification, Lauren M. Cagle

LSU New Orleans Theses and Dissertations

Wastewater treatment is essential to protecting the environment and human welfare. Although chlorination is widely used, the environmental and health concerns associated with chlorine are growing. Treatment facilities are implementing alternative technologies, though the cost and efficiency associated with these practices leave much room in the wastewater field for innovation.

Hydropath Technologies Limited introduced a piece of equipment that uses the properties of a transformer to pass an alternating electric current through the pipe and into the contents of the channel. Hydroflow claims that the charged microorganisms react with the oppositely charged water molecule to force osmosis and kill the …

Electric Currents Due To Stress-Activated Positive Hole Charge Carriers In Ice, Cary T. Keller P.E., Friedemann T. Freund, Dale P. Cruikshank

STAR Program Research Presentations

Jupiter’s satellite Europa, whose surface is composed of ice with a possible water ocean beneath, could conceivably serve as an abode for extraterrestrial life. This and other icy celestial bodies may contain organic macromolecular solid material that is produced when surface ices are exposed to ultraviolet radiation and/or electrical energy. Tidal and tectonic stresses or meteorite impacts in icy crusts may produce electrical discharges, which would provide the energy for in-situ synthesis of the organic solids. This electrical energy can be provided by positive hole charge carrier activation. Positive holes exhibit properties such as the ability to flow out of …