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A new type of composite steel slab system called TUBEDECK (TD) has been proposed, which combines a cast-in-situ RC slab with circular tube voids and profiled steel decks. In order to invest...

The problem of assessing the damage to and remaining life of structures subjected to fatigue is explored, with particular emphasis on railroad bridges, highway bridges, and offshore structures. In railroad structures, the fatigue reliability estimates are typically calculated based on fatigue life predictions. The resulting predictions are used for budgeting purposes rather than for scheduling repairs. Examples are given of economic decision based on fatigue life calculations. Fatigue reliability estimates for highway bridges are also typically based on fatigue life calculations. Target reliability values have been suggested and are used in both the design of new bridges and the evaluation of existing bridges. Given the economics of offshore structures, it is feasible to develop more elaborate fracture mechanics models. These models have the advantage of explicitly allowing updated estimates of fatigue reliability based on inspection results. The economics of inspection of offshore structures also dictate...

The need for reassessment of the fatigue life of existing structures is increasing as the world’s infrastructure ages. A fatigue life reassessment typically begins with an assessment of the current condition of the structure. The condition assessment techniques range from visual inspection to X-ray inspection or detection of acoustic emissions. The fatigue reliability of the structure can be estimated from probabilistic fatigue life or fracture mechanics models. The data obtained from the condition assessment can be combined with these models to estimate the remaining service life of a structure using Bayes’ theorem. Simulation techniques are often used to facilitate these calculations. If the remaining service life is inadequate, it may be desirable to repair the structure; however, repairs must be performed carefully to provide the desired benefit. On the other hand, economic factors may dictate a course of action other than repair, such as replacing the structure or changing the operation of the structure.

The Journal has experienced substantial growth in the last few years which resulted in an additional growth of 300 printed pages, a change in page budget in 2004. During this time, we have also experienced a high impact factor of 0.77 in 2004 which is among the highest for comparable journals in the field. The Immediacy Index for JSE exceeds all other structural engineering and related journals by a wide margin. The Impact Factor and the Immediacy Index are two standard metrics used to measure citations to journal articles over time. The build-up of citations typically follows a curve referred to as the “citation curve.” The impact factor is a measure of the relative size of the citation curve in the second and third years. It is calculated by dividing the number of citations to papers published in the two previous years by the number of papers published in those same years. The immediacy index, on the other hand, provides a measure of the skewness of the citation curve and is calculated by dividing the citations in the current year by the number of papers it publishes in that year. This is a measure of how quickly items in that journal get cited upon publication. While these figures are encouraging, there are some recent trends that are also a cause for concern. The most recent statistics for the Journal indicates that the median turnaround time from submission to publication has increased from 19 to 21 months, despite the fact that there has been an increased in printed pages. The primary cause for the increased turnaround time is mostly delays in the review process. While the blame can sometimes be attributed to Associate Editors handling the review of papers, some of the blame has also to point to those of us, who are called upon to conduct the peer review of submitted manuscripts. Since self-citations meaning citations in a paper to articles previously published in the same journal are included in the impact factor calculation, it is obvious given the 20+ month turnaround that the current impact factor of the Journal is generated almost exclusively by citations to JSE by papers published in other journals. A reduction in the mean turnaround time can contribute significantly to both the appeal of the journal and to further increasing the impact factor. I recognize that focusing on such metrics should not be the sole objective of a premier journal.

The paper presents an adaptive section discretization scheme for the inelastic response analysis of structural members with cross sections that can be decomposed into rectangular and circular subdomains. Each subdomain can consist of a different material. As long as the largest strain in a subdomain does not exceed the specified trigger strain values, the subdomain contribution to the section response is determined by the numerically exact cubature rule for the subdomain. Once the largest strain reaches the trigger value for a subdomain, it is discretized with a fiber mesh and the numerical evaluation of its contribution to the section response is determined with the midpoint integration rule. The fiber mesh with the midpoint integration rule remains in effect for the activated subdomain until the end of the response history. The paper applies the adaptive discretization scheme to the thin-walled sections common in metallic structures and investigates the effect of different trigger strain values on the accuracy and computational efficiency of the inelastic response analysis of wide-flange steel sections and multistory steel frames under static and dynamic excitations.

This paper describes the state of the art of structural steel reuse in Japan. A significant part of the material is taken from a document titled the Architectural Institute of Japan (AIJ) Recommendations for Sustainable Steel Building Construction (Draft) available only in the Japanese language. The motivations for and potential benefits of steel reuse are examined. The affinity between seismic design requirements and steel reuse is highlighted through a concept known as damage-control design. Some technologies for disassembly are introduced. The historical development and changes in Japanese structural steel are summarized, followed by a discussion on reusability of historical steel reclaimed from existing buildings. Reuse projects whose details are known to the authors are listed. The heart of the paper is a design procedure that specifies the structural engineer's role and involvement in planning, material procurement, and executing a steel reuse project. The discussion is concluded by six directions that should be pursued to make steel reuse a widely accepted reality in Japan. Among those directions are research needs to establish a procedure to quantify the remaining structural performance of reclaimed steel considering possible exposure to earthquakes, establish connections that allow for easy disassembly, and introduce modularized structural systems. High seismicity and the general practice to adopt full moment frames pose unique challenges for steel reuse in Japan.

This paper presents the results of an experimental investigation on the performance of half-scale, unbonded, post-tensioning, precast concrete walls subjected to fully reversed cyclic loads. Moreover, this paper discusses the damage progression and failure mechanism of each specimen, associated with their construction details (damper types and confinement details of the boundary elements). Five isolated walls were tested, each consisting of precast concrete panels joined only by unbonded post-tensioning strands. The bottom joint of the walls featured two kinds of dampers: Three specimens had mild steel reinforcement, crossing the bottom joint, and the other two specimens had external replaceable hysteretic dampers, attached to the wall sides. Different types of confinement details at the boundary elements were used among the specimens. Steel fibers were mixed into the concrete of one specimen. The prestressing load ratio was 0.05 in most of the specimens. An additional axial load of 468.5 kN was applied to each specimen (additional axial load ratio of about 0.04), before any lateral loading. Quasi-static, displacement-controlled loads were applied to the specimens until a significant strength reduction was observed. Although only moderate axial loads were applied, most of the specimens sustained drifts above 3% while maintaining their lateral strength, gravity load stability, and self-centering. A better performance was observed in the specimens with external dampers, with drifts above 4%, less residual drifts and less cover concrete spalling, particularly in the specimen with steel fibers. The external dampers were very effective in dissipating energy before fracture, until 3% drifts. On the other hand, the specimens with internal dampers sustained unexpected damage at their bottom joint, after reaching their peak strength. For instance, the gravity load-carrying capacity of one specimen with internal dampers was compromised after 4% drifts. Then, the use of external replaceable dampers provided higher performance and post-earthquake recovery for unbonded post-tensioned precast walls. Additional design recommendations are provided based on the test results. Keywords: Shear walls; Precast concrete; Post-tensioning; Seismic dampers; Self-centering system; Energy dissipation; Hybrid walls.

This paper presents an analytical procedure to assess the monotonic (envelope) force-deformation response (capacity curve) of unbonded post-tensioning precast concrete (UPT) walls with internal and external replaceable dampers. This procedure, which can also be used to design UPT walls, was compared and validated against experimental evidence. A close agreement (strength discrepancies of 2% on average) was found between the response predictions and experimental results. This agreement was maintained until peak strength was achieved. Moreover, fiber-based models were implemented to further study the cyclic behavior of UPT walls designed according to the proposed analytical procedure. The numerical models were accurate in representing the global cyclic behavior of UPT walls in terms of strength, displacement capacity, and energy dissipation; nonetheless, these models showed some discrepancies in capturing the residual drifts of some UPTwalls with internal dampers. A parametric analysis was also conducted to explore the influence of some design parameters on the deformation capacity and energy dissipation of UPTwalls. It was found that the ratio of damper reinforcement is critical for the energy dissipation and self-centering capacity of UPT walls, so ratios of 0.10 to 0.25 should be provided to follow the limit states indicated in this paper. Based on the results, the analytical procedure and limit states presented in this paper are considered suitable for UPT walls with external replaceable dampers under total axial load ratios equal or lower than 0.125. keywords: Post-tensioning; Precast concrete; Self-centering system; Shear walls; Nonlinear analysis; Finite element (FE) analysis; Fiber models; Seismic dampers.

It is generally taken as a given that there is no reasonable design concept that could have prevented the collapse of the Twin Towers, once it was initiated, from progressing all the way down to the ground. This view is rooted in the idea that the force generated during the inevitable impact between what may be called the intact upper section (IUS) and the intact lower section (ILS)—meaning the building sections above and below the initially lost columns, respectively—will exceed by at least one order of magnitude the capacity of the latter. On closer inspection, this turns out to be only partially correct—it is correct with regard to the topmost floor plate of the ILS but not with regard to the columns below this floor plate. This paper shows that if the ILS in the Twin Towers had been topped by a stronger-than-ordinary floor plate allowing the columns below to respond properly, rather than be bypassed, these columns—and with them the ILS—would likely have survived. The paper subsequently proposes a building design concept consisting in the insertion of strengthened floor plates in intervals of 10–20 stories.

This paper, which is the second of two companion papers, presents the results of a large-scale testing program on a novel bridge column design, termed polyurethane (PU)-enhanced rocking col...

This paper, which is the first of two companion papers, investigates the performance of a novel bridge column design, termed polyurethane (PU)-enhanced rocking column with energy dissipatio...

This data paper reviews the experimental research on fully restrained beam-to-column connections for steel moment-resisting frames (MRFs) over the last 50 years worldwide and presents an experimental database consisting of 100 tests with an emphasis on those exhibiting inelastic panel zone behavior. The collected data, which is organized in a consistent format, includes full digitized histories of the local panel zone shear force-shear distortion as well as the global force-displacement hysteretic diagrams of each experiment. In most cases the original data was only available in paper format. The gathered dataset suggests that the existing panel zone models that are currently used for the seismic design of steel MRFs deviate, in some cases considerably, from the measured response quantities of an actual panel zone. These involve the panel zone stiffness and shear resistance at selected inelastic shear distortions of interest to the engineering profession. The assembled inelastic panel zone database provides ranges in which post-Northridge beam-to-column connections, which exhibit considerable inelastic deformations within the panel zone web, may achieve lateral drift demands larger than 4% without experiencing premature fracture. The assembled dataset constitutes an important source for validation of continuum finite-element models that could aid the simulation-based engineering design of steel MRF beam-to-column connections designed with a balanced design approach. The database is made available to the engineering and research communities through a publicly available data repository. (C) 2021 American Society of Civil Engineers.

In this paper, an experimental program is presented consisting of 13 experiments on welded stainless steel I-profile beams subjected to lateral torsional buckling, in which 11 specimens are made of the lean duplex stainless grades EN 1.4062 and EN 1.4162, while the last two specimens are made of the austenitic grade EN 1.4404. The beam heights are 160, 210, and 260 mm, and the beams have a constant flange width of 160 mm. This results in three different strong axis elastic section moduli but similar weak axis bending resistances. The range of beam buckling length covers slenderness values from 0.30 to 0.76. The geometrical imperfections of the specimens were measured using digital image correlation (DIC). The web was first measured along its whole length. Then, the beam was placed on its fork supports, and the imperfection was then remeasured once more to check the influence of both gravity and test setup. Traditional four-point bending tests were carried out, and during which, the displacements were measured using linear variable differential transformer (LVDTs), inclinometers, and DIC. In this paper, the measured ultimate moments, together with results of experiments collected in the literature, are compared to the design rules provided in EN 1993-1-4, for which a safe but rather conservative design is obtained, and to the recent proposal of Taras and Greiner dedicated to carbon steel beams. The latter provides better results for high slenderness values but can be further improved.

Flanged RC squat walls, defined by a shear span ratio less than two, are widely used in conventional buildings and nuclear facilities. However, due to the mechanical defects and insufficient parameters included, equations available in building codes and the literature exhibit significant scatter in predicting the peak shear strength of such walls. In this paper, a modified strut-and-tie model, including effects of flanges, was developed to account for the force-resisting mechanism in flanged RC squat walls and to derive the function form of the peak shear strength equation. Nonlinear regression was conducted to obtain the magnitude of unknown coefficients in the function form using a database containing 119 walls. The finalized equation was simplified and evaluated with models available in the literature. Results revealed that the proposed equation performs much better than current methods and provides guidance for the design of flanged RC squat walls. The work presented in this paper was supported by the Natural Science Foundation of Zhejiang Province, China (Grant No. LQ19E080008); the National Science Foundation of China (Grant No. 51808397), and the Shanghai Pujiang Program (Grant No. 18PJ1410100).

This paper formulates an analytical calculation model for predicting the cracking behavior of reinforced concrete ties to provide more consistent crack width calculation methods for large-scale concrete structures in which large bar diameters and covers are used. The calculation model was derived based on the physical behavior of reinforced concrete ties reported from experiments and finite-element analyses in the literature. The derivations led to a second order differential equation for the slip that accounts for the three-dimensional effects of internal cracking by using a proper bond-slip law. The second order differential equation for the slip was solved completely analytically, resulting in a closed-form solution in the case of lightly loaded members and in a non-closed-form solution in the case of heavily loaded members. Finally, the paper provides a solution strategy to facilitate a practical and applicable method for predicting the complete cracking response. Comparison with experimental and finite-element results in the literature demonstrated the ability of the calculation model to predict crack widths and crack spacing consistently and on the conservative side regardless of the bar diameter and cover. © 2020. This is the authors' accepted and refereed manuscript to the article. The final authenticated version is available online at: http://dx.doi.org/10.1061/(ASCE)ST.1943-541X.0002510

Structural insulated panels, commonly known as SIPs, constitute a panelized building system composed of external facer panels, such as oriented strandboard (OSB) sheets, bonded to a lightweight foam core. As the demand for SIPs increases as an alternative to light-frame construction in residential and light-commercial buildings, so too does the need for proper design requirements to satisfy regulatory agencies and building officials. This paper describes a combined experimental and analytical study whose objective was to investigate the structural behavior of OSB-faced SIPs subject to short-term axial loading. A total of 53 panels with varying types of foam core, thickness, and other construction details were subjected to concentric and eccentric loading. The test results indicated that the strength of SIPs was primarily influenced by the panel slenderness and the type of foam core. Reliability-based design expressions were developed for the ultimate limit state of SIPs subjected to short-duration concentric and eccentric axial loading. The results were also compared to current allowable stress design practices. In addition to presenting important test data for researchers, this paper presents a number of practical design recommendations to improve the performance of SIPs

This paper introduces a grid-purlin system, which was composed of secondary rectangular-hollow-section grids welded onto the top flange of I-shaped beams of moment frames. The welded grid-purlin itself may play a role of a lateral bracing member for the welded beam. However, the ultimate strength, plastic rotation capacity, or other structural characteristics of this grid-purlin system remain poorly understood. This paper presents two full-scale cyclic loading tests on specimens with I-shaped beams 700 mm deep, 240 mm wide, and 13 m long. The diagonal length of grids in the square grid-purlin of the specimen was 1.3 m on-center, and two different depths of the sections were selected for the purlin sections. Both specimens successfully achieved fully plastic moments at a plastic rotation exceeding 0.04 rad. This shows that the grid-purlin system provides reliable lateral bracing. Continuum finite-element (CFE) analysis was performed to simulate the hysteretic experimental response of the grid-purlin system. This CFE model was used to examine the plastic rotation capacity for a variety of combinations of I-shaped beams and grid-purlins.

Web crippling failure governs the behavior of thin cold-formed steel lipped channel beams (LCBs) used in floor systems. This paper describes a numerical modeling–based research study undertaken to investigate the web crippling behavior of LCBs under one-flange load cases and to develop improved design equations for possible inclusion in the cold-formed steel design standards. Finite-element models were developed to simulate the web crippling behavior of LCBs and their accuracy was verified using 36 web crippling tests of LCBs conducted under one-flange load cases using the new standard test method. A detailed numerical parametric study was then undertaken to investigate the web crippling behavior of LCBs using the verified finite element models of LCBs. This numerical parametric study provided an extensive web crippling capacity database and improved the understanding of the effects of key web crippling parameters such as inside bent radius, bearing length, and yield stress on the web crippling capacity. Using these results, new and improved web crippling design equations were proposed in this paper for LCBs under one-flange load cases. They include both unified web crippling equations and the direct strength method–based equations. This paper demonstrated the improved accuracy of the proposed equations and their potential for inclusion in the cold-formed steel design standards.

This paper examines the validity of the Whitmore net section tension capacity for the design of bolted gusset plates. Using simple algebra, this paper first shows that the Whitmore criterio...

This paper investigates the behavior of reduced web section (RWS) steel-concrete composite (SCC) beam-to-column connections with circular web openings through a comprehensive finite element (FE) analysis following experimental and computational studies. Results showed that the presence of a circular web opening is effective to move the plastic hinge away from the column shear panel zone and the main connection components including the welding beam-column welding area, and hence, significantly improve the ductility and energy dissipation of the connection without critically affecting its capacity. The composite action was not considered in the literature to account for the severest case (slab acts as load only) in terms of load carrying capacity. However, this study proves that the composite effect has a decisive role in the calculation of the ductility and rotational capacity, and if not considered may result in an overestimated ductile behavior. On the other hand, in cases where composite action is not provided, depending on the particular flooring system, noncomposite steel connections may be considered where the ductility and energy dissipation gains are definitely higher but the load carrying capacity is lower. This paper establishes the comparison between composite and noncomposite connections and concludes that the contribution of the composite action to the load carrying capacity is higher with the increase of the beam web opening diameter. Therefore, the calculated negative load carrying capacity tends to be very conservative if the composite effect is neglected when a large opening diameter is used.

This paper reports the results of an experimental investigation of the shear behavior of beams made using hybrid fiber–engineered cementitious composites (HFECC). The paper specifically dea...

Recent postearthquake missions have shown that reinforced concrete (RC) wall buildings can experience critical damage owing to lap splices, which led to a recent surge in experimental tests of walls with such constructional details. Most of the 16 wall tests described in the literature thus far were carried out in the last six years. This paper presents a database with these wall tests, including the description of a new test on a wall with lap splices and a corresponding reference wall with continuous reinforcement. They complement the existing tests by investigating a spliced member with a shear span ratio smaller than two, which is the smallest among them. The objective of this database is to collect information not just on the force capacity but mainly on the deformation capacity of lap splices in reinforced concrete walls. It is shown that (1) well-confined lap splices relocate the plastic hinge above the lap splice, (2) lap splices with adequate lengths but insufficiently confined attain the peak force but their deformation capacity is significantly reduced, and (3) short and not well-confined lap splices fail before reaching the strength capacity. The analysis of the test results, which are used in the companion paper for the finite element analysis of walls with lap splices, indicates in particular that the confining reinforcement ratio and the ratio of shear span to lap splice length influence the lap splice strain capacity.

The open-space damping system has been developed to preserve open space within the frame of its installation. An earlier paper by the authors described its function, presented a theory to describe its behavior, and presented computational models to verify the theory. This paper describes an experimental study of a large-scale model with the open-space damping system that is used to acquire data for validating the developed analytical and computational models. Testing consisted of (1) a single portal frame tested under imposed lateral motion, and (2) a single story 146 kN model tested on an earthquake simulator under seismic excitation. Two different configurations of the open-space system (plus a third variant of one of the two) in three different structural system configurations were tested. The tests demonstrate the increase in damping provided by the damping system. Comparisons of experimental results (in terms of structural drift, floor accelerations, and force-displacement loops) to results obtained by computational tools demonstrate the validity of the computational model. (C) 2017 American Society of Civil Engineers.

This paper examines the accuracy of design equations specified in the North American, European, and Australasian codes for cold-formed steel structures in determining the ultimate tilt-bearing capacity of single-shear bolted connections without washers in flat steel sheets. It points out that all the code equations do not properly distinguish the tilt-bearing failure mode from the conventional bearing failure mode. While the latter takes place downstream of the bolt, the former takes place upstream. Unlike the conventional bearing capacity, the tilt-bearing capacity is affected by the width of the connected sheet and does not vary linearly with either the sheet thickness or the bolt diameter. Furthermore, it is not affected by material ductility. Based on the test results of 156 specimens composed of G2 and G450 sheet steels having various dimensional configurations, this paper proposes a design equation that is dimensionally consistent and that is considerably more accurate than all the code equa...

Seismic energy dissipation systems are typically installed in buildings within diagonal or chevron bracing to improve the seismic performance by reducing drift, and under certain conditions by reducing acceleration. Alternative installation methods have been developed in which novel mechanisms are used to magnify the displacements within the damping system, and thus improve performance when drift is small, and to reduce the cost of the damping system. Examples are the lever-arm, the toggle-brace, the coupled-truss, and the scissor-jack damper systems, which have found a limited number of applications. All damping system installation methods visually and physically obstruct an otherwise accessible area within the bay of the frame to which they are installed. This drawback has resulted in the occasional rejection of use of damping systems by architects. This paper introduces a novel configuration for damping devices with the main advantage of preserving open space within the frame of installation (hence the name open space damping system). The paper introduces the concept, presents the theory, and then presents computational models to verify the theory and to investigate the effects of the frame configuration, frame deformations, large rotations of the damping system, and frame inelastic action on the effectiveness of the system. (C) 2016 American Society of Civil Engineers.

Strengthening of deteriorating structural members by fiber-reinforced polymers (FRPs) is an increasingly common and validated technique; however, concerns over means to evaluate the long-term durability of these retrofits exist. This paper explores a novel approach to overcome this concern through the use of a novel self-sensing composite material. Specifically, the objective of this paper is to provide a proof of concept for an integrated strengthening and sensing methodology for structural steel members achieved via infusing more-traditional composites with carbon nanotubes (CNTs). To assess the strengthening and sensing capabilities of the CNT-based composite, a set of unidirectional tensile tests were conducted. The experimental results show stiffness increases and strain reductions due to the application of the CNT-based sensing composites that were in close agreement with both analytical and finite-element models. The sensing aspect was also validated by a corresponding linear change in resi...

The objective of this paper is to employ the results from the extensive instrumentation installed on recently tested full-scale cold-formed steel (CFS)-framed buildings to reveal a deeper understanding of the behavior of the building under seismic excitations. In particular, this paper complements a companion paper that focuses on system-level design and response. Here, utilizing strategically located string potentiometers, strain gauges, and accelerometers, the responses of the walls and diaphragms are isolated from the overall building response and studied. The interaction of shear walls along a wall line, as well as across stories is studied through measured data on strains in hold-down anchors, strains on floor-to-floor strap connecting shear-wall chord studs, and displacements across shear-wall sheathing and openings. The behavior of the floor diaphragm is studied through displacements measured perpendicular to the plane of one wall of the building and accelerometers throughout the floor of t...

The paper presents the experimental and numerical study of a mild steel replaceable dissipation device. The dissipater is made of a milled-down mild steel bar that is confined by a steel tube filled with either grout or epoxy. The use of a reduced area concentrates yielding and plastic straining over a defined length while the tube prevents buckling. The device has been widely adopted in posttensioned rocking systems, and extensive experimental research was carried out on wall and beam-column subassemblies using this external dissipater. As part of those experimental programs, some component testing was carried out; nevertheless, a more comprehensive study was necessary to cover a wider range of geometric and mechanical parameters. The main objective of this research was to calibrate and suggest design parameters to support the design of the dissipation device. The paper shows a comprehensive experimental program under quasi-static cyclic loading carried out with varying geometrical parameters. Th...

© 2016 American Society of Civil Engineers. A simple procedure to calibrate the safety factor of capacity models is presented. The calibration can be carried out based on any available database of experimental tests, even of limited size. The procedure aims to assess the model capability of predicting the test results and to calibrate the safety factor so that the capacity equation meets the target reliability level required by the code or sought by the calibrator. After predicting each test of the database with the capacity equation under consideration, the test-prediction pairs are checked for the property of linearity, and the relative error for the properties of homoscedasticity and normality. Once these properties are fulfilled - which may require a nonlinear transformation of the test values and/or the predictions - the closed-form equation proposed in this paper is employed to compute a target design value. The model safety factor is finally obtained by comparing such target design value with the design value obtained from the code. The paper also proposes two approximate analytical equations to compute the tolerance factor, used to attain any given fractile, as a function of the (even small) number of tests, with any assigned confidence level. A fundamental outcome of the procedure is that it yields an objective indicator of the model accuracy, measured by the standard deviation of its error, which may be regarded as a parameter useful for selecting the most reliable model among different competing ones. In the long run, the application of the proposed procedure will allow achieving a uniform reliability level throughout all capacity models used in codes and guidelines. A further advantage is that the partial safety factors so derived can be straightforwardly updated when more experiments become available. As an example, the proposed procedure is herein applied to the ACI 318 shear design capacity equation for concrete members unreinforced in shear.

Rock-concert events in stadiums have raised complaints among dwellers of neighborhood buildings about annoying vibrations in Buenos Aires, Argentina, Wellington, New Zealand, Medellin, Colombia, and other cities around the world. Controversy about the causes and effects of vibrations has produced demands, alarms among inhabitants, and cancellations of spectacles with large economic consequences. Although the analysis and effects of vibrations on the stadium grandstands are well known, no comprehensive published paper could be found that addressed the effects of vibrations on neighborhood buildings when thousands of spectators jump on a stadium field. This paper covers this gap in civil engineering knowledge, introducing a systematic study (analytical and experimental) to explain the causes, predict building responses, and determine the size of the expected human, structural, and cosmetic effects on neighborhood buildings. First, the equations for modeling are presented: (1) the coordinated jump of...

The material presented in this paper refers to a part of the investigation on cross-laminated (XLam) wall panel systems subjected to seismic excitation, carried out within the bilateral project realized by the Institute of Earthquake Engineering and Engineering Seismology (IZIIS) and the Faculty of Civil and Geodetic Engineering at the University of Ljubljana (UL FCGE). The full program of the research consists of basic tests of small XLam wooden blocks and quasi-static tests of anchors, then quasi-static tests of full-scale wall panels with given anchors, shaking-table tests of two types of XLam systems including ambient-vibration tests, and finally analytical research for the definition of the computational model for the analysis of these structural systems. In this paper, the full-scale shaking-table tests for one XLam system type (i.e., specimen 1 consisting of two single-unit massive wooden XLam panels) that have been performed in the IZIIS laboratory are discussed. The principal objectives o...

The purpose of this paper is to discuss issues associated with ASCE 7-10 standard methods for determining wind loads on buildings and other structures that warrant comment, correction, or improvement. The assessment is intended to serve as a resource in the development of a new version of the ASCE 7 standard and to stimulate a wider participation in that development by the structural engineering community. Issues discussed in the paper include: wind speeds in nonhurricane regions; alternative analytical methods for determining wind loads and wind effects on main wind force resisting systems and components and/or cladding; aerodynamic pressure coefficients; pressures on rooftop equipment; component and cladding pressures on arched roofs; and the wind tunnel procedure. It is noted that the ASCE 49 standard essentially covers wind tunnel testing, rather than the wind tunnel procedure, of which wind tunnel testing is only a part.

This paper presents probabilistic models for the structural performance of rounded dovetail joints. The models are developed with a Bayesian technique, which implies that the model uncertainty is explicitly characterized by random variables. The Bayesian approach also promotes model updating when new test results become available in the future. Practical insight is gained from the modeling process, which includes a novel search for influential parameters, and from the subsequent probabilistic analysis with the models. The models are based on 80 tests of single and double dovetail joints with varying geometric parameters, specifically the flange angle and the dovetail height. A significant effort was made to record variables that conceivably influence the performance of this type of joint, including a series of material parameters: tension strength perpendicular to grain, shear strength parallel to grain, moisture content, density, growth ring density, and growth ring orientation. This paper explor...

This paper presents a new two-dimensional shear-wall and diaphragm model developed as part of a Network for Earthquake Engineering Simulation (NEES) Project entitled NEES-Soft: Seismic Risk Reduction for Soft-Story Woodframe Buildings. A large portion of the older multistory buildings in the California region were constructed with a deficiency that makes them vulnerable to collapse in the first story during earthquakes. This deficiency is referred to as soft-story. The new model presented in this paper was developed using a corotational formulation, which makes it suitable for modeling the side-sway collapse of wood shear walls under large displacement as well as estimating the in-plane stiffness of floor diaphragms. To achieve high computational efficiency, a nodal condensation technique is used to eliminate the degrees of freedom (DOFs) associated with the nail connections from the global DOFs of the model. To verify the validity of the new model, the model was coded into a computer program and ...

This paper describes the cyberinfrastructure (CI) of the George E. Brown, Jr. Network for Earthquake Engineering Simulation (NEES) and examines the evidence that this infrastructure is facilitating earthquake engineering research. Among the key features of the CI are the NEES Project Warehouse (PW), which is a data repository for earthquake engineering, an environment that supports the use of tools for web-based data analysis and simulation, and tools that support research collaboration. The value that such CI offers to the user community is discussed. The CI also gathers a myriad of usage statistics, some of which are presented in this paper. Among them are the number of users, pageviews, recorded NEES projects, and other stored resources. This information demonstrates that the CI is used significantly and increasingly so.

Available capacity models for the assessment of seismic capacity of reinforced concrete columns are mainly based on experimental tests under axial load and uniaxial bending. Furthermore, experimental tests have been mainly performed on columns representative of new constructions. In order to analyze the effects of biaxial bending on the seismic performances of existing r.c. columns with design characteristics non-conforming to present day seismic codes and practices, the paper presents the results of a first stage of tests on r.c columns under both axial load and biaxial bending, which effectively simulate the seismic actions. In particular, the paper presents results of four tests on full scale square columns reinforced with plain bars, subjected to constant axial load and biaxial cyclic actions. Two different cyclic displacement paths were investigated: horizontal displacements with an inclination angle of 45or 30 with respect to the cross section principal axes. The influence of biaxial bending actions on the global behavior of existing r.c. columns in terms of stiffness, strength, and deformation capacity as well as the effects of different horizontal displacements orientation on their performances are herein investigated and discussed; the comparison with experimental outcomes provided by uniaxial bending tests on companion specimens are also presented. Experimental findings showed that biaxial bending actions affect columns rotational capacity more than strength. The rotational capacity reduction owing to biaxial bending actions, even if more significant than the flexural capacity reduction, is not currently taken into account in the available seismic guidelines related to existing r.c. buildings.

This paper deals with the ultimate strength and design of fixed-ended lipped channel columns experiencing local-distortional buckling mode interaction. First, the paper reports the results of an experimental investigation involving a set of 26 columns with several cross-section dimensions and yield stresses that were tested to determine their failure loads and also to provide experimental evidence of the occurrence of local-distortional mode interaction. These results consist of the column geometries, material properties, initial geometric imperfections, nonlinear equilibrium paths, and ultimate strength values. Then, after comparing the experimental column ultimate loads with the estimates provided by the current direct strength method (DSM) design curves against local and distortional failures, which clearly show that they lead to inaccurate and often very unsafe ultimate strength estimates, the paper presents and assesses the quality of DSM-based design procedures based on approaches providing nominal strengths against local-distortional and distortional-local interactive failures. Next, an in-depth comparison is made between all the experimental ultimate strength results available in the literature and their estimates provided by the preceding DSM design procedures. Finally, the paper closes with design considerations and recommendations, motivated by the conclusions drawn from this investigation.

The paper summarizes the main new design provisions included in the recently revised Australian standard for steel storage racks. The standard features multitiered analysis provisions ranging from basic linear-elastic analysis-based provisions to highly advanced integrated design-analysis [geometric and material nonlinear analysis with imperfections (GMNIA)] provisions that allow the analysis and design to be completed in one step. The GMNIA provisions distinguish between beam element–based and shell element–based analysis according to cross section slenderness and provide rules for the imperfections to use for the two types of analysis, including imperfections in the local and distortional buckling modes for the shell element–based analysis. The selection of the system-based reliability (resistance) factor (ϕs) is discussed. The standard is seen as the most advanced design code of its type currently available for frame-type steel structures. The paper also provides an in-depth discussion about th...

This paper examines the accuracy of equations specified by the North American and Australasian steel structures codes for deter- mining the net section tension capacity of a channel brace. It points out that there are three distinct factors affecting the net section efficiency of a cold-formedsteel channelbraceboltedat theweb. Thesefactors include(1) thein-plane shearlagassociatedwith stressconcentration around aboltholethatisalsopresentin flatsheets,(2)theout-of-planeshearlagthatisalsopresentinanI-sectionboltedatthe flangesonly,and(3)the bending moment arising from the connection eccentricity with respect to the neutral axis. Each of the relevant factors is explicitly incorporated into the equation proposed in this paper for determining the net section tension capacity of a cold-formed steel channel brace bolted at the web. The proposed equation is demonstrated through laboratory tests on low-ductility channel braces having practical aspect ratios that were bolted onto flexible plates, to be more reliable than the code equations and those existing in the literature. DOI: 10.1061/(ASCE)ST.1943- 541X.0000650. © 2013 American Society of Civil Engineers. CE Database subject headings: Bolted connections; Cold-formed steel; Shear lag; Tensile strength; Thin wall sections; Bracing; Webs (structural). Author keywords: Bolted connections; Cold-formed steel; Shear lag; Tensile strength; Thin wall sections.

This paper presents procedures for the design of fixed- and pin-ended equal-leg angle columns with short-to-intermediate lengths. First, some remarks concerning the buckling and postbuckling behavior of the angle columns are presented that (1) illustrate the main differences between the fixed- and pin-ended column responses and (2) demonstrate the need for specific design procedures. Then, the paper reports an in-depth investigation aimed at gathering a large column ultimate strength data bank that includes (1) experimental values collected from the literature and (2) numerical values obtained from shell finite-element analyses carried out in the code ABAQUS. The set of experimental results is comprised of 41 fixed-ended columns and 37 pin-ended columns and the numerical results obtained include 89 fixed-ended columns and 28 pin-ended columns; various cross-section dimensions, lengths, and yield stresses are considered. Finally, the paper closes with the proposal of new design procedures for fixed...

This paper describes the implementation of a 3-dimensional concrete constitutive model for fiber-based analysis of reinforced concrete members subjected to combined loadings including torsion. The proposed model is formulated to address the interaction between the axial force, bidirectional shear, biaxial bending, and torsion. The shear mechanism along the beam is modeled using a Timoshenko beam approach with three dimensional (3-D) frame elements with arbitrary cross-section geometry. The model considers the 3D equilibrium, compatibility, and constitutive laws of materials at the section and structural level. The concrete constitutive law follows the Softened Membrane Model (SMM) with a tangent-stiffness formulation. The emphasis of the paper is on evaluation of the effect of the different stress states on the global and local behavior of the member. The ability of the model to assess the ultimate strength, stiffness, energy dissipation, failure modes under 3-dimensional loading is evaluated by correlation of analytical results with experimental tests of RC specimens.

ASCE 7 does not provide design wind loads for roof-mounted solar panels. This paper discusses the use of the wind tunnel test method, called Method 3 in ASCE 7-05, which was originally intended for obtaining design wind loads for individual buildings. Because roof-mounted solar arrays are generally mounted in many configurations on many buildings of many different shapes, additional requirements are necessary to use Method 3 in this situation. The paper describes these additional requirements.

The paper presents the experimental investigation of full-scale RC corner beam-column joints without transverse reinforcement in the joint region leading to nonductile behavior in many exiting RC buildings. The experimental study considered two design parameters: joint aspect ratio and beam longitudinal reinforcement ratio. Four corner beam-column joint specimens were constructed with transverse beams and floor slabs and tested under quasi-static cyclic loading. The specimens experienced joint shear failure without beam hinging mechanism as a result of the absence of transverse reinforcement in the joint region. On the basis of the test results, the paper discusses the effects of these two design parameters and the floor slab on the behavior of corner beam-column joints. The joint shear strengths obtained from the test specimens are compared with the strength recommendations of the ASCE/SEI 41-06 provisions.

This paper presents a computational investigation of the response of steel beam-column assemblies with moment connections under monotonic loading conditions simulating a column removal scenario. Two beam-column assemblies are analyzed, which incorporate (1) welded unreinforced flange bolted web connections, and (2) reduced beam section connections. Detailed models of the assemblies are developed, which use highly refined solid and shell elements to represent nonlinear material behavior and fracture. Reduced models are also developed, which use a much smaller number of beam and spring elements and are intended for use in future studies to assess the vulnerability of complete structural systems to disproportionate collapse. The two modeling approaches are described, and computational results are compared with the results of the full-scale tests described in the companion paper. Good agreement is observed, demonstrating that both the detailed and reduced models are capable of capturing the predominan...

In this paper the implementation and validation of a modified steel bar model including bond-slip of longitudinal bars that was proposed in a companion paper is discussed. The model is developed on the key assumption of linear slip field along the steel bar with different configurations at the ends of the bar. The simplified model is capable of predicting the axial slip displacement with suitable accuracy compared with a refined model but with considerably fewer computational steps. The proposed model avoids nested iterations in the context of fiber model discretization of a section that requires the representation of all actions in terms of stress and strain. The model is applied to two component tests—one with poor and another with improved reinforcing detailing. Findings from the simulations indicate that the proposed model is more suitable for use in connections with poor detailing and pronounced slip in the plastic hinge zones.

This paper presents a simplified model for describing the response of a longitudinal bar embedded in concrete, taking into account the bond-slip phenomenon. The model is developed by assuming a linear bond-slip field along the bar anchorage length and provides a simplified stress-strain relationship to assign to the longitudinal reinforcement. The analytical approach adopted makes the proposed model very convenient from a computational standpoint because, unlike many other refined models, it does not require a multilevel iterative process. Moreover, the assumptions made are particularly appropriate for modeling bond-slip of smooth bars generally used in older reinforced concrete buildings. The implementation strategy of the proposed bond-slip model in general-purpose nonlinear structural analysis software and comparisons with experimental results are discussed in a companion paper.

This paper presents the shake-table tests of a full-scale, 3-story, reinforced concrete masonry structure. The structure was a special reinforced masonry shear wall system designed according to current code provisions for an area of high seismicity. It consisted of three lines of walls arranged in an H-shape in plan view, with one lineal and two T-walls aligned in the direction of the table motion and four lineal walls oriented perpendicular to the table motion. The seven walls were separated by door openings and were connected with lintels and precast slabs with cast-in-place concrete topping. The structure was subjected to a series of dynamic tests including nine seismic excitations with intensities exceeding the maximum considered earthquake used in the design. The structure had a capacity that exceeded considerably the design base shear, and it withstood all but the last two excitations with little or no damage. The paper presents the design of the test structure, its dynamic response to the s...