bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Loading Angle on the Behavior of Fillet Welds
Authors: Deng Kam , Grondin Gilbert Y. , Driver Robert G.
Published: April 2024

The fillet weld design equation in the American and Canadian steel design standards is based upon research on the behavior of SMAW test specimens, therefore, the significant increase in weld strength recognized by these design standards as the loading angle increases might not be suitable for low toughness welds made with other welding processes such as FCAW, which is more commonly used for production welding. An experimental program was conducted to investigate the effect of filler metal toughness on fillet weld behavior. The first phase of this test program included only transverse fillet welds. The variables in the first phase included filler metal classification (both filler metals with a toughness requirement and some without were tested), electrode manufacturer, fabricator, weld size, root notch orientation, and test temperature. A reliability analysis of the test results (102 test specimens) indicated that the current design equation provides a safety index greater than 4.5 for transverse welds. The second phase, which formed the basis of the work presented in this paper, examined the effect of filler metal classification and toughness on the strength and ductility of fillet welds loaded at different angles with respect to their longitudinal axes. The results of this phase were obtained from 30 lap spliced specimens with nominally 12.7 mm (0.50 in.) fillet welds. Twenty-seven test specimens were prepared using the FCAW process. The specimens were loaded in three different directions with respect to the weld axis: 0°, 45° and 90°.
Current Steel Structures Research No. 05
Authors: Bjorhovde Reidar
Published: April 2024

Current Steel Structures Research
Discussion: Flexible Moment Connections for Unbraced Frames Subject to Lateral Forces â€” A Return to Simplicity
Authors: Nethercot David
Published: April 2024

Discussion
Current Steel Structures Research No. 07
Authors: Bjorhovde Reidar
Published: April 2024

Current Steel Structures Research
New Method of Design for Combined Tension and Bending
Authors: Aminmansour Abbas
Published: April 2024

A new method and aids for design of steel members subjected to combined tension and bending are presented based on the AISC Specification using the load and resistance factor design method. While the basic concepts utilized in this process apply to prismatic singly or doubly symmetric shapes subjected to flexure and axial tension, the focus of the discussions as well as the design aids developed in this paper apply to W-shapes only. The new design aids developed and presented in this paper offer the following advantages:

- Save time in design. For example, compactness is already accounted for.
- Can select more efficient sections with appropriate t, bx, and by coefficients depending on the relative magnitude of the applied axial force and bending moments.
- Can choose from a wide range of sections.
- Designer can easily judge the efficiency of a section by observing its values of t, bx, and by coefficients.
- Tables provide means for easy calculation of (phi)tPn for a large number of sections.
Errata: Performance-Based Seismic Design of Eccentrically Braced Frames Using Target Drift and Yield Mechanism as Performance Criteria
Authors: Chao Shih-Ho , Goel Subhash C.
Published: April 2024

Errata
Current Steel Structures Research No. 08
Authors: Bjorhovde Reidar
Published: April 2024

Current Steel Structures Research
Designing for Ductile Performance of Bolted Seismic Connections to Axially Loaded Members
Authors: Muir Larry S.
Published: April 2024

Field bolted connections are often the safest and most economical option for structural steel erection. It is therefore desirable to maintain the use and economy of field bolted connections as an option for seismically loaded structures, even within the seismic load resisting system. This paper addresses two aspects of the AISC 2005 Seismic Provisions for Structural Steel Buildings: bolted joints and the requirement that vertical brace connections be designed for the expected tensile strength of the brace as stipulated for ordinary concentrically braced frames and special concentrically braced frames.
Current Steel Structures Research No. 09
Authors: Bjorhovde Reidar
Published: April 2024

Current Steel Structures Research
Development of A Cast Modular Connector for Seismic-Resistant Steel Moment Frames Part I: Prototype Development
Authors: Sumer Ali , Fleischman Robert B. , Hoskisson Blake E.
Published: April 2024

A cast modular connector (MC) has been developed for use in seismic-resistant steel moment frames. The MC is a field bolted beam flange connection intended to serve as the frame's special energy-dissipating detail. The connector is specifically configured for optimal seismic performance through a casting process. The MC possesses inherent ductility through variable-section arms that minimize plastic strain demand and a reliable yet economical fastening method through a base end-region that virtually eliminates prying forces on bolts. This paper focuses on the development of a Beta prototype design for the MC. This development process focused on the isolated connector rather than full-connection behavior. The MC Beta prototype design was developed using a comprehensive analytical investigation of trial configurations and key parameters using nonlinear (material and geometry) finite element analysis. Lessons were learned from an Alpha prototype. Designs were alternately evaluated for structural performance and castability through the electronic exchange of solid model files with steel foundry industry partners. The analytical results indicate the potential for excellent ductility and energy dissipation characteristics in the MC Beta prototype. A subsequent companion paper will describe the creation of a physical prototype and the experimental program that provides verification of the analytical results presented here.
The Behavior of Steel Perimeter Columns in a High-Rise Building Under Fire
Authors: Garlock Maria M. , Quiel Spencer E.
Published: April 2024

The thermal response of structural steel may affect the behavior of a steel high-rise building exposed to fire. In a plane perpendicular to the exterior wall, a perimeter column is typically laterally braced by one beam. The fire-induced structural response of this beam that frames into the perimeter column (perpendicular to the exterior wall) directly affects the perimeter column behavior and the structural integrity of the frame as a whole. The objective of this research is to evaluate the behavior of perimeter columns in a steel high-rise building that is subjected to a large fire, and examine this behavior as it interacts with the beams that frame into it. This behavior is examined by several analyses that consider the inclusion of fire protection material on the beams and columns as a parameter. A two-dimensional model of eleven upper level floors of a steel framed building subjected to fire is analyzed. The thermal expansion of the beams that frame into the perimeter column induce column lateral deformations and moments that combine with axial gravity forces to create a plastic hinge in the perimeter columns. Since these beams are partially restrained from expanding, large axial forces develop in them, which, combined with bending moments, may lead to beam failure. Once these beams, which brace the perimeter column in one plane, fail, the stability of the column, and structure as a whole, is compromised and could potentially lead to structural collapse. The results of this research confirm the design philosophy in current codes that recommends the same level of fire protection material for these beams as the columns to which they are attached since they significantly affect perimeter column behavior and thus the overall behavior of the frame. This study also shows that the perimeter columns and beams act as beam-columns in a fire (in other words, members under combined axial load and bending) and therefore their behavior and capacity should be evaluated as such.
Effects of Nonverticality on Steel Framing Systems--Implications for Design
Authors: Surovek Andrea E. , Johnson Justin
Published: April 2024

The first section of the paper describes the types of initial imperfections typically considered in planar frame analysis and their effect on members and framing systems. This is followed by a discussion of how the effects of imperfections are treated in the AISC Specification. A parametric study is presented in which the sensitivity of framing systems to imperfection effects is investigated with respect to a number of parameters including slenderness ratios, leaning load levels, gravity to lateral load ratios, and lateral frame stiffness, as measured by a second-order to first-order drift ratio. In addition to the sensitivity study, a number of columns and simple frames were analyzed with and without imperfections using the direct analysis approach for assessing frame stability outlined in Appendix 7 of the AISC Specification. The differences in the interaction checks for simple columns and frames are used to discuss the current limits on when imperfection effects may be neglected.
Designing Compact Gussets with the Uniform Force Method
Authors: Muir Larry S.
Published: April 2024

The Uniform Force Method (UFM) is the preferred method given for determining the forces that exist at gusset interfaces. The UFM provides a standardized way to obtain economical, statically admissible force distributions for vertical bracing connections. One criticism of the method is that it sometimes results in oddly shaped or disproportionately large gusset plates. To overcome this perceived limitation of the UFM, designers have been seeking out alternate methods. This paper demonstrates that removing one unnecessary geometrical constraint from the formulation of the UFM will allow greater freedom in gusset geometry, while maintaining the efficiencies that result from the method. A new formulation of the UFM is presented, and the strengths and weaknesses of other proposed design methods are also explored.
Errata: Limit State Response of Composite Columns and Beam-Columns Part I: Formulation of Design Provisions for the 2005 AISC Specification
Authors: Leon Roberto T. , Kim Dong Keon , Hajjar Jerome F.
Published: April 2024

Errata
Design Aid for Triangular Bracket Plates Using AISC Specifications
Authors: Shakya Shilak , Vinnakota Sriramulu
Published: April 2024

This paper presents a model to determine the nominal strength of a triangular steel bracket plate using the column strength equations in AISC Specification. Also included are two design tables for such bracket plates for two grades of steel. The nominal strengths obtained by using the relations developed by the authors are compared with the available experimental results and results from other available theoretical approaches. The authors' approach predicts results closer to the experimental results than the other theoretical approaches. Two example problems are worked to illustrate the use of the design tables.
Fracture Modeling of Rectangular Hollow Section Steel Braces
Authors: Ding Xiang , Foutch Douglas , Han Sang-Whan
Published: April 2024

Steel braced frames are widely used in all regions of the U.S. including those with high levels of seismicity. Rectangular hollow sections (RHS) are popular because of good section properties and ease of construction. A refined beam model has been developed which is efficient for use in finite element models of buildings. It accounts for local buckling and fracture in the brace and is shown to have good accuracy for nonlinear seismic analyses.
Current Steel Structures Research No. 15
Authors: Bjorhovde Reidar
Published: April 2024

Current Steel Structures Research
Quantifying and Enhancing Robustness in Steel Structures: Part 2--Floor Framing Systems
Authors: Foley Christopher M. , Schneeman Carl , Barnes Kristine
Published: April 2024

The objective of this two-part manuscript is to provide information that can lead to: (a) better understanding of disproportionate collapse in structural steel framing systems; (b) improved understanding of secondary load paths that form within structural steel framing systems in the event of a localized failure; (c) development of minimum general structural integrity provisions for structural steel framing systems analogous to those present in ACI 318; (d) recommendations for minimum tie forces that can be used as the basis of indirect design methodologies for structural steel framing systems; (e) an understanding of the distribution of tensile forces within typical steel floor framing systems to facilitate compartmentalization damage or collapse; and (f) identification of simple and economical means with which to enhance the robustness in the typical structural steel framing system.
Simplified LRFD Design of Steel Members for Fire
Authors: Lee Tai-Kuang , Pan Austin D.E. , Hwa Ken
Published: April 2024

This paper proposes a simplified design methodology for steel members under fire in accordance with LRFD provisions. The fire design criterion compares the required design strength ratio with the design strength reduction ratio. Design strength ratios are derived from the required strength factor and the overstrength factor. Simplified formulas for member strength at elevated temperatures, as well as their corresponding critical temperatures, are derived for steel members under tension, compression and flexure, for unrestrained boundary conditions. An illustrative example is presented and comparisons are made with experimental data.
The Effect of Selected RFI Variables on Steel Fabrication Performance
Authors: Burns Thomas M.
Published: April 2024

The steel fabrication process depends upon documentation that is often in need of clarification due to issues involving completeness and coordination. Clarification is obtained by the steel fabricator through the request for information (RFI) process which allows the shop drawing production process to continue forward. The volume of requests for information sought, as well as time required to receive clarification, are just two of many variables that may influence shop drawing production as well as subsequent fabrication activities. This research identifies specific RFI variables and their significant relationship with shop drawing production and fabrication duration performance. Data from 48 projects were collected from steel fabricators throughout the United States. Regression techniques identified two variables, the RFI performance indicator and the average RFI response time, as significant predictors for both shop drawing production and fabrication duration performance measures. Within the 48 projects studied, approximately 25% of the performance variability in shop drawing production was explained by these two variables. The generalized model developed from these results may be applied by individual steel fabricators interested in performance improvement through RFI management. Project databases using RFI metrics could benefit fabricators by establishing performance thresholds while also providing engineers with a quality service indicator.
Closure: Designing Compact Gussets with the Uniform Force Method
Authors: Muir Larry S.
Published: April 2024

Closure
Acknowledgments
Authors: Grubb Keith A.
Published: April 2024

Acknowledgments
Discussion: Limit State Response of Composite Columns and Beam-Columns Part II: Application of Design Provisions for the 2005 AISC Specification
Authors: Geschwindner Louis F.
Published: April 2024

Discussion
Single-Plate Shear Connection Design to Meet Structural Integrity Requirements
Authors: Geschwindner Louis F. , Gustafson Kurt D.
Published: April 2024

Specific prescriptive structural integrity provisions have been added to both model and local building codes since the collapse of the buildings at the World Trade Center site in 2001. The first building code to incorporate specific requirements was the 2008 New York City Building Code which was followed quickly by the 2009 International Building Code. This paper demonstrates how properly designed single-plate shear connections comply with the structural integrity provisions of IBC 2009 and also make appropriate comparisons with NYC 2008.
A Simple Stepped-Column Buckling Model and Computer Algorithm
Authors: Vasquez Jorge , Riddell Rafael
Published: April 2024

The paper presents a solution to the problem of obtaining the effective length ratios needed for the design of stepped columns. The formulation of a discrete model is presented, and a numerical algorithm is implemented to solve it as a matrix eigenvalue problem. The method is an alternative to using tabulated results, which have been obtained from closed-form solutions for a number of ideal boundary conditions, which in most practical cases is cumbersome and almost always unpredictably inaccurate. A MATLAB coding of the algorithm is provided, and examples illustrating its use are included.
Current Steel Structures Research No. 25
Authors: Bjorhovde Reidar
Published: April 2024

Current Steel Structures Research
A Yield Line Component Method for Bolted Flange Connections
Authors: Dowswell Bo
Published: April 2024

Bolted connections are often used in steel structures to transfer of tension loads into wide flange members. The strength of these connections is determined with a prying action design procedure (outlined in the 13th edition AISC Steel Construction Manual) that checks the limit states of bolt tension rupture and bending of the flange. This procedure is valid only for fittings with limited bolt spacing and limited edge distance. This paper discusses a method to determine the local flange bending strength of a wide flange member using the yield line method. The proposed design method includes the effect of prying action on the bolts, and can be applied to many different connection configurations, including connections with large bolt spacing and edge distances and connections with web stiffeners. Comparisons with test data from 10 independent research projects will be used to verify the accuracy of the proposed method.
Design of Steel Buildings for Earthquake and Stability by Application of ASCE 7 and AISC 360
Authors: Shankar Nair R. , Malley James O. , Hooper John D.
Published: April 2024

Design of steel buildings in the United States typically combines application of ASCE/SEI 7, Minimum Design Loads for Buildings and Other Structures, and ANSI/AISC 360, Specification for Structural Steel Buildings. For buildings designed for seismic effects, ANSI/AISC 341, Seismic Provisions for Structural Steel Buildings, may also be applicable. The ASCE 7 Minimum Design Loads standard includes specific design provisions related to stability under seismic loading which overlap and, in some instances, appear to conflict with the stability design requirements of the AISC Specification. This paper explores the areas of overlap and apparent conflict between ASCE 7 and AISC 360 and offers practical recommendations for seismic design incorporating the provisions of both.
Hybrid Moment-Resisting Steel Frames
Authors: Charne Finley A. , Atlayan Ozgur
Published: April 2024

A new type of moment-resisting steel frame, called a hybrid moment-resisting frame, is described. Unlike a typical moment frame, where all member sizes and connection details fit a specific set of rules (e.g. for a special moment frame), the hybrid frame contains members and connections with a variety of detailing rules, including those typically associated with ordinary, intermediate and special moment frames. Elements that have special detailing are designed to yield at force levels well below the design basis earthquake and thereby provide some inelastic energy dissipation that helps to control dynamic amplification. Elements with ordinary detailing are designed to remain elastic during the design basis earthquake and to provide enough positive stiffness to counteract P-delta effects. The resulting system can be designed to perform better than the traditional special moment frame and to be more economical than the special moment frame because a limited number of elements and connections have special detailing. The behavior of the system is demonstrated through incremental nonlinear dynamic response history analysis.
Design of Steel Columns at Elevated Temperatures Due to Fire: Effects of Rotational
Authors: Agarwal Anil , Varma Amit H.
Published: April 2024

The stability of steel building structures under fire loading is often governed by the performance of the gravity load resisting systems. The inelastic buckling failure of gravity load bearing columns can potentially initiate and propagate stability failure of the associated subsystem, compartment or story. This paper presents a design methodology for wide-flange hot-rolled steel columns (W-shape) under uniform compression at elevated temperatures. A number of simply supported W-shape columns were modeled and analyzed using the finite element method (FEM). The analysis for axial loading followed by thermal loading was conducted using the nonlinear implicit dynamic analysis method to achieve complete stability failure. The models and analysis approach were validated using the results of existing column test data at elevated temperatures. The analytical approach was used to expand the database and to conduct parametric studies. The results are compared to existing column design equations at elevated temperatures and are used to propose revisions to the AISC ambient temperature design equations for steel columns to account for the effects of elevated temperatures and rotational restraints from cooler columns above and below the heated story.
Current Steel Structures Research No. 28
Authors: Bjorhovde Reidar
Published: April 2024

Current Steel Structures Research
Recommendations for Shear Lag Factors for Longitudinally Welded Tension Members
Authors: Fortney Patrick J. , Thornton William A.
Published: April 2024

Section J2.2b of the 2010 AISC Specification for Structural Steel Buildings requires the length of longitudinal welds, used to connect flat plate tension members, to be greater in length than the distance between the longitudinal welds. Currently, weld lengths less than the distance between the welds are not permitted for connections of flat plate members.The procedure for the calculation of the shear lag factor, U, for this type of connection is given by Case 4 in Table D3.1 of the AISC Specification, where U is a function of the length of the longitudinal weld and the width of the plate. Although Case 4 is explicitly defined for plates only, the generally accepted practice in the design of similar welded connections of angles, channels, tees and wide flange members is to apply the same limitation on weld length, and calculate the effect of shear lag as given by Case 2 in Table D3.1 of the AISC Specification, while ignoring shear lag effects with weld lengths between one and two times the distance between the welds. Furthermore, for connection geometries meeting those for Case 2 or Case 4, there is no guideline for considering connection strengths where the longitudinal welds on each side of the member have unequal lengths (e.g., skewed web members or braces), or weld lengths less than the distance between the welds.This paper presents recommendations for a generalized design procedure for welded connections of plate, angle, channel, and tee tension members regardless of the length of the weld or if the length of the longitudinal welds are unequal. A summary of the treatment of various current building codes/specifications (AISC and CSA) on this topic is presented along with the results of several published experimental research projects that evaluated the behavior of these types of connections. Two analytical models are presented, and recommendations for changes to the current AISC Specification are made, followed by an example problem illustrating the practical application of the recommendations.
The Effect of Piece Marking Upon Fatigue Performance of Bridge Steel
Authors: Frank Karl H. , Samaras Vasilis , Helwig Todd A.
Published: April 2024

An experimental study was undertaken to determine if markings used to identify fabricated steel using modern automatic impact stenciling equipment could be used on structures subjected to fatigue loading. The fatigue specimens with both numeric and alphabetic markings were tested. The results showed that fatigue life of marked steel exceeded the fatigue design strength for Category A, the highest fatigue design category. Marking pieces with this equipment will not affect the fatigue design strength of the member.
A Simplified Approach for Evaluating Second-Order Effects in Low-Rise Steel Framed Buildings
Authors: Souhail Elhouar and Yasser Khodair
Published: April 2024

Consideration of second-order effects is one of the most involved tasks in the analysis and design of steel framed buildings. More specifically, the evaluation of amplified moments due to frame level second-order effects is a very time consuming task because, depending on the method used, it may require an additional first order analysis or the introduction of additional notional loads for each considered load case. Although the use of such methods may not present a problem when the design process is fully automated, hand calculations can be quite complicated for checking the results of a computer generated design or for designing a small structure in which second-order effects may not even be significant enough to affect the selection of member sizes. This paper presents a simplified approach for the incorporation of second-order effects in the design of low-rise steel framed structures. The development of this approach involved the design and analysis of a number of systems with various numbers of bays, floors and beam-span to floor-height ratios and included a thorough investigation of the effect of moment amplification on final member sizes. To facilitate this task, a spreadsheet application was developed to automate the design of a typical low-rise steel frame under given loading conditions. A parametric study was then performed to understand the effect of the various design parameters on member-level and frame-level second-order forces and moments. This led to the development of the simplified design approach proposed in this paper.
Prying Action for Slip-Critical Connections with Bolt Tension and Shear Interaction
Authors: Thornton William A. , Muir Larry S.
Published: April 2024

When bolted connections subjected to both shear and tension must be checked for prying action, the interaction between tension and shear must be considered. The 2010 AISC Specification for Structural Steel Buildings (AISC 360-10) presents interaction equations both for bearing connections and for slip-critical connections. This paper demonstrates how these interaction equations may be used when applying the prying action analysis presented in the 14th edition Steel Construction Manual.
Beam Deflections and Stresses During Lifting
Authors: R.H. Plaut C.D. Moen and R. Cojocaru
Published: April 2024

The behavior of horizontally curved beams during lifting is analyzed. The beams are circularly curved, doubly symmetric, prismatic and linearly elastic, and they are suspended at two symmetric locations. The two cables lifting the beams may be vertical or inclined symmetrically. Numerical results are presented for steel I-beams. Weak-axis and strong-axis deflections, roll angle and cross-sectional twist, internal forces, bending and twisting moments, and longitudinal stresses are calculated using newly derived analytical solutions implemented as a freely available spreadsheet at http://www.moen.cee.vt.edu/. Lifting locations along the beam that minimize displacements and stresses are identified.
Conceptual Design of Double Steel Containment Vessels
Authors: Wang Chen-Hwa
Published: April 2024

In conjunction with nuclear plants, huge containment vessels for the enclosure of the pressure circuit, embracing reactor and heat exchangers, have already found acceptance. Inside of the containment vessel, surrounding the primary coolant loops, is a primary shielding wall which is a principal barrier against missiles resulting from internal explosion, affords protection to the vessel itself, and tends to protect the vessel from radiation damage, activation, and nuclear heating. Under normal operation the temperature of the containment is generally accepted as 150°F or less and is subject to only minor thermal stress effects; however, under maximum credible accident, or MCA, the temperature may rise to 300°F or more, depending upon engineered safeguards, free volume, and heat sinks provided in the vessel. Therefore, the vessel sustains a small thermal stress at normal operation but must withstand significant thermal deformation and interior pressure under MCA conditions. At the present time reinforced concrete and prestressed concrete vessels are generally designed for this type of containment, whereas a single steel vessel is considered economically unfeasible because of the large thickness of plate required.
Errata: High-Strength Bolting
Authors: Munse W.H.
Published: April 2024

Errata
The Evolution of German Cable Stayed Bridges- An Overall Survey
Authors: Feige Adolf
Published: April 2024

The evolution of bridges with girders stayed by means of steel cables—referred to as "cable stayed bridges" or "cable cantilever bridges"—has taken place in a relatively short period, namely, about fifteen years. In the domain of highway bridges the structural system in question fills the gap that once existed between the "deck" type bridge (with the girders installed under the bridge deck) and the suspension bridge. It has, however, also been successfully applied to the construction of footbridges. As far back as 1950, more particularly for "deck" bridges, of medium span, the continuous solid-web superstructure with orthotropic steel deck plate functioning also as the top flange showed itself to be superior to other systems. For long spans, however, it necessitated considerable girder depths at the intermediate piers, e.g., as much as 33 ft for the worlds biggest bridge of this type, the bridge over the River Save at Belgrade. The bridge with plate girders of constant depth which has been built over the Sill near Innsbruck has a superstructure with a depth of about 25 ft for a span length of 650 ft, i.e., a depth/span ratio of 1/26. Be that as it may, all the cable-stayed bridges that have been built in Germany in recent years are based on the structural system comprising an orthotropic deck plate and continuous girders.
Box Girder Bridge Design
Authors: Kavanagh Thomas C.
Published: April 2024

This paper discusses the coordinated design research program conducted under the sponsorship of the United States Steel Corporation, on the subject of steel box girder bridges. The assigned objective of this investigation was the development of design theory, methods and specifications for steel box girder bridges of short to medium span lengths, having composite decks. The work has included both theoretical, computer, and model test studies, and has progressed to the point where a draft of a specification has been prepared by the investigators and a number of interested state and federal highway engineers, for presentation to the AASHO Bridge Committee. The use of torsion boxes as flexural girders in bridges is but another extension of the advantageous application of closed structural sections as columns, arch ribs, truss members, or stiffeners for deck plates, where it is desired to achieve improved structural strength, economy, appearance, and resistance to corrosion. Even a cursory survey of current bridge literature will indicate a growing awareness of the potential importance of box girders.
Plastic Design by Moment Balancing
Authors: Gaylord Edwin H.
Published: April 2024

Two theorems are important in the plastic analysis of rigid-frame structures. These are usually called the upper bound theorem and the lower-bound theorem. According to the upper-bound theorem, the load corresponding to an assumed mechanism of collapse will always be greater than, or at best equal to, the true ultimate load. According to the lower-bound theorem, the load corresponding to a given moment diagram for which the moment nowhere exceeds the plastic-moment capacity of the frame will always be less than, or at most equal to, the true ultimate load. If one constructs a moment diagram for a structure—any moment diagram, so long as it satisfies statics—and proportions the structure to this moment diagram so that there are enough plastic hinges to form a mechanism, the upperbound and lower-bound theorems are satisfied simultaneously. This conclusion is the basis for a scheme proposed by Horne1 that is particularly suited for purposes of design. It can be used to construct a distribution of moments about which the structure can then be developed in such a way as to result in a sufficient number of plastic hinges to produce a mechanism. The procedure is very efficient in application to frames of several stories, and offers the designer liberty he does not enjoy in design based on elastic methods of analysis. The method is also useful for preliminary sizing of frames which are to be designed elastically.
Overview of the Development of Design Recommendations for Eccentrically Braced Frame Links with Built-Up Sections
Authors: Berman Jeffrey W. , Bruneau Michel
Published: April 2024

Among the new additions to the 2010 AISC Seismic Provisions are design requirements for eccentrically braced frame links with built-up box sections. Such links do not require lateral bracing in many cases because built-up box shapes have superior lateral torsional stability relative to wide flange sections. The 2010 Seismic Provisions include requirements for built-up box link flange width-to-thickness ratio and other important design considerations. However, the limits on web width-to-thickness ratio default to those used for built-up box beams or columns and are inadequate for links with large inelastic shear and compression strains. Such limits are important for preventing web buckling under shear and/or flexural compression. This paper presents an overview of research on the design and behavior of links with built-up box sections, including the development of recommendations for web width-to-thickness limits and corresponding web stiffener spacing requirements and flange width-to-thickness limits for these link sections. The highlighted research program included derivation of design requirements based on plate buckling considerations; a full-scale, single-story eccentrically braced frame test; a parametric study on the impact of link cross-sectional parameters on link inelastic rotation capacity; and a series of large-scale tests on isolated links.
Errata: Bond Behavior of Concrete-Filled Steel Tube (CFT) Strucutres
Authors: Jie Zhang Mark D. Denavit
Published: April 2024

Errata
Editor's Note: Engineering Journal
Authors: Grubb Keith A.
Published: April 2024

Message from the Editor
HSS Truss Connections with Three Branches
Authors: Packer Jeffrey A.
Published: April 2024

Hollow structural section (HSS) three-branch (or KT) connections frequently occur in modified Warren trusses, but the design of these planar welded connections is beyond the scope of Chapter K of the 2010 AISC Specification for Structural Steel Buildings. Such connections are also not covered by other contemporary HSS design guides and standards. This paper reviews the many potential member and loading arrangements, for both gapped and overlapped KT connections, and offers some design guidance. A worked example for an overlapped square HSS KT connection is then given, in both LRFD and ASD formats, in accordance with the 2010 AISC Specification for Structural Steel Buildings.
Errata: Elastic Buckling of a Column Under Varying Axial Force
Authors: Shrivastava Suresh C.
Published: April 2024

Errata
Evaluation and Repair of Bridge Truss Gusset Plates
Authors: Hill Howard , Mcgormley Jonathan C. , Lewis Jonathan , Clarke Wade , Nagle Thomas
Published: April 2024

Gusset plates used to connect members in large steel trusses are important elements in many existing bridge structures. As such, their capacities can influence bridge structural load ratings, especially when the effects of deterioration and/or damage have become significant. In order to provide accurate load ratings, avoid unnecessary repairs and, when necessary, design appropriate repairs, gusset plate conditions and characteristics must be properly incorporated in the responsible engineer's evaluation. Because the cost of being conservative is far greater for existing structures than for new designs, engineers evaluating existing gusset plates should not rely too heavily on design-based methods when making final load rating and repair decisions. The purpose of this paper is to provide some practical guidance to the process of gusset plate evaluation and repair in order to promote efficient use of limited bridge maintenance resources.
Plastic Strength of Connection Elements
Authors: Dowswell Bo
Published: April 2024

Many connection elements are modeled as rectangular members under various combinations of shear, flexural, torsional and axial loads. Strength design is now used for steel members and connections; therefore, the traditional method of combining loads using beam theory needs to be updated to comply with strength design philosophy. Due to the extensive research available on the plastic interaction of rectangular members, a review of existing equations forms the basis of this paper. In cases where existing research is unavailable, new derivations are provided. An interaction equation is developed for strength design of rectangular connection elements under any possible loading combination.
Double-Tee Members in Axial Compression
Authors: Arber Leigh , Wang Meng , McManus Pat
Published: April 2024

This paper presents tabulated compressive strengths of double-tee members, which are comprised of two WT members oriented with their flanges back to back (referred to as "2WTs"ť or "double WTs"ť hereafter). The benefits and typical use of these members are described, including schematic details of connection designs. All WT members built from the WT7 and WT6 series are included in the table, which gives available strengths in both ASD and LRFD. Slenderness effects and the effects of shear deformations of intermediate connectors are taken into account.
Crippling of Webs with Partial Depth Stiffeners under Patch Loading
Authors: Salkar Raghuvir , Salkar Abhishek , Davids William
Published: April 2024

Chapter J of the 2010 AISC Specification recommends the use of either single-or double-sided minimum half depth transverse web stiffeners where web crippling strength is less than design concentrated load; use of a doubler plate of minimum half web depth is also suggested in the Specification. Commentary on the Specification mentions that since the web crippling phenomenon has been observed to occur in the web adjacent to the loaded flange, a half-depth stiffener (or stiffeners) or a half-depth doubler plate is needed to eliminate web crippling. Research conducted at the University of Maine, however, clearly showed that web crippling can occur even in webs having half depth stiffeners. Further, the AISC Specification does not have a formula to predict crippling strength of webs with partial depth stiffeners under local compressive loads. This paper presents a formula for evaluating crippling strength of webs with partial depth stiffeners which considers the effect of depth of stiffener, width of load, and eccentricity of loading.
Letter from the Editor
Authors: Matthew Margaret A.
Published: April 2024

Letter from the Editor
Tensile Strength of Embedded Anchor Groups: Tests and Strength Models
Authors: Grilli David A. , Kanvinde Amit M.
Published: April 2024

Steel column bases in seismically braced frames and other similar structures must be designed for high uplift or tensile forces. A common detail for this connection involves anchors embedded in the footing with a plate at their lower end, also embedded in the footing. This detail is increasingly prevalent in construction practice because it is exempt from the strength calculations of ACI 318 Appendix D. However, no experimental data or validated design guidelines are available to support the design of this detail. As a consequence, approaches from other similar situations (such as punching shear of slabs) are adapted for this purpose. To address this practical need, this paper presents tension tests on two full-scale specimens featuring this anchorage detail. The main variable examined in the experiments is the embedment depth, such that two depths (12 and 18 in.) are tested. The test specimens exhibit a classic concrete failure cone extending upward from the edges of the embedded base plate. The experimental data provide evidence that the anchorage detail provides an effective means to carry high-tensile loads. The data are evaluated against three strength models, including the ACI 318 Appendix D method, the ACI 318 punching shear equation and the concrete capacity design (CCD) method. It is determined that the ACI 318 Appendix D method is significantly conservative (average test-predicted ratio of 1.34) because it does not consider the beneficial effects of the embedded plate. On the other hand, the punching shear method has an average test-predicted ratio of 0.62. The CCD method shows the most promise, with an average test-predicted ratio of 0.99. Limitations of the study include the small size of the test set and the minimal reinforcement in the specimens.
Design of Horizontal Life Lines in Personal Fall Arrest Systems
Authors: Dranger Thomas S.
Published: April 2024

Personal fall arrest systems have become common in construction, maintenance, and many other activities including recreation. Many use a horizontal lifeline (HLL), often a steel cable. Their design is governed by Occupational Safety and Health Administration (OSHA) regulations that require “supervision by a qualified person” and a factor of safety of at least two. In contrast to a vertical lifeline that can be analyzed as a linear spring, a HLL has non-linear elastic behavior. The analysis is complicated by the fact that both the maximum arresting force and the geometric shape of the HLL at the stopping point are initially unknown. Some suggestions for estimating the arresting forces are known to be grossly in error for the general case. Greater confidence in a design is realized when arresting forces are found by rational analysis. This paper gives a summary of regulations, a reiterative method of analysis, a discussion of the limit states, and some appropriate modifications in the case of unacceptable behavior. The effects of assumptions used in the analysis are discussed in the conclusion.
Notes on the AISC 360-16 Provisions for Slender Compression Elements in Compression Members
Authors: Geschwindner Louis F. , Troemner Matthew
Published: April 2024

Compression member strength is controlled by the limit states of flexural buckling, torsional buckling, and flexural-torsional buckling, as applicable. These compression members may buckle globally or locally, depending on the overall column slenderness and the local plate element slenderness for the plates that make up the shape. If any of the plate elements will buckle at a stress lower than that which would cause the column to buckle globally, the local buckling of the plate will control the overall column strength. When this occurs, the column is said to be composed of slender elements. This paper will briefly discuss past specification provisions for slender element compression members and introduce the new provisions in the 2016 AISC Specification. It will present a simplification that reduces the number of constants that must be used and will present the specification requirements in an alternate format. Because the 2016 requirements result in different strengths than the 2010 requirements, figures are provided to illustrate the overall impact of these changes on column strength.
Updates to Expected Yield Stress and Tensile Strength Ratios for Determination of Expected Member Capacity in the 2016 AISC Seismic Provisions
Authors: Liu Judy
Published: April 2024

The expected yield stress and expected tensile strength ratios for hollow structural sections (HSS), pipe, and steel reinforcement for steel-concrete composite construction have been updated for the 2016 AISC Seismic Provisions for Structural Steel Buildings. For HSS, each grade of steel, including the new ASTM A1085 specification, has its own Ry and Rt values. Expected yield stress and tensile strength ratios have also been defined for different grades of steel reinforcement. The revisions were based on analysis of mill test data for HSS and pipe from a number of producers and a comprehensive mill survey conducted by the Concrete Reinforcing Steel Institute (CRSI).
Design of Wrap-Around Gusset Plates
Authors: Dowswell Bo , Fouad Fouad , Davidson James , Whyte Robert
Published: April 2024

This paper addressed the design of wrap-around gusset plates, which are commonly used where a horizontal brace connects at a beam-to-column intersection. Wrap-around gusset plates must be cut around the column, which can lead to high flexural stresses near the reentrant corner. A rational design method was developed in this paper, based on the results of 15 experimental tests and the corresponding finite element models. The design method, which models the gusset legs as rectangular beams, considers the strength of each leg independently. Because the buckled shapes included both out-of-plane translation and twisting along the leg, the stability behavior is evaluated using a lateral-torsional buckling model according to AISC Specification Section F11. Based on the buckled shape of the specimens and finite element models, design buckling lengths are recommended. Information is also included for calculating the strength of wrap-around gusset plates with the interior corner cut on a diagonal. Three examples are provided to illustrate the proposed design procedure.
Technical Note: Post-Fire Axial Load Resistance of Concrete-Filled, Double-Skin Tube (CFDST) Stub Columns
Authors: Imani Reza , Bruneau Michel
Published: April 2024

This technical note reports findings on a series of squash tests to investigate the effects of a significant fire loading history on the axial load strength of concrete-filled, double-skin tube (CFDST) stub columns. Axial loading tests were conducted on two stub columns that were previously subjected to the first 60 minutes of the standard ASTM E119 (ASTM, 2012) fire. Results were compared to the resistance of an identical virgin stub column. Comparisons indicated an average reduction of 28% in the axial load strength of stub columns when subjected to the mentioned fire loading history.
Steel Structures Research Update:Seismic Performance and Design of Steel Panel Dampers for Steel Moment Frames
Authors: Liu Judy
Published: April 2024

Ongoing work on the seismic performance and design of steel panel dampers for steel moment frames is highlighted. Dr. Keh-Chyuan Tsai, professor in the Department of Civil Engineering at National Taiwan University, leads the team from National Taiwan University and the National Center for Research on Earthquake Engineering (NCREE) in Taipei. In 2018, At NCREE, one recent collaboration with the University of Washington included cyclic tests of a three-story chevron special concentrically braced frame (SCBF). Current seismic design provisions require large beam sizes to resist the unbalanced forces from the chevron braces after brace buckling. The research has explored options for alternative ductile mechanisms and reduced beam sizes. Steel research at NCREE has also included studies on steel beam-to-box-column moment connections and electro-slag-welded (ESW) joints in those connections. Meanwhile, research into premature fracture of ESW diaphragm-to-column joints in beam-to-box-column connections has revealed sensitivity to eccentricity in loading between the beam flange and the diaphragm. Further, a micromechanical-based stress-modified critical stress (SMCS) model has been developed and shown to be capable of predicting the crack initiation of the diaphragm-to-column ESW joint (Li et al., 2018).