Engineering Commons^™

Simplified Seismic Design For Mid-Rise Buildings With Vertical Combination Of Cold-Formed Steel And Concrete Framing, X. L. Yuan, L. Xu

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

Presented in this paper is a practical approach for the seismic design of mid-rise buildings with vertical combination of cold-formed steel and concrete framing. In current design practice the presence of vertical irregularities on both mass and stiffness inherited in such building structures creates a challenge for the seismic design. Currently, a two stage lateral force procedure prescribed in ASCE 7 is prescribed for evaluating the seismic load if the lateral stiffness of the lower structure of the building is considerably more rigid than the upper one. In the proposed approach the requirement associated with the two stage analysis procedure …

Lateral Loading Response Of Cfs Framed Shear Wall With Cement Board Panels, N. Baldassino, M. Accorti, R. Zandonini, F. Scavazza, C. A. Rogers

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

Shear wall panels are commonly used as lateral load resisting elements to provide stability of the cold-formed steel-framed houses in Australia against wind and earthquake actions. The effectiveness of their lateral resistance behavior is obtained usually by experimental testing although it can also be done by analytical modeling. This paper presents racking test results of steel-framed wall panels with different aspect ratios sheathed with fibre cement board subjected to monotonic and cyclic loading protocol. Performance parameters of the wall panels are obtained from the experimentally observed load-deflection curves using various existing methods and evaluation method is proposed. The evaluation method …

Structural Strength Of Lapped Cold-Formed Steel Z-Shaped Purlin Connections With Vertical Slotted Holes, J. Liu, L. Xu, S. Fox

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

Lapped joints of cold-formed steel (CFS) Z-shaped purlins are extensively used in metal building roof systems. The research that has been carried out so far for these lapped connections is primarily focused on connections with round holes. However, the lapped connections with vertical slotted holes are extensively used in current construction practice to simplify the erection of continuous Z-shaped roof purlins. There are no design guidelines or recommendations available for CFS Z-purlin lapped connections with vertical slotted holes.

Presented in this paper are the results of an experimental study on the structural strength behaviour of lapped CFS Z-shaped purlin connections …

Fastener-Based Computational Models With Application To Cold-Formed Steel Shear Walls, G. Bian, S. G. Buonopane, Hung Huy Ngo, Benjamin W. Schafer

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

The objective of this paper is to validate a tool that design engineers could employ to develop mechanics-based predictions of the lateral response of wood-sheathed cold-formed steel (CFS) framed shear walls applicable in a wide variety of situations. Wood framed shear walls enjoy a variety of tools, most notably SAPWood and its predecessor CASHEW, that provide a means to predict the complete hysteretic behavior of a shear wall based on the nail fastener schedule and board selection. The existence of these tools helps engineers in unique design situations, encourages innovation in shear wall design particularly for Type I shear walls, …

Acoustic Performance Of Different Cold-Formed Studs In Double-Leaf Walls By Finite Element Analysis And Experiment, V. B. Nguyen, T. Morgan, M. A. English, M. A. Castellucci

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

Cold-formed steel studs are often used in lightweight partition walls to provide structural stability but in the same time they change the acoustic performance of the whole system. The overall design of such lightweight structures for acoustic sound insulation becomes very complicated as the sound passing through stud needs to be quantified. One of the greatest challenges is to characterise the stud’s geometric effects on the sound transmission of the partition walls. This paper presents a Finite Element modelling approach and results into the acoustic performance of cold-formed studs in double-leaf walls which are placed in between a source room …

Fire Resistance Prediction Of Load Bearing Cold-Formed Steel Walls Lined With Gypsum Composite Panels, Wei Chen, Jihong Ye

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

An innovative load-bearing cold-formed steel (CFS) wall lined with gypsum composite panels was developed with the goal of improving the construction efficiency and fire performance of these walls for applications in mid/high-rise buildings. The gypsum composite panel was formed by sandwiching insulation and plasterboard strips between two layers of gypsum plasterboards. Subsequently, the predicted fire resistance of these CFS walls was predicted based on our previously developed and experimentally validated modeling method. The degenerated material properties of the cold-formed steel and thermal physical property of the gypsum plasterboard and aluminum silicate wool were obtained from our pervious experimental investigations and …

Numerical Investigation Of Cold-Formed Steel Top Hat Purlins, Asraf Uzzaman, Andrzej M. Wrzesien, Robert Hamilton, James B. P. Lim, David Nash

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

This paper considers the use of cold-formed steel top-hat sections for purlins as an alternative to conventional zed-sections. The use of such top-hat sections may be viable for use in cold-formed steel portal framing systems, where both the frame spacing and purlin span may be smaller than in conventional hot-rolled steel portal frames. Furthermore, such sections are torsionally stiffer than zed-sections, and so have a greater resistance to lateral-torsional buckling. They also do not require the installation of anti-sag rods. The paper describes non-linear elasto plastic finite element analyses conducted on top-hat sections. The results of twenty-seven tests on four …

Investigation On Seismic Performance Of Cold-Formed Steel Portal Frames, Yuanqi Li, Zhijian Xu, Yinglei Li, Yunfei Peng

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

A series of monotonous loading and hysteresis loading tests on cold-formed steel portal frames were conducted in this paper. The averaged ductility factor value of tested frames is 3.15 and the strength and stiffness degradation are not obvious during the test. The failure mode of frame is local buckling at column bases followed by local buckling at the top of columns, which lead to the dropping of frame’s load-carrying capacity. Then, the finite element model is developed and the analysis results match well with the test results. The research in this paper indicates that cold-formed steel portal frame has a …

Pull-Through Failure Tests Of Thin Steel Roof Battens Under Wind Uplift Loads, Mayooran Sivapathasundara, Mahen Mahendran

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

Thin profiled steel roof sheeting and battens are increasingly used in the construction of roofing systems of residential, commercial, industrial and farm buildings in Australia. The critical load combination of external wind suction and internal wind pressures that occur during high wind events such as thunderstorms and tropical cyclones often dislocate the roofing systems partially or even completely due to premature roof connection failures. Past wind damage investigations have shown that roof sheeting failures occurred at their screw connections to battens. In most of these cases, the screw fastener head pulled through the thin roof sheeting whilst the screw fasteners …

Design Equations For Tensile Rupture Resistance Of Bolted Connections In Cold-Formed Steel Members, Lip H. Teh, Benoit P. Gilbert

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

This paper summarises and re-examines the authors’ previous research results concerning the tensile rupture resistance of cold-formed steel bolted connections in a flat sheet, in a channel’s web, and in one leg of an angle section. Staggered bolted connections are also included. The fundamental shortcomings of the design equations given in the 2012 North American Specification for the Design of Cold-formed Steel Structural Members are described, and the alternative design equations proposed by the authors are shown. The alternative equations are checked against laboratory test results obtained by the authors and other researchers where the bolts had not been snug-tightened …

Direct Strength Method For Ultimate Strength Of Bolted Moment-Connections Between Cold-Formed Steel Channel Members, James B. P. Lim, Gregory J. Hancock, G. Charles Clifton, Cao Hung Pham

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

Experimental tests have previously shown that the strength of bolted moment-connections between cold-formed steel members, where the connections are formed through an array of bolts in the web, is dependent on the length of the bolt-group. This reduced strength has been observed in tests on portal frame joints as well as over-lapped purlin joints. For a short bolt-group length, in the order of the depth of the section, this paper shows that a reasonable lower bound to this reduced strength can be predicted by using the Direct Strength Method (DSM), modified to include the effect of the bimoment at the …

Development Of A Novel Pinned Connection For Cold-Formed Steel Trusses, Chris D. Mathieson, G. Charles Clifton, James B. P. Lim

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

Cold-formed steel trusses are a popular form of construction for light-weight buildings, particularly portal frame structures, for which spans up to 25m are increasingly common. In these long span trusses, providing high strength connections with sufficient elastic stiffness is a current limitation to developing cost-effective solutions. A novel pin-jointed truss connection named the Howick Rivet Connector (HRC) has been tested, firstly in a T-joint arrangement, then in a truss assemblage to determine its reliable strength and stiffness. Results showed that the HRC performs similarly to a bolted connection in terms of failure modes observed and loads reached. Additionally, the process …

Fragility Curves For Thin-Walled Cold-Formed Steel Wall Frames Affected By Ground Settlements Due To Land Subsidence, Luis A. Hernández-Castillo, Jose A. Ortiz-Lozano, Martin Hernández-Marín, Jesús Pacheco-Martínez, Mario E. Zermeño-Deleón, Juan J. Soto-Bernal, Jorge Ramos-Ruizflores, Miguel A. Soto-Zamora

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

Land subsidence phenomenon due to ground water withdrawal is a current problem in many places around the world, particularly in the shallows of Mexico. This causes ground differential settlements that affect structures, mainly dwellings and buildings based on reinforced concrete and masonry. Eventually, these structural materials do not exhibit an adequate performance beyond a certain level of angular distortion. This work presents the results about a study regarding the performance of thin-walled cold-formed steel wall frames with different sheathing systems affected by angular distortions simulating ground differential settlements due to land subsidence. The wall frames are composed by vertical (studs) …

Experimental Seismic Behavior Of The Cfs-Nees Building: System-Level Performance Of A Full-Scale Two-Story Light Steel Framed Building, Kara D. Peterman, Rob L. Madsen, Benjamin W. Schafer

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

In the summer of 2013, testing of two full-scale cold-formed steel (CFS) framed buildings under seismic excitations took place at the Structural Engineering and Earthquake Simulation Lab (SEESL) at the University at Buffalo. Utilizing the twin shake tables, the two-story building specimens were subjected to ground motions from the 1994 Northridge earthquake. These experiments were conducted as a part of the CFS-NEES experimental effort in an attempt to advance cold-formed steel earthquake engineering and design. Two buildings were tested: the first, a specimen constructed with only structural components (CFS-framed gravity walls, shear walls, floor and roof diaphragms, with OSB sheathing …

Towards Quantifying Beneficial System Effects In Cold-Formed Steel Wood-Sheathed Floor Diaphragms, A. Chatterjee, Y. Xiang, C. D. Moen, S. R. Arwade, Benjamin W. Schafer

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

Cold-formed steel wood-sheathed floor diaphragm system behavior is analyzed from a system reliability perspective. Floor systems consisting of oriented strand board (OSB), cold-formed steel (CFS) joists, tracks and screw fasteners are modeled using shell and spring elements in ABAQUS. (Dassault-Systems ())The models consider typical seismic demand loads, with careful treatment of light steel framing diaphragm boundary conditions and OSB sheathing kinematics, i.e., two sheets pulling apart or bearing against each other at an ultimate limit state, consistent with existing experimental results. The finite element results are used to build surrogate mathematical idealizations (series, parallel-brittle and parallel-ductile) for the critical system …

Local Buckling Hysteretic Nonlinear Models For Cold-Formed Steel Axial Members, D. A. Padilla-Llano, C. D. Moen, M. R. Eatherton

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

This paper studies the energy dissipation and damage in thin walled members that experience local buckling and presents an approach to model cold-formed steel (CFS) axial members that experience local buckling deformations. The model is implemented in OpenSees using hysteretic models for CFS axial members calibrated using experimental responses. Results from thin-shell element simulations using ABAQUS show that energy dissipation in thin plates dissipates through inelastic strains and yielding that concentrates in damaged zones that extent approximately the length of a buckled half-wave (L_cr). Generally damage accumulates in one zone but when more than one damaged zone occurred …

Improvements To The Prediction Of Brace Forces In Z-Purlin Roof Systems With Support + Third Point Bracing, Michael W. Seek

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

The Component Stiffness Method is a displacement compatibility method used to analyze C- and Z- section supported roof systems. The method provides a detailed analysis of the flexibility in the roof system and the distribution of forces as they flow out of the system. Parametric studies of the equations for typical roof systems have shown that by ignoring the flexibility of some of the components, the method can be simplified with little impact on the anchorage forces calculated. Changes have also been made to the way in which cross section deformations are incorporated into the method. This paper focuses on …

Towards Load-Deformation Models For Screw-Fastened Cold-Formed Steel-To-Steel Shear Connections, C. D. Moen, D. A. Padilla-Llano, S. Corner, C. Ding

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

This paper summarizes results from an experimental program considering single-fastened cold-formed steel-to-steel shear connections. Fastener motion (displacement and tilting angle) and bearing deformation occurring on the connecting members at the fastener location were captured using an automated, optical non-contact measurement procedure. The results are used to relate cold-formed steel-to-steel shear connection load-deformation response to tilting and bearing response. A general steel-to-steel single shear fastener load-deformation equation is also proposed and demonstrated.

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 …

Constrained Finite Element Method: Demonstrative Examples On The Global Modes Of Thin-Walled Members, S. Ádány

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

In this paper a novel method is presented for the modal decomposition of thin-walled members. The proposed method follows the logic of the constrained finite strip method (cFSM), however, polynomial longitudinal shape functions are applied together with a longitudinal discretization. Thus, strips are transformed into multiple shell finite elements. The longitudinal shape functions are selected in such a way that modal decomposition similar to cFSM can be realized, therefore, the new method can conveniently be described as constrained finite element method (cFEM), possessing all the modal features of cFSM, but with significantly more flexible applicability. The method is briefly presented …

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 …

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 …

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 …

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 …

The 2013 Aisi Cold-Formed Steel Design Manual, Joshua Buckholt, Richard C. Kaehler, Helen Chen

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

The 2013 edition of the AISI Cold-Formed Steel Design Manual has been published. The new edition includes updated and newly developed example problems and design aids covering new material in the 2012 edition of the AISI North American Specification for the Design of Cold-Formed Steel Structural Members (NA Specification). Also published with the Manual are the NA Specification and the Commentary.

Cold-Formed Lean Duplex Stainless Steel Rectangular Hollow Sections In Combined Compression And Bending, Yuner Huang, Ben Young

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

An experimental investigation of cold-formed lean duplex stainless steel members in combined compression and minor axis bending is performed. The test specimens were cold-rolled from flat strips of lean duplex stainless steel grade EN 1.4162 into two rectangular hollow sections. Different eccentricities were applied to the rectangular hollow sections, so that a beam-column interaction curve for each series of test can be obtained. Initial overall geometric imperfections of the members were measured prior to testing. The ultimate loads and the failure modes of each specimen were obtained. Failure modes include flexural buckling as well as interaction of local and flexural …

Steel Deck Institute Design Manuals For Floor And Roof Deck, Thomas Sputo

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

The Steel Deck Institute (SDI) has developed new design manuals to assist in the use of their consensus floor and roof deck standards. The SDI Floor Deck Design Manual, 1st Edition (FDDM) is based on the requirements of the ANSI/SDI NC-2010 Standard for Non-composite Steel Floor Deck and the ANSI/SDI C-2011 Standard for Composite Steel Floor Deck-Slabs. The SDI Roof Deck Design Manual, 1st Edition (RDDM) is based on the requirements of the ANSI/SDI RD-2010 Standard for Steel Roof Deck. Both manuals contain information on available deck profiles and finishes, and design and installation information. Additionally, both manuals …

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 …

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 …