bluuebunny/crossref_metadata_2025 huggingface dataset:
Computer-Aided Analysis and Design of Steel Frames
Authors: Pierson George , Orbison James G. , Mehringer Vincent
Published: April 2024

A computer package has been developed for the analysis and design of steel plane frames. The package will, with the stiffness method, analyze a plane frame and select the leastweight wide-flange section for each member within the frame. The two modules of the package, the analysis and design, may be used independently of, or in conjunction with, one another. When used together, they interact to establish an analysis/design iteration sequence by which the least weight design is obtained. Within the analysis module, graphical displays of the structure allow for visual verification of structural data as well as analytical results. The design module minimizes data entry by making design condition assumptions, all of which can be altered. By calculating internally various design parameters, such as effective column length factors, a fast, easy design session is permitted. The package is presently being used in upper-level structural analysis and steel design courses. A student using the package has the benefit of conceptualizing the entire analysis and design process rather than the fractionized procedure often presented in texts. To enhance further the students understanding of the process, the package saves all values used in the final analysis and steel section selection for verification.
Effect of Burrs on Bolted Friction Connections
Authors: Polyzois D. , Yura Joseph A.
Published: April 2024

Burrs develop at the edge of drilled or punched holes during the fabrication process. But, depending on the speed with which the bolt hole is formed and the condition of the drills or punching equipment, burrs may be large enough to prevent the solid seating of connected parts, as required by the present Research Council on Structural Connections (RCSC) Specification for Structural Joints Using A325 or A490 Bolts, hereafter referred to as the RCSC Specification. Since it is not clear in the specification what size burr will prevent contact within the faying surface, fabricators go through the expense of removing all burrs prior to assembly to satisfy this provision of the specification. Although a considerable amount of research has been directed towards evaluating the static shear capacity of joints with solid seating of the connected parts, there are no data that address the slip resistance of joints when the plates are not in solid contact because of burrs at the edges of the holes. This paper deals with the results of an experimental program carried out at The University of Texas-Austin to determine the effect of burrs on the slip performance of both paint-free and painted connections, and also to examine the effect of burrs on the clamping force produced by the turn-of-nut installation.
The Use of Jumbo Shapes in Non-column Applications
Authors: American Institute of Steel Construction
Published: April 2024

The Use of Jumbo Shapes in Non-column Applications
The Significance of Weld Continuities Regarding Plastic Failure
Authors: Gresnigt A.M.
Published: April 2024

The answer to whether weld discontinuities affect the correct functioning of welded joints, depends on the demands made on those joints, the extent of the weld discontinuities and the mechanical properties of the weld metal and the base metal. In Sect. 2, a summary is given of the demands which are made on welded structures. Section 3 demonstrates briefly how the "Design rules for arc-welded connections in steel submitted to static loads"1 meet these demands. The influence of weld discontinuities will then be discussed. Finally, conclusions and recommendations are made.
Experience with Use of Heavy W Shapes in Tension
Authors: Fisher John W. , Pense Alan W.
Published: April 2024

During the last five years, a few cracking and fracture problems have been observed with welded, large rolled jumbo sections. This type of rolled section is classified as a group IV or V shape in the 8th Edition AISC Manual of Steel Construction. They include W12 and W14 rolled steel sections equal or exceeding 210 lbs./ft. The cracking has been observed in sections equal or exceeding 370 lbs./ft. They have been observed in sections produced without special metallurgical requirements as well as in sections produced with killed fine grain practice. This paper reviews the characteristics of these steel sections, the conditions that led to the cracking and provides recommendations for splicing and use of these members in tension applications. In addition, there are suggestions for weld splices in compression. When first introduced in the 1960s, these sections were intended as columns in structures resisting large axial loads. However, with passage of time the sections were gradually introduced in large trusses as tension members. This provided a means to develop the large forces in the chords and diagonals of long-span trusses or shorter spans carrying heavier loads. Figure 1 shows the fractured chord of a large truss fabricated from these rolled sections.
Behavior of Semi-rigid Composite Connections
Authors: Ammerman Douglas , Leon Roberto T.
Published: April 2024

The 1978 AISC Specification allows three types of framing. Type 1 is for fully rigid moment connections, Type 2 is for pinned connections (although the moment capacity inherent in these connections is recognized and assumed to act in resistance of wind loads), and Type 3 is for semi-rigid connections. The behavior of a composite connection is similar to that of a non-composite connection, with the slab steel replacing the top angle. The higher strength of the rebar steel, the increased moment arm and the presence of a slab result in a stronger, stiffer and more ductile system. The substitution of the angle with the rebar also results in a much more linear initial behavior. The moment-rotation curves are fairly linear within the range that should be used for service loads, and thus serviceability checks might not be as difficult as previously thought. For design purposes, the connection can probably be considered linear with a stiffness similar to those obtained at the beginning of GL3, if shakedown can be assumed to have taken place during GL2. Thus the use of a complex approach, requiring B-splines or polynomials to approximate the moment-rotation characteristics, might not be required for everyday office use.
Material Considerations in Structural Steel Design
Authors: Barsom J.M.
Published: April 2024

Engineering structures, with very few exceptions, perform safely and reliably. The safety and reliability of these structures has been achieved primarily by adhering to the appropriate specifications that govern the material, design, fabrication and inspection for the particular structure. These specifications undergo periodic reviews and, when necessary, are changed to improve their accuracy and applicability. Deviations from the specifications requirements, misinterpretation of specifications, the use of highly restrained complex welded details and use of new and unproven concepts in design may impair the safety and reliability of a structure. The collapse of a structure or the fracture of a structural component may occur as a result of improper material properties, design, fabrication, inspection, erection and operating conditions. This paper focuses on material considerations and presents a brief discussion of some material factors that should be understood and considered in the fabrication and design of steel structures. The effects of deoxidation practice on segregation in steel ingots, and in the final product are discussed. Also discussed are the variability in the yield and tensile strength properties within a plate or a structural shape and the effects of temperature and rate of loading on these properties. Finally, the paper discusses the variability in fracture toughness and the effects of temperature and rate of loading on this material property. Charpy V-notch test results are used to describe the variability in fracture toughness and the critical stress-intensity factor is used to describe the effects of temperature and rate of loading on fracture toughness. Correlations between CVN test results and the critical stress intensity factor are also presented.
Design of Diagonal Cross Bracings: Part 1 Theoretical Study
Authors: Picard A. , Beaulieu D.
Published: April 2024

Diagonal bracing is commonly used in steel structures to resist horizontal loads. In current practice, the design of this type of bracing system is based on the assumption the compression diagonal has negligible capacity and the tension diagonal resists the total load. If the diagonals are connected at their intersection point (usual practice), this design procedure is conservative because the effect of this connection on the out-of-plane buckling capacity of the compression diagonal is ignored. The restraint provided to the compression diagonal by the loaded tension diagonal is generally sufficient to consider that the effective length of the compression diagonal is 0.50 times the diagonal length (KL = 0.5L) for out-of-plane buckling as for in-plane buckling. Analytical and experimental results have also shown the ultimate horizontal load on the bracing system is much higher than the horizontal component of the yielding strength of the tension member, because of load sharing between the diagonals. The assumption that the compression diagonal has negligible capacity usually results in overdesign. This paper presents the results of a theoretical study aimed at the determination of the transverse stiffness offered by the tension diagonal in cross-bracing systems and at the evaluation of the effect of this stiffness on the out-of-plane buckling resistance of the compression diagonal. The theory is supported by seven transverse stiffness tests and 15 buckling tests. The test results are reported in the second part of the paper.
Applications of Orthotropic Decks in Bridge Rehabilitation
Authors: Wolchuk Roman
Published: April 2024

A bridge deck, subject to direct loading by heavy truck wheels and exposed to weather effects, is the most severely stressed structural element of a bridge. The static and dynamic effects of the moving wheel loads and the high ratio of live to dead load cause a wide range of alternating stresses in the deck. Repeated millions of times during the deck life, these stresses precipitate material fatigue. The decks are designed for standard loads stipulated in the AASHTO specifications. However, the actual wheel and axle loads are frequently much heavier and may cause severe overstress. Another significant contribution to flexural deck stresses is due to differential deflections of the supporting stringers, which is not addressed in the current design specifications for concrete decks. Exposure of the deck to wide temperature variations, moisture and freeze-thaw cycles further decreases the deck strength by causing concrete volume changes and cracking. However, the most important cause of deck deterioration is the action of deicing salts that penetrate concrete and corrode reinforcing steel. High pressures exerted by the rust cause further cracking, spalling and delamination of concrete, opening the way to more salt penetration and thus accelerating the irreversible process of concrete deck failure.
Columns: From Theory to Practice
Authors: Bjorhovde Reidar
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.
Field Welding to Existing Steel Structures
Authors: Ricker David T.
Published: April 2024

Field welding to existing members is becoming increasingly common. During the recycling of older structures, new performance requirements often require addition of reinforcing material to increase load-carrying capacity, to restore areas eroded by corrosion, to strengthen fireweakened members or perhaps alter the appearance of a member by changing its shape for aesthetic reasons. One of the many advantages of a steel-framed structure is that it can be reworked more readily than structures of other materials. Field conditions are often far from ideal and it is necessary to ascertain the effects of the field work on the existing structure, especially the common method of attachment—welding. Over the years, various rules-of-thumb have been applied: no welds where calculated stress exceeds 50% of working stress; no transverse welds across tension members; no welds where calculated stress exceeds three ksi unless shored; make all welds parallel to stress lines, etc. Most of these made sense at the time and were the result of practical experience plus common sense.
Secondary Stresses in Trusses
Authors: Nair R. Shankar
Published: April 2024

Secondary stresses in steel trusses may be neglected in most cases. It is important, however, that secondary stresses be defined properly and the analysis and design be consistent with each other, as follows: If the truss members are designed for the axial forces that would occur if the members were pin-connected, then the flexural stresses indicated by a more refined analysis may be defined as secondary stresses and may be neglected, within reasonable limits. If the axial forces for member design are obtained from an analysis that includes flexural effects, flexural stresses cannot be dismissed as secondary stresses, since the presence of flexural effects in the analysis might have reduced the axial forces indicated by the analysis. In this case, the designer who wishes to neglect flexural stresses must first judge whether (and by how much) the axial forces indicated by the analysis were affected by flexural effects. And he must then make appropriate corrections in the axial forces to be used for design.
Design of Single Plate Shear Connections
Authors: Astaneh-Asl Abolhassan , Call Steven M. , McMullin Kurt M.
Published: April 2024

Single plate shear connections, often referred to as shear tabs, have gained considerable popularity in recent years due to their efficiency and ease of fabrication. Shear tab connections are primarily used to transfer beam end reactions to the supporting elements. The connection consists of a plate welded to a support at one edge and bolted to a beam web. Figure 1 shows typical applications of single plate shear connections. This paper presents the summary of a research project on the behavior and design of single plate shear connections. Based on experimental and analytical studies, a new design procedure is developed and presented.
Serviceability Guidelines for Steel Structures
Authors: Ellingwood Bruce R.
Published: April 2024

Serviceability limit states are conditions in which the functions of a building are disrupted because of local minor damage to or deterioration of building components or because of occupant discomfort. Many serviceability limit-states are the result of excessive structural deformations or motions. Current codes and standards used in steel design deal with the complex problems of serviceability limit-states with simple rules. Some of these rules have remained essentially unchanged for over a century. For the most part, they require only a check of deflections of the floor or frame under service load conditions. Thus, approach to serviceability presumes that a broad spectrum of building structure performance issues can be dealt with simply by means of static deflection checks. A closer look at serviceability issues is warranted by trends in modern construction. Changing architectural and building-use requirements, improvements in structural analysis and design made possible by the widespread use of computers, the use of lighter and less rigid cladding, uncoupling of nonstructural elements from the structural frame, the increasing use of high-strength steel leading to longer spans and bay sizes; all have resulted in building structural systems that are less stiff and massive. Such systems may deflect or vibrate excessively at service-load levels.
Uniform Pin-based Crane Columns, Effective Lengths
Authors: Fraser Donald J.
Published: April 2024

A parametric computer study is used to investigate the buckling of pin-based rectangular frames containing uniform crane columns. The study showed that the effective length factor of the lower segment of the heavily loaded column could be related to the nominal effective length factor obtained from the standard alignment chart. Easy-to-use formulae are presented and the K-factors for the other column segments are calculated from the heavily loaded segment. An approximate frame, in which the beam is lowered to the level of the crane, was also investigated but gave results that were not consistent enough for design use. The proposed procedure is illustrated with a numerical example.
The Results of Experiments on Seated Beam Connections
Authors: Roeder Charles W. , Dailey Ronald H.
Published: April 2024

Seated beam connections have been used for many years. They have historically been designed by tabular methods, and this tradition was recently continued in the new LRFD Manual. The derivation of these design tables are discussed elsewhere and will not be repeated here. It should be noted that the tables have historically considered local yielding of the beam web under edge loading, the strength of bolts or welds, the yielding capacity of the seat angle and the normal detailing dimensions. The new AISC LFRD Specification includes the new equation (K1-5) which checks the beam web for crippling or buckling. In this paper, the term buckling is defined to mean a vertical crimping or crippling of the web due to the application of a concentrated load on the flange. This is a stability mode of failure rather than a web yielding failure as presently considered in ASD design (8th Edition Manual). Unlike a web yielding formula, it includes the depth and the flange thickness of the beam as variables. Table 1 summarizes LRFD beam web capacities according to Eq. (K1-5) and a 3-½ in. bearing length. It can be seen that there are cases where the tabulated unstiffened seat capacities exceed the beam web buckling capacity. Therefore, AISC funded a research program at the University of Washington to study these connections. This paper summarizes some of the results of this experimental program.
Approximate Plastic Modulus of Wide Flange Beam Sections
Authors: Gilsanz Ramon
Published: April 2024

New preliminary design rules are presented for use with the AISC LRFD Manual. The use of preliminary design rules for AISC has been treated elsewhere. A simple and easy rule to use for estimating plastic section modulus of braced wide flange beams is presented here.
Practical Analysis of Semi- Rigid Frames
Authors: Barakat Munzer , Chen Wai-Fah
Published: April 2024

This study attempts to introduce a simplified method of flexible frame analysis that builds on some aspects of the already established AISC/LRFD design approaches, namely the B1 and B2 amplification factor method. Two idealized connection models are proposed: The first is a modified initial stiffness representation; the second is a model determined by the beam-line method. The connection models are designed for implementation in a first-order analysis of the nonsway and sway configurations of frame, thus determining the moment values Mnt and Mlt, respectively. The design moment Mu is obtained in a procedure similar to that conducted for rigid frames using the amplification factor method. The effective length factor concept is utilized with some modifications to account for connection flexibility. A modified relative stiffness factor for elastically restrained members is suggested, which allows the use of existing alignment charts for determining the effective length factor of columns.
LRFD Beam Tables for Structural Tubes
Authors: Sputo Thomas
Published: April 2024

In his practice, the author often uses structural tubes as flexural members in areas that will be visible in the completed structure. Tubes, being closed sections, have excellent resistance to lateral-torsional buckling and are more visually pleasing than W-shapes. An allowable stress design aid for structural tubes used as beams has been previously published in this Journal. As this author is shifting his practice from allowable stress design to LRFD, load factor design selection tables were developed in accordance with the LRFD Specification. These tables are set up similar to the beam selection tables in Part 3 of the LRFD Manual of Steel Construction.
Closure: Design of Single Plate Shear Connections
Authors: Astaneh-Asl Abolhassan , Call Steven M. , McMullin Kurt M.
Published: April 2024

Closure
Discussion: Design of Single Plate Shear Connections
Authors: Richard Ralph M.
Published: April 2024

Discussion
Proposed Revision of the Equivalent Axial Load Method for LRFD Steel and Composite Beam-Column Design
Authors: Uang Chia-Ming , Wattar Samer W. , Leet Kenneth M.
Published: April 2024

After studying the interaction equations that form the basis of the equivalent axial load method for selecting a trial section for a beam-column, the authors propose a series of revisions to the design aids and procedures in the current edition of the LRFD manual. The revisions affect both steel and composite beam-columns. The suggested modifications will permit designers to select a better trialsection, thereby Reducing the computation time for the design of beam-columns.
Behavior of a Two-Span Continuous Plate Girder Bridge Designed by the Alternate Load Factor Method
Authors: Moore Mark , Grubb Michael A.
Published: April 2024

A large experimental test program to evaluate the behavior of a continuous plate-girder bridge with precast prestressed deck panels, designed according to Alternate Load Factor (Autostress) procedures, has been conducted at the FHWA Turner-Fairbank Highway Research Center in McLean, Virginia. The project was sponsored jointly by the American Iron and Steel Institute (AISI) and the Federal Highway Administration (FHWA). A 0.4 scale model of a two-span continuous plate-girder bridge was subjected to a series of tests at each of the three AASHTO load levels—Service Load, Overload, and Maximum Load. At the Service Load level, elastic lateral live-load distribution was studied. At the Overload and Maximum Load levels, the adequacy of the Alternate Load Factor Design limit-state criteria to satisfy related structural performance requirements was analyzed. Deck panel behavior was studied at all three load levels. The prototype bridge had two equal spans of 140 ft, an overall width of 48 ft with three girders spaced at 17 ft, and 10-in. thick composite modular precast deck panels prestressed in the transverse and longitudinal directions. The girders were designed using Alternate Load Factor (Autostress) procedures. Alternate Load Factor Design (ALFD) is a limit-states design approach that more realistically approximates the actual behavior of continuous steel members at higher loads than present design procedures. ALFD recognizes and takes advantage of the ability of continuous steel members to adjust automatically for effects of controlled local yielding. An AASHTO guide specification presently permits the use of ALFD for braced compact sections. This model bridge study is part of a comprehensive research program to extend ALFD procedures to noncompact girders with slender webs.
Reinforcing Steel Members and the Effects of Welding
Authors: Tide Raymond H.R.
Published: April 2024

Reinforcing structural steel compression members to increase the cross-sectional area or decrease slenderness by attaching additional bars, plates, angles and channels is an economical method of increasing load-carrying capacity. Supplemental reinforcement has been installed under various loading conditions. In most cases the attachment is achieved by welding, although bolting may be chosen for some particular technical or administrative reason. The author has been involved in both methods, and usually experience and the specific conditions dictate which attachment method is more appropriate. This paper presents a review of several proposed reinforcement methods and discusses factors that must be considered for each. The focus of this paper is welded reinforcement methods, although an appropriate reference to a bolted study is made. Whenever the existing steel members are in good condition and their composition is known, the welding requirements are straightforward. However, for older unknown or corroded steel, other factors are involved, such as weldability, contaminants and deep pitting. These issues were addressed by Tide and Ricker in earlier papers and are not repeated herein.
1989 AISC Specification (Ninth Edition) Allowable Bending Stress Design Aid
Authors: Hulshizer Allen J.
Published: April 2024

Simple to use, accurate graphic solutions to compressive bending stress equations are provided to readily facilitate taking full advantage of actual bracing and continuity conditions to achieve design time and material efficiencies.
An Analytical Criterion for Buckling Strength of Built-up Compression Members
Authors: Farhang Aslani And Subhash C. Goel
Published: April 2024

In current design practice, North American and European specifications differ significantly regarding the rules governing the design of stitched built-up struts. The British and German specifications treat such members essentially like battened columns and apply more stringent provisions to limit their shear flexibility. Consequently, built-up struts designed according to these specifications must be closely stitched. Furthermore, the strength of built-up members are reduced due to shear flexibility. The American and Canadian specifications (except for recent AISC-LRFD), on the other hand, do not treat stitched built-up struts in a way similar to battened columns. They only require that minimum individual slenderness ratio between stitches not exceed the governing slenderness ratio of the built-up strut as a whole. Thus, in strength calculation, the detrimental effect of shear flexibility is not taken into account. Recently, AISC-LRFD Specification introduced an empirical equation to modify the overall slenderness ratio of built-up struts, including stitched members, in order to take into account the detrimental effect of shear flexibility on their strength. The criterion is based on experimental study by Zandonini on stitched double channel struts and verification by Astaneh and Goel on double angle bracing members. In 1952, Bleich proposed a similar but analytical criterion to modify the overall slenderness ratio of battened columns. The equation has the limitation of being strictly applicable to battened columns because of simplifications made in the derivation process. Another limitation of Bleichs equation is that it was derived strictly for hinged-end members. This paper presents a generalized version of the analytical equation proposed by Bleich. Thus, it does not have the limitations of Bleichs equation. Therefore, the proposed analytical equation is applicable to all built-up struts with general end conditions. The equation is verified both analytically and experimentally. For analytical verification, a parametric study is performed in which, for different over-all and individual slenderness ratios, the buckling load is calculated according to the proposed analytical equation, Bleichs approximate analytical equation, and the LRFD empirical equation. The results are compared and discussed. For experimental verification, test results from another study by the authors are compared with the calculated buckling load according to the proposed analytical equation and the LRFD empirical equation. All comparisons verify the validity of the proposed analytical equation.
Application of Second-Order Elastic Analysis in LRFD: Research to Practice
Authors: White Donald W. , Hajjar Jerome F.
Published: April 2024

The AISC Load and Resistance Factor Design Specification,1 states, "In structures designed on the basis of elastic analysis, Mu may be determined from a second-order elastic analysis using factored loads." At the present time, a designer who wishes to use this type of analysis has many choices of methods, all of which may be termed "secondorder elastic." This paper compares and contrasts several of the current most commonly used methods (B1/B2 approaches and a number of P-Delta approaches) to matrix analysis approaches based on stability function and geometric stiffness formulations. The matrix approaches are comprehensive in that they account for both P-d and P-D effects and place essentially no constraints on the manner in which the structure is modeled for analysis. As these approaches increasingly become available in commercial software, they will provide a powerful facility for the analysis and design of ordinary as well as irregular and complex three-dimensional structures. In the last twenty to twenty-five years, a large amount of research has been devoted to the nonlinear elastic and inelastic analysis of frame structures. In parallel with the development of more sophisticated analysis methods, the speed, memory capacity, and advanced graphics capabilities of personal and workstation computers continue to increase each year. The capabilities of these new machines have made it possible to employ analysis and design techniques that in the recent past were generally impractical for most engineering firms. As an example, for certain types of building systems, it is now commonplace to perform a three-dimensional linear elastic analysis which accounts for the interaction between shear walls and various other types of structural framing. With each new generation of personal computers and workstations, there are fewer and fewer constraints on analysis technique and size of the analysis model.
Correction: Building Floor Vibrations
Authors: Murray Thomas M.
Published: April 2024

Correction
Reliability of Rotational Behavior of Framing Connections
Authors: Rauscher Thomas R. , Gerstle Kurt H.
Published: April 2024

Recent studies have pointed to the behavior of beam-column connections as having an important effect on stiffness and strength of steel frames, and considerable work has been done to develop analysis methods intended to include not only member, but also connection behavior. Design methods as outlined in the AISC Allowable Stress5 and LRFD6 Specifications authorize inclusion of connection effects under the heading of "Type 3" in the former, and "Partially Restrained" (PR) in the latter. In both analysis and design including connection effects, connection behavior must be known. For typical beam-to column connections of building frames, voluminous, if fragmentary, data are available. Attempts at rational prediction of connection behavior have been less than successful, but empirical expressions, based on test data, of the relation between the applied moment M and the resulting connection rotation q are available. Among these, the most commonly used are those of Frye and Morris. The deterministic moment-rotation curves shown in Fig.1, and others similar, are often based on one single test, and do not account for the scatter which may inevitably be expected of connection behavior, specially if field-bolted. Little is available in the way of replicate tests which might provide a database necessary for statistical prediction of connection behavior. Until such information about reliability of connection behavior is provided, its inclusion in design or analysis rests, at best, on a shaky basis. This paper reports a study the aim of which is to provide a statistical database for the purpose of establishing the degree of reliability of strength and stiffness for one connection type. To this end, nominally identical framing connection specimens from different sources were tested under identical conditions. The individual moment-rotation curves obtained from these tests form the database for probabilistic determination of the reliability with which specified behavior of these connections can be expected.
A Method for Incorporating Live Load Reduction Provisions in Frame Analysis
Authors: Ziemian Ronald D. , McGuire William
Published: April 2024

The effects of live load are often reduced to reflect the low probability of all live load existing simultaneously throughout a substantial portion of a structure. An approach for incorporating live load reduction provisions within system analyses is presented. By determining an appropriate applied live load, the resulting forces in both the beams and the columns will include the ASCE 7-88 live load reduction provisions. In applying this live load, any displacements calculated by a structural analysis will be consistent with the reduced internal member force Distribution. Joint equilibrium will be maintained. Because the procedure does not rely on applying the principle of superposition, it may be used with either linear or nonlinear structural analyses.
Non-Slender Single Angle Struts
Authors: Elgaaly Mohamed , Davids W. , Dagher H.
Published: April 2024

A literature search indicated a lack of test results regarding non-slender single angle struts. The primary objective of this paper is to present and discuss the results of the tests conducted by the authors on non-slender single angle compression members. These angle members have equal legs and were tested to failure as part of a three-dimensional truss. The paper briefly describes the authors experimental program. The method of calculation of the member forces from the strain readings is discussed. The test results are given and six failure modes are identified. These failure modes depend on the member slenderness ratio, the angle leg width/thickness ratio, the end connection detail, and the eccentricity of the applied load. These failure modes can be generally classified as global with no appreciable local failures or local failures which triggered global failures in some cases. Finally, the design rules given by the AISC Specification for Structural Steel Buildings1-3 and the ASCE Manual 52 for the Design of Steel Transmission Towers4 are evaluated.
Simple Equations for Effective Length Factors
Authors: Dumonteil Pierre
Published: April 2024

In theory at least, the design of a column or of a beam-column starts with the evaluation of the elastic restraints at both ends of the column, from which the effective length factor K is then derived. To get a K-factor, the designer is much more likely to use the two charts provided in the Column Design section of the AISC Manuals, rather than to solve the transcendental equations on which the charts are based. However, having to read K-factors from an alignment chart in the middle of an electronic computation, in a spreadsheet for instance, prevents full automation and can be a source of errors. The fact that spreadsheets cannot accept so-called circular references makes their use awkward for the automatic solution of transcendental equations. A side benefit of an excellent article by Barakat and Chen was the demonstration of how powerful an engineering tool the electronic spreadsheet can be: it automates many routine calculations, and it is well suited for tedious column and beam-column calculations. Barakat and Chen did not elaborate on how they obtained the K-factors used in their examples; from the context, it seems that the factors were manually entered into the spreadsheet. Obviously, it would be convenient to have simple equations take the place of the charts in the AISC Manuals. The American Concrete Institute4 does publish equations, but their lack of accuracy may be why they seem not to be used in steel design. Better equations have been available in the French Design Rules for Steel Structures5 since 1966, and have been included in the European Recommendations6 of 1978, with only a change in notation. These equations are accurate, yet simple enough to be easily programmed within the confines of a spreadsheet cell. For this reason, they may be useful to North American engineers.
Plastic Design of Multi-Story Buildings—A Progress Report
Authors: Yura Joseph A. , Driscoll Jr.
Published: April 2024

At the AISC National Engineering Conference held in Omaha, Nebr., in May, 1964, the beginnings of Lehigh Universitys research on plastic design of multi-story frames were reported. This paper is a progress report on work which has continued since that time. The 1963 AISC Specification recommends plastic design for low buildings using ASTM A7 and A36 steels. It also permits the use of plastic design for continuous beams in multi-story buildings which are fully braced against sway. Now research is underway in the Civil Engineering Department at Lehigh University to extend plastic design to buildings using high-strength steels and to all members inmulti-story frames, whether they are braced or without bracing.
Shell Shapes Framed in Steel
Authors: Geiger David H.
Published: April 2024

In considering the use of steel framing for shell shapes, ones attention turns immediately to the problems of detailing members and designing joints. The author had occasion to consider these problems while doing the structural design for the Johnson Wax Pavilion at the New York Worlds Fair. An architectural feature of this pavilion consists of six "petals" or shell shapes which flare out from the top of columns that also support the theatre. It was decided to frame these petals in steel. The framing for one petal consists of a "spine" which is in effect a continuation of the column, curved "ribs" transverse to this spine, and two warped channels and a warped angle which serve as edge beams. In addition to doing the structural design, the author also supplied the fabricator with the geometry required for detailing these members. From this data individual pieceswere detailed and shop drawings made.
Buckling of Framed Domes
Authors: Buchert Kenneth P.
Published: April 2024

The use of steel framed domes has increased considerably in recent years. Domes of the order of 1,000 ft in base diameter are now being designed for sports stadiums and other large structures where it is desirable to cover large open areas. As the size of domes increases, general buckling analysis becomes an important part of the design. The recent failure of a 307 ft diameter dome in Bucharest has caused dome designers to make a careful analysis of their design for buckling.
Thermal Prestressing of Structural Steel
Authors: Wichman Sven H.
Published: April 2024

The thermal prestressing method discussed in this article consists of shop welding heated high strength steel cover plates to the bottom flanges of beams and girders. Heat is produced with a simple device, such as a gas torch; elongation of the plate is measured with a dial indicator. After cooling, the plate creates predetermined favorable stresses in the beam which in effect permit less steel to do more work. Considering all costs, the savings over conventional construction are shown to amount to about 6 percent. Advantages, limitations and proposed applications of the method are discussed. Underlying theory is limited to end results.
Serviceability Limit States Under Wind Load
Authors: Griffis Lawrence G.
Published: April 2024

The increasing use and reliance on probability based limit states design methods, such as the recently adopted AISC LRFD Specification, has focused new attention on the problems of serviceability in steel buildings. These methods, along with the development of higher-strength steels and concretes and the use of lighter and less rigid building materials, have led to more flexible and lightly damped structures than ever before, making serviceability problems more prevalent. The purpose of this paper is to focus attention on two important serviceability limit states under wind loads; namely, deformation (including deflection, curvature, and drift) and motion perception (acceleration). These issues are particularly important for tall and/or slender steel and composite structures. A brief review of available information on these subjects will be presented followed by a discussion of current standards of practice, particularly in the United States. Finally, proposed standards will be presented that, hopefully, will focus attention, debate, and perhaps new research efforts on these very important issues in design.
Correction: Fast Check for Block Shear
Authors: Burgett Lewis B.
Published: April 2024

Correction
A Tentative Design Guideline for a New Steel Beam Connection Detail to Composite Tube Columns
Authors: Azizinamini Atorod , Prakash Bangalore
Published: April 2024

Steel tubes of relatively thin wall thickness filled with high strength concrete have been used in building construction in the U.S. and Far East Asian countries. This structural system allows the designer to maintain manageable column sizes while obtaining increased stiffness and ductility for wind and seismic loads. Column shapes can take the form of tubes or pipes as required by architectural restrictions. Additionally, shop fabrication of steel shapes helps insure quality control. In this type of construction, in general, at each floor level heavy steel beam is framed to these composite columns. Often, these connections are required to develop shear yield and plastic moment capacity of the beam simultaneously. This paper summarizes results and recommendations from a pilot study conducted to develop a moment-resisting steel connection detail for connecting steel beams to composite columns of the type described above. The focus of this pilot study was on composite columns having a square or rectangular cross section.
Optimal Design of Steel Frames to Enhance Overall Stability
Authors: Pezeshk S. , Hjelmstad K.D.
Published: April 2024

Civil engineering structures are generally proportioned by the method of trial and error, wherein provisional designs are analyzed and checked for compliance with specified design criteria. If the performance of the structure does not meet the specified criteria, then the provisional design is modified. Design improvements are generally inspired by the desire to save weight in materials and are often achieved through ad hoc procedures suggested by the violated criteria (e.g. if a stress limit in a certain member is exceeded, then the size of that member is increased). A design that satisfies all specifications is adequate, but is probably not the best design available. Computational mechanics and optimization can be valuable allies of the structural design engineer, particularly in the final design stages of complex facilities or simpler facilities governed by complex behavioral criteria. Both of these sources of complexity often push the limits of experience and intuition. The design of building structures to provide adequate overall stability is an instance in which design improvements are not always intuitively obvious, and hence might benefit from a more systematic computational approach. In this paper we present the simplest case of the general stability-based design procedures developed in our earlier work. Specifically we examine the problem of the design of a planar steel framed structure subjected to a single load case, using a single design variable for each cross section. The value of examining this special case is its power of illustration. The formulas that drive the design procedure, reduced to their simplest forms, yield insight into the physical interpretation of the design process. The design procedure is applied to a four-story frame, initially designed according to UBC and AISC specifications. The optimized design is then checked for conformance with these same specifications. Through this ex-ample we hope to clarify the connection between the more traditional design and the enhanced design, and to examine the fate of design constraints not formally included in the procedure.
Low-Cycle Fatigue Behavior of Semi-Rigid Top-and-Seat Angle Connections
Authors: Mander John B. , Chen Stuart S. , Pekcan Gokhan
Published: April 2024

Constant amplitude reversed cyclic load tests were performed to investigate the low-cycle fatigue behavior of a commonly used class of semi-rigid connection: the top-andseat angle. All specimens had the same geometrical properties. The test results show that the plastic moment capacity and connection stiffness are sensitive to how the nut and bolts are oriented when tightened. However, upper and lower bounds of strength and stiffness can be predicted using standard yield line (plastic) theory. The variability in strength and stiffness does not appear to affect the fatigue life. Fatigue life predictions can be made for this class of connection using relationships analogous to the well-known Manson-Coffin1,2 strain-life equation for metals. Mean rotation (analogous to mean stress) effects are also examined and are shown not to be significant over the range of plastic rotations (0.003 to 0.10 radians) considered. Hysteretic energy-life and energy-rotation relations were also developed. Such relations are useful in seismic damage modeling. For the top-and-seat angle connections considered in this study, the large fatigue based plastic rotation capacity (approx. 3 percent) would generally significantly exceed expected demands for most structural steel systems in a typical US earthquake, where total drift rarely exceeds 2 percent.
The Accuracy of Column Stability Calculations in Unbraced Frames and the Influence of Columns with Effective Length Factors Less Than One
Authors: Hajjar Jerome F. , White Donald W.
Published: April 2024

Until 1993, AISC design specifications did not permit the use of effective length (K) factors less than one in unbraced frames. However, it is well known that, in certain practical situations, a column which is in an unbraced moment resisting frame may exhibit a K factor less than one. While there are a number of equations that have been suggested for the calculation of effective length, to the authors knowledge the accuracy of these different equations has not been thoroughly studied and compared for unbraced frames in which the K factor of one or more of the columns is less than one. This paper investigates and attempts to elucidate the stability behavior associated with columns in unbraced frameworks which possess this effective length characteristic. Based on an isolated column subassembly and a set of small frames that are felt to be representative of a wide range of situations encountered in practice, the accuracy of various methods for calculating effective length factors is identified. Although a variety of methods may be used to calculate the effective length factors in such frames, some of the formulas appear to be consistently more accurate than others. In addition, and perhaps more importantly, it is demonstrated that, for any of the effective length approaches considered in this paper, the accuracy of the effective length computations is identical for every column in a given story, regardless of whether these values are less than or greater than one. Thus, the conclusions from this paper are in many respects relevant to all unbraced frames, regardless of whether some of the frames members have an effective length factor less than one.