Structural Engineering Commons^™

Load Distribution In Floor To Wall Connections, D. M. Fox, D. R. Knill, R. M. Schuster

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

Presented in this paper is a cold formed steel load distribution system developed by iSPAN Systems LP that enables the installation of floor joists without the need to align them with the supporting wall studs. The floor joists are supported by a shear connection attached to a cold formed steel perimeter distribution member. In addition to the load distribution aspect, the system results in a simplified lateral design approach. An experimental verification study was carried out to establish the load distribution capability of the system, resulting in a simplified procedure to determine the connection requirements and load transfer characteristics to …

Seismic Performance Of Steel Sheathed Cold-Formed Steel Shear Walls, Mehran Zeynalian Dastjerdi, Hamid Reza Ronagh

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

In this paper the performance of steel sheathed cold-formed steel shear walls is evaluated by testing seven full scale walls under cyclic and monotonic loading. Of particular interest are the specimens’ maximum lateral load capacity and deformation behaviour. The study also looks at the failure modes of the system and investigates the main factors contributing to the ductile response of the CFS walls in order to suggest improvements so that the steel shear walls respond plastically with a significant drift and without any risk of brittle failure, such as failure in the connections. The walls tested are of different configurations …

Numerical Modelling And Calibration Of Cfs Framed Shear Walls Under Dynamic Loading, I. Shamim, C. A. Rogers

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

This paper describes the numerical modeling using OpenSees of steel sheathed cold-formed steel framed shear wall test specimens under dynamic loading. Two modeling phases were carried out; the first phase comprised non-linear models calibrated using existing reversed cyclic shear wall test data, and the second phase involved more advanced models calibrated using data from dynamic shake table tests of single- and double-storey shear walls as well as other ancillary test programs. The second phase models incorporated the behaviour of the hold-downs, floor framing and blocked bare frame, in addition to the sheathing. The final calibrated models were able to accurately …

Improved Reliability Determination When Testing Cold-Formed Steel Components, V. M. Zeinoddini, B. W. Schafer

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

The objectives of this paper are to (a) determine the sensitivity of the reliability calculations in Chapter F of the AISI Specification (AISI-S100-07) to controlling load combinations and loading ratios, and (b) develop a more robust alternative for the use of Chapter F. To complete this study the bias factors and variances for all loading conditions are established. In addition, a range of practical load ratios is agreed upon. Parametric studies are performed to explore load case and load ratio dependency for use in the determination of the resistance factor, Φ; specifically, the pre-factor term CΦ and the load variance …

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 …

Compression-Tension Hysteretic Response Of Cold-Formed Steel C-Stection Framing Members, D. Padilla-Llano, C. D. Moen, M. Eatherton, L. Mcanallen, T. Bruce

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

This paper summarizes results from an experimental program designed to evaluate the tension-compression cyclic axial response of cold-formed steel C-section structural framing members. A new cyclic loading protocol for cold formed steel members is presented that defines the target axial displacement based on elastic buckling parameters. The protocol is used to explore the cyclic response of members experiencing local buckling, distortional buckling, and global buckling deformation. In the experiments, post-bucking energy dissipation was observed along with tension stretching and softening. The quantity of dissipated energy per cycle increased as cross-section and global slenderness decreased. Specimens experiencing local and distortional buckling …

Design Of Nonstructural Members In Accordance With Aisi S220, Roger A. Laboube, H. Chen, J. W. Larson

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

AISI S220, the North American Standard for Cold-Formed Steel Framing - Nonstructural Members, was developed in 2011 to help clearly delineate and eliminate confusion between the requirements for cold-formed steel structural members and nonstructural members. This paper is intended as an introduction to this standard and as an illustrative guide for applying the provisions to the design of nonstructural members.

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 …

Finite Element Analyses Of Lipped Chanel Beams With Web Openings In Shear, P. Keerthan, M. Mahendran

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

Cold-formed steel members are increasingly used as primary structural elements in buildings due to the availability of thin and high strength steels and advanced cold-forming technologies. Cold-formed lipped channel beams (LCB) are commonly used as flexural members such as floor joists and bearers. Shear behaviour of LCBs with web openings is more complicated and their shear capacities are considerably reduced by the presence of web openings. However, limited research has been undertaken on the shear behaviour and strength of LCBs with web openings. Hence a numerical study was undertaken to investigate the shear behaviour and strength of LCBs with web …

Behaviour Of Litesteel Beams Subject To Combined Shear And Bending Actions, P. Keerthan, D. Hughes, M. Mahendran

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

This paper presents the details of a numerical study of a cold-formed steel beam known as LiteSteel Beam (LSB) subject to combined shear and bending actions. The LSB sections are produced by a patented manufacturing process involving simultaneous cold-forming and electric resistance welding. They have a unique shape of a channel beam with two rectangular hollow flanges. To date, however, no investigation has been conducted into the strength of LSB sections under combined shear and bending actions. Hence a numerical study was undertaken to investigate the behaviour and strength of LSBs subject to combined shear and bending actions. In this …

Shear Buckling Of Thin-Walled Channel Sections With Complex Stiffened Webs, Song Hong Pham, Cao Hung Pham, Gregory J. Hancock

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

For cold-formed channel section design in shear, the traditional approach has been to investigate shear plate buckling in the web alone. Recently, an improvement in the elastic buckling stress of the whole thin-walled channel section including flanges and lips in pure shear has been demonstrated. For webs with relatively large depth to thickness ratios, the local buckling mode in shear occurs mainly in web. The structural efficiency of such a web can be improved by adding intermediate stiffeners cold-formed longitudinally in the middle of the webs. This paper presents numerical buckling analyses implemented by means of the Semi-Analytical Finite Strip …

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 …

Behavior Of Composite Beams With Cold-Formed Steel Joists And Concrete Slab, Cheng-Tzu Thomas Hsu, Pedro R. Munoz, Sun Punurai, Yazdan Majdi, Wonsiri Punurai

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

A new composite beam and floor system has been developed herein to achieve a stronger strength and ductility, as well as to yield a more economical design purpose. This new composite beam system consists of three elements: reinforced concrete slab on corrugated cold-formed metal, back to back cold-formed steel joists, and cold-formed furring shear connector. The shear connectors are screwed through the top flange of the support joists in order to provide vertical interlocking and horizontal shear resistant between the concrete slab and the cold-formed steel joists. The self-drill fasteners are used for fastening the furring shear connector through the …

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 …

An Efficient Genetic Algorithm For The 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 real-coded genetic algorithm (GA) optimizer proposed considers both building’s topology (i.e. frame spacing and pitch) and cross-sectional sizes of the main structural members as the decision variables that are optimized. Previous GAs in the literature were characterized by poor convergence including slow progress that usually results in excessive computation times and/or frequent failure to achieve an optimal or near-optimal solution. This is the main issue addressed in this paper. In an effort to improve the performance of the conventional GA, a niching strategy is presented …

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 …

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 …

Top Arc Seam Weld Shear Strength And Stiffness For Sheet-To-Sheet Connections, R. Nunna, J. Martin, J. Mattingly, P. Bodwell, D. Boltz, K. Cullum, Roger A. Laboube

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

The North American Specification for the Design of Cold-Formed Steel Structural Members does not provide specific design guidance for sheet-to-sheet top arc seam welds in shear. A collaborative industry study has developed design guidance for both strength and stiffness of the connection to facilitate analytical evaluation of floor and roof diaphragm assemblies and wall assemblies. The test program was performed per AISI S905 and addressed material ductility, weld length, sheet thickness and the distribution of the force being transferred by the weld connection.

Improved Protocols For Automated Wheelpath Crack Detection In Pavements, Daniel Patrick Byram

Graduate Theses and Dissertations

Roadway pavement distress evaluations are vital to understanding the mechanics of pavement stability, determining the distribution of rehabilitation costs, and knowing the appropriate rehabilitation strategies. Advancements in technology over the past two decades have changed the way these surveys have been performed by means of automated data collection and interpretation. More and more state agencies have invested in automated road analyzing vehicles that are able to collect high resolution images of the pavement. Fewer have adopted automated data processing software with the ability to interpret road distresses due to the common discrepancies in distress classification algorithms.

In addition to automated …