bluuebunny/crossref_metadata_2025 huggingface dataset:
Effective Length of Columns with Semi-Rigid Connections
Authors: Driscoll Jr.
Published: April 2024

The effective length of a column depends on the boundary conditions at the ends of its unbraced length. In a framed structure, the boundary conditions depend on the stiffness of the beams framed to the column. Design guides available for determining the effective length are provided for cases where beams are rigidly framed to the column and have their far ends rigidly framed to another column, fixed, or hinged. This paper will present a solution for the case where beams are framed to columns using semi-rigid connections. Frequently, in the design of frames for tall buildings, it is found that beams must be selected based on their stiffness to resist frame drift, rather than on the strength needed to resist wind forces. In this case the actual bending moments required to be resisted at the ends of beams may be substantially smaller than the moment capacity of the beams. It is economically attractive to consider the use of semi-rigid connections adequate for the actual bending moment. However, the semi-rigid connection may have a lower stiffness than an equivalent portion of the beam, since its strength is weaker than the beam. This paper will present a set-up for a general solution for the stiffness of beams with semi-rigid connections. A solution will be made for a simplified case and available information for one type of semi-rigid connection will be used to illustrate the effect on the effective length of a column.
Capacity of Columns with Splice Imperfections
Authors: Popov Egor P. , Stephen Roy M.
Published: April 2024

During the erection of a structure, the milled or cut surfaces at column splices may not make perfect full and even contact. The results of these tests indicate that the lack of perfect contact at compression splices of columns may not be important, provided that the gaps are shimmed and welding is used to maintain the sections in alignment. It is noted that the spliced columns, rather independently of the gaps introduced at mid-height, behaved very much like the unspliced column, and their column strengths were essentially the same. It must be pointed out, however, that the Kl/r ratio of the columns tested was low, being on the order of 30. A slenderness ratio in the range 25-30, however, is not at all uncommon in actual buildings. It may be desirable to extend the research to include columns with higher slenderness ratios, to determine the effect of the splicing on a wider range of columns. The significance of the splice location for longer columns than those tested may have to be considered.
History of Steel Beam Design
Authors: Galambos Theodore V.
Published: April 2024

This paper is about the history of the design of steel beams. Mainly, it is a brief review of how beams were designed according to the various revisions of the American Institute of Steel Constructions Specification for the Design, Fabrication and Erection of Structural Steel for Buildings since this specification was first adopted on June 1, 1923. The term "beam" as used herein defines structural elements in which axial force is so small as to be negligible. Such beams are relatively long compared to their cross section, and their cross section is made up of plate elements which are relatively thin compared to the depth of the members. Beams are loaded such that they resist the loads, which act transverse to their longitudinal axis, by flexure and shear. Such elements occur in many forms in steel construction, and in any frame they comprise a substantial percentage of all load-carrying members.
Mill Building Design Procedure
Authors: Bakota John F.
Published: April 2024

The design of an industrial mill building involves myriad assumptions and parameters. In the current state of the art, there is disagreement about the validity of many of these assumptions and parameters. Inconsistencies exist among designers and in textbooks. Most of these inconsistencies concern design loads, combinations of design loads, effective column lengths, location of bracing, and function of the integrated structure. A limited amount of information exists in two to three dozen publications and textbooks. To the authors knowledge, there are no recent texts which treat mill building design in its entirety. Consequently, an effort was undertaken by the author to consolidate the various publications into a design guide.
Discussion: Yield Line Analysis of Bolted Hanging Connections
Authors: Dougherty Henry W.
Published: April 2024

Discussion
Shear in Beam-Column Joints in Seismic Design of Steel Frames
Authors: Krawinkler Helmut
Published: April 2024

In unbraced steel frames, structural stability and resistance to lateral loads require the transfer of bending moments between beams and columns. Depending upon stiffness and strength requirements, this transfer of bending moments can be achieved by either semi-rigid or rigid beam-column connections. In both cases, the intersection between beams and columns (the beam-column joint) will be subjected to high shears whenever a significant unbalance of beam moments is present at the joint. A significant unbalance usually exists at exterior and corner joints, and at interior joints in the case of lateral load application such as wind or seismic effects. Somewhat simplified, the effect of an unbalance of beam moments on the moment and shear force diagram along the column is illustrated in Figs. 1a and 1b. Figure 1c shows the forces acting on a free body of an interior joint. The effect of the shear forces in joints must be accounted for in the design of frames. In the design for strength, the joints must be capable of transmitting the high shear forces through the columns in accordance with the selected design procedure, which may be based on allowable stresses or ultimate strength. In the design for stiffness, it may be necessary to verify that the joint distortions caused by the shear forces do not excessively affect the story drift under lateral loads.
Analysis of Vierendeel Frames for Deflections
Authors: Abdul-Shafi A.
Published: April 2024

A quick and simple method is described herein for the solution of deflections in symmetrical vierendeel type structures such as multistory one-bay frames and vierendeel trusses. The method takes shear and flexural effects into consideration. A solution for moments, that can be conveniently utilized in the evaluation of deflections, is also briefly described. The deflections are solved for by use of two factors: one factor is associated with fixed end momentsin chord elements, and the other is related to the distributed moments at both ends of the element.
A Simple Formula for the Polar Second Moment of Area of a Regular Skew-Symmetric Bolt Group
Authors: Irvine H.M. , Bradfield C.D.
Published: April 2024

Some years ago the authors worked together for a London firm of consulting engineers on the design of long span bridges. There they encountered the problem of calculating the polar second moment of area of very large skew-symmetric bolt groups. At that time, the second author derived the results which appear as Eq. (5). Recently, the first author has simplified those results to obtain Eq. (10). The purpose of this paper is to derive both results.
Errata: A Simplified Method for the Flexural Design of Stiffened Hybrid Girders
Authors: Chong Ken P.
Published: April 2024

Errata
Fast Design of Beams with Cb Greater Than 1.0
Authors: Burgett Lewis B. , Tide Raymond H.R.
Published: April 2024

The allowable flexural stress for steel beams with less than full lateral support is given by AISC Eqs. (1.5-6a), (1.5- 6b), or (1.5-7). Each of these equations contain the term Cb , a coefficient dependent upon the moment gradient. In Part 2 of the AISC Manual are curves for beams with allowable moment plotted for varying unsupported lengths. The curves are for Cb = 1.0. The following procedure affords a fast selection of a beam using the beam curves when the value of Cb is other than 1.0. A considerable saving of steel can result.
Calculation of Effective Lengths of Stepped Columns
Authors: Agrawal Krishna M. , Stafiej Andrew P.
Published: April 2024

Travelling cranes are frequently used to move heavy loads in industrial buildings. To accomplish a general movement, the crane traverses a crane bridge, which in turn moves on rails along the length of the building, supported by the main building columns. Designers frequently choose stepped columns, with the wider lower section serving a dual purpose: (a) to support the crane rail and (b) to provide the necessary strength to support the extra load from the crane. The design of the stepped columns is time-consuming and complicated. Effective lengths, which must be calculated for each segment, depend upon the following: the end fixity types at the two ends, the ratio of segment lengths, the ratio of the segment inertias, and the ratio of the applied axial loads applied at the top of the column and at the stepped levels.
Plastic Design of Unbraced Multistory Steel Frames with Composite Beams
Authors: De Buen Oscar
Published: April 2024

A method for the plastic design of unbraced multistory steel frames under combined permanent gravity loads and horizontal accidental loads due to wind or earthquake effects is described in Ref. 1. The method permits the designer to plot horizontal load-lateral displacement curves (Q-D curves) for one or more stories, corresponding to assumed preliminary sizes of beams and columns, considering the formation of successive plastic hinges and taking into account the PD effect. The characteristics of these curves and the sequence of formation of plastic hinges indicate whether the sizes assumed for beams and columns are adequate or not, and furnish the designer with information about the individual members whose modification would more likely contribute to obtain a satisfactory behavior. Final shapes are selected keeping in mind the convenience of having all plastic hinges forming in the beams.
Plastic Behavior of Beams with Mid-Depth Web Openings
Authors: Afifi Aglan Ahmed , Qaqish Samih
Published: April 2024

It has become common practice to cut holes in the webs of steel beams in building structures in order to provide for the passage of service facilities such as ducts, water and sewage pipes, etc. This results in a considerable reduction in the depth between the ceiling and the floor above. Consequently, considerable savings in building costs can be achieved. The plastic analysis of steel I-beams with a single rectangular mid-depth hole has been extensively studied. Analysis was carried out by assuming the predicted normal and shear stresses at failure in the top and bottom parts of the beam, and obtaining the failure load (bending moment and shearing force at the center of the hole) by considering the equilibrium of the external and the assumed internal forces. These analyses are somewhat lengthy compared to the authors analysis. This paper presents a new approach to the problem, in which plastic hinges are assumed at the corner of the hole. Formulas for the predicted failure loads have been derived and can be solved by hand or by small calculators. Analyses of beams with double or multiple holes have also been investigated. The authors analysis can be extended to provide a simpler solution for such beams.
A General Solution for Eccentric Loads on Weld Groups
Authors: Brandt G. Donald
Published: April 2024

Eccentric loads on weld groups traditionally have been analyzed by elastic methods in which the individual effects of an axial load (applied through the centroid of the weld group) and a pure moment (in the plane of the weld group) were combined. In the 7th Edition Manual of Steel Construction of the American Institute of Steel Construction, as in earlier editions, such a procedure was used to create tables which could be used to determine allowable eccentric loads on selected weld groups. These tables were criticized as having non-uniform factors of safety when compared to the actual ultimate loads which the welds could support. An "ultimate strength method" was proposed in which the resulting force per unit of length of each weld element is calculated.
Steel Cable Creates Novel Structural Space Systems
Authors: Zetlin Lev
Published: April 2024

Structural engineering is inherently a creative profession. Nevertheless, as often practiced, structural engineers are involved mainly in the design of a few wellknown structural systems, while research and development are usually directed towards greater economy of material and labor in those systems. However, creativeness in structural engineering should be measured by the evolving of structural systems which offer more flexibility for architectural planning and whichcould be constructed more economically than structural systems of yesterday. Flexibility could be measured by greater span lengths and aesthetics of the structural systems. Such structural systems could be left exposed and thus save in exterior finishes.
Discussion: Lateral Support for Tier Building Frames
Authors: Hooper Ira
Published: April 2024

Discussion
AISC Orthotropic Plate Design Manual
Authors: Milek Jr.
Published: April 2024

The structural system with which we are concerned is orthogonal anisotropic plate (popularly termed "orthotropic"). This means orthogonal—at right angles—andanisotropic—different properties. Thus, we are talking about a steel plate that has different physical properties in mutually perpendicular directions. Can this be right? For all practical purposes, steel has the same modulus of elasticity, the same elastic limit, the same Poissons ratio, the same ductility, and the same ultimate strength in all directions. Considering these facts, there cannot be such a thing as orthogonal anisotropic steel plate. There cannot be because steel is an isotropic material. On the other hand, an assemblage of isotropic steel elements consisting of a steel plate stiffened and supported on a system of ribs, beams and girders may be thought of as having anisotropic properties. In other words, anisotropy is due not to different elastic properties of the material but to the physical dimensions and arrangement of the components of the assemblage. When we use the term "orthotropic steel deck" we are talking about bridges whose steel decks are idealized as orthotropic plates—all parts working together as a unit rather than individual pieces designed separately on the basis of their individual functions.
Stiffened Thin Shell Domes
Authors: Buchert Kenneth P.
Published: April 2024

The design of ever larger clear span roofs is a challenge to structural engineers, architects, fabricators and steel producers. The type of roof proposed in this paper is a thin steel shell that is either reinforced with stiffeners or is made of two thin shells that form a double or "sandwich" shell. It is proposed that this type of roof could be used as an economical solution for covering stadiums, tanks, supermarkets, shopping centers and eventually to cover significant areas of cities. The use of shell type structures has increased significantly in recent years. The trend in shell construction has been toward larger and thinner shells. As shells are made larger and thinner, elastic buckling becomes one of the most important design considerations and construction cost becomes of prime importance. Actually elastic buckling has been a major factor in limiting the size of certain types of shells.
Curvilinear Grid Frames
Authors: Hutton Charles R.
Published: April 2024

In dealing with a structural system for the first time, especially when the system is new, one finds himself consciously involved in many facets of design which would ordinarily be intuitive in the more familiar systems of construction. One must first satisfy himself about the limits and the possibilities of the systems per se, before he can even begin to think about developing an architecture out of the constructional method. The use of curved surfaces is a case in point. From a structural point of view, there are two problems which face a designer. The first deals with a succinct knowledge of the stress distribution within the framework of the design project, and the second with the assurance that the materials applied to the resolution of the internal stress pattern will react in a predictable manner. The first is usually a paper problem using a more or less idealized situation. The second is a laboratory or field problem. Not all structures are capable of a rational analysis, particularly shells, and those structures, if built, must undergo experimental analysis to a lesser or greater degree. This is where the applied researcher renders his valuable service. And yet his role also involvesthe examination of those units for which there is a rational approach, if for nothing else than to instill confidence in a particular analytical method.
Tests of Steel Moment Connections
Authors: Beedle Lynn S. , Christopher Richard
Published: April 2024

This report has been written to consolidate and discuss the results of some of the more important studies of rigid moment connections in building frames, and to suggest some possibleareas of future work. Three types of connecting media are considered: welding, riveting and bolting. In turn, three types of connections receive primary attention: the corner connection, the beamto- column connection, and the beam splice. Primary attention is focused upon the moment capacity and deformation capacity of these connections. The criterion used in this report is the ability of the connection to undergo inclastic strain resulting in joint rotation many times that associated with initial yielding, while providing a predictable resisting moment. The tests reported herein were conducted at the following schools: Cambridge University, Cornell University and Lehigh University. Investigations of significance conducted at other schools are also briefly considered. The most important result of these tests is that for all properly designed and detailed welded and bolted moment connections the plastic moment of the adjoining member was reached and large plastic rotation capacities were observed. There were no premature failures except those which could have been predicted and prevented.
Book Review: Detailing for Steel Construction (AISC)
Authors: Stanczak John S.
Published: April 2024

Detailing for Steel Construction
The Application of Flexural Methods to Torsional Analysis of Thin-walled Open Sections
Authors: Boothby Thomas E.
Published: April 2024

The analysis of torsionally loaded thin-walled members of open cross-section is complicated by the presence of warping stresses. Warping normal and shear stresses arise from restraint of longitudinal warping of the cross-section due to end restraints or variations in the internal torque along the length of the member. In a typical thin-walled open member, such as a rolled or cold-formed steel section, warping normal stresses tend to be the critical torsional stress component. The usual method for analysis of warping stresses involves solution of the torsion differential equation to determine rotation of the member about the longitudinal axis. Torsional and warping stresses are functions of various order derivatives of the rotation with respect to the length. This method is described in detail in many sources, including Refs. 1 and 4-9. A recent AISC publication1 presents nondimensionalized solutions of the torsion differential equation for various end conditions and loading cases of a single span straight member, which can be used for determination of torsional stresses. For steel I sections, torsional loading can be resolved into opposite lateral forces acting on flanges and an upper bound to warping stresses can be obtained by determining the resulting bending normal and shear stresses in the flanges. This flexural analogy is applied to determination of warping normal and shear stresses in Refs. 6, 8 and 9. A more general bending-warping analogy, presented in Ref. 7, can be applied to C, Z and other sections commonly used in cold-formed construction.
Bolt Preload Measurements Using Ultrasonic Methods
Authors: Notch James S.
Published: April 2024

Significant research efforts and technological advances have occurred over the past years with regard to the design of high-strength bolted connections. The development of quality assurance programs aimed at evaluating whether sufficient bolt pre-tension has been achieved during field bolt-up is equally important. A high-strength bolted connections superior strength characteristics are based on the development of frictional forces between the clamped plates or members. High-strength bolts are not, as in the eyes of many laymen, merely "bearing type" pins holding the joint together—they are fasteners which must achieve sufficient pre-tension to clamp the connection plies together and thereby provide adequate slip resistance. The importance of developing sufficient clamping force is even more important with todays prevalent use of oversize and slotted holes. In addition to direct tension indicator devices which have shown merit, the most common recognized method of bolt tightening is the turn-of-the-nut method. Based primarily on strain control, the method relies on a specified incremental turn to elongate the bolt. Although simple in concept, the method is difficult to control under field conditions. The greatest variables are the definitions of "snug tight," the starting point for the incremental turn, and the accuracy of the rotational measurements.
Approximate Stiffness and Bending Strength for Compact-Rolled Sections
Authors: Lampitt Edwin A.
Published: April 2024

Approximate Stiffness and Bending Strength for Compact-Rolled Sections
A Beam Design Aid for Structural Tubing
Authors: Siddiqui Faruq M.A.
Published: April 2024

Structural tubing is used primarily by designers for pipe and equipment supports. Recently, tubes have also been used in other major structures. Square and rectangular structural tubes have excellent resistance to lateral torsional buckling depending on their lateral dimensions. They are also pleasing aesthetically and assure cleanliness by eliminating dirt-collecting flange areas. The 1978 AISC Specification1 has explicit provisions for the use of square or rectangular tubes for beams. However, there are no beam design aids in the steel manual for tubes, other than section property information. Design aids are available however in the form of "Beam Load Tables" showing allowable uniform loads for laterally supported beams.
Mill Building Frame Analysis: Distribution of Lateral Loads
Authors: Vilas Howard K.
Published: April 2024

In recent years, few papers have covered the subject of mill buildings. In one of the papers,1 a programmable solution for mill building columns was given using the equations proposed in the Murray-Graham stepped column model. It dealt with a truss-column system with knee braces or parallel chord trusses where both chords were connected to the columns, providing a partially fixed condition at the truss column interface. Not all mill buildings have knee-braced roof trusses because of the lack of clearances and other restrictions. This paper is an analysis of such mill buildings. Also, it is an attempt to relate the stiffness of trusses and columns in a mill building with knee braces and to develop a method of analyzing such frames. It deals only with the distribution of horizontal loads acting along the transverse direction. The horizontal loads, either external loads or those induced from vertical loads, are carried by the frame or bent along a transverse row. The analysis, involving trusses and columns, is on the basis of a plane frame, i.e., loads on a frame in a row are carried by that frame only and not shared by adjacent rows. This assumption is more valid for wind loads than for localized crane wheel loads (localized compared to the length of the building). However, in this paper it is assumed bottom chord bracing, which makes it possible for adjacent rows to share crane-induced loads, is either not present for the entire length of the building or not effective enough.
Flexural-torsional Buckling for Pairs of Angles Used as Columns
Authors: Brandt G. Donald
Published: April 2024

Flexural-torsional Buckling for Pairs of Angles Used as Columns
Column Flange Strength at Moment End-Plate Connections
Authors: Curtis Larry E. , Murray Thomas M.
Published: April 2024

Current American Institute of Steel Construction (AISC) design recommendations for moment end plate connections are basically limited to the end-plate, bolts, and the compression region of the column side of the connection (AISC). Although specific design procedures for column flange strength at the tension regions of the connection have not been included in AISC design manuals, much research on this topic has been conducted in Europe and the United States. The purpose of this paper is to present design recommendations for required column flange strength at the tension region of the moment end-plate connection configurations. The configuration will be referred to as the 4 bolt stiffened end-plate and as the 8-bolt stiffened end-plate. A design procedure for the latter configuration has recently been published.
Variation of Lift Load Distribution Due to Sling Length Tolerance
Authors: Duerr David
Published: April 2024

Sling tension calculations made for engineered lifts typically assume that all of the slings are of the exact specified lengths. Some codes, particularly in the offshore industry, provide load or skew factors by which these tensions are multiplied to attempt to account for variations in the lengths. Another approach often used assigns a somewhat arbitrary split of the total lifted load between diagonally opposite pairs of slings in a four-point lift, e.g., 75% of the load to one pair and the remaining 25% to the other. Both of these methods have the same major problem: they deal with the symptom rather than with the problem. This paper shall present the results of a computer study that evaluates the effect of sling length tolerance on load distribution among a set of four slings. Both sling stiffness and lifted load stiffness were varied to examine the resulting changes in sling tension. More importantly, load distribution within the lifted load framing was tabulated and compared to the framing loads obtained by application of the above referenced code provisions. Recommendations are then made which suggest a means of best dealing with unknown but very probable sling length errors in design.
Notes on Bracing Design
Authors: Wyczolkowski Adam
Published: April 2024

It is a common practice among engineers to design a bracing system to utilize maximum allowable stresses in all its members. This is done to arrive at economical or optimal design. This approach, however, is consistent with the basic principles of economical design only in the case of statically determinate systems or in some specific cases of indeterminate systems.
Behavior and Design of Flexibly- Connected Building Frames
Authors: Gerstle Kurt H. , Ackroyd Michael H.
Published: April 2024

Although the behavior of connections in steel construction extends over the full range from near pinned to almost-rigid, traditional engineering practice has considered only the extreme limiting cases: either perfectly pinned, as in ideal trusses, or fully rigid, as in rigid-frame construction. The neglect of real connection behavior can lead to unrealistic predictions of the response and strength of steel structures, and less than optimal design in steel construction. This paper was written in order to demonstrate that more realistic connection behavior can be included in analysis without undue pain, and that design of flexibly-connected steel frames is fully within reach of professional office practice. We have tried to explain the concepts and procedures in a simple fashion, and to demonstrate the benefits of a more realistic approach by means of several examples.
Short Span Pre-Stressed Steel Bridges
Authors: Densford Thomas A. , Hendrick Thomas L. , Murray Thomas M.
Published: April 2024

The concept of prestressed steel flexural members was extensively studied in the 1960s1; however, the actual use of such members for bridge construction is a recent development in the United States. The recently completed Bonners Ferry Bridge in Idaho and the Muddy Boggy River Bridge in Oklahoma are two examples of cable-stressed plate girder bridges. The INVERSET system of fabricating small river crossing bridges, which is gaining wide use in Oklahoma and other southern states, is another example of prestressed-steel bridge construction. The principal advantage of prestressing is, of course, a reduction in material quantities needed. Non-composite, composite and prestressed optimized designs are compared. The advantages of prestressing are obvious. This paper reviews the available methods for prestressed steel concrete slab bridge construction, discusses advantages and disadvantages of the method of construction, and presents some test results concerning shrinkage, creep and fatigue of a prestressed-steel concrete slab bridge unit.
Design of Base Plates for Wide Flange Columns: A Concatenation of Methods
Authors: Thornton William A.
Published: April 2024

The Murray Stockwell (MS) method for design of base plates has the capability of producing very thin, and hence economical, small base plates for lightly loaded columns. The method has two problems, however, which make its incorporation into a general method for all base plates, i.e., large as well as small plates, and heavily as well as lightly loaded plates, difficult. First, the boundary between lightly and heavily loaded plates is not defined. Application of the MS method to a particular situation can lead to a base plate thicker than would be required by the AISC 8th Ed. Manual method, or can lead to a numerical failure of the method as indicated by mathematically imaginary solutions in terms of complex numbers. This problem has been demonstrated by Ahmed and Kreps. Second, the MS method assumes a peak bearing pressure of Fp over an H-shaped region adjacent to the column crosssection whereas the conventional assumption (i.e., AISC Manual 8th Ed. and AISC LRFD Manual 1st Ed.) is a uniform pressure fp over the entire contact area between the plate and the concrete. This problem led the author to propose a yield line method (referred to as Model 2 in Ref. 5) to replace the MS method for small base plates. Ref. 5 demonstrates that Model 2 coupled with the cantilever method for large base plates yields plate thicknesses equal to or less than the AISC 8th Ed. method. However, Model 2 yields thicker plates than the MS method when the plate is lightly loaded. In order to maintain the benefit of the MS method for lightly loaded plates, to define the boundary between lightly and heavily loaded plates, and to effect a merger of the two different pressure distributions and three methods into a single method, consider the following analysis.
Designing Longitudinal Welds for Bridge Members
Authors: Alexander Warren G.
Published: April 2024

By far the greatest amount of welding in all structures consists of longitudinal welds used to join components of axially loaded members so that they will act in unison to form effective and stable structural members. Many designers opt to use complete joint penetration groove welds "just to be safe" when other weld types or combinations of welds would be a better choice in terms of limiting residual stress and distortion, avoiding lamellar tears, and reducing the cost of welding and fabrication. Since all properly designed continuous longitudinal welds of good quality have the same static life and same fatigue life, why do designers think it is safer to use complete joint penetration groove welds? This paper examines the choices available to engineers in designing longitudinal web-to-flange welded joints in I-shape and box-shape members and endeavors to briefly discuss materials, design, and welding information that affects that choice.
Full-Scale Tests of Butt-Welded Splices in Heavy-Rolled Steel Sections Subjected to Primary Tensile Stresses
Authors: Bruneau Michel , Mahin Stephen A.
Published: April 2024

Experimental results from full-scale testing of full and partial penetration butt-welded capacity. Qualitative explanations are given as to the cause of the observed failure. The splice with full penetration welds exhibited satisfactory strength and ductility. It is believed that a great amount of care must be taken in the execution of this weld type. Future research needs are examined.
U.S. Seismic Steel Codes
Authors: Popov Egor P.
Published: April 2024

Major changes and recommendations for the seismic design of steel buildings were recently introduced into several U.S. design codes and specifications. Many of these changes deal primarily with material and detailing requirements. However, these problems cannot be separated from the underlying issues of lateral seismic loads. Therefore in this paper a broader point of view is adopted, and a brief discussion of relevant findings from seismology and geotechnical engineering is presented first. A general discussion of structural code developments and the relationships among the lateral load requirements in different codes follows. Specific issues pertaining to the seismic design of structures are then brought in. Limitations of the currently dominant elastic methods of analysis and design for seismic resistant structures are critically examined. The paper concludes with suggestions for future research.
Unified Autostress Method
Authors: Schilling Charles G.
Published: April 2024

A new unified method of inelastic analysis that can be applied in both the AASHTO overload and maximum load checks is developed in this paper. Formerly, different methods of analysis were used in these two checks in the AASHTO alternate load factor design procedures. The new method, which is called the Unified Autostress Method, can account for yielding at any number of negative- and positivebending locations, such as pier and flange-transition locations. The new method is founded on classical indeterminate theory and can be readily adapted for computer programming.In continuous spans, automoments are caused by yielding at various locations and remain after the loading is removed. These automoments are calculated by satisfying a continuity relationship at all pier locations and a rotation relationship at all yield locations. The continuity relationship depends on the stiffness properties along the entire length of the member, and the rotation relationship depends on the properties of the cross sections at the yield locations. An iteration procedure is required for more than two spans; one such procedure, which has been shown to work satisfactorily, is outlined.
Forces on Bracing Systems
Authors: Nair R. Shankar
Published: April 2024

The bracing systems that are the subject of this work are structural components or assemblies that are intended to prevent buckling or reduce the effective unsupported length of columns, towers, truss chords, and other members or structures loaded in compression. (In some applications, the same system is also used to resist externally applied loads.) Widely varying criteria, with little or no rational basis, are in use for the design of these bracing systems. It is generally recognized that bracing systems need stiffness (to limit deformation of the braced components or structures and to cause them to behave in the intended manner) and strength (to provide the necessary stabilizing forces). In many situations, the stiffness and strength requirements are related to each other: reduced stiffness allows greater deformation, which in turn results in increased force on the bracing. Rigorous analysis to determine the required stiffness and strength of bracing systems can be very complicated. Fortunately, rigorous analysis is rarely necessary. The simple, approximate, bounded solution proposed in this paper is applicable to most situations that designers are likely to face.
Application of Tuned Mass Dampers To Control Vibrations of Composite Floor Systems
Authors: Webster Anthony C. , Vaicaitis Rimas
Published: April 2024

Although the incidence of floor vibration problems appears to be on the rise, the use of mechanical damping devices to control vibrations is limited. In a recent survey of vibration control methods, Murray reports that passive-mechanical damping methods, including viscous damping, visco-elastic damping, and tuned-mass dampers, have often gone untried outside the laboratory or have had marginal impact in actual buildings. This is particularly unfortunate because mechanical dampers can sometimes control floor vibrations more cheaply than structural stiffening, and are often the only viable means of vibration control in existing structures. This paper details the successful implementation of a tuned-mass damping system to reduce the steady-state vibrations of the longspan, cantilevered, composite floor system at the Terrace on the Park Building in New York City. The experience with this implementation suggests that tuned mass dampers (TMDs) can be successfully employed to control steady-state vibration problems of other composite floor systems. The potential for general application of TMDs in composite floor systems is discussed, and areas for further research are suggested.
A Novel Approach for K Factor Determination
Authors: Lui E.M.
Published: April 2024

Current specifications for the design of steel members and frames in the U.S. make extensive use of the effective length factor, K. The effective length factor is employed in the member interaction equations to facilitate the design of framed members by transforming an end-restrained compressive member to an equivalent pinned-ended member. In frame design, the effective length factor can also be regarded as a parameter which emanates the stability interaction effect among various members of the frame. At present, the effective length factor K for a framed member under compression is determined from a pair of alignment charts. Although the charts provide an easy and a convenient means for designers to evaluate the K factor, the models used in the development of these charts embody a number of assumptions which are not readily realized in actual situations. As a result, the K factor so obtained is often inaccurate.
Strength and Serviceability of Hanger Connections
Authors: Thornton William A.
Published: April 2024

Hanger connections involve bolts in tension due to direct loads and prying action and bending of tee flanges or angle legs. It is the purpose of this paper to show that the analysis method of the latest AISC Manuals, both ASD and LRFD versions, can with minor modification allow for a greatly increased design strength and a more reliable prediction of serviceability loads. The strength of hanger connections is due mainly to the strength of the bolts but is affected by the bending of the hanger flanges which induces prying action in the bolts. Previous emphasis on this problem has focused on the determination of the actual prying force Q rather than the overall behavior of the connection itself. This paper concentrates on assessing the strength of the connection, both ultimate strength and yield (or separation) strength.
Short Span Highway Bridges with Wide Stringer Spacing and a Two-way Reinforced Concrete Deck
Authors: Grossman Stanley
Published: April 2024

Cconfronted with the large number of bridges to be constructed as part of the burgeoning highway program that is imposing an additional burden upon the already overburdened fiscal capacity of all levels of government, it is an appropriate time for bridge engineers to examine the factors underlying current bridge practice for the purpose of determining what, if any, alterations of this practice are in order. This determination necessarily requires an evaluation of the trends and possibilities in bridge design, fabrication and erection. The magnitude of the design problem presented is not great, and perhaps it is for this reason that little attention has been given to optimizing and aesthetically improving the design of short span highway bridges. However, the magnitude of the cost of all such bridges to be built in the United States suggests that efforts be directed toward improving their design.
Pushout Tests on Lightweight Composite Slabs
Authors: Chinn James
Published: April 2024

Tests have been performed at the University of Colorado on composite specimens using a locally produced lightweight aggregate and a commercially available headed-stud shear connector. The aggregate is an expanded shale, crushed prior to burning in a rotary kiln to produce a sealed surface. It is produced in three sizes—coarse, ľ in. to No. 4; medium, No. 4 to No. 16; and fine, No. 16 to pan. Only one mix, a six-sack mix recommended by the manufacturer, was used in tests. It weighed 93 pcf and tested in excess of 5,000 psi at 28 days when properly batched. Strengths produced in these tests, however, ranged from 3,010 to 5,818 psi. Studs used in tests were ˝, 5/8, ľ, and 7/8-in. in diameter. Lengths were roughly four times the diameter, with some variation. Tensile yield strengths ranged from 61,000 to 69,000 psi with ultimate strengths from 65,100 to 75,200 psi. Elongation in 2 in. gage length ranged from 18.5 to 25.5 percent with reductions in area from 52.8 to 66.7 percent.
Cost Studies of High Strength Bolted Connections
Authors: Graves Frederick E.
Published: April 2024

The new high strength bolt specification of the Research Council on Riveted and Bolted Structural Joints permits use of both ASTM A325 and ASTM A490 bolts in structural joints. The choice of which of these fasteners to use is essentially an economic decision. If the time and effort that have gone into the development of the new specification are to be justified, the new rules should lead to more economical joint designs with high strength bolts. This paper is intended to assist the engineer and the fabricator to achieve more economical designs. Cost comparisons between A325 and A490 joints are presented and discussed. Costs for producing holes and for installing bolts and washers were obtained from fabricators and erectors, and represent a cross section of cost information received. These costs vary from region to region, and even from fabricator to fabricator; however, it is believed that the cost comparisons achieved by the use of these average costs are valid.
Discussion: Steel Column Bending Amplification Factor
Authors: Scheiner Alfred
Published: April 2024

Discussion
Strength of Shear Studs in Steel Deck on Composite Beams and Joists
Authors: Easterling W. Samuel , Gibbings David R.
Published: April 2024

Composite beam or joist and slab systems typically provide the most efficient design alternative in steel frame construction, and indeed it is one of these systems that make steel an economically attractive alternative to concrete framed structures. Composite beam specification requirements and design aids are given in the American Institute of Steel Construction (AISC) Load and Resistance Factor Design (LRFD) Manual. The LRFD composite beam design procedure results in designs that are typically 10-15 percent more economical than those obtained using the AISC allowable stress design (ASD) procedure. The efficiency of composite beam design using LRFD procedures has, in the authors opinions, been the primary motivating factor for the use of the LRFD specification2 to date. The design strength and stiffness of composite beams depends on the shear connection behavior. The strength of the shear connectors may be reduced because of the influence of the steel deck geometry. An empirical expression for this reduction was developed by evaluating results of composite beam tests in which the deck ribs were oriented perpendicular to the steel beam.
Design Aid of Semi-rigid Connections for Frame Analysis
Authors: Kishi N. , Chen Wai-Fah , Goto Y. , Matsuoka K.G.
Published: April 2024

In this paper, a useful design aid for determining the values of the initial connection stiffness Rki, the ultimate moment capacity Mu, and the shape parameter n of a three-parameter power model describing the moment-rotation curve (M-qr) of semi-rigid connections with angles is prepared for its use in the practical design of flexibly jointed frames with angles. A set of nomographs allows the engineer to rapidly determine the M-qr curve for a given connection. Applying the design aid, numerical simulations on drift and column moment of a flexibly jointed frame with angles are illustrated.
Correction: ASD/LRFD Volume II- Connections Shear Tab Design Tables
Authors: American Institute of Steel Construction
Published: April 2024

Connections Shear Tab Design Tables
Discussion: Design of Pipe Column Base Plates Under Gravity Load
Authors: Iwankiw Nestor R.
Published: April 2024

Discussion
Examination of Fillet Weld Strength
Authors: Bowman Mark D. , Quinn Brian P.
Published: April 2024

The strength of a fillet weld is influenced by many different factors. For example, the welding process, electrode type and strength, weld-metal chemistry, welder skill, weld profile, joint penetration, joint fit-up and restraint, and preheat and interpass temperatures all contribute, in some part, to the resultant weld strength. Many of these factors, such as skill of the welder, joint fit-up, and preheat and interpass temperatures, are dealt with through particular requirements and provisions of the AWS Structural Welding Code. Weld qualification tests, for instance, are required to demonstrate whether an individual has adequate skill and training to produce a particular weld with a desirable level of quality. The design methodology used to compute the strength of fillet welds does not directly reflect all of the factors that influence fillet weld strength. The design method utilized for many years to compute the strength of a fillet weld involves multiplying the effective fillet weld area—the product of the effective throat size and the weld length—times an allowable or ultimate stress, depending upon whether an allowable stress or limit states design approach is being used. The effective throat dimension of the weld is taken as the shortest distance from the root of the weld to a line that connects the top and bottom weld toes; this procedure gives an effective throat that is 71 percent of the weld leg size for welds with equal leg sizes. It should be noted that this procedure ignore the influence of the weld root penetration and the weld profile. These factors will result in a true weld throat size that is different than the theoretical effective throat utilized for design purposes. The purpose of the study reported herein was to study the influence of geometrical factors that influence the true effective throat of fillet welds. Specifically, a series of tests were conducted to evaluate the influence of weld leg size and fabrication gaps on the strength of fillet welds.
Effective Lengths of Uniform and Stepped Crane Columns
Authors: Lui E.M. , Sun Manqing
Published: April 2024

Crane columns are used extensively in warehouses and mill buildings to support overhead cranes. In addition to carrying the dead and live loads of the moving cranes, crane columns are required to support the roof structure of the buildings. The cross-section of a crane column can be uniform or stepped. In the former, a bracket bolted or welded to the face of the column is used to support the runway girder as shown in Figure la. In the latter, the runway girder rests directly on the enlarged segment of the column as shown in Figure lb. In earlier years, it was common practice to erect the crane column independent of the frame column. The two were then connected by batten plates or laces to act as a composite unit as shown in Figure 1c. In any case, the base of the column may be pinned or fixed. If the upper shaft of the column is rigidly connected to the roof of the building, resistance to inplane translation is provided by rigid frame action and the base of the column can be designed as pinned or fixed. However, if the upper shaft of the column is not rigidly connected to the roof as for the case when prefabricated roof trusses are used, the base of the crane column must be designed as rigid so that resistance to sway can be provided by cantilever action of the column.