bluuebunny/crossref_metadata_2025 huggingface dataset:
Experiments on the Effects of Power Actuated Fasteners on the Strength of Open Web Steel Joists
Authors: Engelhardt Michael D. , Kates Zachary , Beck Hermann , Stasney Blake
Published: April 2024

A series of 10 full scale tests were conducted on roof subassemblages consisting of open web steel joists and roof deck. In these specimens the roof deck was fastened to the joists by using either 5/8-in. diameter puddle welds or by using power-actuated fasteners (PAFs). PAFs are small high strength nails pneumatically or powder driven through the roof deck into the joist top chord angles. In these tests, the joists and roof deck were loaded to failure under downward acting vertical loads. The purpose of these tests was to determine if the presence of the PAFs produced any detrimental effects on the gravity load capacity of a joist roof system. The test results showed essentially identical performance for specimens using puddle welds as for specimens using PAFs. The PAFs produced no detrimental effects on the load capacity of the joists in these tests.
Discussion: Ponding Calculations in LRFD and ASD
Authors: Milbradt K.P.
Published: April 2024

Discussion
Tables for the Design Strength of Eccentrically-Loaded Single Angle Struts
Authors: Sakla Sherief S.S.
Published: April 2024

The design of eccentrically-loaded single angle struts is a tedious and lengthy procedure. A computer program was developed to perform these time consuming calculations and generate design tables for 36 ksi and 50 ksi equal and unequal leg angles. The program uses the less conservative approach permitted by the AISC Specification for Load and Resistance Factor Design of Single-Angle Members (AISC, 1993). This approach involves applying the interaction equation separately at the corner and the two leg tips of the angle, with the proper signs for compression and tension. Two step-by-step numerical examples are presented in this paper to outline the procedure implemented to generate load tables for equal and unequal leg angles.
Story-Based Effective Length Factors for Unbraced PR Frames
Authors: Xu Leiand , Liu Yuxin
Published: April 2024

This paper proposes a practical method to evaluate the effective length factor K for compressive members in unbraced partially-restrained frames under elastic buckling. In light of story-based buckling and the introduction of the end-fixity factor to characterize the beam-to-column connections of partially-restrained frames, the lateral stiffness of columns with consideration of the effect of axial load is derived. The formulations and procedure of calculating story-based column effective length factors are presented. Numerical examples are then presented to illustrate the effectiveness of the proposed procedure. With the adoption of the end-fixity factor, different member end rotational conditions can be readily modeled by derived formulations. Therefore, the proposed approach is comprehensive and can be applied for both unbraced partially and fully restrained frames.
Perfobond Shear Connector for Composite Construction
Authors: Medberry Sara B. , Shahrooz Bahram M.
Published: April 2024

Composite construction produces stiffer, stronger sections by the efficient use of both steel and concrete. The desirable composite action, however, is not possible unless adequate shear transfer at the steel member-concrete interface is provided. During the last several decades, several types of shear connectors have been developed to insure this transfer of shear; the most common connector is currently the headed stud. This type of shear connector requires a certain amount of slip to occur before composite action can be established. A new type of shear connector for composite construction, called the Perfobond shear connector has recently been developed to eliminate some of the problems and difficulties associated with standard shear studs. A coordinated experimental and analytical study was undertaken to further examine the behavior of composite members utilizing the Perfobond shear connectors, and to develop a reasonably simple, yet reliable design equation.
Design Concepts for Jib Cranes
Authors: Fisher James M. , Thomas Steven J.
Published: April 2024

Jib cranes are either attached to a building column or cantilever vertically from an independent floor mounted column. Shown in Figure 1 is a representation of a column mounted jib crane. This paper will primarily address jib cranes that are attached to building columns. Essentially a jib crane is a boom with a moveable trolley hoist. The trolley hoist moves along the length of the boom and the boom swivels allowing the lifted load to be maneuvered about in a relatively small semi-circular area. The hoists and trolleys of jib cranes are usually slow moving and either manually or radio operated. The arcswing is usually manually accomplished but can be mechanized when required.
New Fatigue Provisions for the Design of Crane Runway Girders
Authors: Fisher James M. , Van de Pas Julius P.
Published: April 2024

Proper functioning of bridge cranes is dependent upon proper crane runway girder design and detailing. The runway design must account for the fatigue effects caused by the repeated passing of the crane. Runway girders should be thought of as a part of a system comprised of the crane rails, rail attachments, electrification support, crane stops, crane column attachment, tie back and the girder itself. All of these items should be incorporated into the design and detailing of the crane runway girder system. Engineers have designed crane runway girders that have performed with minimal problems while being subjected to millions of cycles of loading.
Dynamic Amplitude Prediction for Ballroom Floors
Authors: Hanagan Linda M.
Published: April 2024

To avoid excessive vibration in ballroom-type floors, engineers can evaluate a floor system design before construction using the procedures outlined in the AISC Design Guide 11. These procedures are most appropriately applied to simply supported beam systems where dancing is expected to occur over the entire span. This paper presents a modification to assess beam/girder systems subjected to dance type loads over only a portion of the bay. This modification is especially useful for long-span systems where meeting the serviceability requirements is difficult.
Block Shear and Net Section Capacities of Structural Tees in Tension: Test Results and Code Implications
Authors: Epstein Howard I. , Stamberg Hans
Published: April 2024

Structural tees in tension, bolted to connections only through the flanges, are subject to shear lag. Previous research has shown that shear lag, a reflection of connection length, overall length and the eccentricity to the centroid, strongly influence the efficiency of such connections. This paper reports the results of 50 tests of structural tees. Varying the eccentricity and the connection length produced failures that transitioned from net section to block shear. The tests show that as connection lengths decrease or eccentricities increase, or both, the efficiency of the connections decreases. For net section failures, the decrease is more pronounced than predicted by current AISC specifications provisions that account for eccentricity and connection length. Although not accounted for by current AISC specifications, eccentricity is also shown to influence block shear capacity. The primary purposes of this paper are to present test results and possible alternative approaches to dealing with the areas of tension connection efficiency and shear lag.
Discussion: Torsion of Rolled Steel Sections in Building Structures
Authors: Burton John C.
Published: April 2024

Discussion
Vibration of Steel Joist-Concrete Slab Floors
Authors: Lenzen Kenneth H.
Published: April 2024

Developments in materials and technology have led to lighter types of construction in floors with little decrease in factors of safety. These economical methods of construction have resulted in occasional floors with insufficient stiffness to prevent noticeable vibration induced by human impact. This problem has not been limited to any type of construction or construction material. The Steel Joist Institute, in order to acquire basic knowledge and test data in the field of floor vibration, initiated and sponsored a research program at The University of Kansas. Copies of the final report can be obtained from either The University of Kansas or from the Steel Joist Institute at Washington, D. C. The program consisted of analytical and experimental work both in the field and laboratory. Two floors were built in the laboratory for control purposes, and to obtain floors which were subject to annoying vibrations. These floors were at the limit of the acceptable design range. Figure 1 shows the first floor loaded with dead weight to design load. In addition, measurements were taken on 46 different floors in the Kansas City area. The floors were designed for many different usages; offices, churches, schoolrooms, halls, and assembly rooms. The floors were in buildings in use for years as well as buildings under construction. The condition of the supported concrete slabs was a large variable. Some floors had badly cracked concrete, and others were in excellent condition. The thickness of the concrete varied as much as 2 in. from that indicated on the drawing. In only three floors of those investigated, would the disagreement between the predicted and measured frequency have been of any consequence if a vibration problem were present.
Plastic Design of Eccentrically Loaded Fasteners
Authors: Abolitz A. Leon
Published: April 2024

Bolts, rivets, and other fasteners in structural connections are often used in single or multiple shear. If the force incident upon a group of such fasteners is eccentric, the fastener group is subjected to a moment in addition to the force. The capacity of the group to transmit force is in general reduced if a moment must be transmitted at the same time. For each group of fasteners and for each direction of force a relationship exists between the values of the force F and of the moment M that may be applied simultaneously. This relationship may be termed interaction, and is usually expressed in formulas, curves or tables. In many published tables the eccentricity E, rather than the moment M, is used, but by means of the relationship M = FE these tables can be easily converted to the type which gives M versus F. A knowledge of the interaction is indispensable for the design or checking of a group of fasteners under an eccentric load. A fastener group is sometimes loaded by a pure force F0, without any moment. The capacity of a group for pure force F0 is simply the sum of the capacities of the individual fasteners. A group may also be subjected to a pure moment M0, unaccompanied by force; an example is furnished by the bolts in a flanged connection transmitting power in a rotating shaft. The capacity of a group for pure moment M0 is the sum of the contributions of the individual fasteners; this individual contribution is the force exerted by the fastener times the distance to the center of rotation.
The Dry Floor-- A New Approach to High Rise Apartment Buildings
Authors: Newman Joseph H.
Published: April 2024

Tishman Research Corporation has been studying new construction approaches to residential high rise building in connection with the parent companys desire, as owner-builders, to provide more value in what it builds; to help trim costs for other interests whom they serve as a consultant or owners representative; and as part of a team directed by the School of Architecture of Pratt Institute seeking cost reduction methods for low income high rise housing—under HHFA and Ford Foundation grants. Regardless of the auspices, there is a common objective—to decrease costs without sacrificing or by enhancing value. Although the studies and development activity are not quite complete, presented here is a particular approach to the buildings structural system which is believed to have sufficient promise to warrant attention now. It is hoped that it will inspire others and provide a basis to expand thereon. It has already sparked sufficient enthusiasm so that it is planned for use in a high rise project in Philadelphia during 1967.
Updating Standard Shape Material Properties Database for Design and Reliability
Authors: Bartlett F. Michael , Dexter Robert J. , Graeser Mark D. , Jelinek Jason J. , Schmidt Bradley J. , Galambos Theodore V.
Published: April 2024

This paper summarizes the mechanical properties of ASTM A992 steel as determined by tests of 207 flatstrap tensile test specimens at the University of Minnesota and the University of Western Ontario carried out in accordance with ASTM A370. Samples were obtained from 38 heats of steel from eight different shapes provided by three producers. The objectives of the study were to quantify statistical parameters for the mechanical properties of A992 steel and to investigate the necessity of updating the resistance factor for steel in the AISC LRFD Specification (AISC, 1999). The lower tail of the yield strength data is accurately represented by the lognormal distribution reported by Dexter, Graeser, Saari, Pascoe, Gardner, and Galambos (2000). The ratio of the observed yield stress to the corresponding value reported on the Mill Test Report averaged 1.002, with a coefficient of variation of 0.044. The ratio of the flange yield strength to web yield strength averaged 0.95. The difference between the static yield strength
and the yield strength recorded at ASTM A370 strain rates averaged 4.4 ksi. It is concluded that A992 steel has smaller bias coefficients and smaller coefficients of variation compared to the parameters for A36 steel used in the original calibration that have increased the reliability index slightly. At the AISC LRFD calibration point of a live-to-dead ratio of three, the reliability index for a braced compact beam with a resistance factor of 0.9 increases from 2.5 to 2.6 if the discretization factor is ignored or to 2.8 if the discretization factor is included. However, an increase of resistance factor from 0.90 to 0.95 is not recommended without further study.
Development of Design Rules for Composite Construction
Authors: Viest Ivan M.
Published: April 2024

Historical development of the requirements for the design of composite structures made up of steel elements and concrete, as practiced in the United States, is reviewed. Included are buildings and highway bridges. After a brief description of the origins of composite construction in America, an emphasis is placed on early design rules issued by the American Institute of Steel Construction (AISC), American Association of State Highway Transportation Officials (AASHTO), the Joint Committee on Concrete and Reinforced Concrete, and the American Concrete Institute (ACI). The discussion is divided into two parts. The first, dealing with composite beams, traces the development of the AISC and AASHTO requirements; it also includes remarks on the strength of stud shear connectors placed in the trough of a steel deck. AISC, Joint Committee and ACI provisions for composite columns are the subject of the second part of the discussion. Extensive practical experience has demonstrated that composite construction is a system suitable for areas of high seismicity. It has been used in Japan for decades but on the west coast of the United States its use spread only relatively recently. The first U.S. seismic provisions for composite construction were included in the 1994 version of the National Earthquake Hazards Reduction Program's Recommended Provisions for Seismic Regulations for New Buildings issued by the Federal Emergency Management Agency in 1994. AISC included composite construction in the 1997 Seismic Provisions for Structural Steel Buildings and the provisions were also included by reference in the 2000 edition of the International Building Code.
Rationale Behind and Proper Application of the Ductility Factor for Bracing Connections
Authors: Hewitt Christopher M. , Thornton William A.
Published: April 2024

Referenced in Chapter 13 of the AISC LRFD Manual, 3rd Edition is a somewhat elusive stress factor for bracing connections based on research by Dr. Ralph M. Richard at the University of Arizona. The stress factor, commonly referred to as the "Richard Factor"ť, was incorporated into bracing connection design philosophy in the Uniform Force Method to ensure ductility in the connection. The history and relevance of this ductility factor is clarified in this paper, with particular attention given to its function in the current recommendations of the manual.
Effects of Variable Pretension on the Behavior of Bolted Connections with Prying
Authors: Amrine Jennifer J. , Swanson James A.
Published: April 2024

A series of 34 bolted T-stub type connection specimens were tested at the University of Cincinnati as part of an effort to determine if varying levels of pretension within a connection affect the connection's performance. The test program included three different lengths of A325 fasteners, one length of A490 fasteners, and three different levels of pretension. Bolts used to connect the test specimens were instrumented with strain gages and were calibrated to facilitate monitoring of bolt forces during the experiments. Independent testing of the fasteners, which included the monitoring of load/deformation behavior, was performed to verify manufacturer certifications and provide a baseline for comparing connection behavior. It was found that varying the level of pretension in the connection did not appreciably affect the connection strength but did affect the connection stiffness and deformation capacity.
Steel Plate Shear Walls Are Not Plate Girders
Authors: Berman Jeffrey W. , Bruneau Michel
Published: April 2024

Steel plate shear walls that are allowed to buckle in shear and form a diagonal tension field have been the subject of several experimental and analytical studies. In some of these studies, references are made to the physical and analytical similarities between steel plate shear walls and vertical cantilever plate girders. Though these comparisons allow engineers to become quickly familiar with steel plate shear wall concepts in a qualitative way, they have led some to believe that steel plate shear walls can be quantitatively designed using standard plate girder shear strength equations. In this paper, the shear strength of steel plate shear walls found using an accepted model based on plastic analysis, and the shear strength for plate girders calculated from design code equations, are compared with the ultimate strengths of steel plate shear walls obtained from various experimental studies. It is shown that plate girder design equations significantly underestimate the strength of steel plate shear walls, leading to designs with greater-than-expected strength and a breakdown in the capacity design philosophy (i.e. leading to the occurrence of unintended failure modes) as well as an uneconomical use of steel. Strengths calculated from plastic analysis of an accepted analytical model for steel plate shear walls agree well with the experimental studies.
Recommended Procedures for Buckling- Restrained Brace Frames
Authors: Sabelli Rafael
Published: April 2024

This paper contains a document that has been developed to serve as a supplement to existing building codes in order to give guidance to design engineers wishing to employ buckling-restrained braced frames on projects in the United States, as well as to the building officials to whom such designs are submitted. It is expected that the Recommended Provisions for Buckling-Restrained Braced Frames will be included in the 2005 edition of the AISC Seismic Provisions for Structural Steel Buildings. All of the provisions presented are currently under review in the draft of the 2005 Seismic Provisions. The provisions, as they are presented, are suitable for use with the 2002 Seismic Provisions, and include references to other sections of those provisions throughout. Therefore, consistent with the 2002 Seismic Provisions, LRFD format is used.
SAFIR: A Thermal and Structural Program for Modeling Structures Under Fire
Authors: Franssen Jean-Marc
Published: April 2024

SAFIR is a computer program specifically written for modeling the behavior of structures subjected to fire. It allows a determination of the temperatures in the structure resulting from the fire and, in a subsequent analysis, determination of the successive positions of equilibrium of the structure until collapse. The main hypotheses, the possibilities, and the limitations of this program are presented in this paper, as well as a limited number of examples. The equations are given for the determination of the temperatures in the structure, as well as for the truss, the beam and the shell finite elements used in the step-by-step mechanical analyses that can be performed after the thermal analysis.
Performance of the AISC LRFD Specification in Predicting the Capacity of Eccentrically Loaded Single-Angle Struts
Authors: Sakla Sherief S.S.
Published: April 2024

Experimental load-carrying capacities of eccentrically-loaded single-angle struts are used to evaluate the predictions of the current and previous AISC LRFD specifications. Some 91 tests conducted on equal-leg angles and 42 tests conducted on unequal-leg angles were examined. It is shown that the current AISC LRFD specification (AISC, 2000) compares satisfactorily with available experimental results and provides a much better estimate of the load-carrying capacity when compared with the previous version of the specification (AISC, 1993). The current specification provided a lower bound for all unequal-leg test results and slightly overestimated the load-carrying capacity of 15 equal-leg test results. A reliability study, using Monte Carlo simulation, revealed that both equal- and unequal-leg single-angle struts exceeded the target reliability index in the current specification. The common practice of detailing the end connection of single-angle members in such a manner that the load point, located along the connected leg, is as close as possible to the projection of the angle centroid on the connected leg has been investigated using the provisions of the current AISC LRFD specification. As per the current specification, locating the load point at the projection of the centroid on the connected leg does not result in the largest achievable load-carrying capacity.
Toward the Simplified Design of Single-Angle Beam-Columns
Authors: Earls C.J. , Keelor D. Christian
Published: April 2024

Single angle compression members are frequently used as diagonal and lacing members in trusses and in lattice towers. Within this context, connection geometries at the angle ends frequently involve attachment though only one leg of the angle cross-section; thus introducing loading eccentricities and their concomitant end moments. AISC requires that this case be treated as a beam-column involving second order amplification of moments. In contrast, ASCE recommends that the eccentricities in loading be treated though the use of modified effective length factors in conjunction with standard column design methodologies. Recent research by Mengelkoch and Yura compares the two approaches and makes additional recommendations. This latter research is at the heart of proposed modifications to the new combined specification. The current research expands on the new single angle design approach by studying additional column slenderness ratios, loading eccentricities, and varying degrees of rotational restraint at the column ends beyond what was considered by Mengelkoch and Yura.
The Analyses of Extended Shear Tab Steel Connections Part II: Stiffened Connections
Authors: Mahamid Mustafa , Ruhman Adeeb , Ghorbanpoor Al
Published: April 2024

The objective of this paper is similar to the companion paper published in the same issue of the Engineering Journal, to develop a viable, comprehensive 3-D finite element model capable of predicting the nonlinear behavior of shear tab connections, except this paper addresses in detail the analyses and failure prediction of the stiffened shear tab connection versus the unstiffened connections discussed in Part I. Correlation between the results of the computational finite element method and the experimental investigation is established and verified. Past experimental investigations have shown that the unstiffened shear tab connections are prone to twisting failure and low load-carrying capacity. Therefore, the use of stiffened shear tab connections is a viable design approach to overcome these problems. This paper compares various predicted failure modes from a finite element analysis with those observed in a recent experimental study performed by Sherman and Ghorbanpoor. In this paper, three, six, and eight-bolt stiffened extended shear tab connections are analyzed and compared. In addition, five FE models of 2-bolt and deep connections are analyzed in the plastic range to predict their failure modes. These models are two-bolt beam-to-column, 10-bolt beam-to-girder connection, 10-bolt beam-to-column connection, 12-bolt beam-to-girder connection, and 12-bolt beam-to-column connection.The three- and the five-bolt connections failed primarily in shear yielding, bearing failure of the holes around bolts, and in bolt shear. Secondary failure was observed in the form of girder web mechanism and shear tab twist. The eight-bolt connection failed primarily in bolt shear and bearing of holes around bolts. The failure modes predicted by the FE analysis were in agreement with those from the experimental investigation. The locations of high plastic strain, bearing failure of holes, plate twisting mechanism, and the web deterioration were identical in the FE model and the experimental observations. The FE model generated in this analysis proved to be accurate in predicting the failure mechanism of the extended shear tab connections.
Modified Slenderness Ratio for Built-up Members
Authors: Sato Atsushi , Uang Chia-Ming
Published: April 2024

Based on a review of theory, background for the historical development of the AISC specifications, and an updated experimental database, a simple model which maintains the accuracy for the calculation of the modified slenderness ratio of built-up members with closely spaced individual components (for example, double angles and double channels) that are connected by welded or pretensioned bolted connectors is proposed.
Behavior of Steel Joist Girder Structures with PR Column Bases
Authors: Kim Uksun , Leon Roberto T. , Galambos Theodore V.
Published: April 2024

Little guidance is provided by current building codes for the seismic design of one-story, frame-type industrial buildings. This paper describes tests and companion analytical studies on the behavior of a full-scale, one-bay, two-frame joist girder structure aimed at developing seismic design guidelines for joist girder frames. Two issues are highlighted: the use of a capacity approach for seismic design and the influence of both the girder-to-column and column base-to-foundation connections on the seismic performance of these structures. The cyclic test results indicated that the beam-to-column connections can be considered as rigid when properly detailed and that a simplified model based on the 'component method' approach can provide good estimates for both column base stiffness and strength. The companion analytical studies with different column base fixity indicated that the roof drift decreased and base shear increased appreciably when the effect of the column base fixity was accurately modeled. Finally, a practical method that considers the effects of column base fixity and a modified column base design procedure are described.
Limit State Response of Composite Columns and Beam-Columns Part I: Formulation of Design Provisions for the 2005 AISC Specification
Authors: Leon Roberto T. , Kim Dong Keon , Hajjar Jerome F.
Published: April 2024

The 2005 Specification for Structural Steel Buildings contains substantial changes to the design of composite members and composite columns in particular. These revisions are intended to reflect the extensive research in the area of composite steel-concrete structures during the past two decades, as the previous specifications were based on studies from the late 1960s-1970s. This paper describes the databases created and the process followed to develop the new provisions. This process includes the development of both new strength equations for encased and concrete-filled columns and new interaction equations for composite beam-columns as well as considerable liberalization of local buckling and material limits. The paper also discusses other important areas of composite design, such as bond stress between steel HSS sections and concrete, where specification provisions are under development. This is the first of a two-part paper; the second part contains detailed design examples.
Direct Analysis and Design Using Amplified First-Order Analysis Part II: Moment Frames and General Framing Systems
Authors: White Donald W. , Surovek Andrea , Chang Ching-Jen
Published: April 2024

This paper presents an application of the Direct Analysis Method (DM) introduced in the 2005 AISC Specification for Structural Steel Buildings for moment and general combined framing systems. The DM accounts explicitly for nominal initial out-of-plumbness of the framing as well as the reduction in the stiffness of the structure at the maximum strength limit of its most critical member or members. As a result, this approach provides a more rational estimate of the internal forces at the maximum strength limit. Also, the column and beam-column strength checks in moment frames may be based on K = 1 by using this method. One additional modification to a conventional elastic analysis is required in general for beam-columns in moment frames, in other words, the flexural rigidity must be reduced by an additional column inelastic stiffness reduction factor, tau, for columns loaded by axial forces in excess of 0.5Py. This paper proposes two modifications to the underlying amplified first-order elastic analysis approach presented in Part 1 of this paper (published in the same issue), to extend this procedure to general rectangular framing involving any combination of moment, braced and gravity systems. Suggestions are also provided for approximate handling of frames with large axial compression in the beams or rafters and/or nonrectangular geometry.
Limit State Response of Composite Columns and Beam-Columns Part II: Application of Design Provisions for the 2005 AISC Specification
Authors: Leon Roberto T. , Hajjar Jerome F.
Published: April 2024

The 2005 AISC Specification for Structural Steel Buildings contains substantial changes to the design provisions for composite members and composite columns in particular. This paper presents detailed and cross-sectional analysis and design examples for composite columns illustrating the new provisions. The paper focuses on providing a detailed description of the development of simplified equations for the creation of interaction curves for composite beam-columns. This is the second part of a two-part paper; the first paper contains detailed discussion of the development of the new provisions.
Effects of Slab Post-Tensioning on Supporting Steel Beams in Steel Framed Parking Deck Structures
Authors: Sharma Bhavna , Harries Kent A.
Published: April 2024

AISC Design Guide 18, Steel Framed Open-Deck Parking Deck Structures, discusses the use of cast-in-place post tensioned concrete slabs in steel framed parking structures. In Section 3.3.2.1 of Design Guide 18, the authors reflect on the manner in which the post-tensioning force is resisted by and affects the supporting beam: in a noncomposite or composite manner. They conclude that the post-tensioning force is carried almost entirely in a composite manner (minus effects of shrinkage and elastic shortening). This conclusion is based on results of unpublished research and is corroborated by earlier design guidance. The objective of this field study is to quantitatively assess the effect that slab post-tensioning forces have on their supporting steel members.
Current Steel Structures Research No. 17
Authors: Bjorhovde Reidar
Published: April 2024

Current Steel Structures Research
Closure: Block Shear Equations Revisited...Again
Authors: Epstein Howard I. , Aleksiewicz Lance J.
Published: April 2024

Closure
Current Steel Structures Research No. 18
Authors: Bjorhovde Reidar
Published: April 2024

Current Steel Structures Research
Collapse Performance of Low-Ductility Chevron Braced Steel Frames in Moderate Seismic Regions
Authors: Hines Eric M. , Appel Mary E. , Cheever Peter J.
Published: April 2024

This paper discusses non-linear dynamic collapse behavior observed in analytical models of low-ductility chevron braced steel frames designed for 3-, 6-, 9- and 12-story building configurations in Boston, Massachusetts. For each building configuration, three separate designs were developed assuming R = 2, 3, and 4 with no seismic detailing, but accounting for some lateral capacity in the gravity system. A fourth design was developed as a low-ductility dual system, with a primary braced frame system designed to resist wind only, and a secondary moment frame reserve system. These analyses bring to light the need for a clear design philosophy for low-ductility structures in moderate seismic regions. Based on encouraging results for the low-ductility dual system, the concept of reserve system design offers a step toward the definition of this philosophy.
Experimental Study of Bolted Connection Strength at Elevated Temperatures
Authors: Yu Liang , Frank Karl H.
Published: April 2024

Single bolt (A325) connections were tested at temperature up to 800 C (1472 F) to investigate the effect of temperature upon their bearing capacity. Significant stiffness and strength losses were found between 400 C (752 F) and 800 C (1472 F). The failure mode changes from bearing to bolt shear between 300 C (572 F) and 400 C (752 F). Two-bolt (A490) connections are tested from ambient temperature to 800 C (1472 F) to study the effect of temperature upon the block shear capacity. Both the stiffness and the strength of the two-bolt connections decrease between 400 C (752 F) and 800 C (1472 F). The estimated strengths of steel at elevated temperatures given in the Appendix 4 of the 2005 AISC specification overestimated the strength of the connections which failed in block shear of the plate or shear of the bolts. The constant load test results agreed well with constant temperature quasi static test results indicating that creep under constant load does not change the strength of connection at elevated temperature. Residual slip resistance capacity of fully tightened A490 bolt connection was tested after exposure to temperatures up to 800 C (1472 F). After exposure to a temperature above 400 C (752 F), the slip load resistance reduces considerably.
A Beam Design Aid for Structural Tubing
Authors: Geschwindner Louis F.
Published: April 2024

The 2005 AISC Specification includes a stiffness reduction factor, Ï„b, in Appendix 7 to be used in the direct analysis method to account for the presence of residual stresses and their influence on the second order effects of frame behavior. The 2005 Commentary includes a stiffness reduction factor, Ï„a, to be used along with the effective length nomograph to account for the influence of column inelasticity due to residual stresses on effective length. These two stiffness reduction factors are intended to account for the same effect yet they are different. This paper provides the background for these two factors, and it will demonstrate that Ï„b is the more correct stiffness reduction factor. The 2010 AISC Specification will recommend its use with both the direct analysis method and the effective length nomograph.
Impact of Diaphragm Behavior on the Seismic Design of Low-Rise Steel Buildings
Authors: Rogers Colin A. , Tremblay Robert
Published: April 2024

Modern building codes allow engineers to use reduced seismic loads in design provided that the seismic load resisting system (SLRS) of the structure is adequately designed and detailed to withstand strong ground shaking through ductile inelastic response. This approach has been adopted by the North American model codes which typically include special provisions to achieve satisfactory inelastic seismic performance. Single-story buildings often incorporate a steel roof deck diaphragm that is relied on to transfer lateral loads to the vertical bracing bents. The vertical braces are usually selected as the energy dissipating fuse element, while the diaphragm and other elements in the SLRS should be designed such that their capacity exceeds the nominal resistance of the braces. Steel bracing members designed for compression inherently possess significant reserve strength when loaded in tension, which means that large brace tension loads must be considered in the design of the surrounding protected structural components. Capacity design seismic provisions have led to the need for much thicker roof deck panels and more closely spaced diaphragm connection patterns compared with past practice in Canada. This paper describes the current U.S. seismic design approach and provides examples as it is applied to single-story buildings and their diaphragms. An overview of the related aspects of an on-going research project on the flexibility and ductility of the roof diaphragm in low-rise steel buildings is also included.
Mathematical-Mechanical Model of WUF-B Connection Under Monotonic Load
Authors: Yim Hyun Chang , Krauthammer Ted
Published: April 2024

Connections in a steel frame are complex configurations composed of members and elements that contain different geometries, shapes, and material properties. Therefore, one needs to take into account the contributions of such individual components to the overall connection behavior characteristics. This study presents a comprehensive mathematical-mechanical model to determine the welded unreinforced flange-bolted web (WUF-B) connection behavior. The model was developed considering nonlinear characteristics and coupling of individual component properties. The parameters in the mathematical expressions were derived based on collected data from numerical simulations, combined with modified and newly developed mechanical component equations. The models were evaluated by comparing them with finite element analysis results of nonlinear three-dimensional connections. The characterization models, (i.e., equations and procedures) introduced in this paper defined the mechanical properties of the WUF-B connections for a fast and accurate frame analysis of blast-oriented progressive collapse.
An Experimental Analysis of Strength and Ductility of High-Strength Fasteners
Authors: Moore Amy M. , Rassati Gian A. , Swanson James A.
Published: April 2024

A total of 1,533 structural bolts, consisting of four different bolt grades and six different diameters, up to 5 in. in length, were tested in direct tension and shear with the threads excluded and not excluded from the shear plane. Thread lengths, tensile and shear strength, and elongation at failure were measured. The experimental values were then compared to the requirements of the current AISC, RCSC, and ASTM specifications. This paper presents and discusses the results of the experimental tests and of the subsequent comparisons. It is concluded that all fasteners tested meet the minimum strength required by ASTM and RCSC. Furthermore, it is noted that while the strength in tension and in shear with the threads excluded from the shear plane are conservatively assessed by AISC specifications, the strength with the threads not excluded from the shear plane is often not conservatively predicted. As a consequence, an alternative expression for the shear strength with the threads not excluded from the shear plane is proposed. It is also concluded that the actual thread length can be different than the nominal values, potentially affecting the available cross section in shear. Finally, the measurement of the elongation at failure shows that all grades of fastener tested have a satisfactorily ductile behavior.
Transfer Forces in Steel Structures
Authors: Dowswell Bo
Published: April 2024

Transfer forces are loads that are transmitted across joints in a structure. For connections to be designed properly, the transfer forces must be communicated to the connection designer. This paper discusses the calculation of transfer forces and how the connection configuration affects the calculations. Two examples are provided to illustrate the calculation process.
Prediction of Bolted Connection Capacity for Block Shear Failures along Atypical Paths
Authors: Cai Qing , Drive Robert G.
Published: April 2024

Failure modes such as bolt tear-out and the so-called alternate block shear path observed in tees are closely related to the classical block shear limit state, but they have not been addressed as such in current design specifications in North America. In previous work conducted at the University of Alberta, a unified block shear equation was proposed that provides accurate test-to-predicted block shear capacity ratios and results in consistent reliability indices over a variety of connection types. A total of 104 specimens that failed in bolt tear-out and 14 tees that failed on the alternate block shear path are considered from the literature, along with 12 new bolt tear-out tests conducted as part of this research program. It is shown that the unified block shear equation provides accurate and consistent results for these failure modes as well.
Plastic Moment of Intermediate Horizontal Boundary Elements of Steel Plate Shear Walls
Authors: Bruneau Michel , Qu Bing
Published: April 2024

This paper presents results of an analytical study of plastic moment in horizontal boundary elements (HBEs) in steel plate shear walls. To account for the effect of shear and vertical stresses in HBE web, the reduced axial yield strength was studied using the von Mises yield criterion. In the spirit of classic plastic analysis, analytical procedures for estimating plastic moment of the intermediate HBE under equal top and bottom tension fields are developed. Those analytical procedures are then extended for intermediate HBE under unequal top and bottom tension fields. Both positive and negative flexures are considered. Results from the analytical procedures are shown to agree well with those from finite element analysis. Simplified models for estimating plastic moment of HBEs are also developed for design and shown to be accurate.
Strength Design Criteria for Steel Beam-Columns with Fire-Induced Thermal Gradients
Authors: Dwaikat Mahmud M.S. , Kodur Ventkatesh K.R.
Published: April 2024

When exposed to fire, restrained steel members develop significant internal forces, and these forces transform their behavior from beams or columns to that of beam-columns. The current provisions for fire-resistance assessment of such beam-columns through P-M interaction equations are an extension to the ambient interaction equations. These fire design equations take into consideration the reduction in the capacity arising from temperature-induced degradation of strength and stiffness properties but do not take into account the effect of other critical factors, such as thermal gradient, end restraints and realistic fire scenarios (with cooling phase). In this study, the different fire design equations for steel beam-columns are compared against results from nonlinear finite element simulations. Results from the analysis show that fire-induced thermal gradient leads to not only a reduction in the P-M diagrams, but also a noticeable distortion in the shape of the P-M diagrams. Therefore, modifications are proposed to the current design interaction equations for steel beam-columns at elevated temperatures. The modified P-M design equations are validated against results from fire tests and from finite element analysis and then illustrated through a design example. The proposed approach requires minimum computational effort and provides better assessment of beam-columns under fire when compared to current provisions
Performance of the Unified Block Shear Equation for Common Types of Welded Steel Connections
Authors: Steven A. Oosterhof and Robert G. Driver
Published: April 2024

Block shear describes a steel connection failure mode in which a combination of tensile and shear failures along perpendicular planes results in a block of material being displaced from a member. This behavior has been observed to govern the design of many bolted connections and has been well researched, resulting in design equations of various forms. Certain arrangements of welded connections are also susceptible to block shear. This paper reports on the potential application of a "unified"� block shear equation, proposed by Driver et al. (2006) for bolted connections, to various welded connections. Experimental results for welded steel lap plate connections loaded concentrically in tension are examined. The results of these tests are used to describe the connection behavior and to evaluate the performance of several design equations, including the proposed "unified"� equation. The application of the unified equation to welded connections of slotted hollow structural sections (HSS) and to coped beams supported at their ends by a clip angle welded to the beam web.
Current Steel Structures Research No. 26
Authors: Bjorhovde Reidar
Published: April 2024

Current Steel Structures Research
Mechanical Properties of ASTM A992 Steel After Fire
Authors: Lee Jinwoo , Engelhardt Michael D. , Taleff Eric M.
Published: April 2024

When evaluating the condition and safety of a steel structure following a fire, an issue of concern is the mechanical properties of the steel after the fire. The exposure of the steel to high temperatures during the fire, and the subsequent cooling of the steel after the fire can potentially affect the mechanical properties of the steel. A testing program was undertaken by the authors to measure the mechanical properties of ASTM A992 steel after being subjected to various patterns of heating and cooling. This paper presents results of the test program and provides data on the effect of various heating and cooling cycles on key mechanical properties, including yield strength, tensile strength, elastic modulus, elongation, Charpy V-Notch(CVN) impact values, and hardness.
Bond Behavior of Concrete-Filled Steel Tube (CFT) Strucutres
Authors: Jie Zhang Mark D. Denavit
Published: April 2024

To achieve internal force transfer while avoiding the use of steel stud anchors or a bearing mechanism within concrete-filled steel tubes (CFTs), an accurate assessment of the bond strength of CFTs is required. However, calculation of the bond within CFTs remains a challenging problem due to lack of a general procedure that can account for the range of connection configurations seen within composite construction. A new approach for assessing the nominal bond strength for both rectangular and circular CFTs is proposed. Based on the results of push-out experiments of CFTs, the nominal bond stress is shown to vary with tube shape and dimensions, and formulas are proposed to capture this behavior. The longitudinal bond transfer length is derived by examining the distribution of bond stress along the height of the column as well as experimental data from CFT connection tests. The circumferential bond transfer width is identified as the entire perimeter of the interface, accounting for the contribution to the bond strength from the interface on the sides that do not have girders or braces framing in. The resulting nominal bond strength is then shown to have a resistance factor of 0.45 for load and resistance factor design (LRFD) and safety factor of 3.33 for allowable strength design (ASD).
Discussion: Ponding of Two-Way Roof Systems
Authors: Sawyer Donald A. , Marino Frank J.
Published: April 2024

Discussion
Discussion: Allowable Loads on Beams without Lateral Support
Authors: Grant James K.
Published: April 2024

Discussion