bluuebunny/crossref_metadata_2025 huggingface dataset:
Light Gage Steel Infill Panels in Multistory Steel Frames
Authors: Miller Craig J.
Published: April 2024

In the design of multistory structures, providing adequate lateral stiffness is often more difficult than satisfying strength requirements. For steel structures of 20 or more stories, deep or heavy beams are often required to maintain drift within acceptable limits. In many structures, vertical trusses, concrete shear walls, or a combination of these and rigid frames are used to achieve the required displacements. For very tall structures, various types of tube construction are often used. The price paid for achieving stiffness in these ways is a decrease in the ductility of the structure, with important effects on its behavior under earthquake loading. The reason for this is that the increased total lateral base shear, required for stiffer systems by the Uniform Building Code, sometimes results in a change to a less ductile system. It is desirable to achieve an increase in stiffness without paying the penalty in decreased ductility. One attempt to do this is the slit concrete panel construction which the Japanese have developed. Normally, the strength and stiffness of infilling elements such as interior and exterior partitions are ignored in designing multistory frames, although such elements are acknowledged to make a substantial contribution to the lateral stiffness of the structure. A research program sponsored by the Committee of Structural Steel Producers and the Committee of Steel Plate Producers of the American Iron and Steel Institute was begun at Cornell University to assess the suitability of light gage steel infill panels for providing additional stiffness in multistory structures. The first portion of the research focused on developing the capability to analyze the infill-frame combination, making use of the finite element displacement method of analysis. The second portion, which is currently in progress, is an attempt to verify the analytical results experimentally and to assess the behavior of the panel-frame combinations at loads for which elastic analysis is not valid.
Approximate Analytical Model for Multistory Frames
Authors: LeMessurier William J. , McNamara Robert J. , Scrivener J.C.
Published: April 2024

In the preliminary design of tall, slender buildings, the member forces and displacements produced by the action of lateral loads on the structure are of prime importance in proportioning the members. For all but the simplest of structures, the analysis of the structure is a highly indeterminate and complex problem, and for its accurate study, in particular to find the effects of varying girder, column or bracing stiffnesses, electronic computers must be used. Complete analysis of the structural frame by computer programs is presently available. However, the preparation of input data and cost of computation time for investigating alternate framing and bracing schemes may not be justified within the budget of a given project. A method of analytically modeling multistory building frames to reduce the scale of the problem is presented herein. The modeling of large structures into smaller ones enables the designer to analyze very large structures efficiently and economically on a small computer.
Errata: Simplified Approach to AISC Bending Formulas
Authors: Stockwell Jr.
Published: April 2024

Errata
Application of AISC Design Provisions for Tapered Members
Authors: Lee G.C. , Morrell M.L.
Published: April 2024

The use of tapered structural members having tapered depths and/or widths was first proposed by Amirikian for reasons of economy. Typically, tapered members are used in single story structures of one or more bays (Figs. 1a and 1b) and in cantilevered sections of buildings (Fig. 1c). Some low-rise structures also contain tapered members (Fig. 1d). In view of the lack of basic understanding of the behavior of tapered members, as well as design criteria, a joint WRC-CRC subcommittee was established in 1966 to coordinate research studies. In addition, a subcommittee of the MBMA Technical Committee was established in 1973 to facilitate the development of design guides for tapered members. Two previous papers containing design recommendations were a result of the technical guidance of these subcommittees. The major thrust of these papers deal with the formulation of allowable axial stress, allowable bending stress, and combined axial-flexural compression for tapered members. These design recommendations have been incorporated into the AISC Specification as Appendix D. The examples presented here serve to illustrate the use of the design specifications for tapered members as required by AISC Specification Appendix D. There are still several unanswered questions regarding the rational design of tapered member. Three topics of current interest are (1) local buckling limitations, (2) tension flange support requirements,6 and (3) the Cm factor for beam-columns in unbraced frames. The designer must still use experience and sound engineering judgement regarding design procedures not provided by Appendix D of the Specification.
Errata: Partial Tube Concept for Mid-Rise Structures
Authors: Colaco Joseph P.
Published: April 2024

Errata
Discussion: Yield Line Analysis of Column Webs with Welded Beam Connections
Authors: Stockwell Jr. Frank W.
Published: April 2024

Discussion
The Effective Length of Unbraced Single Story Columns
Authors: Marx Christopher
Published: April 2024

The AISC Manual provides the engineer with a simplified method for the design of columns in unbraced frames for stability in the form of an "Alignment Chart for Effective Length of Columns in Continuous Frames, Sidesway Uninhibited." In addition, there have been many significant papers written recently which enable engineers to achieve a greater understanding and accuracy in the design of steel columns. The effective length concept is based on the relative stiffness of the column to its bracing members. As long as these bracing members are steel, the connections are fairly standard, and the AISC Manual can be used directly with reasonably accurate results. But when the bracing member is a concrete footing, there is a choice given to the designer. The Manual states that "for column ends supported by but not rigidly connected to a footing or foundation, G ... may be taken as 10 .... If the column end is rigidly attached to a properly designed footing, G may be taken as 1.0. Smaller values may be used if justified by analysis." For multistory buildings this does not usually represent a very wide range when making a column selection. However, for single story structures, the designers choice of 1.0 or 10 will frequently result in a significant difference in total column weight. In such cases it therefore seems warranted to make a further investigation. The Alignment Chart does not provide the designer with a method of making an engineered evaluation of column bases, merely giving limit recommendations. Presented are simple and approximate methods, which allow the designer to do this. Although not included for the sake of simplicity of illustration, these methods are equally suitable for the design of columns with wind or other lateral loads.
AISC Column Design Logic Makes Sense for Composite Columns, Too
Authors: Furlong Richard W.
Published: April 2024

Structural engineers of North America have regarded the composite column generally as a curious stepchild who does not quite belong to a family, yet appears to behave very well. Fathers of the American Concrete Institute have provided shelter by permitting their own ACI routines to be applied to "concrete compression members reinforced longitudinally with structural steel shape, pipe, or tubing." As a "concrete compression member" the stepchild is restrained from doing its own thing as effectively as its structural steel cousins are allowed to do. The ACI Building Code forbids consideration of axially loaded columns by insisting that all columns also function as beams. Within the structural steel shape and tubing family, compression members can be assembled for design as axially loaded columns. Composite columns that are incorporated into structures with connections identical to those used for steel shapes or tubes ought to be considered analytically to behave exactly the same as the shapes or tubes.
Girder Stiffness Distribution for Unbraced Columns
Authors: Stockwell Jr.
Published: April 2024

In the gravity design of unbraced columns, the Alignment Chart (Fig. C1.8.2) in the AISC Commentary is very useful. However, this chart is conservative due to several assumptions made in its preparation. One of these assumptions is that the column above and the column below a particular joint share equally in the girder stiffness available at that joint. In reality this is rarely how it works. What happens is that each column takes stiffness in proportion to its particular need for restraint.* This paper discusses a rational method for distributing girder stiffness to each column tier at a given joint, and the significance of this distribution in actual design.
The New Guide to Stability Design Criteria for Metal Structures
Authors: Johnston Bruce G.
Published: April 2024

The purpose of this report is to review the 3rd Edition of the "CRC Guide" for readers of the AISC Engineering Journal. There has always been a close and special relationship between the American Institute of Steel Construction and the Column Research Council, officially renamed the "Structural Stability Research Council" in March, 1976. The new name reflects the broadened coverage of the Council that has been gradually achieved over the past 32 years of its history. The name of the 3rd Edition of the "CRC Guide", published in April of 1976, has likewise been changed as indicated in the above title of this review. In 1961 the AISC Advisory Committee on Specifications made major revisions in the AISC Specification for the Design, Fabrication and Erection of Structural Steel for Buildings. These included extensive improvements in clauses pertaining to the buckling behavior of laterally unsupported beams, columns, and beam-columns. These changes were needed because of the introduction at that time of higher strength steels and by the corresponding possibility of achieving greater economy and correctness in the design of steel structures. The AISC Advisory Committee on Specifications turned to the Column Research Council to provide backup and substantiation for the new specification it was about to introduce. It was at that time, too, that architectural concepts in the construction of steel buildings were breaking sharply away from the traditional types of the past. Simplified procedures that had evolved through successful past experience were no longer adequate for the new steels and the new, varied shapes of current construction practice.
Errata: Design Example for Beams with Web Openings
Authors: Kussman Richard L. , Cooper Peter B.
Published: April 2024

Errata
A New Design For Torsion Resistant Suspension Bridges
Authors: Samelson Harold
Published: April 2024

The proposed design for improving torsional stiffness of the Manhattan Bridge was developed by the author as an alternate to published plans for reducing the excessively high maintenance costs of the bridge. A preliminary simplified model incorporating the principal components of the proposed design was analyzed. The results indicated a decrease in torsional deflections approaching 90%. Finally, a rigorous check was made using the computer to analyze three dimensional models of two suspension bridges. The bridges were the same in overall dimension and member size, except that one was conventionally framed and the other contained elements of the authors designs. The result supported all of the conclusions drawn from the analysis of the simple model; in fact, torsional deflections diminished by more than 90%.
A Practical Method of Second Order Analysis Part 1; Pin Jointed Systems
Authors: LeMessurier William J.
Published: April 2024

Most designers were trained in methods of structural analysis which assume that the change in shape of a structural system due to loading does not significantly affect the magnitude of the internal forces of the system. Except for consideration of local effects such as buckling of individual columns or beams, knowing the absolute stiffness of members in relation to loads has generally been unneccessary for determining the internal forces of a system. The method discussed here was developed for pin jointed structures without bending moments. It gives exact results within the limitations of small deflection theory. In a continuation of this paper, to be published in the AISC Engineering Journal in the near future, the method will be extended to include frames with bending moments.
Discussion: The Effective Length of Unbraced Single Story Columns
Authors: Green Robert W.
Published: April 2024

Discussion
Discussion: On Inelastic Column Buckling
Authors: Matz Charles A.
Published: April 2024

Discussion
Direct Feasible and Optimal Design of Laterally Unsupported Beams
Authors: Brandt G. Donald
Published: April 2024

When a beam is laterally supported throughout its length, the axis of bending is prescribed, and most efficient use of material results if the moment of inertia around that axis is made as large as possible. The only structural restriction is that width-thickness ratios must not become so large as to cause local buckling; of course, architectural and clearance considerations may impose other limitations. Such beams may be rapidly and optimally designed in steel, using either the Section Modulus Tables in the AISC Manual (pgs. 2-7 to 2-20) or the Allowable Uniform Load Tables (pgs. 2-28 to 2- 81). When a beam is laterally unsupported over some of it length further investigation is required, since the beam tends to become unstable and twist or buckle about its weak axis. If the unsupported length is small enough (L less than Lu), design proceeds using the same tables referred to above, although the allowable bending stress may need to be decreased from that allowed for compact sections to 0.60 Fy. Selecting the optimum is still relatively easy.
Discussion: A New Design For Torsion Resistant Suspension Bridges
Authors: Birdsall Blair , Samelson Harold
Published: April 2024

Discussion
Fatigue Strength of Steel Members with Welded Details (T.R. Higgins Award)
Authors: Fisher John W. , Yen Ben T.
Published: April 2024

Early studies on the fatigue of welded steel structures and components revealed the influencing factors such as stress magnitudes and geometry of structural details. Approximate design relationships were developed in the 1940s and, overall, very few problems occurred with steel bridges and structures as a result of fatigue. The fatigue cracking of coverplated steel beam bridges of the AASHO Road Test3 in the early 60s led to further examinations of the controlling factors and more extensive studies. A substantial amount of experimental data has been developed on steel beams since 1967 from a study sponsored by the National Cooperative Highway Research Program (Project 12-7) and carried out at Fritz Laboratory, Lehigh University. These studies have shown that the most important factors which govern the fatigue strength are the stress range and the type of details. For each type of welded structural detail, regardless of the strength of the steel, the applied stress range was found to cause propagation of fatigue cracks from initial discontinuities at the details. The fatigue life of a detail was nearly exhausted when the crack had propagated through the thickness of the flange plate. These findings were observed to be applicable to rolled beams, welded beams, beams with groove-welded flange splices, coverplated beams, and to beams with welded stiffeners and attachments. Comprehensive specifications based on stress range alone have been developed for bridge and building structures 6-8 utilizing these beam test data and other available information in the literature. This paper reviews very briefly the governing parameter of stress range, the experimental results on welded stiffeners and attachments, the phenomenon of crack propagation, and the data basis for the specifications. In addition, some secondary considerations which have caused fatigue cracking are examined and possible ways of retrofitting cracked structural details are suggested.
The AISC Quality Certification Program
Authors: Peshek Jr.
Published: April 2024

In recent years, the quality of construction methods and materials has become the subject of increasing concern to building officials, highway officials, and designers. One result of this concern has been the enactment of ever more demanding inspection requirements intended to ensure product quality. In many cases, however, these more demanding inspection requirements have not been based upon demonstrated unsatisfactory performance of structures in service. Rather, they have been based upon the capacity of sophisticated test equipment, or upon standards developed for nuclear construction rather than conventional construction. Adding to the problem, arbitrary interpretation of specifications by inspectors has too often been made without rational consideration of the type of construction involved. The result has been spiraling increases in the costs of fabrication of structural steel and of inspection, which must be paid by owners without necessarily assuring that the product quality required has been improved. Product inspection, although it has a valid place in the construction process, is not the most logical or practical way to assure that structural steelwork will conform to the requirements of contract documents and satisfy the intended use. A better solution can be found in the exercise of good quality control and quality assurance by the fabricator throughout the entire production process.
Combined Shear and Tension on Grouted Base Details
Authors: Adihardjo Rianto , Soltis Lawrence A.
Published: April 2024

Braced structures with large height-to-width ratios, i.e., transmission towers, water towers or industrial equipment support towers, when subjected to lateral loads, often have resultant uplift and shear forces transmitted to their foundations. The base details must transmit combined tension and shear from the column to the foundation. For ease of construction, the columns are often set with base plates shimmed 1 to 2 in, above the top of the foundation; the shimmed volume is later grouted to complete the base detail. The two major codes governing steel and reinforced concrete construction do not specify design formulas for grouted anchor bolt-base plate connection details. The Uniform Building Code, representative of general building codes, states bolts shall be solidly embedded in plain or reinforced concrete, and the connection shall be designed so that the tension or shear on every bolt is not greater than a value defined in their tables. Previous investigators have studied anchor bolts embedded in concrete subjected to combined shear and tension, but have not included the effects of the grout.
Allowable Axial Stresses in Segmented Columns
Authors: Barnes D.W. , Mangelsdorf C.P.
Published: April 2024

An axially loaded column which is stepped, or one for which axial loads and/or reactions are applied at points other than its ends, may be referred to as a segmented column. Each segment of such a column has constant properties and constant load along its length. Crane columns and pipe supports are typical examples. Frequently such columns have eccentric or lateral loads which also produce bending, but for determining allowable axial stresses the columns may be reduced to forms. For elastic behavior, the critical condition in a segmented column with a given combination of proportional loads usually depends upon a complex interaction between the segments such that the whole column may be regarded as buckled. The contribution of each segment is a function of its properties, its load, and the position of the segment along the length of the column. The critical condition for an individual segment is generally unknown, because each segment relies on the other segments for its end conditions.
Prefabricated Press-Formed Steel T-Box Girder Bridge System
Authors: Taly Narendra , GangaRao H.V.S.
Published: April 2024

The conventional bridge construction methods are time consuming and costly because of the high costs of material and labor. In addition, bridge maintenance costs are increasing rapidly. Hence, the need for more economical techniques of rehabilitating existing bridges and building new ones is well recognized. To this end, several innovative modular bridge systems are being developed by the authors and have been reported in the literature. This paper presents the details of an all-steel superstructure system that is economical and suitable for span ranges of 40 to 100 ft under HS20-44 loading. Herein, it is referred to as the press-formed prefabricated steel box girder-bridge system.
Plastic Design of Steel Floor Beams
Authors: Hawes William H.
Published: April 2024

The potential for savings in material and improvement in performance which can be realized by use of plastic design for continuous floor beams, warrants increased attention from fabricators and designers. Various facets of application of this concept will be discussed. The top flanges of floor beams are generally the same nominal elevation as those of the girders. Consequently, whether framing to girders or to columns, the beams could be spliced at a plastic hinge point. Such an arrangement, utilizing A36 steel beams, is assumed in this paper. Items such as reduced restraint for end spans, deductions for bolt holes, and problems in developing full plastic moment capacity at connections are details which require attention if the full efficiency of plastic design is to be achieved. Some compromises, as discussed below, are desirable to avoid overcomplicating the fabrication and erection, in the attempt to save a last increment of beam weight. From the foregoing, it is evident that plastic design in general, and plastic-composite design in particular, does reduce the cost and improve the performance of steel beam floor systems. The continuous connections need not be complicated. Using the M-Seat as a base detail, a means for specifying and detailing connections has been presented, which allows the fabricator and erector to use a method best suiting their fabrication and erection practices and capabilities, while adhering to sound standards for performance and integrity.
Moment Resisting Connections for Mixed Construction
Authors: Hawkins Neil M. , Mitchell Denis , Roeder Charles W.
Published: April 2024

Structural steel and reinforced concrete are often combined in modern structures. While such mixed construction offers a number of advantages, it also requires reliable connections between two very different materials. Headed metal studs are one method for connecting structural steel and concrete. Studs have been used for many years to provide shear connections between steel beams and concrete floor slabs. More recently, in response to mixed and precast concrete construction needs, their range of application has been expanded to include connections such as those shown in Fig. 1. In such moment-resisting connections there is a combined axial force and shear loading on each stud. However, since the studs act as a group, the best distribution of the applied Forces between individual studs for design purposes is not obvious. Information is needed on the factors affecting the strength and behavior of such connections and how best to design them. This paper describes the results of a series of 22 tests performed at the University of Washington on specimens of the type shown in Fig. 1. These specimens provide basic information relevant to two connection types found in practice. For mixed construction, the steel wide-flange section can be said to represent the end of a main member of a steel frame for which a moment resistant connection is required to a concrete column or wall. Alternatively, for either mixed o r precast concrete construction,6 the steel wideflange simulates part of a corbel connection used to support another member. The tests covered a variety of moment, shear, and stud embedment conditions, and a widely varying range of connection behavior was obtained. The results of these tests are compared with the results of previous Studies and existing design recommendations. Conclusions as to the effectiveness of these connections are presented and a recommended design procedure described.
The Analysis and Design of Single Plate Framing Connections
Authors: Richard Ralph M. , Gillett Paul E. , Kriegh James D. , Lewis Brett A.
Published: April 2024

The single plate framing connection has been considered by designers to be a flexible connection that is economical in both material and fabrication requirements in the erection of steel buildings. Two typical single plate framing connections are shown. In both cases, the connection comprises a single plate, with prepunched bolt holes, that is shop welded to the supporting member. During erection, the beam with prepunched holes is brought into position and field bolted to the framing plate. The standard design procedure for the single plate framing connection is to assume each bolt carries an equal portion of the total shear load and, in agreement with the simple support assumption, that relatively free rotation occurs between the end of the beam and the supporting member. In fact, because of these simplifications the single plate framing connection is often called the "shear tab." Investigations into the structural action, strength, and ductility of the single plate framing connection have been limited and none have satisfactorily proved or disproved the validity of the standard design procedure. Even though this connection has an apparent failure-free performance record, this does not necessarily indicate that good design procedures have been used; the actual load and stress distributions should be understood and the design methods and specifications should reflect the actual structural behavior.
An Update on Eccentric Seismic Bracing
Authors: Popov Egor P.
Published: April 2024

Experimental and analytical results for diagonally braced frame models with eccentric connections of the type shown in Fig. 1, first reported by Roeder and Popov in 1978, aroused considerable interest in this system of bracing for resisting seismic forces. Four major buildings have now been designed and are being built in California using this concept. The steel frames designed on this basis are lighter than the equivalent moment-resisting frames, and while essentially retaining the elastic stiffness of concentrically braced frames, the eccentrically braced frames are more ductile. The adoption of the eccentric frames in several projects provides strong evidence of the practicality of the system. By employing eccentrically braced frames, the story drift control at working loads, such as recommended by SEAOC, can be achieved with economy. Moreover, a reduced horizontal force factor can be justified, since at extreme lateral loadings, such as may occur during a major earthquake, these frames behave in a very ductile manner. Some specific details on the practical design of eccentrically braced frames for resisting seismic forces can be found in Refs. 4, 5, and 6. This discussion is confined to some elaborations on the design of the shear link, i.e., the beam element between the face of the column and a brace.
Generalized Design of Columns Subjected to Combined Axial Load and Bending Moment
Authors: Monasa Frank , Snyder John K.
Published: April 2024

The design of wide-flange steel columns subjected to combined axial compression load and bending moment according to the AISC Manual of Steel Construction involves a trial-and-error procedure. In this method the applied bending moment is converted to an equivalent axial load by using a bending factor. This allows the selection of a trial section from the AISC Column Tables. Then, using the modified AISC interaction formulas, the required axial tabular load can be determined. From this load, another trial section is selected, and the procedure is repeated until a satisfactory section is obtained. The selected section must be checked for compliance with the AISC Formulas (1.6-1a), (1.6-1b), and (1.6-2). This process is often tedious and time consuming and is not efficient for usage in the design office. Several methods have been presented which tend to simplify the AISC design procedure for columns subjected to combined axial load and bending moment. These methods either modify the AISC column interaction equations to minimize the number of trials used in selecting the final section, or present design charts, graphs, and tables. This paper provides a rapid selection of steel wide-flange columns subjected to combined axial compression load and bending moment about the strong axis of the member, in compliance with the AISC Specification.
Stress Reduction Factor for Unsupported Lengths
Authors: Roy Ranjit
Published: April 2024

The AISC Specification allows Fb = 0.66Fy for structural shapes meeting the compact criteria of Sect. 1.5.1.4.1, when loaded in the plane of their minor axis. A reduced bending stress, Fb = 0.6Fy, is allowed for shapes failing to meet the compactness criteria. The above allowable values require that the compression flange be braced at a maximum interval of lengths as determined by the smaller value obtained from the expressions described in this paper.
Stability of Metal Structures--A World View (Part 3)
Authors: SSRC ECCS
Published: April 2024

The advantages of the design interaction equation suggested by Chen et al.172 are that both strength and stability are covered by the same basic equation and the equation has universal applicability, for if the exponent for the particular section being designed has not been determined, it may conservatively be assumed to be unity.
Suggestions for Avoiding Beam- to- Column Web Connection Failure
Authors: Driscoll George C. Jr. , Beedle Lynn S.
Published: April 2024

The following discussion draws attention to certain connection details that may not provide the commonly assumed ductility. Such ductility is important in applications where dependence is placed upon redistribution of moments, in plastic design, and in seismicresistant design. The potential for ductility problems increases as material thickness increases beyond that commonly encountered in building construction. Although the AISC Specification recommends allowable stresses which provide a larger ratio of limiting stress to service stress for connectors than for the connected members, designers may not be aware of the potential for fracture resulting from the effects of localized high restraint in some connection details. The paper is also intended to provide a qualitative "feel" for the manner in which stresses are transferred in a beam-to-column web moment connection, so that engineering judgment may be exercised in the design of such connections until the results of research in progress provide information on which quantitative provisions may be based.
Lateral Wind Bracing Requirements for Steel Composite Bridges
Authors: Heins Conrad P. , Hou C.K. , Kato H.
Published: April 2024

The design of moderate multi-span composite bridges requires utilization of cross frame diaphragms between girders and bottom lateral wind bracing. The AASHTO code1 specifies that cross frames or diaphragms shall be provided at each end of the bridge and intermediate frames spaced at intervals not to exceed 25 ft. Previously, AASHTO specifications required that bottom lateral bracing should be provided, located near the bottom of the flange, on spans of 125 ft or longer, if the system has a concrete floor or a floor of equal rigidity. It is the intention of this paper to present the results of a recent study,2 which evaluated the effectiveness of bracing in redistributing wind load and formed the basis for the lateral bracing provisions of the 1982 AASHTO Interim Specifications. This effect has been determined by examining the response of single-span, multi-girder, composite bridges, when subjected to wind load. The bridges examined had span lengths of 80 ft, 120 ft, 180 ft, and 300 ft, with girder spacings of 6 ft, 10 ft, and 14 ft. The resulting response of these bridges indicates that the bottom lateral bracing has minimal effects on the redistribution of the wind load. The important parameter in load redistribution is the diaphragm spacing and span length. The utilization of cross diaphragms, in reducing the flange stresses due to wind loading, are given in a series of design equations.
Allowable Stress for Bending Members
Authors: Maitra N.
Published: April 2024

The allowable bending stress is a very important design parameter. It controls not only the design of beams, but also of columns when subjected to bending in addition to axial load. The following design examples in the AISC Manual show how the allowable bending stress controls the design. This paper presents a table and a formula which would help to find the value of the allowable bending stress, Fb, expeditiously. The table and formula have been derived from AISC equations.
Tips for Avoiding Crane Runway Problems
Authors: Ricker David T.
Published: April 2024

Mill and heavy industrial type buildings are usually designed with two main functions in mind: to provide a sheltered work area and to support lifting devices which serve to move loads from one location to another. Providing shelter involves fairly routine design procedures, utilizing well-known and tested guidelines. But supporting the transporting device, or crane system, is a more complicated and intricate task and efforts in this regard have not always been successful. In fact, many otherwise sound heavy industrial structures are plagued with problems which stem from the method of supporting the crane system. There are several different types of cranes: overhead traveling, underslung, jib, gantry, and monorail are among the most common. A building may contain one or several of the above, either singly or in various combinations.
Wearing Surfaces for Orthotropic Decks
Authors: Gilligan John A.
Published: April 2024

Chapter 8, "Wearing Surfaces", of the AISC Design Manual for Orthotropic Steel Plate Deck Bridges1 contains the most complete descriptions of current steel deck surfacing systems and specific information on surfacing materials to be found in English language references. This paper presents new information on steel deck surfacing systems in use in the United States, systems proposed for three large orthotropic steel plate deck bridges being constructed or to be constructed in North America, and suggestions on novel components for surfacing systems that possibly justify consideration and further research. Despite the number of unprotected steel plate deck bridges giving satisfactory service in this country, there is agreement that a steel plate bridge deck requires some type of surfacing. Most existing steel plate bridge decks employ "pattern" or "checkered" steel plates. Such plates have different regular patterns of metal projections on the plate surface. The principal objection to unprotected pattern plate for highway bridge decks has not been corrosion of the steel plate, but the low friction developed between the steel plate and rubber tires in most conditions of service. It is generally agreed that steel plate decks require surfacing to improve resistance to skidding. It then follows that the surfacing system must be impervious to moisture. Trapped moisture on a steel plate under a surfacing system, admitted through cracks or holes in the surfacing system, will create a corrosion condition considerably worse than if the surfacing system were not present. The importance of the steel plate deck in orthotropic plate construction, as a member to distribute loads to stringers and as the top flange of stringers and floor beams, requires that the steel deck not be subject to corrosion. Thus, the two foremost requirements for a steel deck surfacing system are that the system must not admit moisture to the steel plate and the surface of the system must provide good resistance to skidding.
Castellated Beams - New Developments
Authors: Boyer J.P.
Published: April 2024

"Castellated beam" is a name commonly used for a type of expanded beam. It is made by expanding a standard rolled shape in a manner which creates a regular pattern of holes in the web. The name is derived from this pattern of web holes, because castellated means "built like a castle, having battlements, or regular holes in the walls, like a castle". Fig. 1 illustrates a castellated beam. It is made by separating a standard rolled shape into two halves by cutting the web in a regular alternating pattern as shown. The halves are rejoined by welding, after offsetting one portion so that the high points of the web pattern come into contact. Some design conditions make it advantageous to increase the depth even more. This is done by adding web plates between high points of the tee sections. These added plates are called "increment plates".
Space Frame Structures
Authors: Naslund Kenneth C.
Published: April 2024

Interest on the part of architects and engineers in the socalled space frame has prompted the preparation of this paper. Its purpose is to present some of the factors to be considered for designing structures of this type. Among these factors are descriptions of various types of space frames, the effect of support locatiosn, the selection and arrangement of chord spacing, web systems, joint details, the collection of loads at support, and the methods available for analysis and design.
Steel is Changing the Los Angeles Skyline
Authors: Johnston Roy G.
Published: April 2024

Visitors to the city of Los Angeles recently have noticed a great change in the character of the city. Today, tall multistoried structures are projecting above the skyline—many twenty story buildings, some thirty stories, and at least one in the design stage of forty-five stories. Construction records are being broken daily. Prior to 1957, the city was flat; the important building structures were "box-like", all apparently the same height. By law, the buildings were limited to thirteen stories and not more than 150 ft in height.
End Restraint and Column Design Using LRFD
Authors: Lui E.M. , Chen Wai-Fah
Published: April 2024

The ultimate strength of a structural member is the maximum resistance it can offer to resist the applied force before failure. Design based on the ultimate strength of the structure or its component parts is referred to as limit state approach to design. A valid limit state approach to analysis and design of any structural member requires the consideration of all important factors that are imperative to determining the behavior of the member throughout the entire range of loading up to the maximum capacity of the member. In the case of columns, the three main factors that need to be considered are (1) residual stresses; (2) initial geometrical imperfections; and (3) end restraints. The purpose of this paper is to summarize the results of some recent research on in-plane behavior of imperfect columns with modest end-restraints. The incorporation of end restraint in the design of columns using the Load and Resistance Factor Design (LRFD) format is then proposed. Simple design examples will be given to illustrate how the effective length concept can be used for the design of imperfect columns with small end restraints.
Calculation of Wind Drift in Staggered-Truss Buildings
Authors: Leffler Robert E.
Published: April 2024

The important feature of a staggered-truss framing system is the story-high steel trusses that span the full width of the building. These trusses are used in a staggered arrangement, so that they occur at every other column row on each story. The floors, typically precast prestressed concrete, span from the bottom chord of one truss to the top chord of the adjacent truss, so that the span of the floor system is half the truss spacing. As the height of steel-framed staggered-truss buildings is extended beyond 20 stories, the need for calculating wind deflection (drift) becomes more important. However, because the staggered-truss system differs from conventional framing systems, the appropriate method for calculating drift may not have been apparent. Consequently, a method was developed for calculating drift in staggered-truss buildings and, through finiteelement computer analysis, the accuracy of the method was verified. Specifically, a NASTRAN model was made for the building described in this paper, and a complete analysis was made to calculate the deflections on each floor. The result showed that the difference in results between the handwork calculations and the NASTRAN analysis was generally less than 1.5%. A design example is presented to illustrate the hand-calculating method.
Some Economic Considerations for Composite Floor Beams
Authors: Lorenz Robert F.
Published: April 2024

To the discerning structural engineer, changes in specification rules always offer an economic opportunity to find new and better ways to implement savings in material or labor costs. In a subtle manner, a 1978 AISC Specification rule change for partial composite design of steel flexural members strongly improved the opportunity to make important economic savings in optimizing the floor system costs. The change was simply the introduction of a squareroot power instead of a linear relationship in Specification Eq. (1.11).
Structural System--Getty Plaza Tower
Authors: Wong Charles
Published: April 2024

In areas of strong seismic activity, the lateral load resisting structural systems for buildings need to be designed with appropriate stiffness and ductility, which are often counter objectives. Adequate stiffness is needed to resist building displacement during wind and moderate earthquake loadings, primarily in order to control damage to non-structural elements—and for taller buildings to mitigate perception of building sway during frequent wind storms. Secondly, adequate ductility is needed in the structural elements and connections as well as in the overall structural system to provide sufficient reserve of strength at large displacement to absorb severe earthquakes without building collapse. The need to provide overall building stiffness and strength at least cost has lead to development of various structural framing systems. In particular, the braced-frame and tubular framing systems have gained a wide acceptance with structural steel application. A framed-tube structure typically has closely spaced perimeter columns that are interconnected at floor levels with deep spandrel beams, thereby creating a relatively rigid peripheral grid. The shear lag along the flange frames is greatly reduced, thus improving the effective cantilever stiffness of the overall structure.
Structural Engineering for the 80s and Beyond
Authors: McGuire William
Published: April 2024

Shortly after its founding in 1921, the American Institute of Steel Construction took the step that established its future. It is described in the preface to the Institute's first specification: "In 1923, AISC undertook the work of promoting uniform practice in the industry, and in order that its efforts would not be interpreted as being unduly influenced by commercial interests it selected a committee from among the leading talent in the academic, engineering and architectural professions to prepare a Standard Specification on the Design, Fabrication, and Erection of Structural Steel." The committee, consisting of two practicing engineers, an architect, and two academicians, was indeed an eminent one, and did its job well. The specification produced the same year was less than nine pages long, but met its objectives and gained the respect of the engineering profession. The consistency and integrity with which the principles of that statement have been applied over 61 years are remarkable. I know of no other standard sponsored by a private industry that has achieved and maintained the worldwide recognition the AISC Specification has.
Concrete Slab Stresses in Partial Composite Beams and Girders
Authors: Lorenz Robert F. , Stockwell Jr.
Published: April 2024

Although calculation of compressive flexural stresses in the concrete slab of composite steel beams and girders is a routine procedure, engineers are discovering certain ambiguities in such an analysis when the partial composite concept is used. The problem presents itself when applying the rules in Section of 1.11.2.2 of the AISC Specification. This section states, in part, "The actual section modulus of the transformed composite section shall be used in calculating the concrete flexural stress...." The intent of the Specification is to determine the actual stress distribution corresponding to the actual number of shear connectors in the partial composite design approach. This paper describes a suggested procedure to determine concrete slab stresses based on assumed elastic behavior. The basic justification for the partial composite theory is the fact that shear connectors are inadequate to maintain strain compatibility at the interface of the concrete slab and the top of the steel beam. This results in a limited amount of horizontal slip, which would reduce the concrete compressive strains, and their corresponding stresses
Column Web Compression Strength at End-Plate Connections
Authors: Hendrick Alan , Murray Thomas M.
Published: April 2024

Current North American specifications provide design criteria to prevent local failure of H-shaped columns when flanges or moment connection plates are welded to the column flange. This design criterion was developed strictly for these types of connections. Application of these criteria when bolted end-plate connections are used for welded and welded-bolted connections. Unnecessary use of column stiffeners may result in opposite beam flanges being tensioned. Installation of column stiffeners is expensive and stiffeners can interfere with weak axis framing into the column. If stiffeners between the flanges of H-shaped columns can be eliminated, the fabrication process is greatly simplified.
Single-Plate Framing Connections with Grade-50 Steel and Composite Construction
Authors: Hormby David E. , Richard Ralph M. , Kriegh James D.
Published: April 2024

Single-plate framing connections are widely used because of their economy of material and ease of construction. References 1, 2 and 3 present design guides that ensure their ductility and account for their moment resistance when used in symmetrical connections or with stiff supporting structures. These design procedures are applicable to connections with A307, A325 and A490 bolts used with A36 non-composite steel beams. Research completed at the University of Arizona has expanded these design guides to include (a) connections with slotted holes, (b) connections with Gr. 50 steel beams, (c) off-axis framing plates (Fig. 2) and (d) single-plate framing connections with simply supported shored and unshored composite beams.
Bracket Loaded Webs with Low Slenderness Ratios
Authors: Hopper Bruce E. , Batson Gordon B. , Ainso Heino
Published: April 2024

Welded bracket connections to the web of rolled sections are common connections. However, the AISC Manual of Steel Construction has no guidelines for estimating their capacity. Generally, the maximum load corresponds to the development of a two-dimensional yield mechanism in the web; but for sections whose webs have significant thickness relative to the T-distance, the maximum load may occur in the flanges. Abolitz and Warner conducted a theoretical investigation into bending of seated connections. By applying work methods to several yield line patterns, they developed an expression for the lowest value of the ultimate load.