Structural Engineering Commons^™

Distortional Buckling Of Cold-Formed Steel Flanges Under Stress Gradient, Robert S. Glauz

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

The strength of cold-formed steel beams with stiffened flanges may be controlled by distortional buckling. Buckling stress prediction methods have been developed for flanges under uniform compression. However, channel sections are commonly used where bending occurs about the minor axis with flanges under stress gradient, such that the edges are in compression and the flanges may experience distortional buckling. Current design specifications do not explicitly address this failure mode, which could lead to unsafe designs. This paper presents and verifies an analytical approach for distortional buckling stress prediction for flanges under stress gradient. The approach is consistent with the design …

Experimental Study On Uplift Capacity Of Purlins Considering Restraints From Standing Seam Roof Systems, Wei Luan, Yuanqi Li

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

A total of 32 specimens of single-span purlin roof assemblies considering uplift wind load were tested to investigate the structural behavior of cold-formed steel purlins with one flange fastened to standing seam roofs. Failure modes and failure loads of purlins with different parameters were obtained. Full finite element models, incorporate purlins, clips and standing seam roof panels, were developed, and the analysis results were consistent to a high degree with the test results. Using the same element type and material model, the rotational restraint of test roof systems and corresponding influence factors were investigated by finite element models. Finally, using …

Stressed Skin Design Of Steel Sheeting Panels – Part 1: Shear Resistance And Flexibility Of Screw Lapped Joists, A. M. Wrzesien, James B. P. Lim, I. A. Macleod, R. M. Lawson

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

The shear resistance and flexibility of a steel roof diaphragm depend largely on shear resistance and slip flexibility of the single screw lap joint. In this paper, screw connections relevant to modern roof construction are investigated. The tests provided experimental values of shear/tearing resistance and joint flexibility of seam connections, cladding/purlin connections and purlin/rafter connections. The novel aspects of the experimental research include investigation of the behaviour of shear connections in 0.5mm thick sheeting and thick-to-thin connections in S550 high tensile steel. Overall, six series of tests were conducted and each test was repeated five times in order to demonstrate …

Human-Structure Interaction In Cold-Formed Steel Floor Systems: An Analytical Perspective, Sigong Zhang, Lei Xu

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

Designing cold-formed steel (CFS) floors to prevent annoying vibrations induced by human activities such as walking is still a challenge because human occupants not only generate impact loads but also behave as dynamical systems that interacting with structures. Such interaction, known as human-structure interaction (HSI), can be significant for lightweight floor systems particularly for the case when the mass of human occupants becomes comparable to those of the floors. The aim of this study was therefore to investigate the HSI in vibration of CFS floors subjected to human walking excitations by using the recently proposed damped plate-oscillator model to predict …

Using Generalized Beam Theory To Assess The Behavior Of Curved Thin-Walled Members, Nuno Peres, Rodrigo Goncalves, Dinar Camotim

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

In this work, the first-order behavior of naturally curved thin-walled bars with circular axis, without pre-twist, is assessed with the help of the Generalized Beam Theory (GBT) formulation previously developed by the authors. With respect to the previous work, which dealt with simple cross-sections, the present paper presents a method to obtain the deformation modes for arbitrary flat-walled cross-sections. Despite the complexity involved in this generalization, the standard GBT kinematic assumptions are kept, since they are essential to (i) subdivide the modes in a meaningful way and (ii) reduce the number of DOFs necessary to obtain accurate solutions. It is …

Comparison Of Experimental And Numerical Results For Flexural Capacity Of Light-Gage Steel Roof Deck, Christopher H. Raebel, Dawid Gwodzdz

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

The objective of this paper is to present a comparison between experimental results to each of two numerical analyses of cold formed steel roof deck in flexure. Prior numerical studies using the Direct Strength Method (DSM) and the Equivalent Width Method (EWM) have shown discrepancies between results obtained by the two methods. The goal of this research initiative was to compare results from each of the two numerical analysis methods to experimental results in an effort to determine which numerical method is most appropriate for analyzing steel deck in flexure.

Twenty-four physical tests were conducted using four different deck gages …

Localised Screw Connection Failures In Cold-Formed Steel Roofing Systems, Mayooran Sivapathasundaram, Mahen Mahendran

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

Lightweight roofing systems made of thin and high strength steel roof sheeting and battens are commonly used in low-rise buildings. However, they often fail frequently at their screw fastener connections during wind storms due to inadequate connection capacities. Two localised failures, known as pull-through and pull-out failures at the screw fastener connections, have been the root cause for extensive loss of roofing systems under high wind uplift loads. Such premature connection failures often cause partial or even complete loss of steel roofing systems and severe damage to building contents. Therefore many experimental studies have been conducted to investigate the pull-through …

A Finite Element Study Of Corrugated Steel Deck Subjected To Concentrated Loads, Vitaliy V. Degtyarev

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

An extensive parametric study was initiated to get a better understanding of steel deck behavior under concentrated loads and to develop design recommendations for a wide range of deck profiles. This paper presents first results from the study related to 1.5-in. deep roof decks of types B and F. The study was performed on non-linear finite element models of deck validated against available test data. Deck gage, span length, span condition, concentrated load locations along and across the deck span were varied in the study. The observed deck behavior under concentrated loads, as well as the effects of the studied …

Sidelap And Structural Fastener Tests For Steel Deck Diaphragms, Y. Shi, S. Torabian, Benjamin W. Schafer, W. S. Easterling, M. R. Eatherton

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

Steel deck diaphragm systems, which are commonly used for roof construction in steel-framed buildings, consist of many parts such as corrugated steel deck sheets, sidelap fasteners between adjacent sheets, structural fasteners from the sheets to the supporting beams or joists, chord elements, and collectors. Load-deformation behavior of a steel deck diaphragm system is typically dominated by sidelap and structural fastener limit states. To understand and accurately model the behavior of steel deck diaphragm systems, it is therefore necessary to characterize the behavior of the individual fasteners. The effect of local geometry and detailing at these fasteners such as how the …

Tensile Strength And Serviceability Of Cold-Formed Steel Clip Angles, Wenying Zhang, Zhishan Yan, Mahsa Mahdavian, Mohamad Yousof, Cheng Yu

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

This paper reports the recent research findings of cold-formed steel clip angles in tension. The relevant experimental program and the proposed design methods are presented. The test program involved two phases of testing: Phase I of program focused on the pull-over strength of screw connections on the anchored leg of the clip angles, and Phase II of program concentrated on the tensile strength of the anchored leg of the clip angles within the service deflection limit. Design methods for predicting the pull-over strength as well as tensile strength within the serviceability deformation limit are proposed based on the test results …

Influence Of Gypsum Panels On The Response Of Cold-Formed Steel Framed Strap-Braced Walls, Sophie Lu, Colin A. Rogers

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

In cold-formed steel construction the steel frame is supplemented with either diagonal strap braces or structural sheathing panels (typically steel or wood) to provide overall stability to the structural system and to directly transfer lateral wind and seismic loads through to the foundation as per the design provisions found in AISI S240 (2015) and AISI S400 (2015). Gypsum panels are often specified to provide a fire-resistance rating for the CFS frame, as well as to ensure that adequate sound-proofing exists between adjacent rooms or building units. The engineer may choose to rely on this gypsum to provide additional lateral resistance, …

Design Of Rivet Fastened Rectangular Hollow Flange Channel Beams Subject To Local Buckling, L. Sundararajah, M. Mahendran, P. Keerthan

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

The innovative, rivet fastened Rectangular Hollow Flange Channel Beam (RHFCB) is a new type of cold-formed steel section, proposed as an extension to the widely researched hollow flange beams. The hollow flange beams have garnered much interest in the past due to the sections having capacities more typically associated with hot-rolled steel sections. Various researches have been carried out to investigate the behavior of continuously welded hollow flange beams but little is known on the behavior of RHFCBs. The structural behaviour of the RHFCB is unique compared to other conventional cold-formed steel sections and its moment capacity reduces with rivet …

Web Crippling Of Cold-Formed High Strength Steel Square And Rectangular Hollow Sections Under Two-Flange Loading Conditions, Hai-Ting Li, Benjamin Young

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

The web crippling behavior of cold-formed high strength steel (HSS) square and rectangular hollow sections under End-Two-Flange and Interior-Two-Flange loading conditions is studied. The cold-formed HSS tubular sections had nominal 0.2% proof stresses of 700 and 900 MPa. Finite element (FE) models were developed and validated against test results, showing the capability of replicating the experimental web crippling strengths, failure modes and load-deformation histories. Upon validation of the FE models, an extensive parametric study comprised 112 FE analyses was performed. The web crippling strengths obtained from the experimental and numerical investigations were compared with the nominal strengths calculated from the …

Parametric Studies And Design Recommendations Of Cold-Formed Steel Sections With Edge-Stiffened Circular Holes Subjected To Web Crippling, Asraf Uzzaman, James B. P. Lim, David Nash, Amir M. Yousefi, Benjamin Young

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

A parametric study of cold-formed steel sections with edge-stiffened circular holes subjected to web crippling under one-flange loading condition was undertaken using finite element analysis. The effect of different hole sizes, edge-stiffener length and distances of the web holes to the near edge of the bearing plate on the web crippling strengths of channel sections were investigated. The web crippling strengths are influenced by various geometry parameters: the ratio of the hole depth to the flat portion of the web, a/h, the location of the hole as defined by the distance of the hole from the edge of the …

A Preliminary Study On Stainless Steel Hollow Flange Beams Featuring Lateral-Distortional Buckling, Shuang Niu, Zhidong Zhang, Feng Fan

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

To explore the potential of using stainless steel structurally, extensive research has been carried out to study the structural behavior of stainless steel member as associated with the nonlinear stress-strain relationship. Hollow flange sections feature improved structural efficiency and a unique issue of web distortion. Steel hollow flange sections have been studied and commercially distributed (e.g. the very first HFB section and lately LSB section). As a proactive study, this paper investigates stainless steel hollow flange beams of double-symmetric section with numerical modeling and parametric analysis. The validity of the idealized FE model was verified with existing study on steel …

Study On Distortional Buckling Of Cold-Formed Stainless Steel Beams, Shuang Niu, Zhidong Zhang, Feng Fan

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

In the current research, distortional buckling of cold-formed stainless steel open-section beams was investigated. Four-point bending tests of eight C-section stainless steel beams, made of S30401 alloy, were carried out with global and local buckling precluded by careful design of specimen and test rigs. A detailed finite element model based on ABAQUS was developed and verified against test data. Parametric study was carried out with the verified model, covering four types of sections (C, Z, SupaCee, and SupaZed), three stainless steel alloys (S30401, S44330, S32101), and a series of section slenderness. A convenient method to identify distortional buckling point in …

Flexural Strength Of Continuous-Span Z-Purlins With Paired Torsion Braces Using The Direct Strength Method, Michael Seek

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

A procedure is presented to calculate the local and distortional flexural buckling strength of continuous span purlins with paired torsion braces using the Direct Strength Method. Displacement compatibility is utilized to determine the forces interacting between the purlin, the flexible diaphragm and the torsion braces. The biaxial bending and torsion effects caused by this interaction are superimposed, and the actual distribution of stresses within the cross section are calculated at critical locations along the span. With this distribution of stresses, a finite strip buckling analysis is performed to determine the local and distortional buckling strength. In current design practice, results …

Bracing Design For Torsional Bucking Of Cold-Formed Steel Wall Stud Columns, C. D. Moen

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

A method is presented for calculating the required brace stiffness and strength to limit torsional buckling deformation in cold-formed steel wall stud columns. The bracing (bridging) design method utilizes recent insight from classical stability solutions that define twist of singly and doubly-symmetric columns with an initial twist imperfection as a function of column compressive load. A wall stud design example is provided.

Behavior Of Beam To Column Cold-Formed Section Connections Subjected To Bending Moments, Maged T. Hanna, Mohamed M. El-Saadawy, Ghada M. El-Mahdy, Ehab H. A. H. Aly

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

Cold formed sections are often used in the construction of mid-rise buildings due to their high strength weight ratios, and fast erection. In these buildings, the connections between joists and studs are mainly simple connections. However, application of these sections can be extended to moderate span frames where connections between members are subjected to bending moments. Strength and stability of such frames depends to large extent on the behaviour of the connections between their members. Over the last twenty years, several researchers undertake tests on cold formed section connections subjected to bending moments. Major of them classify the connections as …

Bearing Strength Of Untightened Double-Shear Bolted Connections In Cold-Formed Steel Construction, Refat Bhuiyan, Lip H. Teh

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

This paper presents the experimental investigation of cold-formed steel double-shear bolted connections where both the bolt head and the nut are not in contact with the outer sheets. The inner sheet of each specimen is not constrained from out-of-plane distortion or bulging downstream of the bolt, and fails in bearing. Based on a series of tests involving specimens having bolt diameters ranging from 12 to 16 mm and sheet thicknesses ranging from 1.5 to 3.0 mm, it has been found that the absence of out-of-plane constraint in untightened bolted connections leads to much lower bearing capacities than predicted by the …