bluuebunny/crossref_metadata_2025 huggingface dataset:
Economics of Low-Rise Steel-Framed Structures
Authors: Ruddy John L.
Published: April 2024

The structural engineers input at the conceptual state of a project is his most important contribution. The purpose of this early effort is to determine the materials of construction, and to establish the system which is to use these materials. Inadvertently, these early decisions establish the lower boundary of the economies that can be realized as design progresses. Options available to the engineer are numerous. In addition to the multiple framing options, within the constraints of each option, there are a multitude of permutations of elements which further magnify the options. Confidence that a true optimum solution has been realized seldom exists. The magnitude of the problem certainly does not diminish its importance. Our purpose here is to investigate the structural economic considerations of a one-story framing system in the interest of predicting the optimum bay dimensions. The objective of the investigation is to realize least cost. Least cost is not synonymous with the least weight of the structural steel elements employed. In fact, a least weight approach does not consider all of the structural elements which influence the bay size. Foundation considerations may significantly effect results. An emphasis on cost has the consequence of introducing very subjective elements into the analysis process. The material and labor costs vary from supplier to supplier within a geographic region, and certainly among suppliers or subcontractors nationally. The approach is rational, yet it is intimately tied to those unit costs tabulated in Table 1.
The Importance of Tension Chord Bracing
Authors: Fisher James M.
Published: April 2024

A calculation procedure has been presented which allows the designer to determine the need for tension chord bracing for joists, joist girders and fabricated trusses. Based on these procedures, it is apparent that serious consideration should be given to providing bracing to the tension chord of trusses and providing bridging lines at the first bottom chord panel point for steel joists. The equations upon which the calculation procedure is based are predicated upon the assumption that a P-D force develops for the compression member. These equations may be overly conservative for certain conditions. For example, since the majority of load is delivered to the end compression diagonals shown in Fig. 2 through the adjacent tension diagonal, when the tension chord displaces laterally the tension diagonal also displaces and delivers the load to the compression diagonal concentrically (see Fig. 12), thus the only P-D force that is developed may be that due to the panel point load. It would then appear that to stabilize trusses of the type described here, that one could use only the concentrated panel point loads in the bracing equations, as one would in the case of a Vierendeel truss. Until such time as research indicates this approach is justified, a more conservative approach should be taken.
Interactive Computer Graphics in Steel Analysis and Design--A Progress Report
Authors: McGuire William , Pesquera Carlos I.
Published: April 2024

This is a progress report of research on the development of a system of computer-aided design. It will provide for the description of a two- or three-dimensional steel frame to the computer, preliminary and final analysis of the frame, and review of its adequacy under both service and ultimate loads. Included are provisions for conducting interactively the normal iterative procedures for refining a trial design to its final state. Several levels of analysis are available, from conventional linear elastic analysis, to full geometric and material nonlinear analysis. Design equations are incorporated for use in checking compliance with common standards such as the Specification of the American Institute of Steel Construction and the Limit States Specification of the Canadian Standards Association. The system is flexible; the user does not have to follow a rigid, prescribed routine. It is a progress report in several respects. Some basic provisions, such as procedures for handling local and lateral buckling, need refinement. Also, of course, a computer-aided design system can never be truly complete. There will always be need to incorporate advances in analysis and in the understanding of structures. Further, the system to be described is not a commercial software package. It is the product of continuing research in structural engineering and the ways in which advanced technology can enhance the analysis and proportioning of civil engineering structures. Nevertheless, although the work continues, it has reached the stage where the procedures described are believed to be of practical utility and suited to the needs of many structural design organizations.
Lateral Stiffness of Core and Outrigger Systems
Authors: Boggs P.C. , Gasparini D.A.
Published: April 2024

It is common to increase the lateral stiffness of braced cores by placing horizontal trusses or outriggers from the core to the exterior columns. Outriggers, in effect, apply moments which reduce the rotation of the core at outrigger locations. The smaller rotations at those points in turn reduce the overall sway of the structure. How effective are such outriggers? What are the primary parameters which control their effectiveness? Where along the height are they most effective? For such systems, where should an increment of material be added to affect the largest increment in lateral stiffness? Structural engineers need quantitative answers to such questions to make design decisions. Taranath, McNabb and Muvdi and others have analyzed such systems and have provided insights useful for design. McNabb and Muvdi3 analyzed the case of multiple outriggers and concluded that the gain in stiffness decreases as more outriggers are added. Herein the case of outriggers at only one location is analyzed. The work presented generalizes the results of the references cited by explicitly considering flexible outriggers, nonprismatic elements and a triangularly distributed lateral load. The system model analyzed is shown in Tables 1 and 2. The outriggers are prismatic with a moment of inertia, IG; they can be located at any height, bH, from the base. The exterior columns are pin ended; their area increases linearly from the outrigger location to the base. The vertical core is nonprismatic, with a moment of inertia which increases linearly from the top to the base. Two load models are used; one is a uniform load, the other is a triangular load. The model is statically indeterminate to the second degree, however it is antisymmetric, therefore only one redundant needs to be determined.
Design of Lightly Loaded Steel Column Base Plates
Authors: Murray Thomas M.
Published: April 2024

One of the least-studied structural elements are column base plates. Even less attention has been paid to lightly loaded base plates, defined here as relatively flexible plates of approximately the same size as the outside dimensions of the column supported by the plate. Such base plates are found in low-rise conventional construction and in preengineered metal building applications. In this class of construction, relatively small dead loads and low slope roofs commonly result in uplift loads which must be transferred to the foundation through the base plates. At present, there is no generally accepted practice for the design of such base plates that is not unduly conservative. From results of yield-line analyses and limited supporting experimental data, design procedures for lightly loaded base plates supporting H-shaped columns are proposed. Both concentric axial compression (gravity loading) and concentric axial tension (uplift loading) are considered. Base plate strength for erection safety is also discussed.
Engineering for Steel Construction
Authors: Disque Robert O.
Published: April 2024

Structural engineers are increasingly aware of the importance of details and connections in steel structures. These are not only the key to economy but also may be the source of trouble. For this reason, AISC has just released a new 370-pg. textbook— Engineering for Steel Construction —for the advanced detailer and design engineer. The new book is a companion to Detailing for Steel Construction, which was written for the beginning detailer who might have a high school education. Since both books are self-contained, some material may be common to both. Together, the books, which replace the 2nd Edition of Structural Steel Detailing, are geared to the 8th Edition Manual of Steel Construction.
Vertically Curved Girder Flanges
Authors: Nair R. Shankar
Published: April 2024

Flange plates in steel girders are sometimes bent or curved in the vertical plane to accommodate changes in girder depth. For example, this detail occurs frequently in continuous-span bridge girders that are haunched to provide additional depth at the interior supports, as indicated in Fig. 1. The bottom flange of the girder in Fig. 1 is curved in the vertical plane at each transition between the horizontal and sloping configuration. Curves in flange plates are also common in steel pier bents and other kinds of bridge and heavy building construction (a few examples are sketched in Fig. 11). Most designers recognize that a bend or out-of-plane curve in a flange plate, in conjunction with longitudinal tension or compression in the plate, will give rise to out-of plane (nominally vertical) forces in the flange that will, in turn, produce transverse flexural stresses in the plate. Rigorous three-dimensional elastic analysis of the cylindrically curved plate is much too complicated to be attempted in most real design-office situations. Consequently, transverse flexure of the plate and the possible reduction in effectiveness of the flange are seldom considered in any rational manner, even in the design of very large structures. Simple procedures for evaluating the effectiveness or efficiency of vertically curved flange plates will be developed in this paper. Conditions in the elastic range and at ultimate will be studied separately.
Design Aid for Deflection of Simple Beams Under Concentrated Loads
Authors: Mazzarella Sr.
Published: April 2024

Design Aid for Deflection of Simple Beams Under Concentrated Loads
Industrial Buildings-Guidelines and Criteria
Authors: Fisher James M.
Published: April 2024

The purpose of this paper is to provide the designer of industrial buildings with guidelines and design criteria for the design of buildings without cranes, or buildings with light-tomedium cranes. It would seem a simple task to design a good industrial building. The basic elements of the structure do not present a formidable design task. However, combining the elements: roof deck, purlins, girders, columns and girts into the most functional and cost-efficient system, is a complex task.
Direct Determination of Required Rigidities for Multiple-Bracing Frames
Authors: Wechsler Marius B.
Published: April 2024

The analysis of vertical braces of a braced steel structure requires concurrent consideration of drift and strength requirements. Done by hand calculations, or even by digital computers, this kind of analysis is time-consuming and expensive. The method presented in this paper avoids this tedious work, even though only the simplest arithmetic calculations are used. The simplicity of the described algorithm permits implementation on a pocket calculator, which makes it an important aid for the design of braced steel structures. The guidelines presented here allow the direct determination of the required rigidities for both directions of a braced steel structure so that overloading of braces can be prevented.
Multiple Bolt Anchorages: Method for Determining the Effective Projected Area of Overlapping Stress Cones
Authors: Marsh M. Lee , Burdette Edwin G.
Published: April 2024

To determine the resistance concrete offers to tensile pullout, the concept of the stress cone has been developed. When a tensile load is applied to an anchor bolt, failure may occur by pulling out a cone of concrete which radiates outward from the embedded head to the surface of the concrete. The internal angle of the cones apex is approximately 90 degrees. The calculation of the concretes resistance to pull-out is accomplished by applying a nominal concrete stress to the horizontal projected area of the potential failure cone.
Deflections of Stepped Beams and Girders
Authors: Yamamoto Y. Eugene
Published: April 2024

Stepped beams and girders can be used in many structures. An appropriate application for stepped sections could be on the floor framing of high-rise buildings where the ceiling plenums are kept shallow to limit the floor to floor dimension. Stepped sections provide greater clearance under beams for the ducts and other mechanical systems which are often crowded into ceiling plenums. By proper selection, greater clearance may be achieved with the added benefit of reducing the weight of beams and girders. However, stepped sections are rarely used. The reasons for their unpopularity are possibly due to the lack of familiarity with their deflection characteristics and the unavailability of deflection formulae for such beams and girders. Formulae for deflection and tables to assist in the selection of stepped sections are presented in this paper.
Allowable Bending Stresses for Overhanging Monorails
Authors: N. Stephen Tanner
Published: April 2024

In the design of monorails for trolley hoisting devices it is often necessary to extend the monorail out beyond the last available support (as in Fig. 1), so the lifting point is clear of obstructions. Such a monorail supported vertically at two locations can be analyzed as a simple beam with overhang so the maximum bending moment is easily obtained. However, the question of the allowable bending stress immediately presents itself. The intent of this paper is to address the problem and present a simple design solution.
LRFD Analysis and Design of Beams with Partially Restrained Connections
Authors: Lindsey Stanley D. , Loannides Socrates A. , Goverdhan Arvind
Published: April 2024

It has been well established that connections considered to be simple, non-restraining connections have some predictable amount of moment capacity. Goverdhan has collected many of the moment-rotation curves for these so-called simple connections and derived expressions for prediction of the moment rotation curve characteristics. Through LRFD, a mechanism for designing structures using the predictable amount of connection restraint is now available. The purpose of this paper is to show how, using the moment rotation curves for single-plate framing connections and LRFD design techniques, a system of beams can be designed utilizing, without any change in the simple connection, its natural end restraint to reduce the size and deflection of beams with this type of connection. One actual design application for such a design procedure is in the design of roof purlins where purlins cannot be continuous, but must frame into or between supporting members. Heretofore, in these cases simple-span purlins or expensive moment connections were used on the ends of the purlins to develop continuity to reduce deflections and beam sizes. This paper demonstrates that using the natural restraint of the so-called simple connection can reduce the size and deflection of a simply supported purlin. Although only the design of roof purlins with single plate shear connections is illustrated in this paper, the technique is general and can be applied to any set of beams using partially restrained (PR) connections with known moment-rotation characteristics.
A Unified Approach for Stability Bracing Requirements
Authors: Lutz Leroy A. , Fisher James M.
Published: April 2024

Columns and beam flanges in compression often require intermediate lateral bracing to satisfactorily carry the required load. Usually this is a finite number of braces at a spacing S. Many engineers are familiar with the ideal stiffness needed to fully brace the compression member over the length S, and that the required stiffness is generally taken as twice the ideal stiffness. If the compression member does not need to be fully braced at each support point, due to either the magnitude of loading required or the size of member used, considerably less bracing stiffness may be required than would be calculated. A means to evaluate an accurate value of required stiffness is important for examining structural members whose integrity is questionable because of limited bracing stiffness and strength, and for obtaining economical bracing design for members repeated many times in a structure. No simple technique other than continuous bracing expressions, exists for obtaining the less-than-full bracing integrity. In this paper, the bracing stiffness required for the range from continuous point bracing to a single point brace is presented. The required brace strength is also summarized. The bracing expressions are given in the form most familiar for point bracing. The expressions provide an understanding of the relationship between bracing stiffness and buckling behavior of the compression member. Furthermore, an expression for tangent modulus of elasticity is proposed as a means to apply the bracing expressions for all levels of critical load less than the yield load.
Stepped Columns: A Simplified Design Method
Authors: Castiglioni Carlo A.
Published: April 2024

A simple method is offered for the design of stepped columns which presents, with respect to the classical effective length method, some advantages (mainly swiftness and precision), when designing members in compression and bending. The method is based on a simplified model with two degrees of freedom. It is possible to obtain the ultimate interaction domains for stepped members, taking into account the effects of both geometrical and mechanical imperfections and of the loading path. Some of these domains are presented, and compared with available numerical results.
Limit Analysis and Plastic Design of Grid Systems
Authors: Vukov Ante
Published: April 2024

Limit analysis and plastic design are techniques developed to represent more realistic behavior of indeterminate steel structures. They take advantage of the fact these structures have a greater load-carrying capacity than indicated by the elastic analysis and the allowable stress design concept. Furthermore, the theoretical and experimental research of the last 40 years or so has led to the realization that the assumption of perfectly elastic behavior of structures is by far too simple. The actual performance of structures often departs considerably from pure theory of elasticity. In many instances, the calculated local stresses will be exceeded due to residual stresses from rolling, welding and cold-forming. Additional stresses can also be a product of erection and differential settlement of foundation. When highly stressed sections of a continuous structure yield, they merely transfer additional moments to less stressed areas and readjust themselves to carry the load more efficiently. In fact, there is not a valid reason to insist the calculated service stresses in a steel structure should be below yield stress, as long as there is no danger of low cycle-fatigue or brittle failure. This paper presents the upper bound approach to the analysis of orthogonal grid systems applying the kinematic or mechanism method. The corresponding virtual work equations are formally written and solved for the value of the ultimate load. The load obtained in this way is the correct limit load only if the corresponding bending moments nowhere exceed the maximum plastic moments (the plasticity condition).
A Programmable Solution for Stepped Crane Columns
Authors: Moore II
Published: April 2024

The basic equations for the solution of a stepped column with a fixed base are easily derived, but the pinned top equations are the only forms found in generally available literature such as the AISC book on Industrial Buildings. This paper presents the 10 basic equations required for a general solution of the stepped crane column and describes the use of these equations with the generally accepted Murray-Graham model of crane column action. The 10 equations are applicable to both bayonet and double-shaft crane columns and by setting I equal to I may be applied to single-shaft columns with a bracketed crane girder. The equations also allow the designer to locate the crane thrust at the proper location instead of at the column step, a refinement which complicates needlessly the solution for manual calculation but which presents no problem to the computer.
Combined Shear and Tension Stresses
Authors: Goel Subhash C.
Published: April 2024

The current AISC Specification calls for allowable stress in tension and in shear. Checking the stresses in tension and shear separately against the corresponding allowable values in the base metal is generally considered adequate enough. This practice can be defended rationally in situations where maximum normal and shear stresses do not occur at the same point, such as in the design of bending members (except for plate girder webs where tension field action is utilized). Quite frequently, however, situations are encountered where maximum normal and shear stresses occur simultaneously, such as in members subjected to combined bending and torsion or in connection design. Checking the section at the base of gusset plate for an inclined bracing member is a common example. Such situations are not covered in the current AISC Specification. Keeping the normal and shear stresses within their individual allowable limits in these cases may lead to grossly unconservative results. A rational design criterion for these situations should be based on combining the two stresses in some reasonable manner. This paper examines the problem briefly from a theoretical viewpoint. A simple empirical equation is proposed for use in practical design. The proposed equation gives results which are in close agreement with those obtained by using Von Mises yield criterion.
Least Cost Computer-aided Design of Steel Girders
Authors: Anderson Katherine E. , Chong Ken P.
Published: April 2024

Hybrid steel beams, used for over a quarter of a century, have evolved through many theories of design criteria. In this paper, emphasis is placed on stiffened hybrid girders, although unstiffened and homogeneous girders are also included as special cases. AISC has developed specifications to which a steel member must perform. The formulas in the specifications, however, do not define explicitly the best girder to do a particular structural task. Instead, a "region" is defined which contains a large number of acceptable girders from which the designer must choose. Even when a computer is used for the design, unless special programming is implemented, the output is an acceptable non-optimized region from which the final choice is made. By equipping the design procedure with the ability to rank the acceptable choices by cost or weight, an optimized girder can be located within the region. This ranking process should include the cost and availability factors for several steel grades so that a hybrid girder, having the lowest cost, can be found. Likewise, by including labor costs for manufacturing steel girders, the feasibility of using web stiffeners can also be determined. The innovative design method which follows incorporates the AISC Specifications5 and extends the techniques developed by Ken P. Chong for unstiffened built-up steel sections. The goal of the design process is to define the geometry of the girder by optimizing a particular function, which, in this case, is the depth of the girder.
Plate Girder Design Using LRFD
Authors: Zahn Cynthia J.
Published: April 2024

What differentiates a beam from a plate girder? This may seem to be a trivial question. However, it is a necessary and important part of plate girder design when applying the Load and Resistance Factor Design (LRFD) Specification. Making this distinction and the compactness classification early in plate girder design is important when using the LRFD Specification. The significance of these items can be seen in the LRFD Manual flowcharts for the determination of flexural and shear design strength. With these flowcharts, this discussion will focus on the design of plate girders according to LRFD rules. An explanation of plate girder design in the LRFD Specification will include: flexural design strength, shear design strength, flexure-shear interaction, bearing strength under concentrated loads and stiffener design. Application of the LRFD method will show there is actually little difference between it and Allowable Stress Design (ASD) of plate girders.
Composite Cable-stayed Bridges The Concept with the Competitive Edge
Authors: Taylor Peter R.
Published: April 2024

Recent tenders for three major cable-stayed bridges, Annacis Bridge in Vancouver at 1,525-ft span, Houston Ship Channel Bridge in Texas at 1,250-ft span and the Dartford Crossing in London at 1,476-ft span, have shown that in this span range composite construction can have a significant price advantage over other alternatives. Typically, these bridges comprise shallow steel plategirder cross sections with steel floor beams and a composite precast deck. This paper describes the evolution of the composite cable-stayed bridge, examines the reasons which currently make it economical and looks forward to developments anticipated in the near future.
Understanding Composite Beam Design Methods Using LRFD
Authors: Lorenz Robert F.
Published: April 2024

A recommended source of information for an understanding of Load and Resistance Factor Design concepts is through the composite design sections of the LRFD Specification and LRFD Manual. Specifically, the structural engineer designing a shear-connected composite beam has a new tool in the Composite Beam Selection Tables published in Part 4 of the LRFD Manual. These tables allow the designer much more flexibility in the alternative selection process that leads to better reliability and design economy. To properly exploit these options, however, an understanding of the fundamental composite strength limit theory and the model from which the design tables were created is needed. A particularly attractive benefit is that preliminary design manipulation can proceed with no required information regarding the strength properties of the concrete. When discrete cost parameters of the variable material requirements are known, cost optimization is also feasible.
Optimal Design of Cantilever-suspended Girders
Authors: Gurfinkel German
Published: April 2024

Cantilever-suspended girders are used frequently for bridges and low-rise, long-span buildings. Because this type of design calls for repetitive identical members, it is ideal for prefabricated construction. As a result, examples abound in structural steel. For various reasons, which include use of standard sections, economy and aesthetics, it is not uncommon for designers to specify the same size girders for all spans, particularly in buildings. In other words, prismatic construction is favored. This makes it important to arrive at an optimal design, i.e., to select a minimum-weight girder at the lowest possible design moment. Optimization is possible when one determines the position of the hinge, at the end of the cantilever, in such a way the maximum design moment is minimized. If the full load (live plus dead) were placed over the affected span (to determine the maximum moments that are generated at the suspended portion and over the cantilever support, respectively) the optimal position of the hinge. General methods of analysis, including numerical iteration, are available in the literature to determine both the optimal position of the hinge in a cantilever-suspended span and the design moment.
Connection Flexibility and Beam Design in Non-sway Frames
Authors: Nethercot David A. , Buick J , Kirby Patrick A.
Published: April 2024

Attention is drawn to the fact that virtually all commonly used types of steelwork beam-to-column connections function as semirigid. Representation of this behavior is best achieved by means of the connections moment-rotation (M—f) curve. For the types of connection normally used in non-sway frames, where "simple framing" is customarily employed, this means true behavior differs from that assumed in design. Beam-end moments are produced, the magnitude of which depends upon the M—f characteristics of the particular connection types used. The implications of this for the design of beams in non-sway frames is discussed. Connection behavior is reviewed and the results of a series of tests on a variety of types, conducted under identical arrangements, used to illustrate the range of M—f behavior expected. Special tests incorporating fabrication induced imperfections have been included so as to assess the likely variability of M—f data. A series of ultimate strength analyses on laterally supported beams provided with various forms of end connection are reported. The results provide quantitative indications of the ability of end restraint to reduce deflections and to increase load carrying capacity. Some results from a preliminary study of laterally unsupported beams are also presented. These suggest proper allowance for end restraint, which in this case should include both in plane and out-of-plane components, will also lead to worthwhile economies.
The Reinforcement of Steel Columns
Authors: Tall Lambert
Published: April 2024

There may be a need for a steel column to have load-carrying capacity additional to that planned in the original design. Columns may be reinforced by the addition of material in the form of cover plates, or by changing the residual stress distribution to a more favorable one by the laying of a weld, or by a method that combines both of these effects. For columns carrying design loads, their reinforcement is possible and safe. The strength of reinforced columns is identical for the conditions of reinforced under load and reinforced under no load. The maximum effect of reinforcement is obtained when the reinforcing weld is as close as possible to the edge of the flange of the base shape.
Eccentrically Braced Frames: U.S. Practice
Authors: Popov Egor P. , Engelhardt Michael D. , Ricles James M.
Published: April 2024

Current status of research and U.S. codes on Eccentrically Braced Frames (EBFs) is briefly discussed. Excerpts from the just completed tentative American Institute of Steel Construction (AISC) Specification pertaining to EBFs are given in detail. Comments on these provisions attempt to interpret them in the light of research and design practice. Based on these provisions a 6-story building employing EBFs in end walls is analyzed for seismic response under the action of several severe earthquakes. For these time-history analyses it is assumed that steel behaves as an elasto-plastic material with strain hardening. The behavior of the frames is found to be satisfactory. Several recommended details for EBFs are illustrated.
Design of Connectors in Web-Flange Beam or Girder Splices
Authors: Kulak Goeffrey L. , Green Deborah L.
Published: April 2024

Splices in beams and girders are often required when the lengths of members are limited by fabrication, transportation, or handling facilities available, or by the construction process. Splice plates are lapped across the joint and bolted to the webs and the flanges of the beam in order to transfer the load. This type of splice is usually referred to as a web-flange splice. Current design methods for the connectors in web-flange splices vary. For example, Fisher and Struik recommend that the web splice be assumed to transfer all of the shear and that the flange splice be assumed to transfer all of the moment at the section. The bolt group on one side of the web splice is designed on the assumption that the shear force acts at the centroid of the bolt group on the opposite side of the splice. In a commonly used British design manual, the same approach is recommended. Ballio and Mazzolani present two alternative approaches for design of web-flange splices. In both approaches, the moment at the location of the splice is proportioned between the web splice and the flange splice. For the web splice, the first approach considers the shear force to act at the centroid of the opposite bolt group. This is similar to the recommendation of Fisher and Struik. In the second approach, the bolt group on one side of the web splice is designed assuming that the shear force acts at the centerline of the splice. Bresler, Lin and Scalzi, Salmon and Johnson, and Nethercot also use this second approach, and they further recommend that the web splice be designed to transmit both the eccentric shear force and the portion of the moment that the web was designed to carry. However, Salmon and Johnson suggest that the effect of the eccentricity can be neglected except in cases where the shear and moment are high, and Bresler, et al. recommend neglecting the effect of the eccentricity when the eccentricity is much less than the depth of the web.
Inconsistencies in Column Base Plate Design in the New AISC ASD Manual
Authors: Ahmed Salahuddin , Kreps Robert R.
Published: April 2024

Inconsistencies in Column Base Plate Design in the New AISC ASD Manual
Correction: Flexural-Torsional Buckling and its Implications for Steel Compression Member Design
Authors: Zahn Cynthia J. , Iwankiw Nestor R.
Published: April 2024

Correction
Closure: On Beam-Column Moment Amplification Factor
Authors: Duan Lian , Sohal Iqbal S. , Chen Wai-Fah
Published: April 2024

Closure
Discussion: On Beam-Column Moment Amplification Factor
Authors: Dumonteil Pierre
Published: April 2024

Discussion
Design Strength of Schifflerized Angle Struts
Authors: Adluri Seshu Madhava Rao , Madugula Murty K.S.
Published: April 2024

Latticed triangular-base steel towers have been used as communication structures for a long time. The legs of these towers generally consist of "schifflerized" angles (90 degree equal leg angles bent to 60 degrees). For ready use of designers, the geometric properties and design axial compressive strengths of schifflerized angles are presented using recommendations based on a recent experimental study.
Design Analysis of Semi-Rigid Frames: Evaluation and Implementation
Authors: Barakat Munzer , Chen Wai-Fah
Published: April 2024

The evaluation of the major assumptions, procedures, and proposed models associated with the simplified analysis procedure for unbraced flexible frames is presented. The highlights of this procedure, as well as numerical examples, are also discussed. The implementation of flexible frame analysis and design on personal computers is demonstrated.
Building Floor Vibrations
Authors: Murray Thomas M.
Published: April 2024

Annoying floor motion induced by building occupants is probably the most persistent floor serviceability problem encountered by designers. According to Allen and Rainer (1975), Tredgold in 1828 wrote that girders over long spans should be "made deep to avoid the inconvenience of not being able to move on the floor without shaking everything in the room." If the response of a floor system from normal activities is such that occupants are uneasy or annoyed, the intended use of the building can be radically affected. Correcting such situations is usually very difficult and expensive, and success has been limited. A number of procedures have been developed by researchers which allow a structural designer to analytically determine occupant acceptability of a proposed floor system. Generally, the analytical procedures require the calculation of the first natural frequency of the floor system and either maximum amplitude, velocity, or acceleration for a reference excitation. An estimate of the damping in the floor system is also required in some instances. A human perceptibility scale is then used to determine if the floor system meets serviceability requirements.The purpose of this paper is to present an overview of analytical tools and concepts for controlling annoying floor movement in residential, office, commercial, and gymnasium type environments.
Design Chart for Vibration of Office and Residential Floors
Authors: Hatfield Frank J.
Published: April 2024

Occupants of some buildings may observe that routine activities cause floors to vibrate noticeably. This may be a consequence of the high strength-to-weight ratio of the structural material and system, and is not necessarily indicative of inadequate strength or excessive deflection. In addition to assuring that a floor satisfies strength and static deflection requirements, the designer should be concerned with vibration perceived by occupants. The chart presented as Fig. 1 facilitates estimating the level of acceptability of the expected vibration of an office or residential floor. The chart implements two acceptance criteria8, of many that have been proposed. Those criteria were developed by determining occupants perceptions of vibrations caused by routine activities and then correlating those perceptions to measured or predicted levels of vibration caused by heel-drop tests. Application of the criteria embodied is limited to quiet but tolerant environments such as offices and residences, and to vibration caused by activities normally associated with those occupancies. In particular, the criteria in the chart may be unconservative for floors supporting precise work such as surgery, and for excitation by vehicles, machinery, or rhythmic activities such as dancing and aerobic exercise.
Considerations in the Design of Large-Size Welded Tubular Truss Joints
Authors: Bouwkamp J.G.
Published: April 2024

The rational design of welded truss joints built from tubes has been complicated by the radial flexibility of the chord tube wall. For certain types of joints this flexibility might be efficient, under static axial loads, since it provides, under increasing loads, a load-distributing action between branch members and chord tube. However, for most joints the flexibility is a source of severe stress concentrations. In connections subjected to dynamic loads, as for example offshore well drilling structures, stress concentrations can be most hazardous. Although even an approximate analysis of tubular joints of different configuration is extremely difficult, several designs are presently used and aimed at reducing the influence of the wall flexibility. This objective can be achieved by using thicker-walled tubes, or by inter-welding incoming branch members. In the latter instance the force acting normal to the chord tube can be reduced considerably. A second group of joints incorporates gusset plates or stiffening rings, which are intended to either contain the load transfer primarily within the gusset plate or to provide an element—the stiffening ring—to stiffen the chord wall and to distribute the forces over a larger part of the chord member wall.
Discussion: Failure of Simply-Supported Flat Roofs by Ponding of Rain
Authors: Walsh Jr. , Martin P.
Published: April 2024

Discussion
Discussion: Lessons from Crane Runways
Authors: Murray J.J.
Published: April 2024

Discussion
Discussion: Column Stability Under Elastic Support
Authors: Zweig Alfred
Published: April 2024

Discussion
Closure: Design of Pipe Column Base Plates Under Gravity Load
Authors: Sputo Thomas
Published: April 2024

Closure
Column Base Plate Design Table
Authors: Chhabra Surendra J.
Published: April 2024

The column base plate design procedure given in AISC ASD Ninth Edition manual1 differs considerably from the Eighth Edition manual. Additionally, the procedure contained in the first printing of the Ninth Edition manual has been refined in the later printings of the manual to incorporate improvements proposed by Thornton. These changes result in lighter base plates under certain conditions of loading and base plate geometry. The purpose of this paper is to provide a design table that includes AISC Ninth as well as Eighth Edition base plates, and to compare the two designs. The basis for the design method contained in the AISC manual has been discussed in detail by others, and will not be repeated here.
Local Buckling Rules for Rotation Capacity
Authors: Daali M.L. , Korol R.M.
Published: April 2024

Structural frames designed or proportioned to resist seismic forces must possess adequate ductility to redistribute internal forces or have needed energy absorbing capability. This paper addresses the interaction effects of a steel members plate slenderness values and its lateral slenderness on rotation capacity. It is shown that members with slenderness values close to the limits specified by the codes of practice may not be able to redistribute moments adequately under seismic loading. A critical value for the lateral slenderness is proposed to be used with current local buckling rules prescribed in North American standards for a structure to develop its full ductility potential.
Effects of Connection Stiffness and Plasticity on the Service Load Behavior of Unbraced Steel Frames
Authors: Bhatti M. Asghar , Hingtgen James E.
Published: April 2024

Accurate determination of the relative restraint of beam-to-column connections is important for both the strength and serviceability of structural frames. Overestimating the connection restraint can result in underestimating lateral sway and underestimating the connection restraint can lead to underestimating forces developed in the beams and columns. Both conditions can influence structural instability. This paper examines the effects that certain connection parameters have on the serviceability limit state of unbraced steel frames. The connections are modeled as elastic-perfectly plastic and are described by their elastic stiffness and the ultimate moment capacity. The second order P-delta effects are included. The effect of connection geometry on lateral sway for an unbraced, 3-bay and 5-story office building is studied. Three types of bolted connections: single and double web-angle, top- and seat-angle, and top- and seat-angle with double web-angles are examined and their effect on lateral sway is compared with and without second order P-delta effects.
Effective Width of Composite L-Beams in Buildings
Authors: Brosnan David P. , Uang Chia-Ming
Published: April 2024

The latest AISC design specifications permit the use of wider effective widths for steel-concrete composite exterior beams (or L-beams) than previous editions. This sometimes results in more flexible beams which quite often support deflection-sensitive nonstructural components. An analytical study of composite L-beams was conducted within a practical range of span and spacing for buildings. Both the conventional stress-based and rational stiffness-based definitions of effective width were considered. Effective widths were computed from the results of finite element analysis of three dimensional models permitting longitudinal slip between the concrete slab and the steel beam. It was concluded that the AISC effective width criteria for L-beams tends in an unconservative direction; a stiffness-based formula dependent on the spacing/span ratio is proposed.
Partially Restrained Composite Beam-To-Girder Connections
Authors: Rex Clinton O. , Easterling W. Samuel
Published: April 2024

Advancements in design technology and construction materials have enabled engineers to design longer spanning and shallower composite beam floor systems. The beams in these floor systems are typically designed as simply supported members which, in many instances, leads to the design being controlled by construction or live load deflection criteria rather than strength. If the beams were designed as continuous beams (having rigid connections) or partially continuous beams (having partially restrained connections) then deflection problems would be minimized and the strength of the composite beam could be more fully utilized. In recent years several research programs have investigated the strength and rotational stiffness of beam-tocolumn connections in buildings with composite slabs that are continuous over the connection region. These connections have been termed "Semi-Rigid Composite Connections" (SRCC) or more recently "Partially Restrained Composite Connections."ť This research has shown that SRCC are capable of providing a range of rotational stiffness from what could be classified as a pinned connection to what could be classified as a rigid connection. The key to SRCC behavior is the continuous composite slab which is reinforced with reinforcing steel and passes over the connection region. Because the composite slab is also continuous over beam-to-girder connections it seems probable that the idea of SRCC could be applied to these connections. This would lead to beam-to-girder connections with rotational resistance (partially restrained (PR) beam-to-girder connections) that could then be used to design composite beams as partially continuous rather than simply supported.
Correction: A Practical Approach to the Leaning Column
Authors: Geschwindner Louis F.
Published: April 2024

Correction
Correction: Steel Rigid Frames With Leaning Columns—1993 LRFD Example
Authors: Folse Michael D. , Nowak Paul S.
Published: April 2024

Correction
Optimization of Large Steel Truss Structures Using Standard Cross Sections
Authors: Soegiarso R. , Adeli H.
Published: April 2024

A multi-constraint optimality criteria discrete optimization algorithm is presented for minimum weight design of large steel truss structures subjected to stress, displacement, and buckling constraints. The structures are subjected to actual constraints of AISC Allowable Stress Design (ASD) and Load Resistance Factor Design (LRFD) specifications. A design linking strategy is used to reduce the number of design variables. An efficient integer mapping strategy is presented for mapping the computed cross-sectional areas to the available standard wide flange (W) shapes. The algorithm has been applied to minimum weight design of two structures: a 52-story structure with 848 members and an 80-story structure with 5860 members. This research also sheds some light on the comparison of the AISC ASD and LRFD specifications. For the examples presented, designs based on the LRFD specifications resulted in weight savings of 5 to 9 percent.
LRFD Crane Girder Design Procedure and Aids
Authors: Laman Jeffrey A.
Published: April 2024

The design of crane girders and supporting columns has traditionally followed allowable stress design (ASD) philosophy. With the growing acceptance of load and resistance factor design (LRFD) it has become important to review the ASD design procedures and to establish the corresponding design procedures in an LRFD format. In addition, new design charts and tables will make the design of these industrial building elements much simpler and less time consuming. This paper discusses the steps for LRFD design procedures, reviews the critical limit states, and presents design tables and charts useful for wide flange and channel combination sections.
A Summary of Changes and Derivation of LRFD Bolt Design Provisions
Authors: Carter Charles J. , Tide Raymond H.R. , Yura Joseph A.
Published: April 2024

Technical changes made in the 1994 RCSC LRFD Specification for Structural Joints Using ASTM A325 or A490 Bolts include such areas as shear-tension interaction for high-strength bolts in bearing connections and clear distance- based bolt bearing strength. In this paper, corresponding changes are proposed for the AISC LRFD Specification for Structural Steel Buildings and the supporting background information is summarized. Additionally, a change is proposed for the service-load slip resistance reduction factor for shear-tension interaction in slip-critical connections in both documents. Finally, a change made in 1993 AISC LRFD Specification Section J8.1 covering bearing strength of pins is documented.
Discussion: Strengthening of Existing Composite Beams Using LRFD Procedures
Authors: Kocsis Peter
Published: April 2024

Discussion
Discussion: A Summary of Changes and Derivation of LRFD Bolt Design Provisions
Authors: Biren Joseph
Published: April 2024

Discussion
Historical Note on K-Factor Equations
Authors: Dumonteil Pierre
Published: April 2024

It is the intent of this informal note to provide some historical background on the formulae giving effective-length factors, or K-factors, in the simple cases where such formulae are applicable.