bluuebunny/crossref_metadata_2025 huggingface dataset:
Maximum A325 Bolt Loads at a Glance
Authors: Stetina Henry J.
Published: April 2024

Some designers and detailers have voiced a need for a method that enables a more rapid and clearer determination of the most efficient load capacity for high strength boltsused for single and double shear connections on thin supporting webs and similar material where bearing may control. In friction-type connections, load capacities are not affected by thickness of material or by shear planes intersecting bolt threads; therefore, the bolt capacities are constant. This paper suggests a technique that is advantageous in building-type structures where both friction and bearing-type connections can be used. Too often, sight is lost of the most efficient, economical solution. The problem is centered on a rather narrow range of supporting material thicknesses (webs, etc.) where the several limitations on bolt capacities seemingly converge. Current specifications governing usage of high strength bolts contain four determinants of bolt capacity, exclusive of applied tension. First is an allowable "frictional" shear where the concept of a friction-type joint is employed. The other three determinants, pertaining to bearing-type connections, are (1) an allowable shear on the nominal cross-sectional area of the bolt when threads are in a shear plane, (2) a higher allowable shear on the nominal cross sectional area of the bolt when threads are excluded from shear planes, and (3) an allowable bearing on the projected bolt area of the supporting member or connections detail material.
The Severity of Fires in Steel-Frame Buildings
Authors: Seigel L.G.
Published: April 2024

Fire severity is a term that has been used to describe the destructive potential of a fire in a building. It has commonly been expressed as a function of time and temperature, andstandard time-temperature relationships have been developed to establish uniform procedures for testing structural members of buildings exposed to fire. In the United States, the accepted standard is the time-temperature curve described by the American Society for Testing and Materials in Standard E119 (Fig. 1). Other countries have developed similar but not identical specifications for fire severity. The ASTM curve was adopted in 1918 as a result of conferences involving 11 organizations representing technical societies, testing laboratories, insurance underwriters, and fire-protection associations. It was intended to represent the fire severity likely to occur in the complete burnout of the contents and structure of a typical brick, wood-joisted building. About 10 years after theadoption of the standard, the National Bureau of Standards conducted burnout tests in two old brick buildings that were scheduled to be demolished in Washington, D. C. Very intense fires developed quickly, and the walls collapsed in about half an hour. Therefore, little data on fire intensity or duration were obtained. However, two temperature measurements taken before the walls collapsed indicated a severity much greater than the standard curve (Fig. 2). But the data were very limited, and the curve established by the committee was retained as the standard.
Calculation of Stress Trajectories Using Fracture Mechanics
Authors: Dowswell Bo
Published: April 2024

In structures composed of plates and plate-like elements subjected to in-plane stresses, the stress flow around discontinuities is an important design consideration. Stress dispersion angles are used extensively in gusset plate design and calculations for web local yielding of wide flange members. The current design values are empirical, and the variables affecting the dispersion angles are not well understood. Due to the wide range of angles published in the literature, an analytical model that accounts for all variables is necessary for full understanding of the behavior of these elements. Using fracture mechanics principles, this paper shows that the dispersion angle is dependent on geometry, constraint and inelastic deformation capacity. A versatile design procedure, which explicitly accounts for all variables affecting the stress dispersion angle, is presented.
Uncertainty in Life-Cycle Assessment Induced by Life-Cycle Inventory Data: The Case of Structural Steel
Authors: Zygomalas Iordanis , Baniotopoulos Charalambos
Published: April 2024

Life-cycle assessment (LCA) is currently widely used to quantify environmental impacts and thus support decision making within business sectors such as steel construction, which utilizes vast amounts of materials to deliver large-scale projects globally. Because the validity of LCA results greatly depends on the quality and appropriateness of the life cycle inventory (LCI) data referring to the environmental inputs and outputs associated with the examined subject, it is necessary to estimate the degree of uncertainty embedded in these data, which will inevitably be incorporated into the final LCA results. The purpose of this research is to examine the extent and the characteristics of uncertainty due to LCI data, based on findings for the case of commonly used structural steel components. Impact assessment results are calculated according to four relevant LCI databases and two assessment methods. The results are compared based on a detailed analysis of the impact caused for the production of the steel members. Major conclusions include the observation that data quality characteristics do not ensure the accuracy of the final LCA results because datasets referring to the same steel member type were found to lead to noticeable divergence. An overall lack of uniformity was observed within each of the mainly burdened impact indicators, while the influence of system boundaries was also examined. Issues concerning the collection of primary LCI data were raised, and it was also shown that different impact assessment methods provide different perspectives, which result in a more complete and factual approach.
Buckling Restrained Braced Frame with All-Bolted Gusset Connections
Authors: McManus Patrick S. , MacMahon Addison , Puckett Jay A.
Published: April 2024

A braced-frame, lateral-load-resisting system was developed in which inelastic deformations due to seismic loading were intended to be isolated to easily replaceable buckling restrained braces (BRB). Bolted brace-to-gusset and gusset-to—beam and column connections were utilized to facilitate simple brace and gusset plate installation and replacement. Full-scale testing using two BRBs was executed to assess performance. Analytical frame models were developed using the nonlinear load-deformation characteristics of the braces. The experimental and analytical results were compared to validate reasonable nonlinear parameters for industry use. All-bolted brace connections designed per AISC requirements provided adequate capacity to develop the BRBs. With proper detailing, inelastic deformations can be isolated substantially to the BRBs such that a repairable system is achieved. Load-deformation data for individual braces as provided by the supplier can be used to create reasonable analytical models for frames designed with all-bolted connections.
Notes on the Nodal and Relative Lateral Stability Bracing Requirements of AISC 360
Authors: Louis F. Geschwindner and Andres Lepage
Published: April 2024

The requirements for stability bracing of columns and beams have been included in AISC specifications since 1999. These requirements are intended to permit properly braced columns and beams to attain the buckling strength of the member as if braced by immovable supports and thus be designed as braced members according to the requirements of the Specification. The Specification addresses lateral stability bracing of columns and beams and torsional stability bracing of beams. This paper will address only the requirements for lateral stability bracing. Although these requirements appear to be fairly straightforward, one question is regularly asked by those trying to put them into practice: What is the difference between "nodal"ť and "relative"ť bracing? This paper looks at the background of the provisions, describes how they have been obtained from the theoretical equations and then suggests how best to distinguish between these "nodal"ť and "relative"ť braces. It also shows that the approach taken by the Specification is safe and permits simple rules to be applied to a wide range of bracing problems. In addition, recommendations are made for revision of the requirements.
Experimental Investigation of Mechanical Properties of ASTM A992 Steel at Elevated Temperatures
Authors: Lee Jinwoo , Morovat Mohammed A. , Hu Guanyu , Engelhardt Michael , Taleff Eric M.
Published: April 2024

This paper presents the results of a detailed experimental study into the mechanical properties of ASTM A992 structural steel at elevated temperatures. Critical testing issues, including temperature measurement, temperature control, and extensometer use along with the testing equipment and procedures are briefly explained. Tensile steady-state temperature tests are conducted on samples of ASTM A992 steel at temperatures up to 1000 Â°C. Full stress-strain curves, representing steel coupons tested to fracture at elevated temperatures, are generated. Important mechanical properties such as yield stress, tensile strength, proportional limit, elastic modulus and elongation are obtained from the stress-strain curves. Results are compared with elevated-temperature properties specified by Eurocode 3 and by the AISC Specification. When defined as the stress at 2% total strain, the measured yield stress values agree reasonably well with the corresponding values from Eurocode 3 and the AISC Specification. However, for more conventional definitions of yield stress, such as the 0.2% offset yield stress, the agreement is poor. It is observed that the yield stress of steel at elevated temperatures up to about 600 Â°C is highly dependent on the manner in which yield stress is defined. The effects of displacement loading rates on steel strength and static yielding behavior are also investigated. It is shown that the displacement rate has a large impact on the steel strength at elevated temperatures, especially at temperatures higher than 600 Â°C. Further work is needed to fully characterize the time-dependent effects on the elevated-temperature stress-strain response of structural steel. Additionally, this paper presents results of Charpy V-Notch (CVN) tests on ASTM A992 steel at elevated temperatures.
Local Stability of Double-Coped Beams
Authors: Dowswell Bo , Whyte Robert
Published: April 2024

Localized web buckling can limit the strength of coped beams. In this paper, the coped portion of the beam is treated as an isolated rectangular member, and a parametric study is used to develop lateral-torsional buckling modification factors for use with 2010 AISC Specification Section F11. The parametric study included finite element models with different cope lengths at the top and bottom flanges and cope depths up to 40% of the beam depth. Compared with the finite element results in this paper, the proposed design procedure is more accurate than the design procedure in the 14th Edition Steel Construction Manual.
Experimental Verification of Spliced Buckling Restrained Braces
Authors: Kenneth T. Tam Ronald L. Mayes
Published: April 2024

A critical facility constructed in the 1980s was housed in a building whose original seismic force-resisting system included chevron-braced frames and pre-Northridge earthquake moment frames. In the mid-1990s, a code-based seismic retrofit was designed. This phased retrofit was only partially completed. A more recent seismic evaluation of the building in its partially retrofitted condition revealed major structural deficiencies. Another retrofit was designed using field-spliced buckling restrained braces (BRBs) that allowed the building to remain operational during construction. The paper summarizes the analyses performed for the seismic retrofit and the development, prototype testing and erection of the spliced BRBs. The project testing protocol was compared with current AISC Seismic Provisions' testing protocol for BRBs (AISC 341-10), which shows that if properly detailed and fabricated, BRBs used for this retrofit project can have peak and cumulative ductility well in excess of the current AISC testing criteria.
Numerical Analysis and Design Provision Development for the Simple for Dead Load--Continuous for Live Load Steel Bridge System
Authors: Farimani Reza , Javidi Saeed , Kowalski Darek , Azizinamini Atorod
Published: April 2024

The proposed connections of steel bridge girders at the pier for the simple for dead load and continuous for live load concept (SDCL) were investigated. Analytical models were developed for four connection types that previously were tested in the structural lab. For the numerical modeling of the tested specimens, nonlinear finite element was utilized. The behavior of the numerical models of each tested specimen was verified by the experimental results. The force resistance mechanism of each specimen was studied using the experimental and numerical data. In developing a resistance mechanism for the connections, the yielding of the rebar in the slab, the steel girder bottom plate and the crushing of the concrete diaphragm at pier were considered. A set of detailed equations was developed to formularize the connection behavior at the ultimate capacity under negative flexure. The developed equations show a good agreement with the finite element analysis results. For practical purposes, simplified equations were derived from the more detailed equations to calculate the negative ultimate flexure capacity, at the section through the pier, for two connection types. To verify the proposed design equations for a wider range of bridges, a parametric study was performed. The nonlinear finite element models of the bridges from the parametric study were used for verification of the proposed equations.
Experimental Investigation, Application and Monitoring of a Simple for Dead Load--Continuous for Live Load Connection for Accelerated Modular Steel Bridge Construction
Authors: Javidi Saeed , Yakel Aaron , Azizinamini Atorod
Published: April 2024

The inherently modular nature of the simple for dead—continuous for live load system (SDCL) makes it a natural fit for the accelerated construction paradigm. A detail capable of connecting pre-topped girders over the middle supports is developed and described in this paper. To evaluate the performance of the proposed connection, a full-scale specimen was built and subjected to cyclic and ultimate load testing. The connection showed very little change during cyclic loading equivalent for 70 years of traffic. During the ultimate load test, the connection demonstrated large displacement ductility, reaching its ultimate capacity after complete yielding of the longitudinal reinforcement. After the successful experimental test, a field application bridge was constructed utilizing a modular pre-topped steel box girder system, which allows much of the construction process to be performed prior to placing the girders. The bridge consisted of three pre-topped steel box units placed side by side and connected using longitudinal joints between pre-topped units. The steel box girders used 70-ksi high-performance steel in the bottom flange and 50-ksi steel in the top flanges and webs. The use of high-performance steel combined with the simple for dead—continuous for live load system allows eliminating the need for section transitions through the length of the structure and using constant cross-section throughout the length of the girders. Long-term monitoring of the structure was performed and showed the system performed as intended.
Behavior and Response of Headed Stud Connectors in Composite Steel Plate Girder Bridges under Cyclic Lateral Deformations
Authors: Hamid Bahrami Eric V. Monzon
Published: April 2024

Most of the mass of steel plate girder bridge superstructures is concentrated in the reinforced concrete deck. During a seismic event, the inertia force that is generated in the reinforced concrete deck is transferred to the support cross frames through the headed stud connectors. Seismic analyses showed that these connectors are subjected to combined axial tension and shear forces. If not designed properly, these connectors may fail prematurely during an earthquake, altering the load path and subjecting other bridge components to forces they are not designed for. To verify these observations, two half-scale models of plate girder bridge subassembly were constructed and subjected to cyclic testing. The two specimens represented two different configurations of headed stud connectors in transferring the deck seismic forces. The connectors in the first specimen connected the girder top flange to the reinforced concrete deck, while the connectors in the second specimen connected the cross-frame top chord to the deck. These experiments showed that the connectors were indeed vulnerable under transverse lateral loading. The failure mode of these connectors is a combination between shear and tensile forces or concrete breakout. Based on this investigation, design equations were proposed and adopted in the AASHTO LRFD Bridge Design Specifications to evaluate the resistance of such connectors under shear and tensile forces.
Seismic Response of Partial-Joint-Penetration Welded Column Splices in Moment-Resisting Frames
Authors: Shaw Sean M. , Stillmaker Kimberly , Kanvinde Amit M.
Published: April 2024

Current standards require that welded column splice connections in special or intermediate moment resisting frames (SMRFs or IMRFs) feature complete-joint-penetration (CJP) groove welds to develop the full flexural strength of the column. CJP welds are often costly, requiring additional material, inspection and labor. Compared to beam-to-column connections, column splices have modest deformation demands. This suggests that perhaps with modern, toughness-rated weld filler materials and welding practices, PJP welded splices may offer acceptable performance under seismic loads. A study featuring five full-scale tests on PJP-welded column splices is presented. The test matrix investigates a range of parameters including column sizes as well as variations in connection details. Specimens were loaded cyclically in a three-point bend configuration subjecting the splice to demands consistent with those in severe earthquakes; a loading protocol was developed specifically for this purpose based on nonlinear time history simulations. All the full-scale specimens exhibited excellent performance. A series of finite element fracture mechanics simulations is also presented to assist with the generalization of test results. The test and simulation data are encouraging from the perspective of adoption of PJP welded splices in IMRFs and SMRFs in seismic regions. Limitations of the research are outlined, along with discussion of future work to develop the concept further.
Evaluating Accumulation of Fatigue Damage in Steel Bridges Using Measured Strain Data
Authors: Fasl Jeremiah , Helwig Todd , Wood Sharon L. , Frank Karl
Published: April 2024

As traffic volumes increase, bridges age, and maintenance budgets are cut, transportation officials often need quantitative data to distinguish between bridges that can be kept safely in service and those that need to be replaced or retrofitted. Strain gages can be utilized to evaluate fatigue damage in steel bridges using the techniques that are discussed in this paper. To evaluate fatigue damage, the cycles induced by vehicular traffic must be quantified using a cycle-counting algorithm, such as a rainflow algorithm. The amount of fatigue damage induced during the monitoring period can then be calculated using the traditional method, the effective stress range, or using a new approach based on the index stress range. One distinct advantage of the proposed method is that the relative amount of fatigue damage accumulated at different locations along the bridge can be easily compared. The advantages and limitations of both methods are demonstrated using measured data from a fracture-critical steel bridge.
Analysis and Design of Stabilizer Plates in Single-Plate Shear Connections
Authors: Patrick J. Fortney and William A. Thornton
Published: April 2024

Single-plate shear connections experience some magnitude of torsional moment, either due to the lateral torsional buckling phenomena or due to the effects of lap eccentricity. When the required torsional strength of the connection exceeds the available torsional strength of the connection, the designer has two options: alter the geometry of the connection to increase the torsional resistance of the connecting plate or provide stabilizer plates. Thornton and Fortney (2011) provide analysis techniques for accounting for the effects of lap eccentricity and lateral torsional buckling strength. Part 10 of the Manual (Steel Construction Manual, 14th ed., 2011) presents a summary of the equations used for such an evaluation. However, no discussion was provided by Thornton and Fortney with regard to the size and detailing of a stabilizer plate when such a plate is required. This paper presents recommendations for the analysis with regard to appropriate stabilizer plate cross-sectional dimensions and the attachment of the stabilizer plate to the connecting material and support. Three different types of stabilizer plates are presented along with recommendations for the design and detailing of the stabilizer plates; the impact that each type has on the design of the single-plate shear connection and the supporting column is presented as well.
Cyclic Inelastic In-Plane Flexural Behavior of Concrete-Filled Sandwich Steel Panel Walls with Different Cross-Section Properties
Authors: Polat Erkan , Bruneau Michel
Published: April 2024

Flexure-dominated, concrete-filled sandwich steel plate walls (CFSSP-Walls) have been studied experimentally by various researchers using a small number of cross-sections and wall aspect ratios. Using these past results to calibrate finite element models, the expected behavior of CFSSP-Walls having different geometries and cross-section properties is investigated here using finite element approaches. Results obtained show that the plastic moment can be used to conservatively predict maximum flexural strength in all cases considered and to provide valuable insights into stress and strain demands at various points during nonlinear response. Results also provide quantification of the contribution of concrete infill on the wall effective stiffness, assessment of wall ductility having a failure criteria based on cumulative plastic strain at steel plate fracture, and effect of wall flange width on the wall behavior of T-shaped sections.
Experimental Evaluation of a Procedure for SMF Continuity Plate and Weld Design
Authors: Mashayekh Adel , Uang Chia-Ming
Published: April 2024

The AISC Seismic Provisions require that continuity plates in a special moment frame (SMF) welded moment connection be connected to the column flanges by complete-joint-penetration groove welds. Tran et al. (2013) have proposed a design procedure that allows the designer to evaluate the required forces in the continuity plates such that more economical welds (e.g., fillet welds) can be used; the required thickness of the continuity plates also need not be the same as that prescribed in the AISC Seismic Provisions. With some minor modifications to the original design procedure, two one-sided reduced beam section moment connection specimens were designed and constructed for experimental verification of the proposed design procedure. To evaluate the effect of potential column kinking on the fillet-welded joints between the continuity plates and the column flanges, weaker panel zones that still satisfied the code requirement were used. Although the AISC Seismic Provisions implicitly assume that continuity plates should remain essentially elastic, the continuity plate thickness of one specimen was intentionally undersized to evaluate the effect of continuity plate yielding on the connection performance. Test results showed that using fillet welds is feasible; no damage was observed in these fillet welds, and the connection performance was not affected by the type of weld joints used. The design procedure also indicates the significant effect of in-plane moment in the continuity plate’s strength check, especially when shallow columns are used.
Web Crippling Strength of Longitudinally Stiffened Steel Plate Girder Webs Subjected to Concentrated Loading
Authors: Loaiza Nelson , Graciano Carlos , Chacón Rolando
Published: April 2024

Currently, the AISC Specification provides guidance for the calculation of the ultimate strength of unstiffened plate girder webs subjected to concentric edge loads. Specifications consider three categories: local web yielding, web crippling, and sideway web buckling. Based on previous studies, the presence of longitudinal stiffeners in the web has not been considered in the calculation procedures. Longitudinal stiffeners in steel plate girders are primarily used to increase bending. In the last two decades, a number of projects regarding the positive effect of longitudinal stiffening on the strength of plate girder webs to concentrated load have been conducted around the world. The results have shown that this type of stiffening enhances ultimate strength for web crippling, depending on the position of the stiffener that modifies the slenderness of the directly loaded panel and flexural and torsional rigidities of the stiffener. This paper presents a methodology for the consideration of longitudinal stiffening on the ultimate strength of plate girders webs subjected to concentrated loads. The methodology is based on the plastic collapse mechanism observed experimentally, in which plastic hinges are formed in the loaded flange and yield lines result in the portion of the web limited by the loaded flange and stiffener. Then, a closed-form solution accounting for the influence of the stiffener is developed following the current expression available in the AISC Specification. Theoretical predictions are compared with available test results, showing that the predicted ultimate loads are in good agreement with experimental results.
Fracture and Fatigue Design of the Wilshire Grand Tower
Authors: Kanvinde Amit , Maranian Peter , Joseph Leonard , Lubberts Jeff
Published: April 2024

The 1,100-foot Wilshire Grand Tower in Los Angeles owned by the Hanjin Group is the tallest building in the United States west of Chicago. The building, whose architect is AC Martin Inc., has a slender elevation in one direction, necessitating the use of heavy steel box columns filled with concrete on the perimeter, connected to the concrete core with outrigger trusses. The building has a slender, 272-ft-tall spire, also constructed from steel plates. The height and slenderness of the tower, as well as the spire, and its location in a seismically active zone motivated comprehensive analysis to mitigate the risk of steel fracture within a performance-based design framework. This analysis includes the following components: (1) development of acceptance criteria for earthquake-induced fracture, especially when it may follow years of wind-induced fatigue crack growth; (2) wind tunnel testing; (3) linear and nonlinear time-history simulations to determine stress demands in critical components under appropriate wind and seismic hazards; and (4) fracture mechanics simulations to characterize trade-offs among various design variables to meet the acceptance criteria. The analysis indicates that wind-induced oscillations have the potential to grow fatigue cracks in some components, affecting their performance during a subsequent maximum considered earthquake. This situation is unusual for steel buildings, being the result of the extraordinary height, geometry, heavy steel members, and location of this particular building. The analysis also indicates that fracture risk may be successfully mitigated through existing design and detailing approaches and acceptance criteria, along with use of steel material exhibiting high, but commercially available and affordable, specified Charpy V-notch toughness values.
Torsion of Rectangular Connection Elements
Authors: Dowswell Bo
Published: April 2024

Traditionally, the torsional design of rectangular members has been based on elastic calculations. For member design, this approach is justified because beams subjected to torsion are usually controlled by torsional rotation serviceability limits. However, designs that are based on a first yield criterion underestimate the strength of connection elements. To evaluate the true torsional behavior of connection elements, various factors affecting the torsional strength of short rectangular members are investigated, showing that the torsional strength of connection elements can be predicted with rational analysis models using an ultimate strength approach. A method is proposed for calculating the strength of rectangular connection elements subjected to any possible combination of loads, including torsion. The design method results in a significant increase in torsional strength compared to traditional analysis methods. The method can be used to analyze extended single-plate connections subjected loads in any direction, including axial forces and combined vertical and horizontal shear forces. Three design examples show the proper application of the design method.
Weld Effective Lengths for Round HSS Cross-Connections under Branch Axial Loading
Authors: Tousignant Kyle , Packer Jeffrey A.
Published: April 2024

Recent experimental and numerical research performed on fillet-welded, round-to-round, HSS Cross-connections is reviewed, along with prior research on round HSS-to-rigid plate connections. The data from these weld-critical tests are then interpreted to determine practical weld effective lengths for such connections, in conjunction with permitting the “directional strength-increase factor” for fillet welds to round HSS. Recommendations are made for the AISC Specification Section K5 and a design example is given to illustrate the approach.
AISC Provisions for Web Stability under Local Compression Applied to HSS
Authors: Wei Fei , Packer Jeffrey A.
Published: April 2024

The relevant limit states for local compression loading on the webs of a rectangular HSS member are reviewed, and the 2016 AISC Specification Chapter J provisions are adapted from their normal application to the single web of a W-shape or I-section to this case. Two recent laboratory tests on matched-width, rectangular HSS-to-HSS cross-connections are described to illustrate the behavior of such connections under branch axial compression. The data from these tests are supplemented by experimental results from a further 76 cross-connection tests, with the branches being either welded plates or welded HSS. From this 78-test database, the existing provisions for local yielding of the chord sidewalls, local crippling of the chord sidewalls, and buckling of the chord sidewalls, are evaluated. Recommendations are made for handling transverse compression loading on HSS webs in the AISC Specification, and a design example is given to illustrate the approach.
Analysis of the Shear Lag Factor for Slotted Rectangular HSS Members
Authors: Dowswell Bo
Published: April 2024

Rectangular HSS tension members are often connected by slotting two opposite walls and welding the slotted walls to a gusset plate. Due to a nonuniform stress distribution in these connections, the tensile rupture strength of the member is dependent on a shear lag factor. The accuracy of the 2016 AISC Specification provisions for the tensile rupture strength of slotted HSS tension members was evaluated using existing data from five previous research projects. The results revealed that the current equations are excessively conservative. The accuracy can be improved by replacing the existing equation for the connection eccentricity with the equation proposed in this paper.
Review of Local Buckling Width-to-Thickness Limits
Authors: Schafer Ben W. , Geschwindner Louis F. , Sabol Tom , Uang Chia-Ming
Published: April 2024

This paper provides a review of local buckling width-to-thickness limits employed in the ANSI/AISC 360-16 Specification for Structural Steel Buildings and ANSI/AISC 341-16 Seismic Provisions for Structural Steel Buildings. The review was conducted by a task group formed to address potential changes in the next and/or future editions of the AISC Specifications. A comprehensive review of existing local buckling limits was completed, including detailing the underlying assumptions and the objectives of the existing limits. In addition, particular attention was given to the potential impact of adopting newer steel materials on the local buckling limits and to considerations of web–flange interaction in local buckling. Further, new methods that have been developed to address local buckling in structural steel design were also examined. It was found that in AISC 360, some lr limits for flexure may not be well aligned with intended objectives, and while all lp limits for flexure ensure the plastic moment may be achieved, rotation objectives are not consistently implemented. Review of lmd and lhd in AISC 341 reveals complications with implementing expected yield stress in the slenderness parameters and highlights the large number of varied objectives for these limits in seismic design, as well as a need for improvements—particularly for deep wide-flange columns. In general, it is found that only minor changes are potentially needed to current width-to-thickness, w/t, limits. Thus, in most cases, it is expected that AISC design can continue unchanged, with the exception of the improved criteria for deep columns. To minimize change while still expanding opportunity, newer local buckling cross-section classification methods could be permitted as alternatives rather than used as replacements to current w/t limits so that advantages of the newer approaches can be utilized when beneficial.
Flange Local Buckling Resistance and Local–Global Buckling Interaction in Slender-Flange Welded I-Section Beams
Authors: Latif Wajahat , White Donald W.
Published: April 2024

AISC Specification Chapter F characterizes the flange local buckling (FLB) strength of I-section members having a slender compression flange as the theoretical elastic plate local buckling resistance, ignoring beneficial local post-buckling strength. Previous research has shown that this results in highly conservative strength predictions for slender-flange members. Additionally, potential interaction between local and global lateral-torsional buckling modes is not considered in the AISC Specification. These aspects can be important in applications involving the use of slender-flange members. This paper investigates a number of potential methodologies to account for local post-buckling strength as well as local–global buckling interaction in beams having slender flanges. A parametric finite element analysis (FEA) study is conducted considering a range of I-section members. The strength predictions from the proposed methodologies and the AISC Specification are evaluated against the FEA results as well as against a database of measured strengths from previous experimental tests of I-section beams governed by FLB. Recommendations are provided focusing on simplicity of the calculations and the efficacy of their predictions.
Rapid Selection of Beam-Columns
Authors: Rubinsky Moe A.
Published: April 2024

This paper presents methods for the rapid selection of members in the design of beam-columns. The members may be subject to bending about either or both axes, with or without direct load. Method PMx converts the direct load and/or the moment about the Y-Y axis into equivalent moments about the X-X axis, reducing the problem to the selection of a beam with bending about the X-X axis only. Method MP converts the moment about the X-X axis and/or the moment about the Y-Y axis into direct loads, reducing the problem to the selection of a column without bending.
Are Tier Building Column Splices Designed?
Authors: Stetina Henry J.
Published: April 2024

The design of splices for multistory building columns sometimes presents an apparent conflict between theory and practice. Examination of several steel design textbooks in current use shows a wide divergence of solutions. Most disconcerting is one statement that the AISC Specification does not spell out requirements for splicing joints of compression members and, therefore, to design the splice, reference must be made to a specification for designing railroad bridges. Even if the AISC Specification did not adequately cover the problem (and it does), the employment of a specification not applicable to buildings can hardly be considered a satisfactory substitute. Misleading information such as the foregoing may be one reason for inefficient, uneconomic details that often appear on design drawings. What are the facts regarding AISC Specification requirements for splicing multistory columns and how are they commonly designed? For nearly 35 years the AISC Specification has contained all the necessary requirements for properly designing splices in compression members, including tier building columns.
Seismic Design and Performance of Composite Coupling Beam-to-SpeedCore Wall Connections
Authors: Varma Amit H. , Ahmad Mubashshir , Shafaei Soheil , Klemencic Ron
Published: April 2024

Coupled composite plate shear walls—concrete filled (CC-PSW/CFs) are an effective seismic lateral-force-resisting system for the design and construction of mid- to high-rise buildings around the world. The coupled system consists of two or more composite plate shear walls—concrete filled (C-PSW/CFs) connected to each other using composite coupling beams located at the story heights. The CC-PSW/CF system can provide higher overturning moment capacity, lateral stiffness, and ductility than uncoupled walls. Concrete-filled steel box sections are typically used for the composite coupling beams, which are designed to be flexure critical members. When the CC-PSW/CF system is subjected to lateral seismic forces, plastic hinge formation and inelastic deformations (energy dissipation) occur near the ends of most of coupling beams along the structure’s height, followed by flexural hinging of the C-PSW/CFs, typically at the base. This paper presents the details and design of four composite coupling beam-to-C-PSW/CF connection configurations. Six connection specimens representing the four connection configurations, with beam clear span-to-section depth, Lb/d, ratios of 3.5 and 5.1, were designed and tested. The lateral force-displacement and moment-rotation responses of the specimens are summarized. All six composite coupling beam-to-C-PSW/CF wall connection specimens (1) developed and exceeded the plastic flexural capacities, Mp, of the coupling beams calculated using the plastic stress distribution method and (2) developed chord rotation capacities greater than 0.03 radian before their flexural strength degraded to 80% of the plastic moment capacity, Mp.
Four-Bolt Unstiffened End-Plate Moment Connections with 36-in.-Deep Beams for Intermediate Moment Frames
Authors: Mercado-Celin Maria A. , Eatherton Matthew R. , Murray Thomas M.
Published: April 2024

Previous testing has shown that four-bolt extended, unstiffened end-plate moment connections can be used with beams up to 24 in. deep and develop sufficiently ductile performance to satisfy seismic qualification. It is desirable to extend this depth limit to allow deeper beams for intermediate moment frames. Three moment connection specimens using built-up 36-in.-deep beams with a four-bolt extended, unstiffened end-plate moment connection were tested to determine if they satisfy the intermediate moment frame qualification criteria given in AISC 341-16 (2016a). The web of the specimens satisfied the moderately ductile section criteria for web slenderness, which is required for intermediate moment frames, but not highly ductile section criteria required for special moment frames.

All three specimens passed qualification criteria for intermediate moment frames (IMFs) as given in AISC 341-16 by retaining at least 80% of the nominal plastic moment strength through 2% story drift. The observed failure modes included lateral torsional buckling of the specimen, flange local buckling, net section fracture of the beam flange, and failure of the beam flange-to-beam web fillet weld. The results of these tests support current moderately ductile limits associated with lateral bracing and cross-section slenderness, given that the associated specimens reached IMF qualification criteria but not special moment frame (SMF) criteria. It was concluded that four-bolt extended, unstiffened end-plate moment connections satisfy intermediate moment frame requirements with a beam depth of 36 in. and that a modification is needed for beam web to flange welds in built-up sections near the moment connection.
Another Approach to Simplified Design of a Curved Steel Girder
Authors: Ketchek Konstantin
Published: April 2024

In recent years several publications discussing an approximate analysis of a curved girder grid system were presented. In the first paper by Richardson, Gordon and Associates, a two-girder system connected with diaphragms was discussed. Further development for the multi-girder system connected by diaphragms was published by U. S. Steel Corporation. The presentation of W. T. Robertson at the ASCE meeting in October, 1965 and the article by James W. Gillespie4 also can be mentioned, among other publications concerned with the same subject. The principal assumption of analysis used in all the above mentioned publications is based on the well established fact that the change in torque between two points of a curved girder subjected to bending is equal to the area of bending moment diagram between these points, divided by the radius of curvature of the girder.
Composite Open-Web Steel Joists
Authors: Tide Raymond H.R. , Galambos Theodore V.
Published: April 2024

This report presents a description of research on the behavior of composite joists. In this type of structure a concrete slab is connected by shear-connectors to a steeljoist. The research to be described consists of tests on beams. The purpose of the research was to determine the behavior of the shear-connectors.
Automated Optimum Design of Unstiffened Girder Cross Sections
Authors: Goble George G. , Moses Fred
Published: April 2024

Since the advent of the electronic digital computer, substantial change has occurred in the practice of structural engineering. This change has been particularly rapid since the second generation machines became available with their substantially reduced computation cost. The third generation machines have been even less expensive to use and much more accessible. For the structural engineer, the greatest application has been in the elastic analysis of large structures and today almost every engineering firm makes routine use of some computer analysis capabilities. The impact on structural design has been less direct. Certainly, the availability of a good analysis has increased the capability and confidence of the designer, but, in general, application design methods have remained practically unchanged. Either the computer has been applied exclusively as an analysis tool or traditional design methods have been programmed for automatic computation. The first approach leads to serious problems with man-machine communications. Large amounts of errorfree input data must be prepared and voluminous output digested. The second approach is successful in many cases as proven by the numerous, elaborate design programs which have been written in the last few years. However, for problems where the number of variables that must be selected is large or closely dependent, direct methods either fail or are extremely inefficient. It seems that programmed optimization methods have reached a stage where they can be useful in solving some of these problems. One purpose of this paper is to present an optimization technique which can be useful to the structural designer today.
Lightweight Concrete-on-Steel Composite Beams
Authors: McGarraugh Jay B. , Baldwin Jr.
Published: April 2024

Current design specifications for composite beams include no provisions for beams with lightweight concrete. Conceptually, the use of lightweight concrete for composite beams can lead to greater economy, since a substantial reduction in dead load can be obtained. However, there have been some questions regarding the use of lightweight concrete in composite construction. Six composite beams with lightweight concrete slabs were tested and the results compared with a previously developed theoretical analysis. The theoretical analysis was then used to study the effects of partial shear connection, modular ratio, and unshored construction on the behavior of composite beams.
The Staggered Truss System-Structural Considerations
Authors: Scalzi John B.
Published: April 2024

The staggered truss system is a new concept in structural steel framing for high rise buildings. The system consists of a series of story-high trusses spanning the total width between two rows of exterior columns and arranged in a staggered pattern on adjacent column lines. The staggered truss system for steel framing is an efficient structural system for high rise apartments, hotels, motels, dormitories, and hospitals. The arrangement of story-high trusses in a staggered pattern at alternate column lines provides large column-free areas for room layouts. The interaction of the floors, trusses, and columns makes the structure perform as a single unit, thereby taking maximum advantage of the strength and rigidity of all the components simultaneously. Each component performs its particular function, totally dependent upon the others for its performance. The staggered truss system of steel framing has become an economical system for high rise, high density occupancy buildings.
Tables for Plastic Design of Beams with Rectangular Holes
Authors: Redwood R.G.
Published: April 2024

The requirement for holes in the webs of beams and girders in building structures for the passage of utility ducts has become common, and rational methods for the design of beams with certain types of such holes have become available. In this paper, tables are presented which provide an aid to the design of reinforcement for rectangular holes in the webs of flanged beams. The reinforcement considered consists of horizontal bars placed above and below the holeand located close to its edge. Single holes centered on the mid-depth of symmetrical beams are considered, and the limitations pertaining to proportioning on the basis of plastic design apply to the beams. (See for example, Sect. 2.7 of Ref. 1, or Par. 30.11 of Ref. 2.) Figure 1 shows typical holeand reinforcement details; the reinforcement may be either on both sides or on one side of the web. The tables give, for a wide range of combinations of moment and shear acting at the center line of the hole, the minimum area of reinforcement required for the beam to carry that moment and shear before plastic collapse, expressed as a fraction of the area of the beam flange. The tables also indicate when reinforcement is not necessary, and when horizontal bar reinforcement is not adequate.
Calculation of Effective Lengths and Effective Slenderness Ratios of Stepped Columns
Authors: Anderson John P. , Woodward James H.
Published: April 2024

The analysis of stepped columns arises in the design of heavy mill buildings. Such columns are generally loaded at the top and at the section where the cross section changes. The application of the AISC Specification requires that the engineer determine the effective length of each section of the column. This is a problem in elastic stability theory, and the results are dependent not only on the end fixities, but also on the ratio of the end axial load to the intermediate axial load, the ratio of the length of the upper segment to the length of the lower segment, and the ratio of the upper moment of inertia to the lower moment of inertia. In this paper the authors have extended the analysis to three cases of practical interest, not previously considered. Consistent non-dimensional characteristic equations are given for all five cases.