bluuebunny/crossref_metadata_2025 huggingface dataset:
Effective Length Factors of Gin Poles
Authors: Lott James L , Jones Ernest R.
Published: April 2024

An iterative numerical method is used to find the first elastic buckling mode and critical buckling load of
gin poles. The buckling loads are used to determine dimensionless, effective length factors, K L ,
referenced to the total gin pole length. A dimensionless, relative stiffness ratio of the supporting
structure to the gin pole is defined and incorporated into a parametric study of the effective length
factors versus the “overhang” distance above the top lateral support. Other parameters include
variations in rigging of load lines and two or three lateral supports.
Yield Line Approaches for Design of End Plate Tension Connections for Square and Rectangular HSS Members Using End Plate Tensile Strength
Authors: Thornton William A.
Published: April 2024

End plates, which are sometimes called flange plates, are a common way to treat HSS members loaded in tension. In this application, prying action must be considered in the design of the plate and bolts. This paper demonstrates that the prying action model can use the end plate minimum tensile strength rather than the yield strength to achieve satisfactory designs. Only connections with bolts on all four sides of the HSS are considered here.
Buckling of Conventional and High-Strength Vanadium Steel Double-Angle Compression Members: Computational Parametric Evaluation of Slenderness Modification Factors
Authors: Talaat Mohamed M. , Mayes Robert L. , Webster Mark D. , Citipitioglu Ahmet , Kan Frank W.
Published: April 2024

High-strength, low-alloy vanadium (HSLA-V) steel offers higher strength and toughness than conventional steel. The resulting lighter weight and more slender structural components are more susceptible to buckling in compression. Of particular interest to this study are open-web joists, which utilize double-angle sections—typically for chord members and often for web members. Design code treatment for both global and specifically local buckling of double-angle compression members is evaluated in this study. Code equation predictions of the buckling strength for a wide range of specimens and material strengths are examined and compared to analytical simulations. This paper proposes two alternative modifications to the so-called Q-factor formulation in order to address the nonconservative buckling strength predictions for double-angle compression members with low Q factors. This study concludes that the adoption of a modified Q-factor formulation for local elements of compression members in the element elastic buckling region produces consistent predictions of the buckling strength. This finding is equally applicable to both HSLA-V and conventional steels. For design and other applications where a lower-bound estimate of the strength is required, this combination of proposed Q-factor formulation and AISC built-up member slenderness modification is recommended.
Assessment of I-Section Member LTB Resistances Considering Experimental Test Data and Practical Inelastic Buckling Design Calculations
Authors: Subramanian Lakshmi , Jeong Woo Yong , Yellepeddi Raja , White Donald W.
Published: April 2024

The current AASHTO and AISC Specification equations characterizing the lateral-torsional buckling (LTB) resistance of steel I-section members are the same, with minor exceptions, and are based in large part on unified provisions calibrated to experimental data. This paper takes a fresh look at the correlation of the flexural strength predictions from these equations with a large experimental data set compiled from research worldwide. To account fully for the moment gradient and end restraint effects present in the physical tests, the study employs practical buckling calculations using inelastic stiffness reduction factors (SRFs) based on the design resistance equations. The study focuses on uniform bending tests as well as moment gradient tests in which the transverse loads are applied at braced locations. Reliability indices are estimated in the context of building design. It is shown that a proposed modified form of the current resistance equations provides a more uniform level of reliability, as a function of the LTB slenderness, consistent with the target intended in the AISC Specification. The paper also calls attention to the limited experimental data pertaining to the inelastic LTB resistances in certain cases. The paper concludes by providing additional recommendations for LTB strength calculations in routine design, including illustrative plots conveying the impact of the proposed changes.
Errata: Stability of Rectangular Connection Elements
Authors: Dowswell Bo
Published: April 2024

Errata to original paper in Vol. 53, No. 4, 2016
Local Strength of Single-Coped Beams
Authors: Dowswell Bo
Published: April 2024

In beam-to-beam connections, the top flange of the supported beam is usually coped to clear the supporting beam flange. Due to flexural and shear stresses in the coped portion of the web, the local strength can be limited by buckling. Design recommendations in previous editions of the AISC Manual imposed limits on the cope geometry and were based on an allowable stress philosophy, limiting the flexural strength to the first-yield moment. To eliminate the limits of applicability and provide equations that take advantage of any available post-yield strength, the design guidance in the 15th Edition AISC Steel Construction Manual has been revised from previous editions of the AISC Manual. This paper discusses the development of the revised design procedure and validates the equations with the results of 25 experimental tests from five independent research projects.
Clearance for Welded Joints
Authors: Dowswell Bo
Published: April 2024

Inadequate clearance can affect weld quality and efficiency. In extreme cases, obstructions may cause a lack of fusion between the base metal and the weld metal, causing a reduction in strength. Although flux cored arc welding (FCAW) and gas metal arc welding (GMAW) have replaced shielded metal arc welding (SMAW) as the primary fabrication processes for structural steel fabrication, existing clearance recommendations are based on the SMAW process. Because the geometry of a FCAW or GMAW welding gun is much different from that of a SMAW electrode, the historic values recommended for the SMAW process may not apply to FCAW and GMAW. Experimental specimens were fabricated with the FCAW process to determine practical limits on connection geometry for welding joints with limited access. Each specimen was evaluated by sectioning and etching the weld at two locations along the length. Two weld clearance issues are addressed: (1) fillet welding near obstructions and (2) doubler plate welds.
Errata: Clearance for Welded Joints
Authors: Dowswell Bo
Published: April 2024

Errata
Steel Structures Research Update: Advances in Design with Hollow Structural Steel Members
Authors: Liu Judy
Published: April 2024

Recent advances in design of steel-frame systems with hollow structural steel (HSS) members are highlighted. The featured work includes new and updated design guides that are co-authored by Jeffrey Packer and Jason McCormick. Dr. Packer’s experimental, numerical, and analytical research informs the design of HSS for various loading conditions, with a bias toward code/specification-related issues and guidance for practicing engineers. Dr. McCormick’s research on HSS members and connections ranges from research on steel HSS-based seismic moment frames to the use of innovative materials (e.g., polymer foam) to control the structural response of HSS members under seismic and wind loads. Selected studies are featured along with a preview of the new design guides. Research on HSS columns under axial and lateral loads fills knowledge gaps in seismic behavior and design. Foam-filled brace and bending member experiments show improved seismic performance with a light-weight polyurethane fill. Field tests, laboratory experiments, and numerical modeling are used to study behavior and develop design methods for hollow and concrete-filled HSS subject to blast and impact loading. Research on single-sided fillet welds of HSS members leads to improved design recommendations. Improved design procedures are also recommended based on research on HSS connections that are in branch compression, near chord ends, or offset laterally.
Continuous Bracing Requirements for Constrained-Axis Torsional Buckling
Authors: Denavit Mark D. , Jacobs William P. , Helwig Todd A.
Published: April 2024

The design of floor and roof framing members is typically controlled by flexural demands; however, if a member serves as a chord or collector it can also be subjected to significant axial compression. Continuous restraint provided by the floor or roof diaphragm is commonly assumed in design to provide adequate bracing of connected wide-flange members against minor-axis flexural buckling; however, these members are still susceptible to major-axis flexural buckling and potentially to torsional buckling about a constrained axis located at the top flange. In addition to the lateral restraint, floor and roof decking systems can also provide continuous torsional restraint through their flexural stiffness and strength. This restraint can be used to increase the calculated constrained-axis torsional buckling strength or inhibit the mode altogether. In this paper, the specific case of a wide-flange steel beam-column with both lateral and torsional restraint located at the top flange is investigated and torsional bracing requirements are derived. The focus of the study is on continuous torsional bracing and its effect on the constrained-axis torsional buckling mode. The requirements are illustrated through a design example and a parametric study is performed examining typical floor and roof decking system configurations, identifying cases where improved design efficiency can be achieved.
Evaluation of AISC Seismic Design Methods for Steel Multi-Tiered Special Concentrically Braced Frames
Authors: Cano Pablo A. , Imanpour Ali
Published: April 2024

Steel multi-tiered concentrically braced frames (MT-CBFs) are commonly used in North America as a lateral load resisting system of tall single-story buildings. Past studies show that MT-CBF columns designed in accordance with the 2010 AISC Seismic Provisions are prone to buckling due to a high axial compression force combined with in-plane bending moments caused by the nonuniform distribution of inelastic brace deformations along the frame height. Special design provisions have been introduced in the 2016 AISC Seismic Provisions to address flexural demands imposed on MT-CBF columns and prevent column instability. In this paper, the seismic design methods for multi-tiered special concentrically braced frames are evaluated using the nonlinear finite element analysis method. A two-tiered special concentrically braced frame was then created, and nonlinear static and dynamic analyses were performed to evaluate the seismic performance of both frames. Analysis results confirmed that the inelastic deformations in the frame designed using the 2010 requirements are not uniformly distributed but rather concentrated in one of the tiers and cause column instability under large story drifts, whereas, the 2016 design method significantly improves the distribution of inelastic deformation along the height of the frame and prevents column instability. Furthermore, it was found that the 2016 AISC Seismic Provisions accurately estimate the axial load but overestimate the in-plane flexural demands and underestimates the out-of-plane flexural demand. Nonetheless, the overestimation of in-plane flexure demands results in acceptable strength capacity even though out-of-plane flexural demands is underestimated.
Design by Advanced Elastic Analysis: An Investigation of Beam-Columns
Authors: Wang Yunfei , Ziemian Ronald D.
Published: April 2024

At the heart of the provisions for assessing structural stability within the AISC Specification for Structural Steel Buildings is the direct analysis method. The fundamental concept for this method is that the more behavior is explicitly modeled within the analysis, the simpler it is to define the AISC Specification design requirements. In other words, the direct analysis method consists of calculating strength demands and available strengths according to a range of well-defined and fairly detailed analysis requirements. This paper begins with an overview of two logical extensions to AISC’s direct analysis method, both of which are now provided in AISC Specification Appendix 1, Design by Advanced Analysis. In establishing these approaches, many systems were investigated in previous research, and it was noted that systems with beam-columns subject to minor-axis bending may deserve additional attention. This paper presents a detailed study that investigates such members, as well as members subject to major-axis bending.
Steel Structures Research Update: Seismic Performance of Nonorthogonal Special Moment Frame Beam-to-Column Connections
Authors: Liu Judy
Published: April 2024

Ongoing research on the seismic behavior of nonorthogonal special moment frame beam-to-column connections is highlighted. Featured is a comprehensive experimental and computational study under way at the University of Arkansas and led by Dr. Gary Prinz, Associate Professor in Structural Engineering. The research team includes PhD students Hossein Kashefizadeh and Damaso Dominguez. Dr. Prinz’s research interests include mechanics and simulation of ductile fracture, seismic design solutions for steel structures, and computer simulation of structures under dynamic loading. He received a National Science Foundation Faculty Early Career Development (CAREER) award to investigate a new micromechanics-based approach to ductile fracture simulation in additively manufactured steels for improved seismic structural fuse design. Dr. Prinz has also been awarded AISC’s Milek Fellowship. The four-year Milek Fellowship is supporting this research on the seismic performance of skewed special moment frame (SMF) connections. The research team is partway through the third year of the four-year study. Selected results from the computational parametric study are highlighted along with a preview of the experimental investigation.
Determination of Second-Order Effects and Design for Stability Using the Drift Limit
Authors: Sabelli Rafael , Griffis Lawrence , Geschwindner Louis F.
Published: April 2024

Buildings for which second-order effects are significant are often governed by drift limits. Amplifier-based approximate second-order analysis, as presented in AISC Specification Appendix 8 (2016), typically utilizes factors based on first-order drift, for which a preliminary design and an analysis are required. This paper derives equations for the amplifier used in approximate second-order analysis, B2, based on the second-order drift. Upper-bound values of amplifiers based on the drift limit can thus be determined in advance of design, eliminating the need for iteration and simplifying the design process; these values are not excessively conservative for drift-governed designs.
Design for Local Web Shear at Brace Connections: An Adaptation of the Uniform Force Method
Authors: Sabelli Rafael , Saxey Brandt , Li Chiao-Hsien , Thornton William A.
Published: April 2024

Recent literature has examined local shear forces in beams in chevron braced frames (Fortney and Thornton, 2015). Subsequently, design methods based on optimal stress distributions to address these shears were developed (Sabelli and Arber, 2017; Sabelli and Saxey, 2021). This paper extends those design methods to gusset connections at columns, utilizing the adaptability of the Uniform Force Method to facilitate design to reduce required member shear strength. The design model presented reduces the required member shear strength required, as compared to the conventional application of the Uniform Force Method. The model allows for redistribution of force from the beam interface to the column interface using a “bypass method,” as well as utilizing the gusset plate as part of a moment connection using the “haunch method.” Finite element analyses are used to confirm the adequacy of a design employing these methods.
Practice-Accessible Methodology for Nonlinear Refined Analysis of Gusset Plate Connections for Steel Truss Bridges
Authors: Mohammadi Alireza , Najjar Walid S.
Published: April 2024

A new approach is proposed for estimating structural capacity of gusset plate connections of steel truss bridges. The approach involves nonlinear refined analysis of a truss model, consisting of a single truss made of shell elements for two gusset plates at a subject connection and frame elements for truss members. Connectors (bolts or rivets) are excluded from the proposed model in order to simplify the model, with the knowledge that their associated failure modes can be addressed by simplified design calculations. Only yielding and buckling failure modes of gusset plates are considered. The new approach is calibrated by comparison with laboratory test data from NCHRP Project 12-84. The primary intent of this paper’s approach is to reduce the complexity of the refined analysis developed under this National Cooperation Highway Research Program project and make it more user-friendly to load rating engineers seeking accurate estimation of gusset plate capacity. Further, an imperfection sensitivity curve characterizing reduction in capacity as a function of lateral imperfection (gusset plate out-of-flatness) in gusset plate geometry is introduced as an added tool for the load rating engineer, providing more confidence in capacity estimation. Based on a limited case study, the proposed refined analysis provides an estimate of gusset plate capacity that is approximately equal to capacity calculated by the truncated Whitmore method of the AASHTO Manual for Bridge Evaluation (2018). In other words, the proposed approach validates the truncated Whitmore method as compared to the more conservative partial shear method of the AASHTO Manual.
Steel-Plate Composite Wall-to-Reinforced Concrete Wall Mechanical Connection-Part 1: Out-of-Plane Flexural Strength
Authors: Seo Jungil , Anwar Hassan S. , Varma Amit H. , Nam Yoonho
Published: April 2024

In safety-related nuclear structures, steel-plate composite (SC) walls are often used in combination with reinforced concrete (RC) walls or foundations. Appropriate connections are required to transfer force demands from the SC walls to the RC components without the connection failure that is often associated with brittle failure mode. This paper presents a design procedure developed for mechanical connections between SC and RC walls. This procedure implements the full-strength connection design approach in ANSI/AISC N690-18, Specification for Safety-Related Steel Structures for Nuclear Facilities, which requires connections to be stronger than the weaker of the connected walls. This paper also presents the results from experimental and analytical investigations conducted to verify the structural performance of the full-strength SC-to-RC connection. The focus of this paper (Part 1) is on the evaluation of the performance, strength, and ductility of SC wall–to–RC wall mechanical connections subjected to out-of-plane flexure. The results include global force-displacement responses, observations on concrete crack propagation, as well as applied force-strain responses of the connection region. The experimentally observed and analytically predicted results verify the conservatism of the proposed design procedure.
Comparison of Simple and Advanced Methods of Analysis in the AISC Specification for Fire-Resistant Structural Design
Authors: Chicchi Rachel , Varma Amit H.
Published: April 2024

AISC Specification Appendix 4 provides criteria to aid structural engineers in structural design for fire conditions. It includes an advanced method of analysis and a simple method of analysis. The simple method provides straightforward equations to determine member capacities at elevated temperatures. However, determination of demands on the structure (forces and deformations) due to elevated temperatures is less clear. This paper aims to minimize these gaps in knowledge. A comparison of these methods will be articulated through the analysis of a 10-story office building. The building is a steel structure with perimeter moment frames and a composite floor system that was designed for hazards in Chicago, Illinois. In order to conduct the advanced analyses, a three-dimensional (3D) finite element method building model was developed using ABAQUS. This model can simulate inelastic deformations, instability failures, connection damage at elevated temperatures, and the effect of temperature on strength and stiffness of materials. The simple analyses were conducted using SAP2000, a commercially available structural analysis and design software. A comparison of results from each method of analysis shows that for gravity framing members, the advanced method produced the longest fire-resistance rating. The fire-resistance rating determined from the simple method was more conservative, resulting in a shorter resistance rating. The simple method was also found to be the most conservative approach for the moment-resisting frame members, making it a less desirable method for designing the lateral system for fire than the prescriptive approach. Use of the simple method may be most advantageous for gravity framing applications only and may be overly conservative for considerations of the lateral framing system.
Experimental Investigation into the Capacity of Concentrically Loaded Steel Connections with Pretensioned High-Strength Bolts and Longitudinal Fillet Welds in Combination
Authors: Waite Christopher D. , Shen Ligang , Soliman Mohamed , Russell Bruce W.
Published: April 2024

This paper presents the results of an experimental study aiming to investigate the behavior of steel connections that combine pretensioned high-strength bolts and longitudinal fillet welds on a common faying surface. A total of 75 double-shear tension splices were tested under direct tension loading to quantify the effect of various connection variables on the load-deformation behavior of the connection. These variables include the (1) bolt pattern (2×2 and 2×3), (2) bolt size (3/4 in. and 1 in.), (3) bolt grade (ASTM F3125 Grade A325, A490, and F1852), (4) bolt pretensioning method (turn-of-nut and tension control bolts), (5) faying surface class (Class A and B), and (6) weld/bolt strength ratio. The variation in the connection characteristics covered a wide range of weld/bolt strength ratios from 0.50 to 2.00. The bolts were installed in oversized holes, and the specimens were assembled in a negative bearing condition to allow for a maximum slip distance. The load-deformation behavior of the combination connections was recorded and compared to that of the bolted- and welded-only control specimens. In all tests, the addition of welds increased the capacity of the connection. The investigation shows that the capacity of the combination connection with pretensioned high-strength bolts and longitudinal fillet welds can be computed by adding the capacities of the individual connecting elements while considering the strain compatibility.
A Novel Performance-Based Evaluation of Built-Up Wide-Flange Steel Columns Subjected to Close-Range Detonations
Authors: Kim Yongwook , Florio Salvatore , Wang Qian
Published: April 2024

Transportation facilities are crucial civil engineering structures, which are vulnerable to increasing risks of potential explosive loadings. The structural members of older facilities were typically made of steel and built up from angles and plates joined together with rivets, rather than directly rolled in steel mills. Most existing blast mitigation design approaches were made for military or petrochemical facilities in rural areas with significant stand-off distances. However, transportation facilities, which are located in congested major cities, with structural members exposed to pedestrians and passengers, are subject to the risks of potential close-range or near-contact detonations. Recently, new approaches were developed to address the potential progressive collapse of high-rise buildings in urban environment, but the approaches do not address the localized deformations or failures on column flange or web elements that are common in close-range or near-contact detonations. For this reason, the existing approaches are not appropriate to the blast mitigation design of the urban transportation structures. Instead, a high-fidelity, nonlinear, explicit finite element analysis is suggested. Typical practicing structural engineers do not have opportunities for education or training for such analysis due to technical challenges, cost, and time constraints. The main goal of the present research is to provide practical guides of the nonlinear, explicit finite element analyses for close-in or near-contact detonation problems that can be followed by practicing structural engineers and to provide simple design charts that can be used as a preliminary tool without performing the analyses. To accomplish the goal, more than 200 parametric study models were built for nonlinear, explicit finite element analysis of built-up steel columns subjected to close-in detonations. Characteristics of the steel materials for the built-up columns were investigated and incorporated in the numerical models. The models were determined so that they can cover practical ranges of columns, stand-off distances, and charge weights. The analysis results were presented on contour graphs using novel performance-based damage criteria. The graphs and design methodology presented in this study can be used as an efficient and practical tool to quickly assess blast resistance of built-up steel columns in transportation structures.
Automated Design of Space Trusses
Authors: Weaver Jr. , Patton Fredrick W.
Published: April 2024

The design by the elastic theory of a complex framed structure consists of the selection of an initial configuration followed by cyclic revisions. In each design cycle the structure is analyzed for predicted service loads and evaluated according to specified stress criteria. Then the structure is modified and the process repeated until a satisfactory design is obtained. The task of computer programming for structural design involves certain considerations not encountered in analysis. Engineering decisions relating to geometry, load systems, types of members, support conditions, stress criteria, and methods of connection cannot be directly incorporated into a computer program. However, if these decisions are made beforehand and are reflected in the input data, an iterative procedure of analysis and revision can be programmed to produce convergence to a suitable design. The role played by the computer in the design process may vary considerably. If the designer intervenes in each cycle, inspects the results, makes decisions, and alters parameters in accordance with his decisions, the operation is said to be "computer-aided design." On the other hand, if all parameters are predetermined and the computer is allowed to iterate to a final selection of member sizes without human intervention, the term "automated design" applies. This paper deals with the latter technique for the design of structures framed as space trusses.
Analysis of Cables as Equivalent Two-Force Members
Authors: Tung David H.H. , Kudder Robert J.
Published: April 2024

In recent years, cable structures have become more widely used because of growing demand for long-span construction for aesthetic, economic, or other practical reasons. Aside from classical suspension bridges, examples of this type of structure are tall guyed towers, cable-stiffened bridges, and suspended roofs. The methods of analysis of suspension bridges have been extensively explored, and will not be discussed herein. Instead, this paper presents a simplified analysis of cable members ordinarily encountered in the other types of structures mentioned above, by treating them as equivalent two-force members. The nonlinear behavior of such cables is accounted for by the use of an equivalent modulus of elasticity as well as equivalent strains. Problems commonly associated with cables, such as stresses (and change of sags) caused by a change of temperature or superimposed loads, or resulting from relative displacement of supports, can be readily solved by this method. It should be noted that the proposed procedure is also applicable to the analysis of transmission lines.
Discussion: Conceptual Design of Double Steel Containment Vessels
Authors: Wahl Howard W.
Published: April 2024

Discussion
A Cost Evaluation of Space Trusses of Large Span
Authors: Geiger David H.
Published: April 2024

This study is the first part of a larger economic study dealing with space trusses, domes and cable roofs. The domes and cable roofs considered are characterized by perimeter support around a circular or elliptical plan. This led to the search for a space truss with support at the perimeter. The particular space truss treated in this work met the above requirement. The mechanics of the structural analysis have been discussed elsewhere by Kato, Takashani, Tsushima, and Hirata in a paper presented at the International Conference on Space Structures, and are presented here in summary form. The methods of analysis and design used here are approximate and give rapid preliminary design solutions. As a consequence of this simplification more than a thousand different problems were solved. More difficult than the analysis and design of the truss is the estimating of its cost. In endeavoring to solve this problem the author became indebted to two structural steel fabricators who spent considerable time examining the structural details and supplying him with fabrication and erection costs.
Discussion: Plastic Design by Moment Balancing
Authors: Gurfinkel German
Published: April 2024

Discussion
The Use of Viscoelastic Material to Damp Vibration in Buildings and Large Structures
Authors: Nelson Frederick C.
Published: April 2024

Controlling the vibration response of structures is a problem which has received the attention of many engineers for many years. This paper discusses some recent developments of a special aspect of this general problem; namely the use of viscoelastic material to damp the low frequency vibration often associated with large scale structures and buildings. The growing concern of structural engineers with the airborne and structure borne vibration environment of their buildings is a reflection of the growing concern of the engineering profession, as well as the general public, with the problem of noise and vibration. Economic considerations and improved design methods have resulted in a trend to lighter weight structures and higher speed machinery, both of which tend to increase vibration levels. The engineer must either develop new methods of controlling vibration or adapt or improve existing methods if the public good is to be served. As an example of adaptation, this paper describes three cases in which constrained viscoelastic layers, first employed in the aerospace industry, have been used to control the vibration of large structures.
Deformation Analysis of Structures Near Collapse Load
Authors: Lavingia Kishor P.
Published: April 2024

The primary function of any structure is to provide adequate strength to resist the loads acting on it without undergoing excessive deformations which, in turn, might render the structure of no further use. For every structure, therefore, deformations under working loads must be within certain definite limits. If the loads are increased beyond their working values, the material at the critical sections is expected to yield. This brings about a sharp increase in the deformations. These increased deformations may cause several forms of premature local buckling in structures composed of mild steel, while in reinforced concrete structures, local fracture of concrete, with resulting failure of the section, is likely to occur due to the brittle nature of the concrete material. These effects may lead to local collapse of structures at loads lower than those otherwise expected to produce failure. It is imperative, therefore, to develop methods for estimating hinge rotations and other deformations at ultimate loads which are simple and economically feasible to put into practice by an average practicing engineer. Various methods to accomplish this have been proposed for steel as well as reinforced concrete structures. They are primarily based on either slope deflection equations or energy methods. The slope deflection equations used for estimating deformations of any structure at ultimate loads, if extended as shown later in this paper, lend themselves to the introduction of the principle of elastic moment distribution. The method presented herein makes use of this principle.
A Composite Action Duct-Beam System
Authors: Vergun Dimitry K. , Shah Kirit N.
Published: April 2024

This paper describes a new method of utilizing steel in building construction, based on a research program Undertaken by Reid & Tarics, Architects-Engineers, for the American Iron and Steel Institute. Specifically the project was intended to generate a structural system to be bid competitively for the URBS (University Residential Building System) Project of the University of California. It appears, however, that the field of application of this concept may have general interest. Basically, the concept is to take advantage of the proven inherent economic advantages of composite design and to combine it with a beam shape (unsymmetrical rectangle) which will allow the beam to serve as an air duct for either warm or cool air. The structural frame of the building thus becomes the primary network of horizontal air distribution, eliminating conventional ductwork in part or in whole. The system has application wherever a central system must be used for ventilation. It has the advantages of minimum steel weight and long span economy inherent in a composite steel structure, coupled with the obvious savings in ductwork and story height.
Admissible Loads of Gable Frames
Authors: Cheng Franklin Y.
Published: April 2024

The mechanism method and the statical method have been presented in standard texts for plastic analysis and design of gable frames. AISC5 devised charts for both calculating plastic moments and locating plastic hinges of various gable frames subjected to uniform forces with or without wind load. It is understandable that those charts cannot be applied to frames subjected to concentrated loads, simply because the collapse load computed under the concentrated forces is a lower bound on the collapse load of the same structure with equivalent distributed force. Pincus discussed a generalized super-position method in plastic analysis of gable frames for which tedious procedures similar to that of the mechanism method are used to search for cancellation of plastic hinges.In this report, two domains of admissible loads of general gable frames are presented, in which the concentrated forces are independent and the structural dimensions are arbitrary. For given numerical values of structural dimensions and forces of a particular problem, the plastic moment and collapse mode can be simply determined from the appropriate domain; or for the given numerical values of structural dimensions and the magnitude of plastic moment, the possible collapse load of the frame may also be found. It is interesting to note that the condition of a structural collapse may be studied from the relationship of magnitude as well as direction of the independent forces in the domain.
Analysis of Horizontally Curved Bridges
Authors: Gillespie James W.
Published: April 2024

Many years ago, highway bridges were located by determining the most convenient crossing site, with little regard to the general alignment of the roadway. After the bridge location was established, the highway designer or surveyor laid out the highway to meet the bridge. During the last several decades, this situation has reversed and now bridges must fit the highway alignment that has been predetermined by many other considerations. The increasingly frequent occurrence of structures on curved alignment is presenting real challenges to engineers, especially in the design of urban freeways where multi-level interchanges must be built within tight geometric restrictions. The present-day emphasis on good appearance is also an important factor. Welding has helped to produce structures with smooth surfaces, interrupted by a minimum amount of detail. Outside transverse stiffeners are no longer used on many highway girders. The use of curved supporting beams or girders in a structure on curved alignment is a natural outgrowth of this trend toward aesthetic design.
Construction Cost Premiums for Risk Category IV SMF Buildings
Authors: Richards Paul W. , McCall Amy J.
Published: April 2024

The International Building Code uses Risk Categories to reduce the probability of damage and collapse for certain buildings. One proposal for improving post-earthquake functional recovery is to design more buildings as Risk Category IV. The purpose of the study was to investigate the construction cost premiums for Risk Category IV buildings with steel special moment frames (SMF). Mathematical derivations were used to bound the stiffness and strength amplifications required for Risk Category IV design, accounting for period effects (as buildings are strengthened/stiffened, design loads increase). To complement this mathematical approach, twelve case study SMF buildings were designed with heights ranging from two to sixteen stories. The primary conclusion of the study is that construction cost premiums for drift-governed SMF buildings are an order-of-magnitude greater than for strength-governed buildings. For many strength-governed buildings, the cost premium for Risk Category IV design is around 1% of the total building cost. For drift-governed SMF buildings, the cost premiums for Risk Category IV design are 6-16% of the total building cost, with the greatest premiums for buildings around eight stories. These cost premiums should be considered when evaluating Risk Category IV design as a strategy for improving post-earthquake functional recovery.
Closure: Design for Local Member Shear at Brace and Diagonal-Member Connections: Full-Height and Chevron Gussets
Authors: Sabelli Rafael , Saxey Brandt
Published: April 2024

Closure to Richards Discussion of "Design for Local Member Shear at Brace and Diagonal-Member Connections: Full-Height and Chevron Gussets
The Adoption of AISC 360 for Offshore Structural Design Practices
Authors: Ku Albert , Zwerneman Farrel , Gunzelman Steve , Chen Jieyan
Published: April 2024

The offshore design standards for U.S. practices refer to AISC specifications when designing structural components with nontubular shapes. The widely used API RP-2A WSD standard (API, 2014) asks designers to use the 1989 AISC Specification. The newly published API RP-2A LRFD and RP-2TOP ask designers to use the 2010 AISC Specification. Although the 2010 AISC Specification has been partially adopted by API, the current offshore practice is still primarily dominated by the 1989 AISC Specification. The key issue hampering the offshore community’s full adoption of the 2010 AISC Specification is the relative ease of accounting for second-order effects in the 1989 AISC Specification. In 2019, API formed a Task Group dedicated to studying this issue, with the main findings summarized in this paper. By illustrating the key code check process in two examples with an easy-to-understand format, this paper aims to assist offshore structural engineers to better understand the latest AISC specification. The authors also hope that this paper will serve as a communication path between the offshore structural community and AISC for current and future standards’ adoption and harmonization.
Discussion: Are Tier Building Column Splices Designed?
Authors: Klayton Thurston
Published: April 2024

Discussion
Reliability Assurance in Navys Welded Steel Shore Structures
Authors: Amirikian Arsham
Published: April 2024

Aside from ships, the Navy construction program covers a wide variety of welded steel structures built on shore, as well as certain types of floating craft in harbor installations. The construction of these structures is under the jurisdiction of the Naval Facilities Engineering Command. In the past, this command, then known as Navy's Bureau of Yards and Docks,had its own codes and standards for workmanship and acceptance. Although these standards contained only minor deviations from the corresponding specifications of the private industry, in recent years a new policy has evolved which, in effect, has resulted in full conformance with current regulations of commercial practice. Government construction agencies are often criticized by the building industry for their unnecessarily restrictive specifications, which they rightly contend to have contributed to mounting costs of fabrication. Rarely a project is completed without involvement in interpretive litigation. Perhaps influenced by this situation, the industry itself is now adopting many of these restrictive clauses. This is particularly true for regulations governing welded construction, and more specifically, the quality and acceptability of welds, which are covered mainly by the American Welding Society's Code for Welding in Building Construction.
Push-up Steel Construction
Authors: Hansen Robert J.
Published: April 2024

For the past few years a team of researchers, architects and engineers at the Massachusetts Institute of Technology have directed their efforts at finding methods for reducing the cost of multistory steel-frame construction. This research, which has been sponsored by the United States Steel Corporation, was initially directed to examine the structural frame of high-rise apartment houses. Our choice of this restricted area of investigation was based on: social need for housing; the possible market for apartment houses; and the competitive position of steel-framed construction vis-Ã¡-vis other possible materials of construction. The push-up concept offers significant potential forreducing project cost for multistory steel-frame buildings. No alteration in building quality is necessary to achieve these savings.
Steel Plate Analysis by Finite Elements
Authors: Firkins Norman L.
Published: April 2024

The finite element method is becoming a popular as well as practical way of analyzing plates, shells, and related structures. The technique of modeling an elastic structure into an assemblage of discrete bars or sections and interconnecting these elements by a finite number of joints or nodal points is not new. The growth and development of the finite element method has been greatly enhanced by the high speed digital computer and matrix methods in structural mechanics. Extended finite element formulation is being carried on to increase the potential of this method in the areas of plasticity, vibration, and three-dimensional stress applications. Although continuous investigation is being undertaken, it might be in order to review the basic finite element formulation and provide a simplified method of evaluation for the practicing engineer.
Homogeneous and Hybrid Girder Design in the 1969 AISC Specification
Authors: Milek Jr.
Published: April 2024

The rules for design of plate girders in the 1969 AISC Specification are basically unchanged from the 1963 edition, except that a highly significant extension has been made to provide for the design of hybrid beams. In addition, Section 1.10 has been editorially revised to increase clarity of intent. The principal formulas governing girder design are unchanged, but the designer now has the option of achieving an economical design by either of two concepts: (1) tension field action in the thin web of a homogeneous girder, or (2) hybrid design using a low strength steel web plate welded to high strength steel flanges.
Temperature Effects on Tall Steel Framed Buildings Part 3-Design Considerations
Authors: Khan Fazlur R. , Nassetta Anthony F.
Published: April 2024

Since the beginning of high rise construction in steel late in the 1800s up to about 1940, the structural skeleton was hidden behind the exterior facade in almost all cases. Typically, such construction used stone or other masonry exterior facades with window openings of relatively small size. Even the pioneering structural and architectural innovations by the Chicago School of Architecture did not basically change the relationship between the structural skeleton and the exterior facade. Although some of the buildings built in the early 1900s, inspired by the Chicago School, did have large window openings between the structural columns, the main structural skeleton was nevertheless completely enclosed and hidden behind masonry or stone cladding. It is therefore not surprising that for all practical purposes severe weather changes, such as those experienced in cities like Chicago and New York, did not cause any undue vertical movements resulting in structural or architectural damage in these buildings. Naturally, until very recently temperature effects on tall structures were seldom considered a design factor. After World War II a new trend in architecture, reflecting the technology of steel and glass, suddenly made the temperature effects on tall buildings a significant factor in design. Metal and glass curtain walls replaced the traditional masonry or stone cladding. As the exterior expression of these buildings became lighter and lighter, it became more rational and architecturally more desirable to expose the main structural frame as a part of the exterior facade. However, it was soon apparent that this new expression of technology in architecture brought with it a new problem of temperature movement.
Painting Structural Steel
Authors: Keane John D.
Published: April 2024

Each material of construction requires its own provision for maintaining appearance and protection. For structural steel, this provision usually takes the form of painting. It has been estimated that about 2 million dollars per year are spent in protecting all kinds of structural steel surfaces, including railroad bridges, highway bridges, buildings, tanks, towers, power plants, water works, refineries, vessels, hydraulic and marine structures, public edifices, underground facilities, and industrial structures of almost infinite variety. Paint not only provides corrosion protection for these structures, but also makes valuable contributions to their safety and appearance. In fact, the painting of structural steel could be described as the principal means of protecting steel against its principal limitation — corrosion. The following discussion is intended to provide architects and engineers with a better understanding of some of the concepts and features of current practice in the painting of structural steel.
Discussion: Design of Composite Beams with Formed Metal Deck
Authors: Winter George , Fisher John W.
Published: April 2024

Discussion
The Effective Length of Columns in Unbraced Frames
Authors: Yura Joseph A.
Published: April 2024

The effective length concept for column design in unbraced frames has been incorporated in the AISC Specification since 1961. In simplified terms the concept is merely a method of mathematically reducing the problem of evaluating the critical stress for columns in structures to that of equivalent pinned-end braced columns. The Euler buckling stress for a column with both ends pinned and no sidesway. The alignment chart gives valid sidesway buckling solutions if the columns are in the elastic range and all columns in a story reach their individual buckling loads simultaneously. For columns that do not satisfy these two conditions, the chart is generally overly conservative or not applicable at all. The design methods presented herein handle these situations by adjusting common procedures: the Column Load Tables in the AISC Manual and the alignment chart can still be utilized. The concepts developed are applicable to a wide range of problems. For example, using the concept of some columns bracing others in the same story of an unbraced frame, it is possible to make the column sizes in a story reasonably uniform, even though individual column loads might vary substantially.