bluuebunny/crossref_metadata_2025 huggingface dataset:
Discussion: Observations from Cyclic Tests on Deep, Wide-Flange Beam-Columns
Authors: Maison Bruce F.
Published: April 2024

Discussion paper on "Observations from Cyclic Tests on Deep, Wide-Flange Beam-Columns" (paper 2015-16) by Gulen Ozkula, John Harris, and Chia-Ming Uang published EJ 2017 1st Quarter.
Probabilistic Assessment of Seismic Force Demands in Biaxially Loaded Columns in Chevron-Configured Special Concentrically Braced Frames
Authors: Burton Henry V. , Doorandish Nilofar , Sabol Thomas
Published: April 2024

Special concentrically braced frame (SCBF) columns are designed as force-controlled elements and are intended to respond elastically during moderate-to-high return-period events. When placed at the intersection of orthogonal chevron-configured braced frames with fixed beam-column connections, SCBF columns are subjected to biaxial loading, including flexural demands developed in the beams due to unbalanced tension-compression brace forces. A probabilistic assessment of the force demands in biaxially and uniaxially loaded columns in chevron-configured SCBF is presented herein. Nonlinear response history analyses are performed on three-dimensional models of 3-, 9- and 20-story SCBFs, and statistical descriptions of the results are used to investigate (1) the force demands relative to the capacity-design-based and elastic designs suggested by the American Institute of Steel Construction (AISC) Seismic Provisions, (2) the implications of the flexural demands transmitted to columns (via braced frame beams), and (3) the combinatorial effects of demands in biaxially loaded columns generated by orthogonal ground-motion components. At the maximum considered earthquake (MCE) hazard level, the median axial force demands in the biaxially loaded first-story columns of the three-story building are approximately at the level corresponding to the expected brace strength and exceed the design forces amplified by the overstrength factor. Axial flexure interaction is especially significant in the biaxially loaded columns of all three building cases. The results also show that the combinatorial effect of axial forces transmitted to the biaxially loaded columns via the orthogonal braces is generally lower in taller buildings and also depends on the demand level.
Steel Structures Research Update: Steel Diaphragm Innovation Initiative
Authors: Liu Judy
Published: April 2024

The Steel Diaphragm Innovation Initiative (SDII) is a multiyear academic-industry partnership to advance the seismic performance of steel floor and roof diaphragms in steel buildings is highlighted. The team includes AISC T.R. Higgins Lectureship Award and AISC Milek Fellowship Award winners for topics ranging from developments in long-span composite slabs to buckling-restrained braced frames to continuity plate detailing for steel moment-resisting connections. The team’s motivations for creating SDII stemmed from issues with respect to the knowledge base for steel diaphragm performance, codes and standards, as well as missed opportunities for advancements in seismic performance-based design. The available research on steel diaphragms was primarily focused on the strength of isolated systems; little was known about ductility or whole-building performance. The team developed a five-year case and plan to “advance the seismic performance of steel floor and roof diaphragms utilized in steel buildings through better understanding of diaphragm-structure interaction, new design approaches, and new three-dimensional modeling tools that provide enhanced capabilities to designers utilizing steel diaphragms in their building systems” (SDII, 2017). The work includes providing research support for much-needed revisions to proposed seismic codes and standards for steel diaphragms. SDII is also working on innovative steel diaphragm solutions for efficient, robust and resilient steel building systems.
Updated Equivalent Axial Load Method for Design of Steel Beam-Columns
Authors: Reynolds Mathew , Uang Chia-Ming
Published: April 2024

The equivalent axial load method is a design aid that aims to select candidate wide-flange beam?columns with minimal iteration. The method itself was described in previous editions of the AISC Steel Construction Manual, but has been removed in recent editions. An expanded version of the tables for sizing of both shallow and deep beam-columns based on the latest edition the AISC Manual is presented. Several examples of uniaxial and biaxially loaded beam-columns are provided to demonstrate the effectiveness of the method. The method is validated using a programmed heuristic which designed beam-columns from randomly generated scenarios.
Design for Gusset Plate Buckling with Variable Stress Trajectories
Authors: Dowswell Bo
Published: April 2024

Gusset plates are used in steel buildings and bridges to connect diagonal members to other framing members in the structural system. Gusset plates subjected to compression loads are currently modeled as rectangular columns with an effective cross section defined by a 30° stress trajectory known as the Whitmore Section. The buckling strength is calculated using the AISC column curve with empirical effective length factors. Previous research has shown local yielding allows the stresses to redistribute, increasing the effective width. Because the inelastic capacity decreases with gusset slenderness, a variable stress trajectory has been established which is dependent on the flexural buckling slenderness parameter. This paper describes a design method for the buckling strength of gusset plates using variable stress trajectory angles. The proposed effective length factors for the equivalent column were evaluated using data from existing research. The design model is valid for single- and double-plane corner gusset plates, including extended corner gusset plates commonly used for seismic design. Compared to the results of 162 specimens from 12 previously-published research projects, the proposed design model is shown to be more accurate than the methods that are currently available.
Empirical Formulation for Compressive Capacity of Gusset Plates
Authors: Gorji Meisam Safari , Cheng J.J. Roger
Published: April 2024

Gusset plates play a critical role in the behavior and stability of bracing systems and truss bridges. While the behavioral characteristics of gusset plates have been widely investigated and analysis procedures have been developed, considerable uncertainty exists in the design equations, due primarily to the complexity of stress distribution in the connection area. Current design procedures rely heavily on highly simplified approaches, which typically result in an inconsistent design factor of safety for various gusset configurations and boundary conditions. In this research, a powerful genetic programming (GP) tool is employed to develop an empirical formulation for compressive capacity of corner gusset plates using a comprehensive database collected from previously published test results and test-validated finite element models. The predictive model correlates the ultimate compressive strength of gusset plates with their mechanical and geometrical properties. A comparative study is performed to evaluate the performance of the derived expression compared to the results of the well-known effective length factor method. The results indicate that the GP-based equation accurately estimates the compressive capacity of gusset plates and its prediction performance is significantly better than that of the current procedures.
A Reliability Study of Joints with Bolts Designed with Threads Excluded but Installed with Threads Not Excluded
Authors: Swanson James A. , Rassati Gian Andrea , Larson Chad M.
Published: April 2024

This paper presents a reliability and probability study focusing on connections using relatively short bolts that in a companion paper have been shown to have the potential to have been designed with threads excluded from the shear plane and then subsequently installed with the threads not excluded from the shear plane. After an introduction outlining the background of the shear strength and associated design of joints in various editions of the AISC Specification, the paper presents a structural reliability analysis as well as a probability study using Monte Carlo simulations, and then finally a discussion of additional considerations and mitigating factors associated with this potential problem. Calculated reliability coefficients and probabilities of failure are tabulated for joints using two diameter groups of 120-ksi bolts (from ? in. to 1 in. and from 1? in. to 1¼ in.) and for joints using 150-ksi bolts. The paper provides an evaluation of the reliability of joints with bolts that have been designed with the threads excluded from the shear plane but installed with the threads not excluded from the shear plane. Although it is recommended that future designs involving short bolts be based on the assumption that the threads are not excluded from the shear plane, this study provides a measure of the reliability of structures that have already been constructed with bolts designed assuming that the threads were excluded but installed with the threads not excluded. The results show that the reliability of joints in this class is dependent on the grade and size of the bolts used, on the length of the joint, and on which edition of the AISC Specification was used for design. It was found that some joints in this class still meet the AISC target reliability for connections, and that many joints meet the AISC target reliability for members.
Dimensional Tolerances and Length Determination of High-Strength Bolts
Authors: Swanson James A. , Rassati Gian Andrea , Larson Chad M.
Published: April 2024

Structural engineers and detailers are often removed from the process of manufacturing bolts, and thus the tolerances and variances that go along with common manufacturing processes. While this does not represent a problem in most cases, being familiar with the manufacturing processes and tolerances associated with high-strength bolts can help prevent some problems from occurring before the design process even begins, particularly when shorter bolt lengths are needed. This lack of familiarity, in some circumstances, might lead to mistaken assumptions regarding the location of the shear plane relative to the threads of the bolt, which may lead to incorrect designs. While an engineer might presume that bolt strength would not control in such short grips, this paper will discuss the cases in which this can become an issue. This paper summarizes the major variances between nominal and actual dimensions, evaluates some of the consequences that those variances can have on design, presents solutions to those issues, and culminates with a proposed design procedure for proper length determination of high-strength bolts with several illustrative examples.
Technical Note: Notes on Determining Required Connector Strength in Built-up Compression Members
Authors: Geschwindner Louis F.
Published: April 2024

Connections between individual components of a built-up compression member carry no force when the member is perfectly straight in the unbuckled configuration under load. Yet AISC Specification Section E6.1 (AISC, 2016) requires that the end connection of these built-up members be welded or connected by means of pretensioned bolts with Class A or B faying surfaces. Nothing is provided in the AISC Specification or Commentary to help the designer determine the required strength of these connectors. This paper suggests one way of determining these required strengths and provides two LRFD examples. Other assumptions may be used to derive different, but equally acceptable, required strengths.
An Experimental Study of the Influence of Eccentricity on Shear Lag Effects in Welded Connections
Authors: Orloff Kenneth L. , Swanson James A. , Rassati Gian Andrea , Burns Thomas M.
Published: April 2024

In the 2010 AISC Specification, the shear lag factor for longitudinally welded tension members was applicable only to plate-type members having equal length welds on each side with a minimum length equal to the distance between the welds (AISC, 2010). Fortney and Thornton (2012) used experimental data from three previous research programs consisting of 175 various tension members to develop a generalized shear lag model that addresses the aforementioned limitations. The members comprising this dataset consisted of 158 flat plates with equal weld lengths, 4 single angles with unequal but balanced weld lengths, and 13 other members having equal weld lengths. The shear lag factor presented in the 2016 AISC Specification Table D3.1, Case 4 (AISC, 2016b) is a product of Fortney and Thornton’s work and applies to longitudinally welded plates, angles, channels, tees, and W-shapes having equal or unequal lengths and no length-to-width limitation. This paper presents an experimental study on the shear lag effects in longitudinally welded tension members under both in-plane and out-of-plane eccentricity through the testing of eight 3×1/2 plate sections and twelve 3×3×1/2 single-angle sections having both equal and unequal longitudinal weld lengths. Experimental shear lag factors were determined for each of the 20 tested specimens and compared to three theoretical values: (1) the shear lag factor in the 2010 AISC Specification (AISC, 2010), (2) the shear lag factor based on a bi-planar model (Fortney and Thornton, 2012), and (3) the shear lag factor from Case 4 in the 2016 AISC Specification. The findings of this experimental study confirm that shear lag factor given by Case 4 in the 2016 AISC Specification provides the best prediction of shear lag factors in welded connections subject to both in-plane and out-of-plane eccentricity.
Design of Simple Steel Connections under Fire Temperatures
Authors: Hantouche Elie G. , Al Khatib Karim K. , Jabotian Hagop V.
Published: April 2024

A methodology is developed for designing simple steel connections (shear tab and double angle) subjected to fire. The proposed methodology is based on quantifying the strength and stiffness of steel framed simple connections at elevated temperatures. To achieve this, first, a stiffness-based model that characterizes the rotational stiffness of simple steel connections when subjected to fire temperatures is developed. The model is capable of predicting the behavior of two widely used simple steel connections (shear tab and double angle) when subjected to fire temperatures. It incorporates the connection rotation of key component elements and the nonlinear behavior of both bolts and base materials at elevated temperatures. The model is validated against experimental results available in the literature under steady-state temperature analysis. The model covers all possible limit states and governing failure modes under different loading and temperature conditions. It can be considered a practical tool for designing simple steel connections for professional structural fire engineers in the United States. Step-by-step design examples of simple steel connections in an isolated frame are provided to illustrate the incorporation of the developed stiffness model in a fire design procedure. The presented design procedure accounts for the additional load demand on the connection during fire. This includes the load demand due to thermal expansion and beam sagging.
Experimental Investigation of a Self-Centering Beam Moment Frame
Authors: Eatherton Matthew R. , Maurya Abhilasha
Published: April 2024

The self-centering beam (SCB) is a shop-fabricated unit that can be implemented in moment-resisting frames using conventional field construction methods to minimize permanent residual drifts after earthquakes and concentrate seismic damage in replaceable elements. An experimental program was conducted on five SCB specimens that were approximately two-thirds scale relative to a prototype building. The results showed that the beam end moments are not equal, as much as 60% different at peak moment, so total flexural strength, calculated as the sum of the moments at both ends, is a better way to characterize SCB flexural strength. Using this approach, the proposed equation to predict flexural strength exhibited an average error of 5% compared to the tests. The SCB was shown to have exceptional deformation capacity as the specimens were subjected to as much as 6% story drift, and the detailing was shown effective at concentrating inelasticity in the replaceable energy dissipating elements. The proposed design procedure is shown capable of controlling the story drift associated with undesirable limit states, limiting story drifts at zero force (eliminate residual drifts), and producing no observable inelasticity outside the energy-dissipating element at design level drifts.
Design for Local Member Shear at Brace and Diagonal-Member Connections: Full-Height and Chevron Gussets
Authors: Sabelli Rafael , Saxey Brandt
Published: April 2024

Large local member shear forces develop in beams in chevron-braced frames due to the delivery of brace forces to beam flanges, which are at a distance from the beam centerline (Fortney and Thornton, 2015, 2017; Hadad and Fortney, 2020). Using the “lower bound theorem” (Thornton, 1984), Sabelli and Arber (2017) developed design methods to address this local member shear by optimizing the internal stress distribution and thus maximizing the resistance utilized in design. This paper further develops those design methods for chevron beams and extends them to gusset connections at columns.
Tearout Strength of Concentrically Loaded Bolted Connections
Authors: Franceschetti Nicolo , Denavit Mark D.
Published: April 2024

The limit state of tearout can complicate the design of steel bolted connections since, in contrast to the limit states of bearing and bolt shear rupture, tearout strength can vary from bolt to bolt within a connection. Under the current AISC Specification, tearout strength is proportional to the clear distance, in the direction of force, between the edge of the hole and the edge of the adjacent hole or edge of the material. However, recent studies on concentrically loaded bolt groups have suggested that the use of clear distance may not accurately represent tearout strength and have proposed alternative lengths for use in strength equations. A reevaluation of the limit state of tearout in concentrically loaded bolt groups is presented in this work, including a thorough evaluation of the proposed alternative tearout lengths using a large database of previously published experimental work and new experiments with various edge distances and hole types. Equations with the alternative tearout lengths were found to be more accurate than those with clear distance, especially for small edge distances. Design recommendations including the alternative tearout lengths were developed. The results of this work increase understanding of the limit state of tearout and offer improved methods of evaluating this limit state in design.
Steel Structures Research Update: Structural Fire Engineering
Authors: Liu Judy
Published: April 2024

Across the United States, researchers are making exciting discoveries and advances in structural fire engineering. Eleven of the leading scholars in the field are featured. Brief research highlights are organized by the topic areas of behavior and design of steel and composite structures for fire, fire following earthquakes, and performance-based fire engineering. For each individual, related steel and fire research is also noted. Meanwhile, due to timing and circumstances, there are structural fire engineering researchers who do not appear in this article. You may find some of their structural steel research in past articles or perhaps a future research update.
Cyclic Behavior of DuraFuse Frames Moment Connections
Authors: Richards Paul W.
Published: April 2024

Most special moment frames (SMF) rely on beam yielding to reach drifts of 0.04 rad and beyond. In contrast, DuraFuse Frames (DFF) incorporate a fuse plate that acts as the yielding element. Nine full-scale DFF specimens were tested using AISC 341, Seismic Provisions for Structural Buildings, Chapter K, to prequalify the DFF connection for use in SMF and inclusion in AISC 358, Prequalified Connections for Special and Intermediate Steel Moment Frames for Seismic Applications. Eight specimens were tested with the standard protocol and exceeded the qualification criteria. The other specimen completed a custom protocol representing three maximum credible earthquakes (MCE) in sequence. The experiments demonstrated that the stiffness of the DFF connection is sufficient to classify the connection as fully restrained (FR).
Steel Structures Research Update: Inelastic Design Method for Steel Buildings Subjected to Wind Loads
Authors: Liu Judy
Published: April 2024

Ongoing research on an inelastic wind design method for steel buildings is highlighted. This study is under way at Brigham Young University, led by Dr. Johnn Judd, Assistant Professor in the Department of Civil and Construction Engineering. Dr. Judd’s research interests include seismic performance of steel moment frame buildings, field evaluation and structural health monitoring of steel bridges, and wind performance assessment of buildings. Dr. Judd has also been awarded the AISC Milek Fellowship for this research on inelastic design methods for steel buildings subjected to wind loads. The research team is in the third year of the four-year study. Selected results from the study are highlighted along with a preview of future work.
The Chevron Effect: Reserve Strength of Existing Chevron Frames
Authors: Sabelli Rafael , Bolin Eric
Published: April 2024

Recently an analysis model has been developed to address the large shear forces (the so-called “chevron effect”) that can develop in the connection regions of chevron-braced frames. These shear forces (and the corresponding moments) are the result of the application of the brace forces at the beam flange, eccentric to the beam centerline. Prior to the presentation of these methods, such forces were not generally considered in design, without apparent incident. Sabelli and Saxey presented an alternative model that determines substantially higher resistance in these connections. Both models resolve the shear and moment within the connection region such that forces outside that region are consistent with those determined using a centerline model. Greater resistance can be determined if the flexural strength of braces and the beam outside the connection region are used to resist a portion of the chevron moment. This paper presents a complete plastic-mechanism strength of the chevron frame with yielding of the beam web due to the local shear forces. This complete plastic mechanism strength can confirm the adequacy of existing designs that did not consider the chevron effect.
Errata: Maximum A325 Bolt Loads at a Glance
Authors: Stetina Henry J.
Published: April 2024

Errata
Space Frame Buckling
Authors: Buchert Kenneth P.
Published: April 2024

The large dome structure is being used more and more because of its structural efficiency, its low cost, and its beauty. The Houston Astrodome (see Fig. 1) is an illustration of future trends in large covered areas. Domes have been built using structural shapes, tubing, shells with stiffeners and composite materials. Buckling analysis is one of the most important considerations facing the designer of such a structure. If buckling failure occurs, it is often sudden and often results in complete collapse of the structure. The failure of the 300-ft diameter dome in Bucharest, Rumania1, is but one example of such a collapse. The purpose of this report is to show that the designer can calculate the general buckling load in the nonlinear stress-strain range and can take into account the important factors in buckling such as yield strength, edge conditions, construction and fabrication tolerances, and residual stresses in structural members.
Design Curves for Plastic Design of Uniformly Loaded Steel Beams
Authors: Hill Jr. , Vanderplaats Garret N.
Published: April 2024

Conventional methods of plastic design are relatively complex when applied to uniformly loaded beams. A curve, developed in this paper, provides a simple, quick, direct method for the design of beams subject to such uniform loads. The beams may have either constant or variable cross sections. A second curve facilitates determination of cover plate lengths.
Discussion: Design for Local Member Shear at Brace and Diagonal-Member Connections: Full-Height and Chevron Gusset
Authors: Richards Paul W.
Published: April 2024

The paper “Design for Local Member Shear at Brace and Diagonal-Member Connections: Full-Height and Chevron Gusset” (Sabelli and Saxey, 2021) develops equations for checking local member shear demands using a Concentrated Stress Method (CSM) and presents a design example. This discussion presents results from a finite element (FE) model, based on the design example in the paper, to quantify the accuracy of the proposed design equations in predicting beam yielding. The FE model confirmed that the beam yielding state would not have occurred for the example frame under the design forces but would have occurred for forces about 4% higher. The stress and strain distributions observed in the FE model were consistent with those assumed in the CSM, although two points for potential refinement were noted. If beam yielding in a concentrically braced frame is forced, through oversized braces, the plastic mechanism would be like an eccentrically braced frame (EBF) but with higher yield force, and higher beam inelastic rotations and strains for the same inelastic story drift.
Steel Structures Research Update: Slotted-Hidden-Gap Connections and Intentional Eccentricity for Steel Brace Members
Authors: Liu Judy
Published: April 2024

Research on alternatives for steel brace members and their connections is highlighted. These studies are a collaboration between Dr. Colin Rogers, Professor and Acting Chair at McGill University, and Dr. Robert Tremblay, Professor at Polytechnique Montreal. Research on braces with intentional eccentricity (BIEs) is motivated by improvements in seismic performance compared to concentrically loaded brace (CLB) members. A brief summary of the background, motivation, and research objectives is presented. Also provided are selected highlights of the experimental program and supplementary finite element study. The slotted-hidden-gap (SHG) connection may eliminate the need to reinforce HSS braces at knife-plate connections, but existing design guidance is limited. Through an extensive, integrated program of numerical parametric studies and physical tests, the research team developed SHG connection design and detailing guidelines.
Application of AISC Specification Requirements for Second-Order Analysis and Stability Design
Authors: Sabelli Rafael , Adams Allen , Landis David
Published: April 2024

Design for stability is inherent in the proper design of every steel structure. As such, every engineer using the AISC Specification (2022) must understand the requirements for stability design and how their own methods (including computer analyses) address the relevant considerations. This discussion provides specific, concise guidance on the application of AISC Specification requirements for stability design and second-order analysis for the practicing engineer.
Component Modeling for Fire Behavior of Shear Tab Connections
Authors: Gordon James A. , Fischer Erica C.
Published: April 2024

During a building fire scenario, the behavior and capacity of gravity connections can significantly contribute to the integrity of steel-framed building structures. Because gravity connections are subjected to axial and flexural force demands and have a limited rotational capacity due to large beam rotations during a fire scenario, a connection model is needed to simulate their behavior when using analytical models to simulate the behavior of a steel structure in fire. This study develops a component model for shear tab connections at ambient and elevated temperatures in the opensource finite element program, OpenSees, to further enable the use of OpenSees for simulating steel structures in fire. Although the developed component model is not limited to implementation within OpenSees. The developed component model is benchmarked against experimental tests of isolated connections and a structural assembly with shear tab connections subjected to mechanical and thermal loads. Through benchmarking, it is shown that (1) the developed component model could be used to simulate connection behavior during a fire scenario and (2) simulating the ductility of connections and connecting components due to damage is critical when simulating the behavior of shear tab connections exposed to fire.
Steel Structures Research Update: Adhesive Steel-to-Steel Connections
Authors: Liu Judy
Published: April 2024

Ongoing research on adhesive steel-to-steel connections is highlighted. This study, currently underway at the University of Massachusetts–Amherst, is led by Dr. Kara Peterman, Associate Professor in the Department of Civil and Environmental Engineering. Dr. Peterman’s research interests include behavior of cold-formed and hot-rolled steel structures under service loads and extreme loads due to natural hazards. Among Dr. Peterman’s accolades for her teaching and research are the University of Massachusetts–Amherst College of Engineering Outstanding Teacher Award, the McGuire Award for Junior Researchers from the Structural Stability Research Council (SSRC), the AISC Terry Peshia Early Career Faculty Award, and the AISC Milek Fellowship. The four-year Milek Fellowship is supporting this research on the holistic design and behavior of adhesive steel-to-steel connections. The research team is partway through year two of the four-year study. Selected highlights from the work to date are presented, along with a preview of future research tasks.
Lateral Force Distributions in Braced-Moment Frames
Authors: Richard Ralph M. , Keldrauk Eric , Allen Jay
Published: April 2024

Braced frames intended to resist wind and seismic loads traditionally have been analyzed and designed as trusses with all joints modeled as pins, such that only the braces provide lateral force resistance. However, frames with gusset plate connections create a rigid joint zone between frame beams and columns, effectively resulting in moment frame behavior, particularly at larger drift angles when braces have yielded or buckled. Described herein are the force distributions for buckling-restrained braced frames (BRBF) subjected to story drift angles, where the lateral resistance of the frame comprises both brace and moment frame action.
Steel Structures Research Update: Innovative Steel Deck System for Highway Bridge Applications
Authors: Liu Judy
Published: April 2024

Ongoing research on innovative steel bridge decks is highlighted. This study, currently under way at the University of Kansas, is led by Dr. William Collins, Associate Professor in the Department of Civil, Environmental, and Architectural Engineering. Dr. Collins’s research interests include fatigue and fracture of metallic structures; bridge design, fabrication, construction, and performance; and evaluation and preservation of historic structures. Among Dr. Collins’s accolades are the Robert J. Dexter Memorial Award, a Fulbright Scholar Award to conduct fracture mechanics research in Finland, and the AISC Milek Fellowship. The four-year Milek Fellowship is supporting this research on innovative steel deck systems for highway bridge applications—the first Milek Fellowship project to focus on bridges. Selected highlights from the work to date are presented, along with a preview of future research tasks.
Design of Unstiffened Girders
Authors: Abolitz A. Leon
Published: April 2024

This paper deals with the design of girders without intermediate stiffeners, on the basis of the current 1963 AISC Specification, Part 1 (Working Stress Method). A typical unstiffened girder is shown in section in Fig. 1. The notation used is shown in this figure and Appendix A. The usual problem in design is to size the girder for a given moment M and shear V. The usual procedure is to try several girder depths, to perform a preliminary design for each depth, to compute the sectional area resulting from each preliminary design, and then to select one of the designs, frequently the one that gives the least area. Table 1 has been developed with the object of guiding and facilitating the designers task. It gives in compact form expressions for the sectional area of unstiffened girders and for some other quantities useful in design. The effect on girder weight of changing the overall depth and the grade of steel are clearly apparent in these expressions.
Bridge Construction Details
Authors: Lally Andrew , Milek Jr.
Published: April 2024

There is a wide variation in the complexity of bridge construction details that satisfactorily perform identical functions. These details have a profound effect on the cost of short span bridges and should be afforded more attention than is usually given to them. One study has shown a range in cost from $0.22/lb to $0.16/lb for the same structure with different framing and details. This has more significance than the 38 percent spread in these prices. Assuming the material cost to be $0.08/lb and deducting this cost from the total, the amount required for fabrication and erection (the remaining portion of the cost) is $0.08/lb for one and $0.14/lb for the other. This is a 75 percent variation in the cost of fabrication and erection due to differences in the design of the framing and details. To achieve the minimum cost, bridge details should be examined in the light of their intended functions. The least sophisticated device that will satisfy the need will generally be the least costly. For all details used in the construction of bridges, the AASHO and AREA specifications provide altitude of choice, with restrictions imposed by individual states or railroads due to geographical differences and special preferences. However, it is not uncommon to disregard this latitude of choice and select standard details, instead of applying objective consideration to the specific need for the detail. This can be costly.
Use of Ultrasonic Testing in the Structural Steel Industry
Authors: Wehrmeister Allen E.
Published: April 2024

It is important to note the distinction between a quality weld and a reliable weld. Many of the discontinuities which will be discussed may not be considered defective to a particular weld joint or structural member. The discontinuities may not make the weld less reliable, but merely lower the quality of the weld. When does a discontinuity become a defect? This is the question which one must ask when separating quality from reliability. The quality of a weld can be determined with ultrasonic tests; however, the reliability of a weld is established from destructive testing or welding history. Test specifications are available based on these tests. It should be mentioned, before proceeding further, that radiography (still a primary weld inspection method), magnetic particle, and penetrant techniques are powerful inspection tools, and should not be overlooked when selecting NDT methods. It is interesting to note, for example, that a discontinuity orientated for maximum radiographic detection is in its poorest position for ultrasonic detection, and vice versa.
Editorial
Authors: None
Published: April 2024

Editorial
Bracing of Continuous Columns
Authors: Urdal Tor B.
Published: April 2024

It is generally accepted that bracing provides elastic support. As shown in this article, the lateral supports for the buckling condition of continuous columns depend onelasticity in three different ways: Case 1: Reactions are proportional to the deflections with respect to the original neutral axis. Case 2: Reactions are proportional to the lateral deflection with respect to the adjacent points of support. Case 3: Reactions are proportional to the relative displacement of successive supports.
Discussion: Bridge Construction Details
Authors: Vansant G.F.
Published: April 2024

Discussion
Yield-Line Analysis and Design of Grids
Authors: Cannon John P.
Published: April 2024

Increasing attention has been given in recent years to design methods which recognize and account for the reserve strength which often exists in a structure beyond the occurrence of first fiber yielding. These methods, variously named, use the structures collapse behavior as the basis for proportioning. Service load checks must then be made on alternative failure modes, such as deflection. Most applications of collapse design have been confined to structures composed of "line elements," e.g., beams and frames. Reinforced concrete designers have been given guarded approval to extend collapse analysis to slabs, if such analysis is accompanied by verifying load tests. Thus the so-called "yield-line" approach affords a powerful slab preliminary design tool which, adequately supported by experimental verification, can be used to determine final proportioning of slab and reinforcing steel. A yield-line type of analysis can also be employed to appraise the collapse strength of steel grid systems. This paper presents yield-line analysis and design procedures for orthogonal grid systems. Confirming laboratory tests are also presented and discussed.
Moment-Rotation Characteristics of Shear Connections
Authors: Kennedy D.J.L.
Published: April 2024

In simple type construction it is assumed that the ends of beams and girders are connected for shear only and are free to rotate under load in the plane of loading. A standard connection used has been a pair of angles fastened to the web by welds and field bolted or welded to the supporting girder or column as shown in Fig. 1. This type of connection, even when designed for shear only, has proved most reliable and among its advantages are: 1. The longitudinal position of the angles can be adjusted slightly to allow for over- or under-cut in the length of the beam. 2. The projection of the angles beyond the end of the beam provide some clearance for erection.
Analysis of Curved Girder Bridges
Authors: Culver Charles , Brogan Darryl , Bednar David
Published: April 2024

Geometric, aesthetic, and economic considerations have led to the increased use of horizontally curved girders for highway bridges and interchange facilities which involve curved alignment. Despite the slightly higher fabrication costs associated with curving the girders, the net costs for such bridges, in certain cases, are lower than those for curved bridges with straight beams placed along the chords of the curved roadway. This overall economy is a result of the elimination of many substructure units (piers) and simplified form work necessary for the roadway slab. Since curved girders may be classified as linear elastic structures, all the various methods of linear structural analysis may be applied to the design of curved bridges. Although considerable analytical work has been done in this area, no attempt has been made to correlate the various methods of analysis or evaluate the degree of approximation inherent in several of the design procedures. The purpose of this paper is twofold. First, the fundamental differences between the behavior of individual straight girders and curved girders loaded normal to the plane of curvature will be established. Second, numerical results obtained from an approximate method of analysis widely used in the design of curved bridges3 will be compared with a rigorous analysis of curved grid systems.
Maximum A325 and A490 Bolt Loads at a Glance
Authors: Stetina Henry J.
Published: April 2024

Several requests have been received for additional tables to those that appeared in the authors article "Maximum A325 Bolt Loads at a Glance", Engineering Journal, October 1967, page 143. The published tables covered only 3/4- and 7/8-in. diameter bolts, for both single shear and double shear connections. The specific requests were for including the one-inch diameter size bolts and for similar tables using A490 steel bolts. For convenience the original tables are repeated; however, the readers attention is called to the minor adjustments in nearly all bolt loads in order to conform with the more precise allowable bearing values given in the 1969 AISC Specification. The allowable bearing on base material is now
Discussion: The Behavior of A514 Steel Tension Members
Authors: Macadam John N.
Published: April 2024

Discussion
Discussion: The Effective Length of Columns in Unbraced Frames
Authors: Gogate Anand B.
Published: April 2024

Discussion
Recommended Design Procedures for Beams with Web Openings
Authors: Bower John E.
Published: April 2024

In todays construction practice, architects and engineers are specifying more and more frequently that holes be provided in the webs of both main and secondary girders and beams of buildings to accommodate the passage of utility components, and thereby minimize the story height and the cost of the building. For this reason, AISC is considering including provisions for such beams in a future addition to its Specification for the Design, Fabrication and Erection of Structural Steel for Buildings. To aid in preparing this addition, an ASCE Subcommittee on Beams with Web Openings (Task Committee on Flexural Members) developed suggestions for the addition. This paper summarizes these suggestions. This is not the first time that the AISC has considered holes in beam webs. In a 1956 AISC publication, Welded Tapered Girders, some design rules were given. The experimental data available at that time was meager, however, and consequently the design rules are, in general, not precise.
Applied Plastic Design of Unbraced Multistory Frames
Authors: Disque Robert O.
Published: April 2024

Many engineers assume that plastic design is too cumbersome when applied to unbraced multistory frames. Actually, a method exists that enables the average structural engineer to perform a plastic design of unbraced multistory frames easily. It is considered sufficiently accurate for the design of frames of limited height. This paper describes this practical procedure. The method is suitable for the design office, since it can be readily adapted to tabular computations or for a computer.
Load Factor Design for Steel Highway Bridges
Authors: Hansell W.C. , Viest I.M.
Published: April 2024

In 1965 an advisory committee was formed by American Iron and Steel Institute to review current bridge design practices and to develop design recommendations for a more consistent and efficient use of steel in highway bridges. That committee, drawn from highway bridge engineers, university professors, and steel industry representatives, initiated a study that resulted in the Tentative Criteria for Load Factor Design of Steel Highway Bridges. The Tentative Criteria were presented to the AASHO Committee on Bridges and Structures in 1968 and were published in 1969 as AISI Bulletin 15. The Criteria in the bulletin were supplemented by a commentary that explained the origins of various provisions, provided supporting evidence, and cited basic references. After a year of study and certain modifications, the Criteria were adopted by the AASHO Committee on Bridges and Structures in 1970 as an alternate design method and were published in the 1971 AASHO Interim Specifications.
A Stub-Girder System for High-Rise Buildings
Authors: Colaco Joseph P.
Published: April 2024

The current trend to "systems" design in building construction has necessitated a new interdependence between the owner, architect, structural engineer, mechanical and electrical engineer, and the contractor. This paper describes one of the new systems—the integration of the mechanical ducts into the structural steel floor beams of a high-rise building. This system is called a stub-girder system. A conventional system of framing a floor in a structural steel structure is shown in Fig. 1(a). The structural system consists of wide flange beams spaced between 7 ft-0 in, and 11 ft-0 in. apart. The floor slab consists of approximately 3.25 in. of lightweight concrete on a metal deck. Composite action between the steel beams and the concrete slab is generally achieved by the use of suitable shear connectors. The mechanical ducts, lights, and ceiling construction are generally placed under the beams. In some instances, penetrations are made in the beams and girders to accommodate the ducts. For a building having a span of 40 ft-0 in. between the core and the exterior columns, the distance between the top of the floor slab and the ceiling is approximately 4 ft-0 in. The stub-girder system is shown in Fig. 1(b). The system consists of a girder spaced approximately 30 ft-0 in. on centers and spanning between the core and an exterior column. This girder consists of a high-strength, wide flange beam with stub pieces shop-welded on the top flange. Floor beams are placed over the girder (between the stub pieces) at approximately 10 ft-0 in. on centers. The floor beams are designed for continuity and are spliced near the points of inflection. The system is completed by the placement of a lightweight concrete slab on metal deck spanning between the floor beams. Composite action is ensured by the provision of shear connectors. The girder is shored while the concrete reaches its design strength.
Errata: Discussion - Shear Strength of Stud Connectors in Lightweight and Normal-Weight Concrete
Authors: Chinn James
Published: April 2024

Errata
Errata: The Case for the Semi-Box Girder
Authors: Schlenker Norman E.
Published: April 2024

Errata
Direct Design of Columns Subjected to Combined Loading
Authors: Phang Michael K.S. , Celenza Eugene
Published: April 2024

The design of wide-flange columns with combined loading according to the procedures presented in the AISC Manual is very time consuming. Methods have been presented which tend to simplify this design procedure. All of these methods convert the applied bending moments to equivalent axial loads, through the use of bending factors. Once the equivalent axial loads are calculated, a trial section is chosen from the AISC Column Tables. Three modified AISC interaction formulas are then used to determine the required axial tabular load. From this load, another trial section is chosen. This procedure is repeated until a satisfactory section is obtained. Because fewer calculations are required, these methods are somewhat less time consuming than the method presented in the AISC Manual. Due to the number of variables involved in designing a wide-flange steel column subjected to combined loading, a trial and error procedure or the common "guess" procedure is usually unavoidable. Once a trial section is chosen, the time is spent in determining the section properties and deciphering the relevant provisions of the AISC Specification for that section. This process must then be repeated for each trial section. Much time is also spent in calculating the factors required for AISC Formulas (1.6-1a), (1.6-1b), and (1.6-2) and finally solving the formulas themselves. Although the trial and error procedure is unavoidable, the excessive time spent can be shortened by the use of a graphical solution.
Discussion: Vibration and Deflection of Steel Bridges
Authors: Murray Thomas M.
Published: April 2024

Discussion