bluuebunny/crossref_metadata_2025 huggingface dataset:
Splices in Plastically Designed Continuous Structures
Authors: Hart Willard H. , Milek Jr. W.A.
Published: April 2024

Plastic design is based on the ductile strength of steel—the ability of structural steel to deform at and above the yield point at a uniform level of stress. If the load on a steel structure is increased sufficiently, the material will pass through the elastic range into the plastic range of stress. At overloads, highly stressed areas are permitted to yield in bending. When such highly stressed portions of a continuous structure yield, they merely refuse to accept larger bending moments and transfer the requirement for additional moment capacity to areas which are stressed to a lesser degree. Thus, as a sufficiently large overload is applied to a continuous structure, the relative size of the positive and negative moments will be readjusted so that the structure can support additional load. This moment redistribution does not take place at the design load. The objective is to design the structural frame so that the redistribution can take place if large overloads are imposed. If the structure is not loaded above the design load, it will act within the elastic range in a manner no different from a structure designed by elastic design procedures.
One Engineers Opinion (Bending of Tees)
Authors: Milek Jr. William A.
Published: April 2024

One Engineers Opinion
Framing Connections for Square and Rectangular Structural Tubing
Authors: White Richard N.
Published: April 2024

The square and rectangular structural tube was introduced as a new structural shape several years ago. In this short period, these shapes have found application in many structures; they have been particularly popular for columns in low-rise buildings such as schools and factories. Other recent applications include space frame and Vierendeel girder construction. Two of the outstanding characteristics of the tubular shape are (a) high efficiency in carrying compressive loads, and (b) clean appearance for exposed framing. In addition, it has exceptional torsional rigidity in comparison to open structural shapes such as the wide flange beam and channelsection. Square and rectangular tubes are now readily available in many sizes and in several grades of steel. While conventional steel design procedures are appropriate for sizing tubular members, there has been considerable question as to the best methods for connecting tubes to tubes and wide flange beams to tubes. The purpose of this paper is to attempt to resolve some of these questions by presenting the results of recent research conducted at Cornell University. Primary emphasis has been on studying the characteristics and behavior of simple connections (AISC Type 2 framing); although some pilot studies have been conducted on rigid connections (AISC Type 1 framing). Both classes of connections will be discussed herein. All tests were conducted on square tubing, but the results should be applicable to rectangular tubing with no significant error.
Plastic Design of a Three-Story Steel Frame
Authors: De Buen Oscar
Published: April 2024

This paper describes the plastic analysis and design of a three-story steel frame for an office building located in Mexico City. Two types of design loads were considered: vertical live and dead loads, classified as "permanent loads" and horizontal earthquake loads, classified as "accidental loads". (The Mexico City area is subject to intense earthquakes; consequently wind loads play a secondary role for design purposes in this type of building.) A conventional plastic design method was used for the analysis of vertical loading and the method of plastic distribution of moments was used for seismic analysis, with certain modifications for adaptation to the particular problem under study. The design method basically follows the latest AISC Specification, Part 2. However, because the steel frame is more than two stories high and is out of the range of thesespecifications, the column design formulas were modified to comply with our particular requirements.
The Economic Impact of Overspecifying Simple Connections
Authors: Carter Charles J. , Geschwindner Louis F.
Published: April 2024

An accurate and complete design will result in an economical and safe connection. Yet it is entirely common for the engineer of record to withhold, either intentionally or unintentionally, the information necessary to the fabricator or detailer to perform a design which is both accurate and complete. Specifically, actual reactions are seldom shown on the contract drawings from which the connections must be designed. AISC states, "For economical connections, beam reactions should be shown on the contract drawings. If these reactions are not shown, connections must be selected to support one-half the total uniform load capacity...for the given beam, span, and grade of steel specified." No quantification is given, however, of the actual difference in economy between the two cases. In fact, this difference is somewhat elusive as it may vary greatly among specific examples. For the general case, however, it is possible to determine a reasonable estimate of the economic sacrifice incurred when a larger connection than required is used. The focus of this paper, then, is this economic sacrifice. For simplicity, a standard configuration of the double angle connection will be considered in which only n, the number of bolt rows (and consequently, the length of the angles), varies. Based on values of n from 2 to 10, the cost of these standard connections will be estimated. Ranges of n compatible with each beam size group will be identified and the percent increase in cost which results when a larger connection than required is used will then be determined over these ranges. Note that the practices which routinely result in uneconomical connection designs are not specifically addressed in this paper. For a discussion of these practices, the reader is referred to "Eliminating the Guesswork in Connection Design—Communication of Design Requirements Between Fabricator and Engineer is Crucial for a Safe and Economic Structure" by W.A. Thornton, in the June 1992 issue of Modern Steel Construction. Also not addressed is the effect of standardization on the detailing costs, ease of fabrication, and overall quality of the constructed product. While in general, standardization will reduce detailing costs, increase the ease of fabrication, and lead to improvements in quality because of decreased variability, these considerations are more project related than connection specific. Thus, it would not be feasible to consider their effect in this paper.
Composite Girders with Partial Restraints: A New Approach
Authors: Wexler Neil
Published: April 2024

Most designs for buildings with steel frames are based on girders with simple connections. To eliminate the problems associated with traditional construction (such as deep and heavy girders and large deflections during construction) structural engineers have been searching for a new design system for a long time. The stub girder system is one example of such efforts. However, the stub girder system proved to be uneconomical for most common buildings. A new and different approach to composite steel/concrete designs was undertaken by the writer resulting in light building frames and cost savings. This new design system is called partial Restraint Girder System ("RGS") (Figure 1). (A composite section is obtained in buildings with metal deck and concrete floors by welding steel studs to the top flange.) With RGS two types of restraint are possible: the first makes use of moment connections to columns; the second includes concrete reinforcement. In buildings utilizing composite girders, deflections were controlled by either shoring, camber, or further increase in girder size. RGS has arisen as a viable and cost effective alternative. In traditional designs, the engineer determined the buildings moment diagram from a moment distribution or stress analysis. In the RGS method, the Structural Engineer can control the maximum and minimum values of moment on the moment diagram (the governing design values) from the outset to fit his design, by establishing the amount of restraint. Although composite girders with partial restraints improve the moment resistance of composite girders significantly, such design is commonly ignored and the codes of practice give no guidance as to procedures that might take advantage of the improved properties.
SI Units for Structural Steel Design
Authors: American Institute of Steel Construction
Published: April 2024

SI Units for Structural Steel Design
Earthquakes: Steel Structures Performance and Design Code Developments
Authors: Marsh James W.
Published: April 2024

Major earthquakes occur several times each year throughout the world with heavy loss of life and property. Recent examples are the 1992 Cairo, Egypt earthquake with the loss of over 500 lives, and the Mexico earthquake of 1985 with the loss of 8,000 lives and the collapse of over 400 buildings. The United States has experienced many large earthquakes, with the most seismic activity to date being located in California, i.e., Loma Prieta, California, 1989, 7.1 Richter magnitude and Landers, California, 1992, 7.5 Richter magnitude. It is evident from past occurrences of earthquakes that the highly seismic regions of the United States have a serious earthquake problem, and the less serious regions in the central and eastern parts of the country now realize that they have an earthquake problem which is being addressed through adoption of the latest seismic design provisions into the BOCA and SBCCI building codes. Some of these newly acquired seismic provisions are taken from the Building Seismic Safety Council program on improved seismic safety. The Building Seismic Safety Council (BSSC) was established in 1979 under the auspices of the National Institute of Building Sciences (NIBS) as an entirely new type of instrument to develop and promulgate building earthquake hazard mitigation regulatory provisions that are national in scope. Its fundamental purpose is to enhance public safety by providing a national form that fosters improved seismic safety provisions for use by the building community in the planning, design and construction of buildings. To fulfill its purpose, the BSSC promotes the development of seismic safety provisions suitable for use throughout the United States. The BSSC believes that the regional and local differences in the nature and magnitude of potentially hazardous earthquake events require a flexible approach to seismic safety that allows for consideration of the relative risk, resources and capabilities of each community. The BSSC itself assumes no standards-making and promulgating role; rather, it advocates that code and standards formulation organizations consider BSSC recommendations for inclusion into their documents and standards. A recommendation that is taking place today in code writing.
Shear Lag Effects in Steel Tension Members
Authors: Easterling W. Samuel , Gonzalez Giroux Lisa
Published: April 2024

The non-uniform stress distribution that occurs in a tension member adjacent to a connection, in which all elements of the cross section are not directly connected, is commonly referred to as the shear lag effect. This effect reduces the design strength of the member because the entire cross section is not fully effective at the critical section location. Shear lag effects in bolted tension members have been accounted for in the American Institute of Steel Construction (AISC) allowable stress design specification1 (ASD) since 1978. The 1986 load and resistance factor design specification2 (LRFD) and the 1989 ASD specification stipulate that the shear lag effects are applicable to welded, as well as bolted, tension members. Past research on the subject of shear lag has focused primarily on bolted tension members. Recently, more attention has been given to welded members, evident by their inclusion in the AISC specifications. Shear lag provisions for welded members were introduced into the specifications primarily because of a large welded hanger plate failure. To maintain a uniform approach to both welded and bolted members, the same provisions for shear lag in bolted members were applied to welded members. Additional requirements for welded plates were added. However, the application of the shear lag requirements to welded members has raised several questions. This paper examines shear lag in steel tension members in the following context. First, the background for the current AISC specification provisions is reviewed. Second, the results of an experimental research program in which 27 welded tension members were loaded to failure is presented. Third, based on the first two parts of the paper, recommended changes to the AISC specifications are presented.
Correction: Shear Tab Design Tables
Authors: AISC Team
Published: April 2024

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

Errata
Discussion: Design of I-Beam to Box-Column Connections Stiffened Externally
Authors: Iwankiw Nestor R.
Published: April 2024

Discussion
Geometrical and Mechanical Properties of Large Rolled Steel Angles
Authors: Madugula Murty K.S. , Kojima Toshifumi , Kajita Yasuyuki , Ohama Michihiro
Published: April 2024

Steel angles are the most frequently used sections in electrical transmission towers. To carry safely the heavy leg loads of 500 kV towers, N. K. K. Corporation, Japan, developed the worlds largest rolled steel angles. The paper describes the manufacturing process and presents the geometrical properties. The statistical analysis of samples over a three year period showed that the steel used is consistently of uniform quality. Based on 12 tensile tests of round specimens in as-supplied condition and another 12 specimens in heat treated condition carried out at 20, —20, —40, and — 65 degree Celsius it was concluded that decrease of temperature did not result in any decrease in elongation and only three percent decrease in the reduction of area. Due to heat-treatment, the maximum reduction in yield stress and tensile strength was two percent, maximum reduction in elongation three percent, and maximum reduction of area two percent.
A Practical Approach to the "Leaning" Column
Authors: Geschwindner Louis F.
Published: April 2024

The "leaning" column has existed as an element in steel structures from the time steel frames were first constructed. Although they provide the title for this paper, they themselves are not the problem which needs to be addressed. It is their impact on the other parts of the structure which must be a consideration in any design. A "leaning" column is a pin ended column which has no lateral stability of its own; thus, it must rely on other parts of the structure to provide for its lateral stability and the lateral resistance for the entire frame. This paper will discuss the situations in which "leaning" columns will occur and look at practical ways to account for them in both LRFD and ASD design.
Optimal Cost Design of Semi-Rigid, Low-Rise Industrial Frames
Authors: Xu Lei , Sherbourne Archie N. , Grierson Donald E.
Published: April 2024

The paper presents an efficient computer-automated method for the optimum design of steel frameworks accounting for the behavior of semi-rigid connections. A continuous discrete optimization algorithm is applied to minimize the "cost" of the connections and members for the structure subject to constraints on stresses and displacements under specified design loads. An example is presented to illustrate the features of the design method. The results suggest that the proposed semi-rigid design method realistically accounts for connection behavior and produces more appropriate member sizes than does the traditional fully rigid design method.
Connections: Art, Science, and Information in the Quest for Economy and Safety
Authors: Thornton William A.
Published: April 2024

Connections are an extremely important part of the final configuration of a steel structure. Many, if not most, collapses are caused by inadequate connections. The constructed cost of a steel frame is heavily dependent on the connections used, both the type of connection and how they are configured. Yet, connections are often an afterthought. Commercially available software will pretty much automatically design the members of the frame, but there is no commercially available software that will do the same for the connections. In fact, the frame design software chooses "optimal" members, usually least weight, with no regard whatsoever as to how these members will impact on the connections. The emphasis in engineering schools is similar to that of commercially available design software, i.e., it is on the design of members. Very little work is done on connections at the undergraduate level and probably also at the graduate level. Connections are considered by many professors as essentially trivial in a mathematical sense. Very sophisticated and mathematically elegant solutions can be prescribed for member and frame design; e.g., lateral torsional buckling of members, and the direct stiffness method for frames. Connections, on the other hand, are thought to be designed by no more sophisticated analysis than counting bolts and determining weld lengths. This is not true except for the simplest connections. While there are essentially only three types of members in a structural frame (beams, columns, and beam-columns), there is an almost infinite variety of connections depending on frame geometry. For this reason, connection design is actually more interesting than member design, because this great variety often requires the designer to rely on intuition and art as well as science.
Steel Rigid Frames With Leaning Columns—1993 LRFD Example
Authors: Folse Michael D. , Nowak Paul S.
Published: April 2024

Many buildings rely on rigid frames to provide lateral stability in one or both directions. Steel rigid frames often support "leaning" columns which hold their contributory gravity loads but rely on the frame for lateral stability. Rigid frames supporting leaning columns require special consideration whether a first-order or second-order analysis is undertaken. The design and analysis of rigid frames with leaning columns in accordance with the 1993 AISC LRFD is studied through use of an example eight story steel building which is supported laterally in each direction by isolated rigid frames. Results of first-order analyses with approximate moment magnification are compared with plane frame and space frame second-order elastic analyses.
Effects of the Latest LRFD Block Shear Code Change
Authors: Epstein Howard I.
Published: April 2024

This paper examines the effects of the required change in the use of the block shear design strength equations resulting from the latest AISC-LRFD code treatment. The latest code either gives the same results as the previous code or is more conservative. The parameters of the connections for which the two treatments differ are presented, as well as the percentages of the differences. On the basis of recently reported experimental results, the need for further refinement of the codes is presented.
Comparative Effectiveness of Tightening Techniques for A490 1 1/4- in. Diameter Bolts
Authors: Dahl Joan S. , Lu Le-Wu , Fisher John W. , Abruzzo John
Published: April 2024

Since the approval of the first high-strength bolt specifications by the Research Council on Riveted and Bolted Structural Joints (RCRBSJ) in 1949 there have been concerns of ensuring that the bolts are properly tightened. In certain applications, such as slip critical and direct tension, current practice requires that all bolts be tightened to reach or exceed a minimum specified preload. Considerable research has been invested on high-strength bolts and the techniques used to tighten them. Most testing on bolt behavior during tightening has been performed using smaller diameter bolts, such as 7/8-in. For larger diameter bolts, the results of these tests have been extrapolated to develop criteria used in establishing the RCSC Specification for Structural Joints Using ASTM A325 or A490 Bolts,2 hereafter referred to as the RCSC Specification. An extensive study at Delft University in the Netherlands explored many different tightening methods including the turn-of-nut as well as load indicating washers. This study detailed the advantages and disadvantages of the different techniques. The significant influence of lubrication on the bolt threads was revealed by Eaves in 1978. Notch showed that hardened washers were needed for the proper tightening of large diameter bolts, and to attain a uniform "snug"ť condition. Early testing of load indicating washers with bolts in the vertical position was performed in 1973 by Struik, Oyeledun, and Fisher. This testing provided a basis for the validity of the washers as load indicators. In 1987, Kulak, Fisher, and Struik published the second edition of the Guide to Design Criteria for Bolted and Riveted Joints and included much of the previous research performed on bolts and bolt tightening techniques. The information on bolt properties and installation contained in this book was extensively used in the course of this investigation.
Strengthening of Existing Composite Beams Using LRFD Procedures
Authors: Miller John P.
Published: April 2024

Many times, the load carrying capacity of an existing composite steel floor beam needs to be increased beyond its original design capacity due to a change in occupancy use classification or the addition of a localized heavy load. For example, this situation occurs frequently in an office building that was initially designed using a live load of 50 pounds per square foot where a tenant wants to locate a library that requires a live load of 150 pounds per square foot. Or perhaps a tenant would like to place a very heavy object in a certain location that is beyond the capacity of the existing floor framing. One of the many advantages of a steel framed structure is the relative ease and economy of the addition of reinforcing to the existing members to increase their load carrying capacity. There are several techniques available to the designer for adding reinforcement to an existing steel beam. Perhaps the most often used solution is to weld a steel shape to the bottom of the beam. This paper deals with the addition of either a flat steel plate or a WT section to the bottom of the beam to moderately increase its load carrying capacity. For a major increase in capacity, the method described in this paper could easily be extended to other reinforcing shapes. This paper describes a procedure for the rapid direct solution of the required amount of steel reinforcement to be added to a composite beam to resist a given bending moment. The solution is obtained using the design aids provided and brief hand calculations. The procedure is based on Load and Resistance Factor Design (LRFD) Theory and is applicable to composite beams designed by either Allowable Stress Design (ASD) or LRFD and with either solid concrete slabs or slabs on metal deck.
Future Use of Composite Steel-Concrete Columns in Highway Bridges
Authors: Itani Ahmad M.
Published: April 2024

Modern seismic design practice of highway bridges tends to limit the inelastic activity during seismic events to the substructure of the bridge. This would limit the damage only in columns which had been designed and detailed to withstand significant inelastic activities. Inelasticity in the superstructure is not recommended in bridge engineering, because it is not feasible nor economical to allow damage to occur in that area. The recent seismic criteria for the design of reinforced concrete bridge columns as outlined in the first draft of Revised Caltrans Bridge Design Specification by the Applied Technology Council (ATC32), require a significant amount of steel to confine the concrete and to prevent buckling of longitudinal reinforcement. This amount of confinement steel tends to be excessive as was recently experienced during the design of the replacement structures in San Fernando Valley, California after the Northridge earthquake.9 Confinement of concrete columns using full steel jackets becomes a feasible design solution since the steel jacket would confine the concrete and also provides strength for the column. The use of Composite Steel and Concrete (CSC) columns in bridges have many advantages especially in high seismic zones. This type of column provide the structure with stiffness and ductility, which are required for the survival of any bridge during severe ground motion. In simple terms, the CSC columns are concrete filled tubular steel columns without any longitudinal or transverse reinforcement. The idea of having the steel and the concrete act compositely has been used successfully in the past for new and retrofit construction. The greatest advantage of this concept is that the two materials are put to their ultimate use. The steel jacket confines the concrete and provides the flexural strength for the system. The presence of the concrete delays steel problems in compression zones such as local and overall buckling and also provides stiffness for the column.
Practical Advanced Analysis for Semi-rigid Frame Design
Authors: Kim Seung-Eock , Chen Wai-Fah
Published: April 2024

This paper presents three practical advanced analysis procedures for a two-dimensional semi-rigid steel frame design. Herein, the nonlinear behavior of beam-to-column connections is discussed, and practical modeling of these connections is introduced. The proposed methods can predict accurately the combined nonlinear effects of connection, geometry, and material on the behavior and strength of semi-rigid frames. The strengths predicted by these methods are compared well with those available experiments. Analysis and design procedures using the proposed methods are described in detail, and a case study is also given. The proposed procedures can be used for the LRFD design without tedious separate member capacity checks, including the calculations of K-factor. The procedures are suitable for adoption in practice.
Truss Analogy for Steel Moment Connections
Authors: Goel Subhash C. , Stojadinovic Bozidar , Lee Kyoung-Hyeog
Published: April 2024

Unprecedented widespread failure of welded moment connections in steel frames caused by the 1994 Northridge and the 1995 Kobe earthquakes have alarmed the engineering communities throughout the world. Beam-to-column connections in steel frames have been traditionally designed by using classical Euler-Bernoulli beam theory which leads to assumptions that the flanges transfer moment while the web connection primarily resists the shear force. The results of a recent finite element study at The University of Michigan have shown that stress distribution in the vicinity of moment connections drastically differs from the pattern assumed following the classical beam theory. This is in agreement with the boundary effect postulate expressed by the famous Saint Venants Principle. The finite element study has shown that the magnitude and direction of the principal stresses in the connection region are better approximated by using truss analogy rather than the classical beam theory. Accordingly, both the bending moment and the shear force are transferred across the connection near the beam flanges through diagonal strut action. Thus, the beam flange region of the traditionally designed connection is overloaded. This conclusion explains, to a large extent, the recently observed steel moment connection failures. This study uses the finite element analysis results and the truss analogy in order to establish a more realistic load path in the welded steel moment connections, a practical and more rational analysis and design procedure has been developed. The new connection design uses a combination of flange cover plates and vertical rib plates to carry the normal and shear stresses created by the truss action. The design procedure was successfully validated through cyclic load testing of a nearly full size specimen.
Low-Rise Building Wind Load Provisions
Authors: Chiu Gregory L.F. , Perry Dale C.
Published: April 2024

The National Standard ASCE 7 was revised and published in January 1996 following many years of study by the Wind Loads Subcommittee of ASCE 7. Contained for the first time are a complete set of provisions for assessing wind loads for the design of low-rise buildings. The provisions are based, for the most part, on the research conducted at the University of Western Ontario during the late 1970s (funded, in part by MBMA), the following extensive research reported from Concordia University, and the very recent activity at the University of Western Ontario supported by the timber industry (as yet not subject to proper peer review). The new low-rise provisions reflect rather substantial reductions in loading requirements for some design applications. The object of this communication is to briefly review the changes incorporated in ASCE 7-95 for Buildings of All Heights, Other Structures and Low-rise Buildings and compare the new wind load provisions with those contained in other codes and standards currently in use. The troublesome items that may impede acceptance of the new Standard and should be addressed in the future are cited.
Practical Application of Energy Methods to Structural Stability Problems
Authors: Nair R. Shankar
Published: April 2024

Simple energy-based formulations can provide convenient solutions for, and fresh insights into, many common structural stability problems. This is true even today, when practicing engineers have ready access to sophisticated computer programs for first- and second-order structural analysis. In general, the direct energy-Lased formulation of a stability problem involves balancing the strain energy resulting from deformation of the structure with the work done by applied loads. The critical load corresponding to any assumed buckled shape can be determined in this manner. In many practical situations, this is a surprisingly simple and straightforward process. At the most basic level, energy concepts can be used to assess whether a particular deformation pattern in a structure is a potential buckling mode: If the deformation causes the applied loads to move in the direction in which they are applied, i.e., if the loads do positive work, the deformation is a potential buckling mode, otherwise it isnt, regardless of the magnitude of loading. This simple concept can be used to determine whether and where bracing is needed in a structure. This paper will begin with a brief reintroduction to the energy-based formulation of buckling problems. The energy formulation will be applied to certain structure types for which buckling solutions, by other means, are readily available. This will show how the energy approach can provide fresh insight into the behavior of structures, by furnishing simple physical explanations for some of the characteristics of familiar solutions. A general procedure for stability analysis based on energy concepts will then be presented, and illustrated with the help of practical examples.
Ponding Calculations in LRFD and ASD
Authors: Carter Charles J. , Zuo Jiahong
Published: April 2024

The definitions of stress indexes in the 1993 LRFD Specification and the 1989 ASD Specification do not result in similar designs. A modification is suggested for the definitions of the stress indexes in AISC LRFD Appendix K2 to eliminate this anomaly. Simplified equations for the flexibility constants Cp and Cs suggested by Milbradt are also validated for preliminary design.
Sidesway Web Buckling of Steel Beams
Authors: Grondin G.Y. , Cheng J.J.R.
Published: April 2024

The lateral stability of the tension flange of doubly symmetric beams with the compression flange braced against lateral movement was investigated experimentally and numerically. Steel beams of W360X33 (W14X22) and W360X39 (W14X26) cross-section were tested to failure. Lateral supports were provided to the compression flange to prevent lateral-torsional buckling while the tension flange was free to move laterally over its entire length. Failure took the form of sidesway web buckling. A numerical model incorporating the effect of residual stresses, initial imperfections, large displacements and material yielding was implemented using the finite element method. The model was validated by comparison with the test results. The current AISC design specification for sidesway web buckling was evaluated by comparing predicted capacities with the test results and the results of a limited parametric study performed with the numerical model. It was found that the sidesway web buckling capacity predicted using the AISC model is very conservative. Less conservative, but safe, prediction equations are proposed as possible alternatives to the current AISC equation.
Modeling of Support Conditions at the Bases of Tall Buildings
Authors: Nair R. Shankar
Published: April 2024

Assumptions regarding the vertical and lateral support conditions at the base of a tall building can have a significant effect on the results of the analysis of the structure, and on the design based on that analysis. This is especially true when the building has a deep basement. There is no generally accepted "standard" way of modeling the base restraints or supports. Several alternative idealizations are in use. These different ways of modeling supports for tall buildings will be discussed and evaluated in this paper. Through an example, some of the simple support models that appear to be in use will be compared with a complete three dimensional analysis. A technique for using a basement as a "virtual"� outrigger to provide a wider base for resisting overturning effects, as proposed in a recent paper (Nair, 1998), will be investigated further in this work. This is shown to be a logical extension of the use of a complete three-dimensional model of the bottom of the building in the analysis of the structure.
A New Approach for Design of Steel Beam-Columns
Authors: Aminmansour Abbas
Published: April 2024

Design aids are developed using the AISC-LRFD Specifications for design of steel beam-columns. These aids give designers more options in design and often allow selection of sections that are more efficient for a given set of conditions than the current design aids do. Several examples are worked out using the current method of practice as well as the proposed method developed in this paper.
Nonlinear Analysis of Composite Steel Girder Bridges
Authors: Deng Linzhong , Ghosn Michel
Published: April 2024

This paper describes a procedure for the nonlinear analysis of composite steel girder highway bridges. The procedure uses a modified grillage (grid) analysis method where material nonlinearity is modeled by empirically derived moment-curvature relationships. These are obtained from experimental data on the behavior of typical composite steel girder bridges. A linear variation of plastic curvature along the length of each beam element is assumed. An equivalent grid plastic hinge length is used to simulate the extent of plastification over the whole length of a grid element. The procedure can account for span continuity by including a negative bending moment curvature relationship. Numerical investigations verify the proposed method's validity by comparing the analytical results with those of in-situ and laboratory full-scale and model-scale bridge tests. This paper also demonstrates that the proposed nonlinear analysis method provides a simple tool that can be used to obtain reasonably accurate representations of the nonlinear behavior of composite steel girder bridges. The method uses a grillage discretization technique whose results are relatively insensitive to variations in the mesh size. The proposed method has a high potential for use in engineering practice because of the simple input requirements and its reasonable level of accuracy.
What You Should Know About Heat Straightening Repair of Damaged Steel
Authors: Avent R. Richard , Mukai David J.
Published: April 2024

The repair of damaged steel through the application of heat has long been considered an art rather than a science. As such both the methodology and results have varied considerably from one practitioner to another. Because steel tends to be a forgiving material, successful repairs outnumber failures. Yet material properties may be compromised resulting in a weakened in-place structure. In addition, it is not unusual for a fracture to occur during the repair process. As a result, the use of heat straightening (or flame straightening) has had limited application. Many engineers are reluctant to allow heat straightening because of the lack of an established method of application as well as the lack of quantification of steel properties after the repair is complete. The purpose of this paper is to provide some engineering guidelines for use of the heat-straightening process.
Fundamentals of Beam Bracing
Authors: Yura Joseph A.
Published: April 2024

The purpose of this paper is to provide a fairly comprehensive view of the subject of beam stability bracing. Factors that affect bracing requirements will be discussed and design methods proposed which are illustrated by design examples. The design examples emphasize simplicity. Before going into specific topics related to beam bracing, some important concepts developed for column bracing by Winter (1960) will be presented because these concepts will be extended to beams later. Two general structural systems are available for bracing beams, lateral systems and torsional systems. Torsional bracing is less sensitive than lateral bracing to conditions such as top flange loading, brace location, and number of braces, but more affected by cross-section distortion. In the 1999 AISC-LRFD Specification (AISC, 1999), stability bracing requirements are specified for the first time for frames, columns, and beams. The research and recommendations presented in this paper provide a background and commentary for the beam bracing provisions that were adopted in that Specification.
The Use of Orthotropic Decks in Redecking of Bridges
Authors: Wolchuk Roman
Published: April 2024

A bridge deck directly loaded by heavy truck wheels and exposed to weather effects is the most vulnerable component of a bridge structure and must satisfy the most severe strength and durability demands. Failed bridge decks typically account for about two-thirds of all bridge deficiency cases. Bridge deck replacement becomes necessary where yearly deck maintenance cost exceeds the yearly life cycle cost of a new bridge deck. Orthotropic decks are well suited for replacement of deteriorating concrete decks, especially on long span bridges where radical reduction of dead weight is necessary to meet which are very costly in the long run and may severely reduce the useful life of the bridge. The special problems encountered in orthotropic redecking are: the design of fatigue-proof connections to the existing superstructure framing within the constraints of limited depth available for the new deck, constructibility under traffic, minimizing traffic restrictions during construction. Redecking examples given in this review illustrate how these problems were solved on these bridges, with various degrees of engineering success and cost effectiveness.
Seismic Behavior and Design of Concentrically Braced Steel Frames
Authors: Tremblay Robert
Published: April 2024

This paper describes the main characteristics of the inelastic seismic response of concentrically braced steel frames. Current Canadian and U.S. provisions for the seismic design of these structures are presented and discussed, together with possible modifications that are currently being considered in view of recent research findings. Alternative bracing systems, which have been proposed over the years to improve the seismic response of concentrically braced steel frames, are also briefly described.
Compactness and Bracing Recommendations for Equal Leg Single Angle Beams
Authors: Earls C.J.
Published: April 2024

Currently, the design of single angle members is governed by the Load and Resistance Factor Design Specification for Single Angle Members (AISC, 2000). The provisions in this document are meant to augment the more general design provisions contained in the Load and Resistance Factor Design Specification for Structural Steel Buildings (AISC, 1999). The design provisions contained in the LRFD Specification for Design of Single Angle Members are the result of the best information available at the time of the preparation of the document in the early, to mid, 1990s. In the intervening years, new information about single angle flexural response has accumulated from research efforts aimed at quantifying structural ductility associated with equal leg single angle beams. This new information will be summarized herein and recommendations made for rational enhancements to the LRFD Specification for Design of Single Angle Members.
Constrained Through-Thickness Strength of Column Flanges of Various Grades and Chemistries
Authors: Dexter Robert J. , Prochnow Sara D. , Perez Minerva I.
Published: April 2024

Tee-joint specimens were fabricated with high-strength "pull" plates welded transversely to opposite flanges of short lengths of heavy column shapes to determine strength, deformation, and fracture behavior of the flanges of wideflange column shapes when loaded in the through-thickness direction. Forty-seven specimens were tested, including wide-flange shapes obtained from four steel mills from 1995 to 2000 conforming to specifications A572 Gr. 50, A992, and A913 Gr. 50 and 65. Sulfur levels ranged from 0.003 to 0.043 percent and Carbon from 0.05 to 0.20 percent, up to the limits of the current specifications. Several shapes with especially high sulfur were specially produced for this research. The through-thickness strength of the column flanges tested exceeded the 690 MPa (100 ksi) yield strength of the pull plates, well above any possible demand that could come from Gr. 50 beam flanges.
Flexural Capacity and Ductility of HPS-70W Bridge Girders
Authors: Yakel Aaron J. , Mans Patrick , Azizinamini Atorod
Published: April 2024

The development of High Performance Steel (HPS), which boasts high yield strengths (70 and 100 ksi), while maintaining ductility and toughness combined with an available weathering finish offers many potential opportunities to steel bridge design. Many of these benefits have yet to be realized due to the limitations in design specifications placed on the use of steels with yield strength above 50 ksi. This paper reports on the experimental results and associated finite element analysis of four girders intended to address the limitations placed on girders in negative bending, e.g., girders spanning over a pier in multiple span bridges. All of the girders tested were able to attain their predicted strength as determined using the AASHTO LRFD Bridge Design Specifications (AASHTO, 1998). However, the compact section tested did not exhibit the amount of ductility implied by the equations. Based on the results of the tests and analyses performed, the limitations with regards to strength could be removed while the compact provisions allowing moment redistribution may require additional investigation.
Errata: AISC LRFD Rules for Block Shear in Bolted Connections—A Review
Authors: Kulak Goeffrey L. , Grondin G.Y.
Published: April 2024

Errata
P-V-M Interaction Curves for Seismic Design of Steel Column Base Connections
Authors: Arlekar Jaswant N. , Murty C.V.R.
Published: April 2024

Recent studies on connections have shown that the beam bending theory cannot predict the flow of forces near the connection regions. In this paper, a new truss analogy model has been proposed to better represent the flow of forces near the column base connections. Also, shear moment strength envelopes, generated for different levels of axial load using the hysteretic stress-strain curves for steel, are presented. The moment and shear demand for the design of column base connection elements are calculated using the normalized P-V-M interaction curves. Appropriate strength factors applied to the moment capacity of the column section to account for the uncertainty in the estimation of yield stress, strain hardening, compactness of the section, and slenderness of the member are discussed. Finally, a generalized procedure for the capacity design of column base connections is proposed.
Design Method for the Bolts in Bearing-Type Connections with Fillers
Authors: Sheikh-Ibrahim Firas I.
Published: April 2024

Filler plates are usually used when splicing two members of different depths or thicknesses. The filler plates are usually added to the shallower or thinner member to eliminate the gap between the two connected members, reduce any eccentricity effects, and to create common faying surfaces as well as shear planes between the connected members. The Guide to Design Criteria for Bolted and Riveted Joints (Kulak, Fisher, and Struik, 1987) defines two types of fillers: tight (or developed) and loose (or undeveloped) fillers. Connections with developed or undeveloped fillers can be either slip-critical or bearing-type. The paper presented here will address only the effect of both developed and undeveloped fillers on the shear strength of bolts in bearing-type connections. A method for the design of bolts in bearing-type connections with fillers is presented in this paper. The method involves a general reduction factor to be applied to the design shear strength of the bolts. The factor is based on a mechanistic model, which takes into account the dimensions of all of the connection plates. The proposed method assumes that the required number of additional bolts is equal for connections with either developed or undeveloped fillers. Therefore, provided that all of the bolts are placed within the main connection, the proposed factor simplifies the design process since it can be used for connections regardless of the type of fillers used.
Errata: An Experimental Study of Block Shear Failure of Angles in Tension
Authors: Epstein Howard I.
Published: April 2024

Errata
Measured and Computed Stresses in Three Castellated Beams
Authors: Douty Richard T. , Baldwin James W.
Published: April 2024

Three castellated beams, representative of those fabricated for the American Dental Association Building in Chicago, were tested at the Civil Engineering Structural Testing Facility of the University of Missouri at Columbia. The three beams were each approximately 37 ft in length and expanded between 40 and 50 percent from a nominal depth of 18 in. In one case rectangular plates were interposed between the chords in order to gain additional depth. The primary purpose of the testing was to obtain a comparison between the stresses measured with electrical strain gages at various points of interest and the stresses at those same locations as determined by a simplified Vierendeel truss analysis similar to an approach proposed by Toprac and his colleagues at the University of Texas. The difference lies in the assumption of the distribution of primary bending stress in the chords. A uniform distribution was assumed in the Texas approach, but a linearly varying distribution was assumed in the design of these beams. The latter approach is described in detail byBoyer in a previous article in this Journal and will not be reiterated here, except to note that for simplification inflection points are assumed at the center of each "truss member" and vertical shear on the beam is assumed to be shared equally by each of the two "chords".
Lehigh Conference on Plastic Design of Multi-Story Frames-A Summary
Authors: Driscoll Jr.
Published: April 2024

In August, 1965, a conference of teachers of structural engineering and practicing structural engineers was held at Lehigh University. The purpose of the conference was to present a comprehensive coverage of new developments in the application of plastic design principles to the design of steel multi-story building frames. The conference consisted of a group of basic lectures and experimental tests performed by members of the Lehigh staff and additional supplemental lectures by outstanding engineers and educators who were attending the conference.