bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of Knee-braced Portal Frames for Vertical Loading: Part 2-Columns of Unequal Stiffness
Authors: Vilas Howard K. , Surtees John O.
Published: April 2024

In our previous paper, "The Analysis of Knee-Braced Portal Frames for Vertical Loading," the example presented had columns of equal stiffness, resulting in a simple computation for sway shear force. The sway shear force was equally divided between the two columns to find the knee-brace loads. This paper investigates the sway analysis of frames of unequal column stiffness. For continuity, the equation and figure numbers are continuous from Part 1. The first step in determining sway shear for the frame is described in the previous paper. Frame sway is first prevented by introducing a temporary horizontal restraint at the beam level. For a one bay portal frame, the initial kneebrace loads due to vertical loading are calculated using Eq. 7 of Ref. 1, and the restraint reactions determined. In the second step, the temporary restraint is removed and the frame allowed to sway due to the sway load, giving the sway correction. The sum of the two steps gives the required result.
Bin Supports--A Caution to Designers
Authors: Moore Jay P.
Published: April 2024

Bin Supports
Book Review: Design of Steel Bins for Storage of Bulk Solids (Gaylord & Gaylord, Prentice-Hall, 1984)
Authors: Iwankiw Nestor R.
Published: April 2024

Design of Steel Bins for Storage of Bulk Solids
Testing Method to Determine Slip Coefficient for Coatings Used in Bolted Joints
Authors: Yura Joseph A. , Frank Karl H.
Published: April 2024

In 1975, the Steel Structures Painting Council (SSPC) contacted the Research Council on Riveted and Bolted Structural Joints (RCRBSJ), now the Research Council on Structural Connections (RCSC), regarding the difficulties and costs which steel fabricators encounter with restrictions on coatings of contact surfaces for friction-type structural joints. The SSPC also expressed the need for a "standardized test which can be conducted by any certified testing agency at the initiative and expense of any interested party, including the paint manufacturer." And finally, the RCSC was requested to "prepare and promulgate a specification for the conduct of such a standard test for slip coefficients." The following Testing Method is the answer of Research Council on Structural Connections to the SSPC request. The test method was developed by Professors Joseph A. Yura and Karl H. Frank of The University of Texas at Austin under a grant from the Federal Highway Administration. The Testing Method was approved by the RCSC on June 14, 1984. This paper is presented here for information only and does not not imply an endorsement by the American Institute of Steel Construction, Inc.
Columns with End Restraint and Bending in Load and Resistance Factor Design
Authors: Chen Wai-Fah , Lui E.M.
Published: April 2024

In this paper, the state-of-the-art design philosophies with particular emphasis on the Load and Resistance Factor Design (LRFD) format are discussed. The background and relevant development of the design methods relating to columns and beam-columns are presented. LRFD is a limit-state design method. A valid limit-state analysis and design of structures or structural members requires more understanding of structural behavior and more demand on structural analysis techniques. For example, in the AISC/LRFD Specification, a direct second-order analysis of the structure to determine the maximum design forces in the member is recommended. Furthermore, an extensive use of stability theory is employed in the development of the specification equations.
Cyclic Behavior of Large Beam-column Assemblies
Authors: Popov Egor P. , Amin Navin R. , Louie Jason J.C. , Stephen Roy M.
Published: April 2024

A series of experiments were conducted to verify the design criteria for beam-column joints under extreme seismic conditions for a 47-story building in San Francisco. The halfscale cruciform specimens were exceptionally large, requiring 18 in. deep sections. The overall size of the specimens was the largest ever tested in the U.S. for this kind of application. The data on the behavior of such large moment-resisting joints under severe cyclic loading are very limited. The experimental evidence clearly supports the use of stiffeners and doubler plates at the joints for the cross-sectional geometries tested. The results are of direct relevance to seismic design of many steel buildings.
Effect of Overspray and Incomplete Masking of Faying Surfaces on the Slip Resistance of Bolted Connections
Authors: Frank Karl H. , Polyzois D.
Published: April 2024

Despite precautions taken to protect contact areas during painting, some overspray from painting of surfaces adjacent to faying surfaces may take place. Although current specifications permit the use of certain coatings, such as hotdip galvanizing, inorganic zinc-rich paints and metalized zinc or aluminum on the surfaces of friction connections, the paint used on the remainder of the structure could be of the type which is not acceptable for use on faying surfaces. The effect of this inadvertent coating of the faying surfaces is not known. It has been suggested that the degree to which overspray affects the slip performance of friction-type connections depends on the average overspray paint film thickness, regardless of the type of paint used. Overspray, however, is not a true paint coating and is, therefore, very difficult to establish a film thickness, as suggested by Ref. 2. This paper deals with the results of an experimental project sponsored by the American Institute of Steel Construction and the Research Council on Structural Connections (RCSC) carried out at the University of Texas- Austin to study the effect of overspray on the faying surfaces of friction-type connections. More specifically, the objectives of this project are to determine the slip performance of friction-type connections under the influence of: (a) overspray on the faying surfaces, and (b) incomplete masking of the faying surfaces.
Deformations in Cold-bent HSS Members
Authors: Kennedy John B. , Seddeik Mokhtar , Brady Frank
Published: April 2024

The purpose of this investigation is to predict the relation between the radius of bend and the distortion of Hollow Structural Section (HSS) members. An experimental program was carried out using twenty-seven different profiles of HSS members. The pyramid-type, three-roller bending machine was used as the method of cold-bending. The cross-section distortion is defined by two parameters that describe the permanent deformations in the flange and web of the crosssection. Multiple regression analysis was used to obtain a relation between each of these parameters, the cross section properties and the radius of bend. The effect of the resulting distortion on the moment of inertia of the HSS member is also studied. A parametric study is undertaken to demonstrate the influence of the change in the cross-section dimensions on the permanent distortion.
Ponding of Concrete Deck Floors
Authors: Ruddy John L.
Published: April 2024

Floor construction consisting of concrete over metal decking and supported by steel beams and girders is a frequently employed structural system. When temporary shoring is not used, the steel framing and decking deflects during placement of the concrete floor slab. If the concrete were placed to the specified uniform thickness, the result would be a floor surface defined by the deflected shape of the supporting members. The purpose of this paper is to present an interim report concerning studies toward an ultimate objective of predicting concrete volumes required to produce an acceptably level slab which is placed over a flexible substrate. As concrete is placed, the supporting system deflects. As more concrete is placed to compensate for the deflection, additional displacements occur. The situation may be considered analogous to the rainwater ponding phenomenon of roof systems. However, there are notable differences between the rainwater ponding phenomenon and the concrete placement operation. Concrete is plastic, not liquid, consequently it does not seek a constant level. Also, the concrete placement process is controlled by man and rainwater deposition is not.
Design Solutions Utilizing the Staggered-steel Truss System
Authors: Cohen Michael P.
Published: April 2024

During the conceptual design stages of most building projects, the structural engineer must consider many different factors before selecting the final structural system. While some basic building properties such as height, shape, usage, etc. lead the structural designer toward certain proven systems, it is not infrequent that architectural constraints, owner requirements and/or building location render these systems unacceptable. Other factors which enter into the selection process include: local economic conditions (both of materials and labor), construction schedule, design loads (vertical and lateral), building behavior and occupant comfort, foundation considerations and coordination with mechanical systems. While these general considerations are required on all projects, each specific building usually presents the designer with an additional set of its own unique problems. This paper outlines the conceptual design and selection process by which the staggered-truss system of structural framing was selected for one particular project. The subsequent design process encountered problems, and their associated resolutions are also reviewed.
Plastic Analysis of Pinned-base Haunched Gable Frames
Authors: Parsanejad S.
Published: April 2024

The plastic analysis of pinned-base haunched gable frames, subjected to distributed vertical and horizontal loadings, has been carried out in a manner amenable to hand calculation. The analysis is based on the simple plastic theory and has resulted in analytical expressions for the plastic moment requirement of the rafter. The analysis is further facilitated by assembling the resulting expressions on non-dimensionalized charts. The method of analysis, a typical set of charts and an example demonstrating the method are presented in this paper.
Moments on Beam-Columns with Flexible Connections in Braced Frames
Authors: Brown Jack H.
Published: April 2024

The theoretical behavior of beam-columns in braced frames with AISC Type 2 connections is examined here to determine the validity of ignoring eccentricity in the design of columns with flexible connections. The AISC Specification for the Design, Fabrication and Erection of Structural Steel for Buildings is not specific on whether eccentricity should be considered, but the British Standard 449 has specific requirements on the eccentricity to be taken. Neither specification provides any relief for restraint offered by the flexible connection as shown in Fig. 1, nor for the stiffness due to the difference in loading of an upper and lower column, continuous through two floors. This paper is a revised version of the one presented at the Structural Stability Research Councils 1986 Tehnical Session in Washington, D.C.
Design of a Rolled Beam Bridge by New AASHTO Guide Specification for Compact Braced Sections
Authors: Hourigan Edward V. , Holt Robert C.
Published: April 2024

The following example illustrates the design of a three span composite continuous beam highway bridge by Autostress procedures. The bridge will carry Route 427 over Seeley Creek near Elmira, New York. The bridge was designed using rolled beams without cover plates and the slab was considered non-composite in the negative moment regions. The design used the proposed "Guide Specification for Alternate Load Factor Design Procedures for Steel Beam Bridges Using Braced Compact Sections" of March 1, 1985. The guide specification contains suggested Autostress design procedures submitted to AASHTO for consideration. ASTM A588 steel has been used in the design. A general elevation and transverse section of the bridge are shown.
Code of Standard Practice for Steel Buildings and Bridges - 1986 revisions to 1976 version
Authors: AISC Team
Published: April 2024

Code of Standard Practice for Steel Buildings and Bridges
A Conceptual Approach to Prevent Crack-related Failure of Steel Bridges
Authors: Verma Krishna K. , McNamara Michael P.
Published: April 2024

Although the safety record of steel bridges is undoubtedly superior to many other engineering structures, there have been a few catastrophic bridge failures. These include the Kings Bridge in Melbourne, Australia (1962), the Silver Bridge in West Virginia (1967) and one span of the Mianus River Bridge in Connecticut (1983). At times, localized failures have rendered an entire bridge unsafe, resulting in emergency repairs and/or corrective measures. These and other failures suggest that not only is there a need for emphasis on thorough inspection and reinspection, but also for greater understanding of the factors which influence the behavior of crack growth. Laboratory tests have shown test specimens of identical materials under equal loads, but different crack sizes, will not exhibit the same fatigue life. Crack size is important in determining the useful remaining life of a particular bridge member. In many situations, the smaller, hard-to-detect cracks can be much more serious in fracture-critical bridge members than the apparent ones which may occur in redundant members. With the advent of fracture mechanics concepts, the significance of crack size and its interrelationship with applied stress and fracture toughness has been recognized by bridge engineers. Progress has been made not only in understanding crack growth through fracture mechanics, but also in crack detection through non destructive testing techniques.
LRFD and the Structural Engineering Curriculum
Authors: Geschwindner Louis F.
Published: April 2024

The new Load and Resistance Factor Design Specification for Structural Steel Buildings will eventually replace the existing Allowable Stress Design Specification for normal engineering design. The speed with which this takes place depends to a large extent on its inclusion in basic undergraduate curriculum. Past experience with major changes in code concepts, such as the reinforced concrete code change from working stress to ultimate strength, has shown the integration of these new concepts into professional practice is due, in large part, to the influx of new graduates into practice. This paper looks at the incorporation of LRFD concepts into a structural engineering curriculum. It identifies some of the advantages and disadvantages of both allowable stress design (ASD) and load and resistance factor design (LRFD) and proposes four options for addressing LRFD and its impact on an academic program.
Design of Partially or Fully Composite Beams with Ribbed Metal Deck Using LRFD Specifications
Authors: Vinnakota Murthy R. , Foley Christopher M. , Vinnakota Sriramula
Published: April 2024

A Hindu saying states, "One picture is worth a thousand words (numbers)." With this optic in mind, the design aspects of steel-concrete composite beams using the recently adopted LRFD specifications are analyzed critically and the significance of several parameters is brought out clearly. Charts are then constructed to facilitate the design of partially or fully composite beams using rolled-steel, wideflange sections of A36 steel or A572 Gr. 50 steel. The slab may be a composite metal deck slab with ribs perpendicular to the beam, a haunched slab or, simply, a flat soffit concrete slab. The charts cover both adequate and inadequate slabs. The charts provided are a valuable tool from the practical standpoint, and also familiarity with them should contribute to the students and young engineers overall feel of the composite beam design problem. The design charts given here complement the composite beam design tables provided in the LRFD manual.
Parking Structure with a Post-tensioned Deck
Authors: Bakota John F.
Published: April 2024

The current trend toward structural steel parking structures with a pre-stress deck evokes many design questions. Some of these questions concern the following topics: 1. Design loads; 2. stability; 3. deck design; 4. beam design with emphasis on long-term stresses and deflections. All of these topics, except for long-term stresses and deflections in beams, especially those induced by prestressing, are discussed in the open literature. Consequently, the author addresses the first three topics and refers the reader to pertinent publications. On the other hand, the last topic, rarely discussed in the open literature, is discussed comprehensively by the author.
Preliminary Minimum Weight Design of Moment Frames for Lateral Loading
Authors: Grigorian Mark , Grigorian Carl
Published: April 2024

This paper introduces a new concept for the design of regular rectangular moment frames under lateral loading. The concept is based on the assumption that the entire framework is composed of imaginary rectangular modules, with each module consisting of four uniform prismatic members rigidly connected at their ends. This concept entails the selection of the properties of the constituent elements of the modules in such a way as to reduce the total material consumption to a minimum, and at the same time maintain the least possible drift for the given loading and geometry. In addition to controlling the sideway deflections of the structure, the method presented not only reduces the otherwise complicated task of structural analysis to direct member size selection, but also it achieves substantial cost reductions by reducing the total weight of the structure to a minimum. The use of this concept results in an extremely simple yet powerful method of design for the class of structure treated in this study. Several numerical examples are presented to illustrate the practical applications of the concept. The validity and the consistancy of the proposed method in both the elastic and plastic ranges of behavior are established by the standard techniques of structural analysis.
Flexural-Torsional Buckling and its Implications for Steel Compression Member Design
Authors: Zahn Cynthia J. , Iwankiw Nestor R.
Published: April 2024

Flexural-torsional and torsional buckling strength of compression members is covered for the first time in the AISC Load and Resistance Factor Design (LRFD) Specification, and, thus, must now be considered in hot-rolled steel design for buildings, in addition to overall flexural and local buckling. This new strength criterion is also included in the 1989 Allowable Stress Design (ASD) Specification. Flexural-torsional buckling is a compression member instability involving a combination of member bending and twisting as well as any local buckling of slender elements. In this behavioral sense, it resembles lateral-torsional buckling of unbraced beams. Torsional buckling is simply a twisting of the entire cross section about its shear center. Flexural torsional buckling applies to all shapes except those that are doubly symmetric. Pure torsional buckling can only occur in these doubly symmetric shapes, such as rolled wide flange sections. Flexural-torsional buckling is strongly influenced by the degree of symmetry in a cross section that is mathematically represented by the location of the shear center relative to the centroid. An interactive coupling effect of flexural and torsional buckling occurs only when these two points are not coincident; when they are identical, as for doubly symmetric, wide-flange shapes, the response reduces to pure torsional buckling.
Autostress Design Using Compact Welded Beams
Authors: Grubb Michael A.
Published: April 2024

After several years of AISI-sponsored research, autostressdesign procedures for continuous steel bridges have been incorporated in a 1986 AASHTO Guide Specification for Alternate Load-Factor Design Procedures for Steel Beam Bridges Using Braced Compact Sections. Autostress is a procedure that extends existing Load Factor Design (LFD) rules by introducing improved limit-state criteria. LFD is a limit-states design method presently contained in the 13th Edition of the AASHTO Standard Specifications for Highway Bridges. The improved limit-state criteria permit inelastic load redistribution in continuous-beam bridges under heavy loads while satisfying the same structural performance requirements as LFD. The autostress procedures in the guide specification are presently limited to rolled-beam bridges (composite and noncomposite), and compact welded-beam bridges that are adequately braced (braced compact sections). AISI is presently sponsoring additional research to extend the autostress procedures to more slender welded plate-girder sections. Autostress-design procedures recognize the ability of continuous steel members to adjust automatically for the effects of local yielding, such as those caused by overloads. Also, the autostress procedures allow a designer to determine the strength of braced continuous compact beams at maximum loads by computing the mechanism resistance using plastic-design theory with some modifications. In both instances, elastic negative bending moments are automatically redistributed by the structure to positivebending regions. The term autostress has been used for the suggested procedures to emphasize that the load redistribution occurs automatically.
Semi-Rigid Composite Connections for Gravity Loads
Authors: Leon Roberto T. , Ammerman Douglas
Published: April 2024

Double web angles, top and seat angles, and seat angle and web clips are some of the most common connections used for floor beams in braced steel frames. These connections are considered to be rotationally weak, and therefore design proceeds along the assumption that these connections can be idealized as pins. In reality, because these connections have a limited amount of moment transfer capability, they are semirigid connections. The economic and structural benefits of semi-rigid connections in braced frames are well known but seldom utilized. The main advantages they provide over simple connections are lower mid-span moments for the beam and lower effective length of the columns. Depending on the geometry of the connection and the size of the angles used, the moment capacity of these simple connections may range up to 20 percent of the plastic capacity of the beam alone, and lead to saving up to 10 percent of the steel required in floor beams. This moment capacity, however, is associated with large, nonlinear rotations that make serviceability and drift computations difficult. Therefore the current design assumption of pinned ends seems justifiable and conservative.
Closure: Material Considerations in Structural Steel Design
Authors: Barsom J.M.
Published: April 2024

Closure
Discussion: Material Considerations in Structural Steel Design
Authors: Stecich J.
Published: April 2024

Discussion
Correction: A Practical P-Delta Analysis Method for Type FR and PR Frames
Authors: Lui E.M.
Published: April 2024

Correction
Correction: Variation of Lift Load Distribution Due to Sling Length Tolerance
Authors: Duerr David
Published: April 2024

Correction
LRFD Aid for Tubeshaped Beams
Authors: Siddiqui Faruq M.A. , Usman Ali
Published: April 2024

In a previous issue of the Engineering Journal, the first author presented beam design aids in the form of an "economic section" table for laterally supported standard tubeshaped beams designed according to the 1978 AISC Specifications. The authors feel that with the increasing use of the 1986 AISC LRFD Specifications, a table similar in scope and content but using the LRFD specifications would be highly desirable. The accompanying tables would greatly facilitate the selection of tubular flexural members and would complement the existing beam design aids available for other rolled shapes in the LRFD manual.The design aid information available here is valid for tubular sections used as beams. It is assumed that the loading is applied in the plane of the minor axis and that the beam deflects vertically in the plane of bending only. This paper uses the same nomenclature as the LRFD manual.
Experimental Study of Gusseted Connections
Authors: Gross John L.
Published: April 2024

Gusset plate connections are common in lateral bracing systems in steel construction. Recent analytical studies have demonstrated that the gusset plate produces a rigid beam-to-column connection, even if the beam flanges are not connected to the column. The importance of this rigid beam to-column connection is that the gusset plate carries a significant load from "frame action" in addition to that from the diagonal bracing member. The influence of framing members on gusset plate behavior has not yet been studied experimentally and the effect of the stresses produced by frame action on the gusset plate capacity is not known. In addition, tests to date have all used configurations in which the centroidal axes of the members framing into the connection have all intersected at a single point. The loads introduced into a gusseted connection when the centroidal axes of the framing members do not intersect at a point have not been experimentally determined. Finally, the column in a lateral bracing system may be oriented so that the gusset is connected either to the flange or to the web. Unless the web is stiffened, a connection to the column web is more flexible than one in which the gusset is connected to the flange. No experimental work to date has addressed the difference in performance between these two types of column connection and no data is available to indicate whether stiffening of the web is required.
A Method To Predict the Fire Resistance of Steel Building Columns
Authors: Lie T.T. , Almand K.H.
Published: April 2024

Using the mathematical model described earlier, the temperatures of the steel of Column No. 1 were calculated. In the calculation, the thermal properties of the steel, vermiculite board insulation and the specifics of the column and furnace, given in Appendix A, were used. Because the thermal properties of the insulation of the other columns were not known, no temperature calculations were made for these columns. The results for Column No. 1 are given in Fig. 7 where the calculated average steel temperatures are compared with those measured. As also shown in previous studies, it is possible, using the mathematical model, to predict the steel temperatures with high accuracy, if the thermal properties of the insulation are known. In this case the thermal properties of the insulation were determined at the National Fire Laboratory, Institute for Research in Construction, NRCC.40 The temperatures are to some extent also dependent on the heat transfer characteristics of the furnace. If the heat transfer is high, however (which is the case for the furnace in which the column was tested), variations in heat transfer have only a small effect on the temperature of the steel.
Load Combinations for Buildings Exposed to Fires
Authors: Ellingwood Bruce R. , Corotis Ross B.
Published: April 2024

Load requirements in ANSI Standard A58.1.1982 appearing in the LRFD Specification for Structural Steel Buildings are selected, whenever possible, using probabilistic load combination analysis and structural reliability theory. The occurrence of a fire with the potential to cause severe structural damage is a rare event in comparison to events giving rise to design-basis load effects. Although probabilistic load modeling techniques reveal that a structure likely is loaded to only a fraction of its design load when a fire occurs, steel structural assemblies normally are fire tested while loaded to the full nominal design load. This paper presents an improved methodology for determining loads and load combinations for use in fire-resistant structural design. The basic methodology is illustrated by determining load combinations involving fire and live loads for limit states design and for use with the standard ASTM E119 fire test. A reduced nominal live load combined with the structural action due to fire apparently provides a load combination that is risk-consistent with other currently accepted load combinations. The method is consistent with the limit states design approaches under development or in use in Europe that recognize the influence of load on fire resistance of steel structures, and is compatible with the LRFD philosophy.
A Simplified Look at Partially Restrained Beams
Authors: Geschwindner Louis F.
Published: April 2024

Over the past few years, a great deal of effort has been expended within the research arm of the structural engineering profession addressing the topic of semi-rigid connections and their impact on structural response. A review of the recent literature shows that this interest is being maintained and even expanded. At the 1990 National Steel Construction Conference sponsored by the American Institute of Steel Construction, at least three papers dealt with semirigid connections1 while at the 1989 conference, the T.R. Higgins Lecture addressed semi-rigid connections. The AISC LRFD Specification, in an effort to increase the design awareness of this type of construction, altered the previously defined types of construction by combining the former type 2 and type 3 into a single category PR, partially restrained. Although the ninth edition of the ASD Specification retained the previously defined three types, there appears to be a heightened recognition that some attention must be given to moment-rotation characteristics of connections, even when it is anticipated that they are really behaving as pins. The intention of this paper is to take a step back and look at some simple analysis techniques and simple structures, thereby generating an improved level of understanding of the overall impact and importance that this type of connection has on building structures.
Reuse of A325 and A490 High-Strength Bolts
Authors: Bowman Mark D. , Betancourt Miguel
Published: April 2024

The reuse of high-strength structural bolts often refers to the removal and subsequent reinstallation of bolts when a structural connection is reassembled. Although bolt reuse is not commonplace, it may be feasible for certain types of structures, such as temporary structures used in construction, reusable military structures, and rehabilitation projects of existing structures. Moreover, a moderate cost savings may be possible if the structural bolts are reused when the structure is reassembled. The primary purpose of this study was to provide information on the effect of reuse on the behavior of various high-strength structural bolts. The performance of bolts which either were loaded in direct tension or were continuously torqued to failure was also examined so that comparisons could be made with bolts that were repetitively tightened and loosened. The influence of lubrication applied to the threads was also studied.
Editors Note: 1989 AISC Specification (Ninth Edition) Allowable Bending Stress Design Aid (paper by Allen J. Hulshizer)
Authors: Staff AISC
Published: April 2024

Editors Note
Design and Construction of Lifting Beams
Authors: Ricker David T.
Published: April 2024

Lifting beams (also known as spreader beams) are used to assist in the hoisting process. Most erectors and riggers accumulate an assortment of lifting beams during the course of time. This arrangement provides two places of attachment to the object being lifted, thus avoiding the possibility of overstressing if a single attachment were used. This also allows for a straight pull on the object rather than an oblique pull as would result if chokers alone were used. This is sometimes important to minimize unwanted erection stresses or to prevent reversal of stress in certain portions of the lifted object. For instance, the oblique pull in Fig. 2A may cause excess compression in the top chord of the truss at a time when that chord is laterally unbraced. The arrangement in Fig. 2B will help to alleviate this tendency and optimum choker locations can be chosen to minimize the stresses during the erection phase. Figure 1B illustrates the type of lifting beam that might be employed in Fig. 2B. The beam has multiple holes at the underside for attachment to the object to be hoisted, thus providing a large range of adjustment. This arrangement will also prevent the object from tilting excessively should the hook be slightly off-center of the balance point.
An Equivalent Radius of Gyration Approach to Flexural-Torsional Buckling for Singly Symmetric Sections
Authors: Bakos Jack D. , OLeary James A.
Published: April 2024

Flexural-torsional buckling of compression members must now be considered when designing under all AISC specifications, i.e., Load and Resistance Factor Design (LRFD) and Allowable Stress Design (ASD). Many practicing structural engineers are probably somewhat unfamiliar with the basic flexural-torsional buckling theory and its meaning and application in the design environment. Zahn and Iwankiw have presented an overview on this topic as a means of providing a practical understanding of this strength limit state. Furthermore, the presentation of this new dimension to novice design students not only poses a similar dilemma, but is compounded by the fact that more and more material must be crammed into an already crowded initial course of steel design. It would seem reasonable that an attempt should be made to find a way of introducing this additional buckling mode to both students and practicing designers that would not only be comprehensive in nature, but easy to apply in the design arena. This could be accomplished by using the concept of an equivalent radius of gyration which has been utilized for many years and in a variety of design formats. Thus, if an equivalent radius of gyration could be easily established for flexural-torsional buckling, that radius could be used along with the other applicable radii of gyration to establish the minimum tangent-modulus Euler load that would produce the governing critical buckling load. Such a concept could be easily explained and applied and, thus, provides the basis for this paper.
Flexural Strength of WT Sections
Authors: Ellifritt Duane S. , Wine Gregory , Sputo Thomas , Samuel Santosh
Published: April 2024

WT sections are commonly used as chord members in lightly and moderately loaded roof and floor trusses. In this application, these members are subjected to combined axial and flexural loads. The design of these sections for flexural loads was not specifically addressed in the ASD Specification. Not until the publication of the LRFD Specification was flexural loading of these sections directly addressed. With the advent of ultimate strength design methods included in the LRFD Specification, it became obvious that these sections could carry increased loads. This paper will look at design capacity for these sections and will report on laboratory experimentation supporting these limits.
Eccentrically Loaded Steel Single Angle Struts
Authors: Adluri Seshu Madhava Rao , Madugula Murty K.S.
Published: April 2024

Results of experimental data on eccentrically loaded steel single angle struts are compared with AISC LRFD (1986) and AISC ASD (1989) specifications. It is shown that the current design practice is conservative and needs reevaluation with respect to axial load-bending moment interaction formulas. Various simplified alternative approaches for the design of steel single angle struts are discussed and results presented.
Computers and Steel Design
Authors: McGuire William
Published: April 2024

Computer aided structural engineering is no longer an idea that has to be sold. In steel structures it is widely used from start to finish—from planning to erection. Nevertheless, its still at a critical stage. Further development is essential and the present incidence of misuse is disturbing. Inevitably, use of the medium will continue to grow and its scope expand. Promotion of the process is one of the two themes of this paper. The other is the need to minimize its misuse.
Structural Details To Increase Ductility of Connections
Authors: Blodgett Omer W.
Published: April 2024

Materials used in steel structures are increasingly becoming thicker and heavier. A greater chance of cracking during welding of beams to columns, for example, has resulted due to increased thickness of material. With weld shrinkage restrained in the thickness, width, and length, triaxial stresses develop that may inhibit the ability of steel to exhibit ductility. This paper will try to explain why these cracks may occur and what can be done to help prevent them by expanding on information presented in the AISC Supplement No. 1 (LRFD) or No. 2 (ASD). We will first consider the pulling of a simple tensile specimen to find out what conditions cause this ductile behavior. Then we will find out why this behavior goes from ductile to brittle when triaxial tension is applied. Finally, we will see what conditions under triaxial stresses the ductility can be restored. This information is then applied to the practical question of how wide the weld access hole in the web of a connection should be to avoid brittle behavior.
Fast Check for Block Shear
Authors: Burgett Lewis B.
Published: April 2024

Block shear is a fracture type failure in which fracture may occur either along the shear plane or along the tension plane (see Fig. 1). The first plane to reach its fracture strength will not fail (separate) but is restrained by the stronger plane until the fracture strength of the second is reached. Just before fracture along the stronger plane the total strength will be the sum of the fracture strength along the stronger plane plus the yield strength of the weaker plane.
One Engineers Opinion (Bolting and Composite)
Authors: Milek Jr. William A.
Published: April 2024

One Engineers Opinion
Effective Length of Columns in Gable Frames
Authors: Lu Le-Wu
Published: April 2024

Usually, single-story, shed-type buildings utilizing gable frames are braced normal to these frames or otherwise receive lateral support so that sidesway in this direction is inhibited. On the other hand, single story gabled frames are not braced against sidesway parallel to the plane of the frames. In the design of columns, the 1963 AISC Specification requires that an effective length factor larger than unity be used when computing the slenderness ratio in a plane where the frame is not prevented from sidesway.
Steel Column Bending Amplification Factor
Authors: Liu William Y.
Published: April 2024

Steel Column Bending Amplification Factor
Design Charts for Bolts with Combined Shear and Tension
Authors: Hagen Hans William , Penkul Richard C.
Published: April 2024

Mechanical fasteners which are subject to a combined shear and tensile stress occur most frequently in connections for diagonal bracing systems. Although the force in a diagonal may be reversible, the axial tensile force is more critical relative to the type of connections being discussed here. To facilitate calculations and to give the designer a feeling for the size of joints to be anticipated, it would be desirable to develop typical design charts.
Failure of Simply-Supported Flat Roofs by Ponding of Rain
Authors: Chinn James
Published: April 2024

A few structures supporting flat roofs have collapsed during rain storms even though they were apparently adequately designed and constructed. Such collapses have occurred in structures constructed of all three of the major building materials. The mechanism of failure is as follows: The structure has an initial deflection due to loads or initial downward camber or both, which creates a depression. Rain water ponds in the depression, causing additional deflection. This collects more water causing still more deflection. The cycle continues until the water spills over the edges or collapse occurs. The action can be analyzed in a step-by-step fashion asjust described. Mathematically, this corresponds to an infinite series. If the series converges, the structure will assume a final deflected position, and the water will spill over the edges. If the series diverges, the structure will, mathematically, continue to deflect as long as the rain continues.
Discussion: Lessons from Crane Runways
Authors: Mueller John E.
Published: April 2024

Discussion
One Engineers Opinion (Vibration)
Authors: Milek Jr. William A.
Published: April 2024

One Engineers Opinion
Composite Design with Lightweight Aggregates on Building Projects
Authors: Leabu Victor F.
Published: April 2024

Composite design using concrete slabs, steel beams and girders with various types of shear connectors has been used with some limitations for the past thirty or thirty-five years. Most of the applications of composite construction have been for highway bridge construction and only since the late 1940s and early 1950s has its application been accelerated in the building field. Increasing use of ultimate strength design methods, development of various types of shear connectors, and extensive research in composite design in the past twelve years has advanced this type of construction and has allowed the structural designer to justify savings over conventional elastic and non-composite techniques. This paper centers itself around building projects using composite design with a type of concrete that is unusual since it is lightweight with densities ranging from 90 to 110 pcf instead of the normal density of 150 pcf. This type of concrete has structural characteristics and physical properties similar to normal weight concrete.
Composite Beams of Steel and Lightweight Concrete
Authors: Benjamin Irwin A.
Published: April 2024

Since publication of the 1961 AISC Specification, interest in composite design has grown. Concurrent with this growth in interest has been the development of new types of shear connectors and the use of composite design with lightweight concrete floor slabs. Data from tests on lightweight aggregate concrete composite beams was not available in 1961 when the current AISC Specification was developed. Since that time tests have been run on beams with lightweight concrete, with satisfactory results. This paper has a twofold purpose: to discuss a general method of evaluating composite beam tests, and to review the data on the effectiveness of shear connectors in lightweight concrete composite beams.
Structural Lightweight Concrete for Composite Design
Authors: Jenny Daniel P.
Published: April 2024

ASTM Designation C330 defines lightweight aggregates for structural concrete in a number of ways: it names most available materials; it lists maximum permissible unit weights of coarse and fine fractions; it describes limiting aggregate tests; and it specifies tests for concrete-making ability. The ACI Building Code defines structural concrete as having a compressive strength of 2,500 psi or more. ACI 613A-59, a standard for Mix Proportioning Lightweight Concrete, establishes a top unit weight for the concrete at 115 1bs per cu ft. Three other major factors work toward limiting which aggregates are considered truly structural lightweight aggregates—availability, cost, and proven performance. The concrete-making properties of most lightweight aggregates are shown in a spectrum of concrete unit weights (Fig. 1). Vermiculite and perlite are extremely light materials used in insulating fill concrete ranging in density from 15 to 50 pcf and in strength from 300 to as high as 1,000 psi. Pumice and scoria are natural lightweight aggregates found in volcanic deposits; hence, they have limited availability. Concrete made with these aggregates is in an intermediate range as far as weight and strength are concerned.
Discussion: Simple Equations for Effective Length Factors
Authors: Moore II William E.
Published: April 2024

Discussion
Correction: Simple Equations for Effective Length Factors
Authors: Dumonteil Pierre
Published: April 2024

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

Round pipe columns are often used in large, low buildings such as warehouses and department stores. No guidance regarding the design of the base plates for these columns is to be found in the Manual of Steel Construction, and no definitive guidance may be found in the literature. In lieu of having a rational method for sizing the base plate, designers have often resorted to rules of thumb to determine the plate thickness. This paper provides a design procedure for determining the thickness of these base plates under gravity loads, applied to Allowable Stress Design criteria. This method is not applicable for uplift conditions where the column is in net tension nor does it consider erection criteria which is within the judgment of the detailer and erector.
Frame Response Considering Plastic Panel Hinges
Authors: Fielding David J.
Published: April 2024

The AISC-LRFD Specification designates connections as fully restrained (FR) or partially restrained (PR). Only a beam-to-column connection that has sufficient rigidity to hold the original angles between members unchanged may be considered as Type FR. The quantification of this requirement has been left to the judgment of the structural engineer. One major source of deformation that occurs in FR connections is shear deformation of the column panel zone when beams frame to the column flange(s). Connections that have traditionally been assumed to be fully restrained are, in fact, only partially restrained because they permit relative rotation between the beam and column.
Ductility of Non-Compact Steel Bridge Beams
Authors: Tabsh Sami W.
Published: April 2024

Since the fifties, composite construction in steel bridges has been used in simple as well as in continuous structures. Composite construction incorporates the concrete deck with the top flange of the supporting rolled beams or welded plate girders. The final result consists of the two components from different materials acting as a unit. The composite action can be accomplished by mechanical bond between the flange and deck in the form of welded channels, studs, or other devices. Either shored or unshored construction can be specified. Composite construction for highway bridge design is most economical for spans in the range of 40-50 ft. and longer. The increase in the moment of inertia of the composite section helps in reducing deflection due to live load and impact. For shorter spans, the saving in steel weight does not usually pay for the additional weight of the shear connections and labor involved. Composite steel girder bridges in the United States are usually designed using the Load Factor Design procedure of AASHTOs Standard Specifications for Highway Bridges. Current AASHTO allows the bending moment capacity of compact sections in positive bending to be based on the full plastic moment. The moment capacity at first yield is used, however, for non-compact sections. In most practical cases, the full plastic moment of composite sections is significantly larger than the yield moment.
Geometric Properties of Hot-Rolled Steel Angles Including the Effects of Toe Radii and Fillet
Authors: Madhava Rao Adluri Seshu , Madugula Murty K.S.
Published: April 2024

Hot-rolled steel angles are an important class of structural members. Currently, the values listed in the AISC handbook for the properties of these sections do not include the effect of corner radii except for torsion constant. In the interest of standardization and consistency, it is suggested that these effects be included in the derivation of all properties. The paper presents a complete list of formulas for the geometric properties of angles including the effect of corner radii, as well as the effect of corner radii on the properties. In addition, relevant aspects of metric conversion are discussed.
Correction: Design of Pipe Column Base Plates Under Gravity Load
Authors: Iwankiw Nestor R.
Published: April 2024

Correction