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22nd International Specialty Conference: Recent Research And Developments In Cold-Formed Steel Structures, Wei-Wen Yu Center For Cold-Formed Steel Structures

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

No abstract provided.

Finite Element Analysis Of Cold-Formed Dimpled Steel Columns, V. B. Nguyen, M. A. English, M. A. Castellucci

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

Dimpled steel products are produced from the combination of an innovative dimpling process and a traditional forming process such as cold-roll forming or press-braking. The wider use of cold-formed dimpled steel members has promoted considerable interest in the local instability and strength of these members. Of particular interest is their buckling behaviour and ultimate strength capacity. However, the dimpling process produces cold-formed sections with a complex ‘dimpled’ surface topography and the ‘dimpled’ material is nonuniformly work hardened through the entire thickness. Owing to these complex issues, there are no existing methods to calculate the buckling strength of the dimpled products …

Compressive Strength Of Cold-Formed Steel C-Shape Columns With Slotted Holes, L. Xu, Y. Shi, S. Yang

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

Presented in this paper is an experimental investigation on the effect of web holes on the strength of cold-formed steel (CFS) C-shape columns. A total of 18 CFS C-shape stub columns were tested without and with web holes. The column length and web height of C-shape section were 490 mm (19 in) and 150 mm (6 in), respectively; and the lengths of the holes investigated were 74 mm (3 in), 114 mm (4.5 in) and 130 mm (5 in) whereas the width of the holes remains as 38 mm (1.5 in). It is noted that for the strength determination of …

On The Influence Of Local-Distortional Interaction In The Behavior And Design Of Cold-Formed Steel Web-Stiffened Lipped Channel Columns, André D. Martins, Pedro Borges Dinis, Dinar Camotim, Paulo Providência

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

This paper reports the results of a numerical (ABAQUS shell finite element analysis) investigation on the influence of local-distortional (L-D) interaction in the ultimate strength and design of cold-formed steel fixed-ended web-stiffened lipped channel columns -- hereafter termed “WSLC columns”. These results concern columns with various geometries and yield stresses, ensuring a wide variety of combined ratios between (i) the distortional and local critical buckling stresses, and (ii) the yield and the higher of the above buckling stresses. The objectives of this work are two-fold: (i) to acquire in-depth understanding on the mechanics underlying the L-D interaction in the WSLC …

Numerical Studies On The Composite Action And Buckling Behavior Of Built-Up Cold-Formed Steel Columns, Davide C. Fratamico, Benjamin W. Schafer

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

An exploratory study is performed herein on the global, local, and distortional buckling behavior of built-up cold-formed steel members constructed using industry standard lipped channel sections. The stability characteristics of these columns under concentric axial compressive loads offers insights on member assembly (e.g. fastener spacing), and on the prediction of buckling loads (e.g., section rigidities) used in design formulations. Currently, built-up column buckling is determined using a modified flexural slenderness ratio, which reduces the buckling capacity in part due to a loss of shear rigidity in the overall member’s interconnections. In this paper, a numerical study is performed to analyze …

Gbtul 2.0 −A New/Improved Version Of The Gbt-Based Code For The Buckling Analysis Of Cold-Formed Steel Members, Rui Bebiano, Dinar Camotim, Rodrigo Gonçalves

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

This paper presents the very recent 2.0 release of software GBTUL – a computer code developed by the authors and made available as freeware at the website of the Department of Civil Engineering of the Technical University of Lisbon (Bebiano et al. 2013). The program performs linear buckling and vibration analyses of thin-walled bars based on Generalized Beam Theory (GBT), a bar theory that accounts for cross-section deformation. Its domain of application is much wider than that of the previous release (1.0ß): indeed, it is now possible to analyze single or multi-span members (i) with various support conditions, including those …

Shape Optimisation Of Cold-Formed Steel Profiles With Manufacturing Constraints - Part I: Algorithm, Bin Wang, Benoit P. Gilbert, Adrien M. Molinier, Hong Guan, Lip H. Teh

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

This paper presents a Genetic Algorithm optimisation method with manufacturing constraints for shape optimisation of cold-formed steel (CFS) profiles. Previous studies on unconstrained shape optimization of CFS crosssections, where the sole aim was to optimise the weight-to-capacity ratio of the profiles, yielded cross-sections that cannot be manufactured. Current coldforming processes, such as roll-forming and brake-pressing, have limited ability to form continuously curved surfaces without discrete bends. This paper defines simple manufacturing rules and introduces them into the evolutionary algorithm. Augmented Lagrangian constraint-handling technique, with equality and inequality constrained violations, is used to avoid ill-conditioned problems. The ability and accuracy of …

Shape Optimisation Of Cold-Formed Steel Profiles With Manufacturing Constraints - Part Ii: Applications, Bin Wang, Benoit P. Gilbert, Adrien M. Molinier, Hong Guan, Lip H. Teh

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

This paper uses the Genetic Algorithm (GA)-based optimisation method for cold-formed steel (CFS) profiles with manufacturing constraints, developed in the companion paper, to shape-optimise simply-supported and singly-symmetric open-section columns. Having a uniform wall thickness of 0.047 inch (1.2 mm), the columns are subjected to a compressive axial load of 16,860 lbf (75kN) and optimised for yielding and global buckling. Column lengths ranging from 3.28 ft (1,000 mm) to 9.84 ft (3,000 mm) are investigated. The algorithm is run with and without considering the manufacturing constraints. Differences between the two types of cross-sections, i.e. manufacturable and non-manufacturable, are evaluated. The influence …

Understanding The Global Buckling Behavior Of Thin-Walled Members With Slotted Web, B. Geleji, M. Szedlák, D. Visy, S. Ádány

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

In this paper flexural buckling of thin-walled members with holes are discussed. Members with few but large openings, as well as with slotted webs are studied. Large number of finite element analyses has been performed, by using a carefully constrained shell finite element model in order to exclude the distortion of the cross-section, which makes it possible to analyze flexural buckling separately from other modes. Based on the results general conclusions are drawn regarding the global behavior of members with holes. Moreover, analytical models are developed for column members with slotted webs, with neglecting or with considering the effect of …

Improved Effective Width Method Considering Distortional Buckling For Cold-Formed Thin-Walled Steel Members With Lipped Channel Section, Xingyou Yao, Yuanqi Li

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

The local buckling, distortional buckling, and overall buckling would occur for cold-formed thin-walled steel members with lipped channel section. The effective width method is used to considering the effect of local and distortional buckling on load-carrying capacity of member in Chinese code. Especially, a very conservative stability coefficient of partially stiffened elements used to considering the local buckling and distortional buckling of flange of lipped channel sections. In this paper, the half-wave length, the elastic buckling stress of distortional-buckling of cold-formed thin-walled steel members with lipped channel section and the corresponding stability coefficient of partially stiffened elements were developed based …

Laser Scanning To Develop Three-Dimensional Fields For The Precise Geometry Of Cold-Formed Steel Members, Xi Zhao, Benjamin W. Schafer

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

Geometric imperfections play an important role in the performance and behavior of cold-formed steel members. The objective of this paper is to detail a newly developed imperfection measurement rig, where the full three-dimensional (3D) imperfect geometry of a cold-formed steel member can be measured and reconstructed. The measurement results in a dense three-dimensional point cloud that may be utilized to provide precise knowledge of the basic member dimensions (width, angle, radius including variation along the length), frequency content in the member (waviness, local dents, etc.), or directly as the exact geometry of the member. Practical applications of the data include …

Tailoring Compression Performance Of Cold-Formed Steel Columns, Talha Ekmekyapar, M. Tolga Göğüş, Mustafa Özakça

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

Since thin-walled structural analysis and design procedures are utilized for cold-formed steel columns, it is first necessary to understand thin plate behavior to employ proper cross sections which will serve under compression actions. As is well known, thin plates without any longitudinally and/or laterally stiffening elements usually are not present in structural applications. These stiffening elements significantly improve local buckling and collapse characteristics of plates, providing optimized solutions in terms of strength and cost. In cold-formed steel industry there exist some tailoring methods for columns to use the cross-section material more effectively. Designing lipped channels instead of plain ones or …

Cold-Formed Steel Lipped Channel Columns Undergoing Local-Distortional-Global Interaction: Experimental And Numerical Investigation, Eliane S. Santos, Pedro Borges Dinis, Eduardo M. Batista, Dinar Camotim

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

Experimental and numerical results concerning the post-buckling behavior and strength of fixed-ended cold-formed steel lipped channel columns experiencing interaction involving local, distortional and global buckling (i.e., stemming from the closeness between the critical buckling stresses associated with these three buckling mode types), are reported. After briefly addressing the column specimen geometry selection, the paper presents and discusses the results of an experimental investigation carried out at COPPE, Federal University of Rio de Janeiro (UFRJ, Brazil) and involving 16 columns − its output consists of steel material properties, initial imperfection measurements, equilibrium paths and failure loads/modes. Then, some test results are …

Cold-Formed Steel Channel Sections With Web Stiffeners Subjected To Local And Distortional Buckling — Part I: Tests And Finite Element Analysis, Liping Wang, Ben Young

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

An experimental investigation of simply supported beams with two different stiffened channel sections has been conducted under both four-point bending and three-point bending about the major axis of the sections. Stiffeners were employed to the web of plain channel and lipped channel sections to improve the flexural strength of cold-formed steel sections that are prone to local buckling and distortional buckling. In this study, the channel sections were brake-pressed from high strength zinc-coated grades G500 and G550 structural steel sheets with nominal 0.2% proof stresses of 500 and 550 MPa, respectively. The high strength stiffened channel sections had the thicknesses …

Numerical Studies Of Rivet-Fastened Rectangular Hollow Flange Channel Beams, R. Siahaan, P. Keerthan, M. Mahendran

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

The rivet-fastened rectangular hollow flange channel beam (RHFCB) is a new cold-formed hollow section proposed as an alternative to welded hollow flange beams. It is a monosymmetric channel section made by rivet-fastening two torsionally rigid rectangular hollow flanges to a web plate. This method will allow the designers to develop optimum sections, with affordable rivet connection between their web and flange elements. In addition to this unique geometry, the rivet-fastened RHFCBs also have unique characteristics relating to their stress-strain characteristics, residual stresses, initial geometric imperfections and hollow flanges that are not encountered in conventional hot-rolled and cold-formed steel channel sections. …

Section Moment Capacity Tests Of Rivet-Fastened Rectangular Hollow Flange Channel Beams, R. Siahaan, P. Keerthan, M. Mahendran

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

The rivet-fastened rectangular hollow flange channel beam (RHFCB) is a new cold-formed hollow section proposed as an alternative to welded hollow flange steel beams. It is a mono-symmetric channel section made by rivet fastening two torsionally rigid rectangular hollow flanges to a web plate. This method will allow the designers to develop optimum sections, with affordable rivet connection between the web and flange elements. The new rivet-fastened RHFCB has unique characteristics that are not encountered in conventional hot-rolled and cold-formed steel channel sections. Therefore an experimental study consisting of 15 section moment capacity tests was conducted with different rivet spacings …

Developments In The Finite Strip Buckling Analysis Of Plates And Channel Sections Under Localised Loading, Gregory J. Hancock, Cao Hung Pham

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

Thin-walled sections under localised loading may lead to web crippling of the sections. This paper develops the Semi-Analytical Finite Strip Method (SAFSM) for thin-walled sections subject to localised loading to investigate web crippling phenomena. The method is benchmarked against analytical solutions, Finite Element Method (FEM) solutions, as well as Spline Finite Strip Method (SFSM) solutions.

The Behaviour Of Cold-Formed C-Sections With Square Holes In Shear, Cao Hung Pham, Yu Han Chin, Peter Boutros, Gregory J. Hancock

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

Cold-formed structural C-section members may be subjected to axial force, bending and shear or combinations of either two or all of these actions. 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 (2012). Both Effective Width Methods (EWM) and the newly developed Direct Strength Method (DSM) can be used for the design. For shear, the NAS S100 2012 Edition has recently included DSM design rules just for the plain sections only. To date, no rules are presented in this specification …

Experimental Study Of Longitudinally Stiffened Web Channels Subjected Predominantly To Shear, Luciano A. Bruneau, Cao Hung Pham, Gregory J. Hancock

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

The Direct Strength Method (DSM) of design of cold-formed sections has recently been extended in the North American Specification for Cold-Formed Steel Structural Members-NAS S100:2012 to include shear. The two new features of the DSM rules for shear researched are the effect of full-section shear buckling as opposed to web-only shear buckling and Tension Field Action (TFA). The prequalified sections in the rules include sections with flat webs and webs with small intermediate longitudinal stiffeners. In order to extend the range to larger intermediate stiffeners as occurs in practice, a series of fourteen shear tests have been performed at the …

Numerical Studies Of Collapse Behaviour Of Multi-Span Beams With Cold Formed Sigma Sections, F. L. Wang, J. Yang, J. Lim

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

Multi-span cold-formed steel beams are widely used for roof purlin and cladding rails due to their high strength to weight ratio and ease of installation on site. There are a wide variety of cross-sectional shapes e.g. C, Z, top hat and sigma sections. A sigma section possesses several advantages such as high cross-sectional resistances and large torsional rigidities compared with standard Z or C sections.

Traditional design methods for cold-formed multi-span steel beams have been based on elastic theory, such as the Effective Width Method (EWM) and the Direct Strength Method (DSM). Both methods ignore the effect of redistribution of …

Development Of A New Beam-Column Design Method For Cold-Formed Steel Lipped Channel Members, Shahabeddin Torabian, Baofeng Zheng, Benjamin W. Schafer

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

The structural strength of cold-formed steel lipped channels under combined axial force and biaxial bending moments has been predicted by geometric and material nonlinear collapse analyses performed in ABAQUS and compared to both current, and a newly proposed, beam-column design method. The ABAQUS analyses utilizes a validated modeling protocol calibrated against previous testing by the authors, and including residual stresses and strains, and geometric imperfections; as well as, appropriate cross-section dimensions, member length, and boundary conditions. A total of 75 different lipped channel cross-sections have been selected and the capacity of the beam-column member has been examined under 127 combinations …

Experimental Investigation On Ultimate Capacity Of Eccentrically-Compressed Cold-Formed Beam-Columns With Lipped Channel Sections, Yuanqi Li, Yinglei Li, Yanyong Song

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

This paper is mainly concerned with the in-plane behavior of eccentrically-compressed cold-formed steel beam-columns with lipped channel sections. The tested members are classified into three series by loading types including: axial compression and major axis bending (X), axial compression and minor axis bending (lips in tension, Y1), and axial compression and minor axis bending (lips in compression, Y2). A numerical model is developed and verified by the experimental results. Then the elastic local buckling loads are discussed based on test results, numerical analysis, and design methods. The comparison between test strength and nominal strength obtained by AISI specification indicates that …

Effective Cfrp Retrofitting Schemes For Prestressed Concrete Beams, Herish Abdullah Hussein

Civil & Environmental Engineering Theses & Dissertations

This thesis presents a detailed theoretical study of a number of retrofitting schemes for prestressed concrete beams using carbon fiber reinforced polymer (CFRP) sheets to increase flexural strength and ductility. A simply-supported beam subjected to a gradually increasing uniformly distributed load is adopted for the study with a variety of CFRP retrofiring schemes. Three different types of beam cross sections are included for quantifying the influence of CFRP retrofitting when used in high compression regions in addition to CFRP use in high tension areas. To achieve this goal, nonlinear moment curvature relations are developed and coupled with a finite-difference solution …

Instrumentation To Monitor Bridge Foundation On The Crosstown Project, Brian Welch

Journal of Undergraduate Research at Minnesota State University, Mankato

The Crosstown Bridge Monitoring Project is located at the intersection of Highway 62 and Interstate I35W a few miles south and west of downtown Minneapolis. The bridge being evaluated is at a railroad overpass located midway along the Crosstown expansion. This research project involved placing instrumentation on the bridge foundation in order to measure the change in the foundation loading during the course of the construction project. For several years there have been questions pertaining to the forces in the pile foundations that support highway embankments. This project placed strain gages on the pile foundations in order to monitor these …

Finite Element Analysis Of Bolted Connections Under Fire, Ke Liu, Qiaqia Zhu, Amit H. Varma

The Summer Undergraduate Research Fellowship (SURF) Symposium

Over the course of human history, fire disasters are one of the major catastrophes that causes loss of lives and properties. In order to ensure building safety against fire, civil engineers seek to understand the behavior of structures at high temperatures. Moreover, they need to study the behavior of bolted connections, given the important role it plays in steel structures. Sarraj (2007) proposed a plate-bearing computational model used to describe this behavior; however, it has never been experimentally verified. Prior to this specific project, a series of single-bolted connection tests at 400°C and 600°C were conducted in the Bowen Laboratory …

Adjustable Resonance Frequency Of Rf-Mems Capacitor By Using Comb- Drive Actuators: A Design Approaches, Agus Santoso Tamsir, Sandy Tannu Wijaya, Dato’ Burhanuddin Yeop Majlis

Makara Journal of Technology

The needs of smaller size RF varactor is a must today, and MEMS comes to be the potential one. In this paper we proposed an adjustable resonance RF-MEMS varactor by using comb-drive actuators placing in each side of the square movable plate. In our preliminary simulation, we found that the device can work properly but some constraints comes such as the dominancies of harmonic resonance frequencies that influences into the nominal capacitances. Therefore for the next step of development we have to find out the window of the structural dimension for a certain spans and a certain operating frequencies.

Make Or Buy Analysis Model Based On Tolerance Design To Minimize Manufacturing Cost And Quality Loss, Cucuk Nur Rosyidi, Reza Rizkichani Akbar, Wakhid Ahmad Jauhari

Makara Journal of Technology

In a manufacturing company, manufacturing costs, or component prices, and tolerance will affect the price and the quality of a product. Companies must produce high-quality products with low manufacturing costs in order to keep their products competitive in the market; however, it is difficult to produce a high-quality product with a low manufacturing cost. Companies have difficulties in determining the components to be produced using their own manufacturing facilities (make) or outsourced to their suppliers (buy). Hence, a make or buy analysis is needed to minimize the manufacturing costs and quality loss and to determine the optimum alternative regarding make …

Observation Of Tunneling Effects In Lateral Nanowire Pn Junctions, Sri Purwiyanti, Arief Udhiarto, Daniel Moraru, Takeshi Mizuno, Djoko Hartanto, Michiharu Tabe

Makara Journal of Technology

As electronic device dimensions are continuously reduced, applied bias conditions significantly change and the transport mechanisms must be reconsidered. Tunneling devices are promising for scaled-down electronics because of expected high-speed operation and relatively low bias. In this work, we investigated the tunneling features in silicon-oninsulator lateral nanowire pn junction and pin junction devices. By controlling the substrate voltage, tunneling features can be observed in the electrical characteristics. We found that the minimum substrate voltage required for tunneling to occur in pn junctions is higher as compared with pin junctions. The main cause of these effects relies in the difference between …

Argon Ion Irradiation Effect On The Magnetic Properties Of Fe-Al2o3 Nano Granular Film, Setyo Purwanto, Isao Sakamoto

Makara Journal of Technology

We studied the effect of Argon (Ar) ion irradiation on Fe-Al2O3 nanogranular thin film. X-ray diffraction (XRD) patterns show that the ion dose might promote the growth of the Fe2O3 phase from an amorphous phase to a crystalline phase. The magnetic and magnetoresistance properties were investigated using a vibrating sample magnetometer (VSM) and a four point probe (FPP). The results suggest that percolation concentration occurred at the 0.55 Fe volume fraction and with a maximum magnetoresistance (MR) ratio of 3%. The present MR ratio was lower than that of previous results, which might be related to the existence of the …

Digestibility Of Betung Bamboo Fiber Following Fungal Pretreatment, Widya Fatriasari, Wasrin Syafii, Nyoman J. Wistara, Khaswar Syamsu, Bambang Prasetya

Makara Journal of Technology

This research evaluated the effect of fungal pretreatment of betung bamboo fibers and enzymatic- and microwaveassisted hydrolysis on the reducing sugar yield. The enzymatic hydrolysis of the pretreated biomass was carried out with cellulase and 10 and 20 FPU/g of substrate in a shaking incubator at 50 °C and 150 rpm for 48 h. The sulfuric acid concentration used in the microwave-assisted acid hydrolysis was 1.0, 2.5, and 5%, either with or without the addition of activated carbon. Microwave irradiation (330 Watt) was applied for 5–12.5 min. The yield of reducing sugar was better with the microwave-assisted acid hydrolysis, and …