Structural Engineering Commons^™

First-Order Generalized Beam Theory For Curved Members With Circular Axis, Nuno Peres, Rodrigo Gonçalves, Dinar Camotim

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

This paper presents a first-order Generalized Beam Theory (GBT) formulation for thin-walled members with circular axis and undergoing complex global-distortional-local deformation. The fundamental equations are derived on the basis of the usual GBT kinematic assumptions (Kirchhoff, Vlasov and wall in-plane inextensibility), leading to a formulation able to retrieve accurate solutions with only a few cross-section deformation modes (cross-section DOFs). It is shown that the classic Winkler and Vlasov theories can be recovered from the derived formulation. A GBT-based finite element is use to analyze numerical examples illustrating the application and potential of the proposed formulation.

A Finite Element Method For Distortional Buckling Analysis Of Thin-Walled Members, Sheng Jin, Xiao Jiana, Rui Chenga, Shidong Niea, Mingyue Chenga

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

This paper presents a method for distortional buckling analysis of thin-walled members without assuming longitudinal shape of buckling modes. In this method, the pure distortional elastic buckling loads and deformation modes are achieved by performing a linear buckling analysis of a specially constrained finite element model of the thin-walled member in ANSYS. The constraints on each cross-section are applied independently and can be divided into two parts. The first part, by which distortional buckling can be distinguished from local buckling, depicts the transvers deformation of a cross-section, while the second part originated from longitudinal displacement patterns of distortional modes is …

Stability Analysis Of Thin-Walled Members With Curved Cross-Section Parts: Inelastic Behavior, D. Jobbágy, S. Ádány

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

In this paper the buckling behavior of thin-walled members with cross-sections with curved parts is investigated. Due to the curved parts, shell-like buckling is a potential mode of failure. The objective of the research is to understand whether shell-like buckling behavior might be governing in practical cold-formed steel members. For this aim, numerical studies have been carried out, involving linear buckling analysis as well as nonlinear analysis with imperfections, by considering various cross-sections. Based on the results it is concluded that shell-like behavior might be critical in certain cases.

Effect Of Web Perforation On The Behaviour Of Cold-Formed Steel C-Shape Slender Column Subjected To Non-Uniform Cross-Sectional Distribution Of Elevated Temperatures, S. Yang, L. Xu

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

Presented in this paper is a numerical investigation on the effect of web perforations on the behaviour of cold-formed steel C-shape columns subjected to non-uniform cross-sectional distribution of elevated temperature with use of finite element analysis. The length of web perforation investigated varies from 0 mm to 630 mm (25 in.). The non-uniform cross-sectional distributions of elevated temperatures are obtained from finite element thermal analysis of insulated CFS walls subjected to standard fire up to 105 minutes. Sequentially coupled thermal-stress analyses were carried out under a transient state condition. The concentrically loaded cold-formed steel C-shape columns with load ratios of …

Distortional Buckling Experiment On Cold-Formed Steel Lipped Channel Columns With Circle Holes Under Axial Compression, Xingyou Yao, Yanli Guo, Zhen Nie

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

The objective of this paper is to research the distortional buckling mode and load-carrying capacity of cold-formed thin-walled steel columns with circle holes in web. Compression tests were conducted on 26 intermediate length columns with and without holes. The test members included four different kinds of circle holes. Test results show that the distortional buckling occurred for intermediate columns with holes and the strength of columns with holes was less than that of columns without circle hole. The ultimate strength of columns decreased with the increase of the total transverse width of hole in cross-section of members. For each specimen, …

Numerical Simulations Of Solid And Slotted Cold-Formed Steel Channels With Different Boundary Conditions In Shear, Vitaliy V. Degtyarev, Natalia V. Degtyareva

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

This paper presents results of a numerical study on the shear strength of cold-formed steel channels with solid and slotted webs. The effects of four different boundary conditions—test setup, realistic, and simply supported with free and restrained ends—on the elastic shear buckling load and the ultimate shear strength were considered. The study was performed on finite element models developed in ANSYS and validated against test data. The obtained results showed that the elastic shear buckling loads and the ultimate shear strengths of the slotted channels are more sensitive to the boundary conditions when compared with the solid channels. The simply …

Finite Element Investigations Of The Effect Of Residual Stress In Cold-Formed Sigma Beams, Feiliang Wang, Jian Yang

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

Press braking is a cold forming operation used to fold the angle along the flat sheet between the top punch and bottom die. The residual stress will be induced in this process as a result of plastic deformation. In the welding process, a dynamic thermal cycle is introduced to generate a non-uniformly temperature distribution on the heat affected zone (HAZ), and the residual stress also occurs in the process as a result of uneven cooling along the welding bead. The existence of residual stress can superimpose onto the external loadings to affect the stiffness and load resistance capacity of the …

Lateral-Torsional Buckling Of General Cold-Formed Steel Beams, Robert S. Glauz

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

The design of unbraced cold-formed steel beams must consider lateral-torsional buckling due to the low torsional stiffness associated with open cross-sections. The American Iron and Steel Institute incorporated design equations for the critical elastic lateral-torsional buckling stress in the North American Specification for the Design of Cold-Formed Steel Members. These equations are based on elastic theory for singly-symmetric and doubly-symmetric sections. However, the equation for point-symmetric sections is only a rough approximation. Furthermore, there are no provisions for lateral-torsional buckling of non-symmetric sections, or sections oriented to non-principal axes. This paper investigates and develops a general formulation of the lateral-torsional …

Unconstrained Cross-Sectional Shape Optimisation Of Cold-Formed Steel Beams And Beam-Columns, Bin Wang, Benoit P. Gilbert, Guillaume L. Bosco, Hong Guan, Lip H. Teh

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

This paper is focused on optimising the cross-sectional shapes of simply-supported, singly-symmetric and open-section cold-formed steel (CFS) beams and beam-columns without manufacturing or assembly constraints. A previously developed Genetic Algorithm (GA) is used in this study. Fully restrained and unrestrained beams against lateral deflection and twist, as well as unrestrained beam-columns are optimised, of which the nominal member capacities are determined by the Direct Strength Method (DSM). The optimised cross-sectional shapes are presented and the evolution of the unrestrained cross-sectional shapes for various combinations of axial load and bending moment is analysed and discussed.

Identifying Shear Buckling Coefficients For Channels With Rectangular Web Stiffeners Using The Generalised Cfsm, Morgan A. Rendall, Gregory J. Hancock, Kim J. R. Rasmussen

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

The Direct Strength Method (DSM) of design for cold-formed sections was recently extended in the North American Specification for Cold-Formed Steel Structural Members (NAS S100:2012) to include members in shear. The method has largely been developed on the basis of work done on lipped channel sections. To utilise the method requires the critical shear buckling load of the section, which may be determined from a minimum point on the signature curve for the section in pure shear. However when longitudinal web stiffeners are added to the channel a minimum may not exist, or may occur at half-wavelengths where the critical …

New Sdi Diaphragm Design Manual, Larry Luttrell, John Mattingly, Walter Schultz, Thomas Sputo

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

The Steel Deck Institute (SDI) has released the new and long awaited 4th Edition of the Diaphragm Design Manual (DDM04). This new edition complies with the requirements of the ANSI/AISI S310-13 North American Standard for the Design of Profiled Steel Diaphragm Panels. At 408 pages, the 4th Edition is larger than its predecessor and will be an invaluable resource to structural designers because of the background information, design examples, and extensive load tables.

The First Edition of the DDM, published in 1981, was authored by Dr. Larry Luttrell, P.E., the Technical Advisor to the SDI. The diaphragm design method developed …

Recent Developments In The Australian/New Zealand Standard As/Nzs 4600 For Cold-Formed Steel Structures, Gregory J. Hancock

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

The Australian/New Zealand Standard AS/NZS 4600 is currently under revision based in part on the latest edition of the North American Specification AISI S100:2012 and partly based on the latest research in Australia and New Zealand. The Direct Strength Method (DSM) of design has undergone substantial research since the 2005 edition of AS/NZS 4600 and this research is now incorporated in the revised edition. The new areas in the DSM include shear, combined bending and shear, combined bending and compression, sections with holes and inelastic reserve capacity. Further, the prequalified sections now include most sections with longitudinal web and flange …

Aisi Standards Developed And Updated In 2015 And 2016, Helen Chen, Roger Brockenbrough, Richard Haws

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

During 2015 and 2016, AISI developed framing standards were consolidated and updated, the North American Specification was updated and reorganized in format, and two new test standards were published. This paper provides an overview of the reorganized standards and major changes, and a brief introduction to the newly developed test standards.

Advancing Bim For Cold-Formed Steel Structures, Adam Johnson, Roni Ramirez, Cheng Yu

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

This paper presents a research project aimed at advancing BIM for cold-formed steel (CFS) structures. The creation of the CFS family for Autodesk Revit is a handy solution for the lack of CFS members and information inside the Autodesk Revit libraries. Revit is one of the industry’s standard software for producing building information models. To overcome the disadvantages of not having CFS members in Revit, this research project focused on two phases to reach completion. Phase one consisted of developing a BIM library of industrial standard CFS members such as studs, tracks, and channels. Parameters were added to the members …

Analyses Of Thin-Walled Sections Under Localised Loading For General End Boundary Conditions – Part I: Pre-Buckling, Van Vinh Nguyen, Gregory J. Hancock, Cao Hung Pham

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

The Semi-Analytical Finite Strip Method (SAFSM) for pre-buckling analysis of thin-walled sections under localised loading has been developed for general end boundary conditions. For different boundary conditions at supports and loading point, different displacement functions are required for both flexural and membrane displacements. As the stresses are not uniform along the member due to localised loading, the pre-buckling analysis also requires multiple series terms with orthogonal functions.

This paper briefly summaries the displacement functions used for different boundary conditions. In addition, the theory of the SAFSM for pre-buckling analysis of thin-walled sections under localised loading with general end boundary conditions …

Measured Geometric Imperfections For Cee, Zee, And Built-Up Cold-Formed Steel Members, X. Zhao, B. 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 present recent results from measurements of cold-formed steel members conducted by a laser scanner. The measurements provide complete and precise three-dimensional point clouds of the specimens and can be processed to determine dimensional variations as well as variations within the plates. Processing of the data can range from simple: e.g., mean lip length, to complex: e.g., modal decomposition magnitudes of the measured imperfections. Three different shapes of cold-formed steel members are selected for study: Cee, Zee, and built-up …

Buckling Behaviour Of Cold-Formed Steel Beams Under Bending And Torsion, Hong-Xia Wan, Mahen Mahendran

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

This research is concerned with the buckling behaviour and design of cold-formed steel beams subject to combined bending and torsional actions. A finite element model considering the effects of initial geometrical imperfections and residual stresses was developed to simulate the combined bending and torsion of cold-formed steel beams. The finite element model was used to conduct analysis on cold-formed lipped channel sections, Z sections and hollow flange channel sections. Elastic buckling analysis was first conducted to study their buckling modes and buckling loads. Nonlinear analysis including the effects of large deformation and material yielding was conducted to obtain their ultimate …

Incorporation Of Elastic Local Buckling In A Plain Channel Section Beam Subjected To Double-Curvature Bending: An Effective-Width Approach, Edwin Lim, Barry J. Goodno, James I. Craig

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

When electrical cabinets are subjected to lateral loads, such as earthquakes, the beams of the cabinet frame typically experience double-curvature bending deformation. These beams are usually constructed from cold-formed plain channel sections so they are vulnerable to elastic local buckling near their ends, where high stresses from applied loads are more likely to develop. To capture local buckling behavior, structural engineers typically use high-fidelity finite element models, but this approach can be complex and computationally expensive. A Timoshenko beam element model is simpler and less computationally costly but it is not capable of capturing local buckling behavior. In this paper, …

Tests Of Cold-Formed Ferritic Stainless Steel Beams, Lianghao Li, Ben Young

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

Ferritic stainless steel is characterized by its low or even no nickel content, which provides a good alternative to a more commonly used austenitic stainless steel (with 8.0-10.0% nickel content) in structural application. The low nickel content attributes to low initial material cost and more stable price for ferritic stainless steel. A series of four-point bending tests was conducted on both square and rectangular hollow sections to investigate the flexural performance of cold-formed ferritic stainless steel hollow sections. The experimental results obtained from this test program and the available data in the literature on cold-formed ferritic stainless steel beams were …

The Design And Development Of New Cold Roll Formed Products By Finite Element Modeling And Optimisation, V. B. Nguyen, P. K. C. Wood, M. A. English, M. A. Castellucci

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

The design and development of new cold roll formed products can incur significant cost and the product may not be optimised for either performance or manufacture. This paper describes a new method to develop an optimum structural design of profile by cold roll forming using a combined approach of finite element analysis and optimisation techniques. To illustrate the concept, the design and development of a new channel beam and a new drain grating subjected to bending are presented. The two case studies, demonstrate how a roll formed profile may be optimised to improved structural performance through use of stiffeners and/or …