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The article discusses the importance of reproducibility in academic research, particularly in the field of structural engineering. It acknowledges the challenges in achieving reproducibility, such as data storage and computing requirements, as well as proprietary issues. The authors argue for the development of a reproducibility policy in the Journal of Structural Engineering and the Journal of Bridge Engineering, taking into account the nature and culture of research in these subdisciplines. They propose a classification system that emphasizes the availability of data and metadata, and encourage authors to go beyond data availability by making models and other materials accessible. To incentivize research and data availability, the journals will provide a visible recognition badge for papers with open data/models/codes and may consider special recognition for these papers. The authors also outline the review process for data-verified papers, which involves three associate editors verifying the availability and representativeness of the data. [Extracted from the article]

The described data set must be publicly available through a digital object identifier (DOI), cited in the paper, and a link provided within the paper to ensure online access to the published data set. Reviewers of an ASCE JSE data paper manuscript will ensure the paper meets the formatting, data and metadata, validation, and data access criteria. The authors provide a DOI and data archive link as well as the metadata such as instrumentation, location and methods, and summary plots of the data. [Extracted from the article]

This paper introduces a topology optimization approach based on the virtual element method (VEM), incorporating uncertainties. The objective of this optimization process is to design an optimal material layout for problems governed by linear elasticity equations to minimize the volume while satisfying probabilistic compliance constraints. The VEM is used to solve the boundary value problem in reliability-based topology optimization (RBTO). In the comparison between the VEM and the standard finite element method (FEM), a key difference emerges in the absence of explicitly defined shape functions tied to discrete degrees of freedom in VEM. Unlike FEM, VEM directly constructs the discrete bilinear form and load linear form without the need for computing shape function derivatives within the elements. This flexibility accommodates meshes with intricate geometries and arbitrarily shaped elements. The paper discusses the computational efficiency of VEM RBTO and explores the geometric impact of tessellations on converged topologies, demonstrating reduced susceptibility to checkerboard patterns compared to conventional quadrilateral elements. Additionally, the single-loop approach is examined, showcasing comparable accuracy to the first-order/second-order reliability methods (FORM/SORM) of RBTO using VEM. Numerical results for several problems that demonstrate the feasibility of the proposed method are presented. [ABSTRACT FROM AUTHOR]

Tensegrity structures, which consist of tension cables and compression rods, are widely used in various fields. It is particularly important to find the tensegrity with definite geometric configuration for the following research and application. This paper presents a traversal topology-finding method for tensegrity structures based on dynamic programming algorithm and ground structure method. After the designer has given the cable topology, the dynamic programming is adopted to realize the traversal selection of the rod. In order to reduce the traversal space and realize the constraint of rod length type, the rod is classified according to length. Compared with existing topology-finding methods, the algorithm can not only output all feasible topologies but also incorporate structural constraints, such as rod length type and prestressed stability, into the calculation process. Four tensegrity numerical examples illustrate the feasibility and effectiveness of the topology-finding method. [ABSTRACT FROM AUTHOR]

Investigates the application of fatigue reliability reassessment procedures to existing world structures and its relevance to structural repair and conservation. Emphasis on structures subjected to fatigue load; Increased need for building repair; Costs in structural conservation; Basis of fatigue life calculation; Dependence of inspection schedule to fatigue reliability estimates.

Summarizes the universally-accepted fatigue reliability reassessment procedures and their application to certain types of world structures commonly vulnerable to fatigue and fracture problems. Increased need for building fatigue life reassessment; Techniques for building condition reassessment; Use of simulation techniques for building evaluation; Inadequacy of building service life.

Performance-based design optimization (PBDO) aims to design safe, resilient, and cost-effective structures. Methods used for PBDO have evolved by integrating numerical modeling, performance-based design principles, and optimization algorithms. The PBDO framework enables the design of structures with optimal performance and cost. This paper provides researchers with a comprehensive review of the rapidly growing field of PBDO. The evolution of PBDO methods is discussed with the goal of identifying the challenges that must be addressed in future studies. Knowledge gaps are brought to the forefront to emphasize the need for further investigation that expands on the application of PBDO in structural design. Various deterministic and probabilistic formulations for PBDO of structural systems under seismic and wind loading are reviewed. The formulations encompass one or more objective functions, including the upfront, life-cycle, and repair costs. Furthermore, the paper reviews retrofit design studies that have used PBDO methods. The high computational demand in performing PBDO is identified as the major challenge. Possible approaches to alleviate this and other challenges are discussed. [ABSTRACT FROM AUTHOR]

Past research efforts have developed several self-centering beam-to-column connections for minimizing structural damage in steel moment frames after severe earthquakes. However, less focus has been on low-damage column base connections. Severe damage at the base of columns in conventional steel structures with moment frames is likely during an intense earthquake, rendering the building nonresilient. This paper evaluates the application of a recently developed viscoplastic damper in low-damage column base connections. The proposed viscoplastic damper is a rubber-steel core damper (RSCD), which consists of a high-damping rubber layer and several ductile steel bolts. The proposed column base connections prevent damage and inelastic deformations in the steel column and its base plate by allowing a rocking mechanism at the base of the column and limiting damage to easily replaceable steel bolts in the dampers. The paper discusses the design and behavior of the column base connections equipped with RSCDs. Continuum finite element models of RSCD dampers were developed and validated using experimental results. The rocking response was validated using experimental results for rocking columns with a silt damper. A total of 21 finite element models of rocking columns with RSCD were used to numerically examine the column response to combined axial loading and cyclic lateral loading. The influence of different parameters on the cyclic response of the proposed column base connections was also evaluated. These parameters are steel bolt diameter-to-length ratio (d/h), rubber thickness, column axial compressive load, number of bolts, and steel material type. The results confirmed the effectiveness of the proposed column base connection for minimizing damage to the steel column and its base plate. An optimal d/h ratio of 0.4 was found for the design of RSCDs. In addition, analytical formulas are presented to evaluate the yield and ultimate strength of the proposed column base connection, and the comparison with FEM results indicates that the presented mechanism has sufficient accuracy. [ABSTRACT FROM AUTHOR]

Shake-table tests of a full-scale 3-story reinforced concrete frame building were performed at the E-Defense facility (Miki City, Japan) as part of the Tokyo Metropolitan Resilience Project. Building data were collected before and after each shake-table experiment, using light detection and ranging (lidar) scanning technology. Three-dimensional point clouds were generated and processed to investigate the damage features that can be extracted, which are important for postdisaster structural assessment purposes. To this end, this paper discusses aspects pertaining to lidar data processing and registration, calculation of residual displacements and interstory drifts, and concrete cracking and spalling identification and measurement. Most notably, this paper deals with very large data sets, processed to extract structural response information at both global and local scales. Limited multiscale work has been done in the past, and the different sets of challenges that arise have typically been addressed separately. Evidently, this gap needs to be filled before lidar can be effectively used in the field for structural assessment applications. A series of examples in which lidar data are processed and analyzed to assess specific structural components is illustrated, showing that point cloud data can indeed be processed to obtain measurements of global residual drifts or of the extent of visible damage (e.g., crack width and spalling). Although preliminary in nature, the results presented in this paper indicate that collecting postdisaster data using terrestrial lidar scanners has the potential to contribute improving how buildings are assessed in the aftermath of seismic events. [ABSTRACT FROM AUTHOR]

Reports that the American Society of Civil Engineers (ASCE) and the Structural Engineering Institute (SEI) are looking for nominations for the 2006 ASCE and SEI Awards. Objective of the ASCE and SEI Honors and Awards Programs; ASCE awards based on meritorious papers; SEI awards.

The special collection on Twenty Years of Advances in Disproportionate Collapse Research and Best Practices since 9/11/2001 is available in the ASCE Library (https://ascelibrary.org/jsendh/twenty years disproportionate collapse). Kong et al. ([8]) report their experimental and numerical findings on the progressive collapse behavior of scaled six-column subframe composite floor systems subjected to the removal of a side column. Beck et al. ([2]) target optimal required ratios of column-to-beam strengths in column loss situations, considering several failure modes and providing conceptual design recommendations to mitigate disproportionate collapse of frame structures. Three papers focus on advances in analysis and design methods for disproportionate collapse ([2]; [7]; [18]) and show that their limitations no longer are a barrier to disproportionate collapse-resistant design that they once were. [Extracted from the article]

Exactly one decade after taking the helm in 2010 and 22 years after joining the board of the I Journal of Structural Engineering i (JSE), I proudly stepped down from my position as editor in chief on September 30, 2020. One of the secrets to the eminence of JSE is that the I Journal i is seamlessly integrated with the committee structure of ASCE's Structural Engineering Institute (SEI). Professor van de Lindt: Incoming Editor in Chief It is with great pleasure that I announce that Professor John van de Lindt has been appointed by ASCE SEI as the new JSE editor in chief starting October 1, 2020 (Fig. [Extracted from the article]

Recent amendments to design ground snow load requirements in current US standards have reduced the size of case-study regions by 91% from what they were in previous standards, primarily in western states. This reduction is made possible through the development of highly accurate regional generalized additive models (RGAMs), stitched together with a novel smoothing scheme implemented in the R software package remap, to produce the continental-scale maps of reliability-targeted design ground snow loads available in current standards. This approach allows for better characterizations of the changing relationship between temperature, elevation, and ground snow loads across the conterminous US (CONUS). RGAMs are shown to have 10% or better improvement in mean absolute mapping error in two independently created data sets when compared with traditional mapping techniques. Structures must be able to withstand environmental stresses without collapsing, including snow. Design ground snow loads are estimated using snow measurements taken at weather stations throughout the US. Mapping techniques allow design ground snow loads to be estimated at regions between weather stations. This paper describes a regional approach for mapping design ground snow loads in CONUS and demonstrates the improved accuracy of the approach, relative to previous methods, on two independently created national data sets. [ABSTRACT FROM AUTHOR]

Large infrastructure projects can efficiently use large diameter bars as longitudinal reinforcement in reinforced concrete elements. In earthquake-prone zones, critical regions of these elements must be detailed for ductility and hysteretic energy dissipation. Longitudinal bars in these regions are expected to sustain large-amplitude strain cyclic reversals before bar fracture occurs, in a mode of failure defining the collapse prevention limit state. To date, no successful large strain-amplitude cyclic loading testing has been reported on large-diameter reinforcing bars to observe the large-strain amplitude fatigue life of such bars, which often involves plastic bar buckling. This paper describes a test program designed to determine the plastic buckling/straightening fatigue life of ASTM A706 Grade 60 No. 18 bars (Ø57 mm) reinforcing bars subjected to cycles of reversed plastic strains. The design and implementation of the loading apparatus, critical for the gripping of the bars, the metallurgical characterization of the bars, and several key test results are discussed in the paper. Finally, the paper discusses a general unidimensional fatigue damage index precursor to bar fracture following a few plastic buckling and straightening cycles. [ABSTRACT FROM AUTHOR]

This paper puts forward an indirect bridge monitoring method using Mel-frequency cepstral analysis of inverse-filtered drive-by acceleration signals collected through smartphones. Crowdsensing-based approaches using data collected by smart cars and smartphones opened a new chapter in bridge monitoring by reducing the costs and increasing the efficiency of the bridge monitoring process. However, the major challenge of the dominancy of the operational effects in the recorded drive-by vibrations overshadows the bridge monitoring objective. This paper proposes an inverse filtering-based monitoring approach to suppress operational effects. The inverse-filtered spectrum is later employed in a Mel-frequency cepstral analysis, leading to the calculation of the abnormality index, which is then used to detect the change in the bridge state. The performance of the proposed method in suppressing operational effects is assessed through a series of laboratory and real-life experiments. Afterward, the damage detection capability of the method is investigated for two damage levels at different locations along the bridge, modeled in a laboratory environment. The results provide evidence for the capability of the proposed method in drive-by damage detection of bridges. Moreover, using the smartphone as the data acquisition device paves the path toward the implementation of the method for crowdsensing-based bridge monitoring in future smart cities, although more operational factors such as passenger interactions and resulting smartphone motions need to be considered in future studies. [ABSTRACT FROM AUTHOR]

Since the 1800s, there have been live load surveys and analyses carried out, particularly of area-dependent loads in office buildings. While some occupancies have received careful examination, there has been no systematic review and consideration of reliability-based scenarios for office gathering space live loads. The results of the research reported here indicates (supports) a more consistent, reliable, and economic design load for office gathering spaces in buildings. These results provide the theoretical and practical basis for design live loads for gathering spaces within offices, a step toward possible enactment in the current standard, and subsequently by adoption into the International Building Code and materials standards. Following a review of historical load surveys and theoretical models, the paper presents models and observations of crowding, serving as a basis for a different approach for such areas, including a Delphi among leading design firms in the United States. The paper concludes with recommendations for a new live load use category for gathering spaces for offices. Modern office usage often contains work spaces for meeting, gathering, and collaboration. The current standard for minimum design loads and associated criteria for buildings and other structures does not directly address this situation. Interpretation has led to conflicting requirements for the design loads of such spaces, including the possibility of assigning them as assembly areas. This can lead to overdesign and uneconomical structures. This research reviews historical office surveys with an emphasis on assembly spaces, presents the results of a Delphi of design firms throughout the United States, and contains a stochastic maximum load analysis. These various assessments lead to a consistent evaluation of plausible loads for such spaces, and a recommendation for a new subcategory in the standard live load table. The study recommends treating these spaces similar to general offices, with a basic live load of 2.39 kN/m2 (50 psf), and permissible live load reduction as is currently in the standard for offices. Exception is made for such work spaces that are directly accessible from outside and intended for use by the general public. [ABSTRACT FROM AUTHOR]

Steel side-plate connections are reliable load path alternatives because they eliminate the fabrication challenges associated with continuity plates, especially for concrete-filled tubes (CFTs). In this paper, a new easy-to-fabricate moment connection for connecting I-beams to CFT columns using the monolithic side-plate technique is proposed. In this connection, the vertical side plates are entirely replaced by column webs to save steel material by eliminating the use of double steel plates in the connection panel zone and resolving the biaxial fabrication issues associated with the lack of welding access between the orthogonal side plates and the column. Four full-scale experimental tests consisting of two couples of relatively identical bolted and welded connections were conducted under a cyclic lateral displacement control loading protocol and a constant compressive axial load was applied to the column to evaluate the seismic performance of the connection. Furthermore, standard geometrical limitations, such as the column width and beam depth, were challenged. The results indicated that the new proposed connection exhibits sufficient stiffness and high level of ductility up to more than 4% of story drift without any strength degradation, implying that this new connection can be classified as a prequalified rigid moment connection to be used in special moment frames (SMFs) located in high seismic regions. In this paper, a monolithic side-plate connection is proposed and four full-scale specimens with oversized geometrical characteristics are experimentally investigated. The favorable results of this study show that this connection can be used as a prequalified rigid beam-to-column moment connection in intermediate and special steel moment frames consisting of box columns. The proposed easy-to-implement connection offers advantages such as decreased weight, fewer welding operations, and biaxial connection capability, which are not possible with conventional side plates. This connection is successfully implemented in an IMAX multicomplex building, with 151,676 m2 gross area and 82.32 m height. The proposed idea is applicable to any project with large box-shaped columns in high seismic regions and the achievements of this study can provide experimental support for the seismic design of these buildings. Critical factors in the connection performance are the column width and side-plate geometry, and considering other specific aspects of this connection, there is a lot of potential for further numerical and experimental investigations. Although not shown in this work, the proposed approach gives us the necessary flexibility to easily develop a biaxial moment connection, and further research is recommended in this case. [ABSTRACT FROM AUTHOR]

The 2010–2011 Canterbury earthquake sequence highlighted the vulnerability of New Zealand light-frame wood buildings that are the predominant typology in residential construction. While life-safety performance was excellent, many buildings experienced widespread cracking of internal wall linings that resulted in costly repairs and disruption. Despite the widespread use of light-frame wood construction in New Zealand, no known shake table tests have been documented for this construction typology. Additionally, New Zealand light-frame wood building performance cannot simply be inferred from international testing because New Zealand adopts a different design philosophy from those of the US and Canada by relying on gypsum sheathing as the primary lateral resisting element. To further investigate New Zealand light-frame wood building performance, this paper discusses shake table testing of a light-frame wood building specimen, constructed on the University of Canterbury unidirectional shake table using modern New Zealand design and construction approaches. The observed damages during the tests were consistent with those observed in similarly built structures that were investigated after the 2010–2011 Canterbury earthquake sequence. This paper also presents a modeling approach using the state-of-the-art software Timber3D, which was verified by simulating the shake table specimen and comparing the observed and predicted dynamic response from the test specimen and model, respectively. The Timber3D modeling approach included analysis and parameterization of screw-slip data using the Evolutionary Parameter Hysteretic Model, formulation of two-dimensional wall component models, and nonlinear time history analysis of a three-dimensional model of the shake table specimen. The model was shown to reasonably predict the displacement response of the shake table specimen and the strength degradation from cracking damage through repeated earthquakes. The modeling approach described is intended to further the development of residential building models toward the performance-based seismic design of light-frame wood buildings in New Zealand. [ABSTRACT FROM AUTHOR]

Origami-based structures have been widely implemented in the design of deployable systems. They possess desirable properties such as easiness in manufacturing, high transportability, programmability, and the capability to fold into complex three-dimensional (3D) structures starting from planar configurations. However, their geometric complexity poses major challenges in developing efficient design methods, in which optimizing their geometries and folding motions remains a challenging task. This paper investigates the motion and shape inverse design of a Miura-based origami deployable system for architectural applications. The proposed structure folds from a flat to different 3D shapes, has 1 degree of freedom, and can fold rigidly being also flat foldable. The capabilities of the structure to fold approximating symmetrical target shapes of different geometries and achieve tailored folding motions are investigated. Furthermore, an inverse computational design workflow is proposed. The structure showed good accuracy in approximating target shapes, folding within desired motion envelopes, and avoiding collisions with surrounding objects. The origami-based system could be designed to deploy in different scenarios at the architectural scale, and could find applications as deployable canopy for improving comfort in outdoor conditions. Although limited to early design stages, the proposed design workflow is a flexible tool that could be applied to shape and motion inverse design tasks by simply variating its objective function. The method could be further applied to different typologies of rigid-foldable origami-based structures at different scales. Current studies on origami-based deployable systems mainly cover geometries that can be deployed, function as static systems, and further folded after the end of their operation. Despite possessing desirable characteristics, such designs fail to take advantage of origami properties such as programmability and dynamic adaptability to different scenarios. In addition, the optimization of such structures and the conception of efficient design workflows remain challenging. This paper proposes a design that could be folded and unfolded dynamically adapting to its environment. Furthermore, a computational design workflow for the design of shape and motion is presented. The novel aspects of the study can be summarized as follows: (1) tailored design of complex 3D geometries using two-dimensional (2D) origami patterns, (2) design of both shape and motion, which extends the common only-shape design approach, (3) development of an efficient and flexible computational design workflow that could be adapted to diverse inverse design tasks with different objectives, and (4) development of the workflow in the Grasshopper interface, in which environmental simulations could be carried out. Thermal comfort, wind comfort, and acoustics are some of the topics of interest that could be evaluated without making any change in the proposed parameterization and optimization framework. [ABSTRACT FROM AUTHOR]

Base dual-mechanism systems that limit both shear force and overturning moment demands are being developed as a new class of seismic force–resisting systems to enhance the control of seismic demands at the base and along the height of tall buildings and to control higher-mode effects. Despite an increasing number of numerical studies that demonstrate the enhanced seismic resilience of tall buildings as a result of better-controlled shear force and overturning moment demands and reduced higher-mode effects through a variety of base dual-mechanism configurations, there are limited design methodologies for buildings with this type of seismic-resistant base system. This paper proposes a simplified method for the performance-based seismic design methodology for these base dual-mechanism systems and the structures above, which consists of (1) designing the dual base-mechanism system using a set of design charts, and (2) protecting the rest of the structure for the maximum expected seismic force demands computed using closed-form equations. The proposed method was used in this paper for the preliminary design of four example core-wall tall buildings with heights of 45, 90, 150, and 300 m. The adequacy of the proposed method was demonstrated using three-dimensional finite-element models. The analysis results were in reasonable agreement with the targeted force and displacement demands estimated using the proposed simplified method for the preliminary design of dual base-mechanism systems. [ABSTRACT FROM AUTHOR]

This paper presents experimental and numerical studies on the local stability and compression resistances of laser-welded stainless-steel T-section stub columns. A testing program was first conducted, including material coupon tests, residual stress measurements, and 20 stub column tests. The testing program was supplemented by a numerical modeling program, in which finite-element models were developed and validated against the test results. The finite-element models were afterward used to perform parametric studies to obtain additional numerical data. The test and numerical data were adopted to evaluate the main design rules in the American and European standards and the continuous strength method. The evaluation results indicate that the American and European standards yield conservative resistance predictions, especially for nonslender T-sections, owing to no consideration of material strain hardening, while the continuous strength method is shown to provide greatly improved design accuracy and consistency over the American and European standards. [ABSTRACT FROM AUTHOR]

This paper presents the experimental results of a study investigating the behavior of bolted glued-laminated (glulam) timber brace connections with slotted-in steel plates under monotonic and cyclic loading. A total of 12 brace specimens with one or two slotted-in steel plates and two different bolt sizes were studied with the aim to determine the ductility of the connections and brace assemblies. The use of self-tapping screws as perpendicular-to-grain reinforcement to prevent splitting and enhance brace ductility was also investigated. The results of the study showed that both connections in a brace can experience significant plastic deformations if the connections exhibit a postyield hardening response. In braces with connections that exhibited postyield softening, plastic deformations were limited to one of the brace connections, resulting in lower brace ductility ratios. The use of self-tapping screws was found to be effective at preventing splitting and increasing the connection yield and ultimate strengths, while also increasing the brace ductility when compared with an identical connection without reinforcement tested under cyclic loading. [ABSTRACT FROM AUTHOR]

Significant advancements have been made in the area of composite structures. Aligned with an innovative design, the motivation behind this research is, first, to make efficient use of timber as an environmentally friendly material and, second, to employ steel alongside timber effectively to prevent buckling of the steel. This research aims to bridge this knowledge gap by exploring the integration of steel, carbon fiber–reinforced polymer (CFRP), and timber. The objective is to create innovative composite column structures that leverage the unique properties of each material to enhance structural performance and efficiency. The authors conducted tests on a set of 24 columns under compression conditions. The results of the structural tests demonstrated significant compression capacities relative to their mass, highlighting the significant advantages of material synergy within these elements. The study thoroughly quantifies these benefits, shedding light on the potentially transformative impact of these innovative composite columns in the field of structural engineering. A significant finding was the influence of the timber section's geometry on preventing column buckling. Furthermore, the positioning of steel within the sandwich columns played a vital role, with steel elements having a greater area with timber exhibiting enhanced structural performance and reduced likelihood of debonding. This paper introduces a new parameter, the inelastic transition area denoted as INT±70% peak , which characterizes the smoothness or abruptness of the transition once the inelastic region begins and the graph descends. This parameter bears significance in risk analysis for structures susceptible to progressive failure. All specimens displaying substantial energy absorption featured larger timber sections, highlighting the pivotal role of timber in absorbing higher levels of energy during structural loading. The findings contribute to the growing body of knowledge on composite materials and their applications in modern construction. [ABSTRACT FROM AUTHOR]

In this paper, we present an unscented Kalman filter (UKF) for fusion of information from an accelerometer, global navigation satellite system (GNSS) instrumentation, and rotational sensor recordings of structural motion. Seismic and structural motions do not only include translations, but further incorporate torsion and twisting of the ground and/or structural components. Accelerometer and GNSS positions are known to be prone to errors introduced by rotation, such as (1) gravitational leakage, (2) misorientation, and (3) antenna pole tilt. In alleviating such effects, we propose fusion of information from six component (6C) data—3C translation and 3C rotation—and demonstrate its applicability for motion tracking on a flexible pedestrian bridge. To simulate a variety of load effects, the bridge was subjected to various sources of excitation such as hammer impulses, jumping, twisting, and running, as well as a combination thereof named the "artificial coupled forcing." The rotation errors of both the accelerometer and GNSS-estimated positions are corrected via a UKF-based fusion. We further identify the modal properties of the monitored bridge, excited by the different excitation sources, using a covariance driven stochastic subspace identification. The twisting of the bridge is shown to be a primary source of rotation errors. These errors ought to be corrected because their order of magnitude can be as large as the actual signal in the case of GNSS positions and up to 10% for accelerometer sensors. We compare the proposed UKF-based fusion for 6C motion tracking against a simplified linear Kalman filter and demonstrate the potential of the former for real-time, broadband, rotation-free displacement, velocity, and rotations tracking. [ABSTRACT FROM AUTHOR]

In this study, the structural performance of a new type of lightweight composite cold-formed steel and timber (CFST) flooring system has been investigated by conducting four-point bending tests on 13 specimens. A bare cold-formed steel system without timber sheathing was also tested to provide a benchmark response to which the strength and stiffness of the composite system were compared. This paper presents key findings on the flooring system's structural behavior and performance parameters, such as ultimate bending capacity, load-deflection response, load-slip response, and failure modes, by categorizing 13 specimens into four subgroups based on shear connector types and spacings. In the proposed composite CFST flooring system, 45-mm thick structural plywood panels were connected to the 2.4-mm thick cold-formed steel C-section joist using self-drilling screws, coach screws, and nuts and bolts. The performance of different types of shear connectors on the composite action is experimentally investigated and compared with the theoretical plastic section. Furthermore, the load-carrying capacity, effective bending stiffness, and deflection of composite CFST beams were computed theoretically using elastic theory and compared to experimental results, which showed good agreement. [ABSTRACT FROM AUTHOR]

Thick rubber bearings (TRBs) have been proven to be effective in mitigating horizontal shaking induced by earthquakes as well as railway-induced vertical vibration. During earthquake excitations, TRBs might be subjected to tension, which should be carefully assessed during design. This paper presents experimental and numerical studies on the behavior of TRBs under tensile loading. Four full-scale thick natural rubber bearing (TNRB) and lead thick rubber bearing (LTRB) specimens were designed and tested under tension, with and without lateral offset. The test results showed that increasing the applied lateral offset decreased the tensile stress and stiffness of the TNRBs, while the LTRBs did not exhibit any reduction. In addition, the test results were compared with design specifications in current codes for conventional rubber bearings. Finally, finite element (FE) models of TRBs were built and validated against the results of uniaxial and offset tensile experiments, and the cavitation of rubber was modeled via a two-phase model. To further estimate the damage due to previous tensile loading, damage variables under cyclic tensile loading were also taken into account. The experimental and numerical results showed that the lead core only slightly increased the initial tensile stiffness of the bearing under uniaxial testing, while it had a significant influence on the tensile properties of the LTRBs under offset displacement. [ABSTRACT FROM AUTHOR]

The tall building design process typically goes through a time-consuming iterative procedure to ensure the cost efficiency of the proposed structural system, especially in the conceptual design stage where the layout is designed. Despite that, this procedure does not guarantee to yield an optimal layout. Consequently, an automated layout optimization procedure will result in a more economical and sustainable design. This paper presents a novel multiobjective lateral load resisting system (LLRS) (i.e., shear walls) layout optimization framework provided for dynamically sensitive tall buildings subjected to a wind load time history. The developed framework relies on an artificial neural network (ANN) surrogate model for constraints and objective function evaluation to reduce the computational time of the optimization process. The adopted surrogate model is built based on an automated finite element models-generated database using MATLAB code via the Open Application Program Interface of the ETABS software. The ANN surrogate model proved its efficiency in capturing complex variations in the structural response with a correlation coefficient that ranges between 90% and 98%. A nongradient optimization algorithm (NSGA-II) is adopted to identify the optimal shear wall layout to resist the applied dynamic wind load. In order to reduce the number of optimal layout solutions on the Pareto front, a pruning algorithm is used to limit the optimal solutions to 24 layouts. This will enable designers to use the direct selection method to choose an appropriate layout that fits the project's objectives. Also, a case study building is presented where the optimized results are analyzed and discussed in the numerical example to verify the effectiveness of the proposed optimization framework. [ABSTRACT FROM AUTHOR]

This paper presents the design, modeling, and characterizing tests of an assembled freely pendulum-type active tuned mass damper (AP-ATMD) for structural vibration control, highlighting its unique features such as noncontact force transmission, nonextra stiffness, and damping members. This device can operate passively as a tuned mass damper (TMD) with optimal tuning when environmental disturbances are minimal, or it can engage efficiently in active control when significant disturbances are present. The AP-ATMD mainly consists of a robust suspension system, an arc-shaped mass block with permanent magnets (PMs), and an arc-shaped electromagnetic motor. Notably, both the electromagnetic motor and the mass block have identical curvatures. A laboratory prototype of the AP-ATMD was designed and fabricated for the purpose of characterizing tests. Furthermore, an electromechanical model based on the Bouc–Wen hysteresis loop was developed to accurately characterize the active force behavior generated by the device. The parameters of this model were identified through a series of characterizing tests of the prototype AP-ATMD under harmonic excitations, and subsequently were validated under random excitation. The results confirmed the efficacy of the proposed electromechanical model in precisely capturing the active force behavior across a wide array of operational conditions. Finally, a numerical simulation of a 3-story frame with the AP-ATMD installed was conducted. The outcomes of the simulation highlighted the AP-ATMD's ability to reduce structural responses significantly. Moreover, the system employing the proposed electromechanical model outperformed a linear model, demonstrating a superior reduction in structural response. [ABSTRACT FROM AUTHOR]

The utilization of ultrahigh-performance concrete (UHPC) as lateral or U-shaped thin layers to strengthen the shear-deficient normal-strength concrete (NSC) beams is an effective and promising way to increase their stiffness and shear capacity. However, the lack of an accurate analytical model to estimate the shear capacity of UHPC-strengthened beams could be a critical obstacle to its further application. This paper presents a new analytical model for calculating the shear capacity of UHPC-lateral-strengthened beams, which is the first to be based on the simplified modified compression field theory (SMCFT). The model is also distinguished by considering the full compressive and tensile stress–strain curves of UHPC instead of only using their ultimate strengths. By assuming a complete strain transfer at the NSC–UHPC interface and the coincidence of the principal stress and strain axes in the NSC substrate and UHPC layers, the strain compatibility between the two components are included in the shear calculation. The model predictions were validated in two steps, first by using principal strain measurements in the shear span of five beams from digital image correlation (DIC) data to confirm the strain evaluation of the model, and second by reproducing the shear capacities of 12 beams from five experimental campaigns. Results showed a clear agreement between the strains calculated by the analytical model and those measured in experiments. The shear capacities of UHPC-lateral-strengthened beams calculated by the analytical model obtained a very high accuracy and a low variance to replicate experimental results. The model allows evaluation of the contributions of each beam components (NSC substrate, stirrups, and UHPC layers). Results confirmed that the increase in the shear capacity of strengthened beams mainly comes from the high tensile strength of the UHPC and the thickness of the UHPC layer, as well as the improved contribution of the stirrups. [ABSTRACT FROM AUTHOR]

The mechanical behavior of mortar joints can be described by means of the cohesive interface element in the mesoscale modeling of masonry structures. In this paper, a novel three-dimensional (3D) constitutive model for the cohesive interface element under cyclic loading is presented. The proposed constitutive model is formulated in the damage-plasticity theoretical framework with the following unique features: (1) two smooth hyperbolic yield surfaces, capable of capturing various failure modes of mortar joints; (2) two damage scalars Dt and Dc to characterize the stiffness degradation; (3) two damage functions ξt(Dt) and ξc(Dc) to describe the strength softening; and (4) an unassociated flow rule to capture the dilatancy behavior. The proposed constitutive model is implemented in the general-purpose finite-element package Abaqus using the user subroutine UMAT. The developed model was validated at the masonry-component level using a mortar-jointed specimen under indirect cyclic tensile loading and three masonry couplets under compressive-shear loading, and then at the structural level using two unreinforced masonry walls characterized by two distinct failure modes. The validation results show that the developed constitutive model is capable of modeling mortar joints and masonry structures with good performance. [ABSTRACT FROM AUTHOR]

This paper presents an experimental study on the determination of the mechanical behaviors of Grade 8.8 and 10.9 high-strength bolts at elevated temperatures. Strength reduction coefficients are obtained based on test results at temperatures ranging from 20°C to 900°C, for both yield and ultimate stresses. Simplified expressions are presented to identify the strength reduction factors at considered temperatures. At 400°C, the yield and ultimate strengths of bolts decrease by 30%–35% for both grades compared to those in ambient temperature. Yield strengths are 30% and 20% of yield strengths of Grade 8.8 and 10.9 bolts at ambient temperature, respectively, when the temperature exceeds 500°C. The ultimate strength decreases slightly slower than the yield strength at high temperatures. Although the decrease in ultimate strength follows the decrease in yield strength at elevated temperatures, it is slightly slower. About 3%–6% of yield and ultimate strengths at ambient temperature remain for both grades at 700°C. Moreover, a series of expressions are provided to obtain the full range stress–strain curve of high-strength bolts at elevated temperatures. Comprehensive literature studies are taken into consideration to propose a more generalized description of the stress–strain curves. The proposed model can be fully drawn by only using elastic modulus, yield, and ultimate stresses at ambient temperature. It is shown that the proposed model has enough efficiency to describe the general material behavior at elevated temperatures. [ABSTRACT FROM AUTHOR]

Interstory drift response is one of most important quantities to quickly assess performance and damages in buildings. Nevertheless, direct measurement of interstory drift is difficult and expensive, because a stationary reference is required to attach measurement devices. With the goal of accurate and fast reference-free estimation, this paper proposes a new strategy to determine dynamic interstory drifts using accelerations. In particular, a Tikhonov regularization is adopted in a generalized minimization problem to achieve an efficient and stable finite impulse response (FIR) filter. Furthermore, due to independent clocks in wireless sensors, accurate time synchronization of the records is critical; consequently, a strategy for accurate synchronization is also presented. Finally, the proposed strategy has been deployed on edge devices for onboard real-time interstory drift estimation. The proposed method for dynamic interstory drift estimation is validated, first, by numerical simulation using earthquake records as base excitation of linear and nonlinear buildings, as well as through laboratory shake table experiments. Both numerical and lab test results show good agreement of dynamic interstory drifts between the measured value and estimated results, demonstrating the efficacy of the proposed method to estimate the dynamic displacements of seismically excited structures. [ABSTRACT FROM AUTHOR]

The durability of profiled metal-faced insulating sandwich panels (MFISPs) in terms of exposure to high temperatures and thermal cycles is critical for their use in civil engineering applications. In this paper, a total of 20 full-scale panels made with two different thicknesses were tested under instantaneous lateral pressure loading at ambient conditions as well as under various combinations of high temperatures, thermal cycles, and lateral pressure. The pressure was applied through a vacuum chamber whereas thermal blankets were used for sustained and cyclic thermal exposure of the panels. Each thermal cycle entailed 24 h of time duration with a temperature range of 20–80°C. The results show a consistent reduction in the initial stiffness, local buckling pressure, and strength of the panels when they were loaded at high temperatures. These reductions were more substantial (up to 24%) under the combined effects of high temperature (80°C), thermal cycles, and pressure loading. The study also shows that the thickness of the foam core can play an important role in controlling the local buckling capacity and strength of the MFISPs. A nonlinear finite-element analysis was also conducted with a relatively good correlation with the test results. The numerical results provide further insights into the structural response and explain certain aspects that could not be obtained from the tests. Given that MFISPs are typically used for roof panels, where the combination of high temperatures and wind load is inevitable at certain regions, the results presented in this work are recommended for consideration in their design. [ABSTRACT FROM AUTHOR]

This paper investigated the lateral resistant behavior of grid-reinforced steel corrugated shear walls (GR-SCSWs), which are applied to shear walls with large width-to-height ratio. By revealing the resistant mechanism, the stiffness requirement of the subgrid, the wall–frame interaction, and the overall lateral resistance were studied. First, compared with ordinary steel corrugated shear walls, the lateral resistant behavior of GR-SCSWs and the bending moment of the boundary column were analyzed. Second, the threshold stiffness ratio was defined for the subgrid, and design suggestions were proposed to ensure that the infill panel has high and stable in-plane lateral resistance. Finally, the yielding development and shear force distribution in GR-SCSWs were explored, and an improved plate–frame interaction (PFI) model and formulas predicting the lateral resistance curve of GR-SCSWs were established by numerical analysis and theoretical derivations. It was found that, due to the full out-of-plane restraining effect of the subgrid, the GR-SCSW with optimized subpanels can achieve an in-plane shear yielding mechanism. GR-SCSWs can resist lateral loading with an appropriate yield sequence from the infill panel to the subgrid and then to the boundary frame. The modified PFI model proposed fully considered the interaction between the infill grid-reinforced panel and the boundary frame, while the theoretical formulas agreed with the FEA results and can be used to predict the lateral resistant curve and shear force distribution of GR-SCSWs. [ABSTRACT FROM AUTHOR]

This paper discusses the results of 1∶25 scale shake table tests evaluating the seismic response of multiblock tower structures (MTSs) conceived as energy storage systems. The tests described here are a part of a comprehensive research campaign involving smaller physical models, computational model validation, and the theoretical background required to compare results across scales. The 6.46-m-high MTSs consisted of over 7,000 concrete blocks stacked vertically without any bonding agent, interacting only by friction and rocking. Three MTSs were tested under two different ground motions. Dynamic digital image correlation (DIC) and low-cost micro electrical mechanical system (MEMS) accelerometers were used for dynamic response measurements. Towers 1 and 3, subjected to repeated strong-intensity earthquake ground motions, collapsed during the third repetition due to the accumulation of residual displacements. Tower 2 was subjected to a single near-fault ground motion representing an extreme event and collapsed during the test. Different collapse mechanisms were identified in the test program. Data collected from individual blocks showed in-plane and out-of-phase block rotation and sliding, which contributed to the system's energy dissipation during the tests. [ABSTRACT FROM AUTHOR]

Predicting the moment-rotation response parameters of semirigid steel connections can be challenging given the many components contributing to the connection's elastic and plastic deformations. This is the case for the popular flush endplate beam-to-column connections (FEPCs). The literature has highlighted the limitations of current analytical, mechanical, and traditional empirical models in providing accurate predictions of the FEPCs' moment-rotation response. Considering this limitation, machine-learning methods have gained wide attention recently in structural engineering applications to address problems associated with complex structural deformation and damage phenomena. To that end, the superior nonlinearity of artificial neural networks (ANN) is employed herein to predict the response characteristics of FEPCs. A large data set of about 200 specimens, collected from past experimental programs, is utilized to train the ANN for predicting the bilinear response of FEPCs including strain hardening. The paper describes the deduction of the response parameters from test data using data fitting, the determination of significant geometric, material, and layout features, the ANN architecture and algorithms, and the accuracy metrics of the new model. The Shapley algorithm is used to explain the inner workings of the model. A computer tool as well as a descriptive guide to the mathematical construction of the ANN are provided to aid with model implementation in practice. [ABSTRACT FROM AUTHOR]

This paper presents an extensive numerical study on the seismic performance of steel eccentrically braced frames (EBFs) designed according to the ASCE 7-16 standard. A series of EBF building structures ranging from 2 to 12 stories located in downtown Los Angeles are designed with different yielding links, including conventional and replaceable links. The performance of the structures is investigated through nonlinear time-history analyses (NLTHAs) under a suite of 40 ground motions, selected and scaled to match the target uniform hazard spectrum. The peak deformations are first examined to assess the performance of the buildings as well as the design procedure. Residual deformations are also evaluated and critically compared with acceptable limits, to provide insight into the downtime and recovery time of EBFs after major earthquakes. Previous studies have demonstrated that the response of stable yielding systems to major earthquakes is often accompanied by significant residual deformations, and that residual drifts exceeding 0.5% can cause hindrance to the buildings occupants. In EBFs, in addition to residual drifts, residual link rotations are also relevant and expected to be more severe due to the localization of inelastic deformations in the yielding link. For replaceable modular yielding links, significant residual link rotations after major earthquakes will hinder repairs and the link replacement process, which is one of the important design objectives. The performance of EBFs is also compared with what was observed in previous studies for buckling restrained braced frames and special moment resisting frames. In the end, the results from the extensive NLTHAs are used to establish a relationship between peak drifts and peak link rotations in EBFs. [ABSTRACT FROM AUTHOR]

Mitigating tornado damage remains a critical challenge for communities throughout much of the United States. Enhanced construction techniques typically used in hurricane-prone regions are often recommended as at least part of the solution, but the effectiveness of these techniques lacks empirical evaluation. This study investigates the performance of modern wood-frame residential structures in Arabi, LA, constructed to hurricane-resistant standards, that were impacted by a strong tornado on March 22, 2022. Field teams deployed beginning March 25, 2022, just three days after the tornado touched down, capturing perishable data on the building performance using vehicle-mounted surface-level panoramic cameras, forensic engineering investigations, and unmanned aerial systems. This paper describes the field deployments and identifies common failure mechanisms observed by the field teams. Analytical fragility functions are developed based on the load path observations and compared to empirical fragility functions generated from linking the building performance observations with wind speed estimates at each building derived from a parametric wind field model conditioned to tree-fall patterns. The study finds that despite the frequent use of hurricane-resistant hardware, such as hurricane straps and anchor bolts, key weak links elsewhere in the load path compromised the resistance and led to premature failures. The agreement between the empirically- and analytically-derived fragility functions was lacking, demonstrating the challenges that remain in understanding near-surface tornado wind loading and structural response. Nonetheless, the study provides a consensus framework for future tornado assessments that can help improve our understanding of tornado loading through the utilization of reconnaissance data. Further, the study findings on deficiencies in the load paths of homes in hurricane-prone regions have practical value to risk assessments and future construction practices. [ABSTRACT FROM AUTHOR]

The traditional approach to formulating building codes often is slow and labor-intensive, and may struggle to keep pace with the rapid evolution of technology and domain findings. Overcoming such challenges necessitates a methodology that streamlines the modernization of codal provisions. This paper proposes a machine learning (ML) approach to append a variety of codal provisions, including those of empirical, statistical, and theoretical natures. In this approach, a codal provision (i.e., equation) is analyzed to trace its properties (e.g., engineering intuition and causal logic). Then a ML model is tailored to preserve the same properties and satisfy a collection of similarity and performance measures until declared equivalent to the provision at hand. The resulting ML model harnesses the predictive capabilities of ML while arriving at predictions similar to the codal provision used to train the ML model, and hence it becomes possible to use in lieu of the codal expression. This approach was examined successfully for seven structural engineering phenomena contained within various building codes, including those in North America and Australia. The findings suggest that the proposed approach could lay the groundwork for implementing ML in the development of future building codes. [ABSTRACT FROM AUTHOR]

Elastomeric isolation bearings exhibit complex coupled horizontal-vertical behavior. Most existing macroscopic models simulate the quasistatic test results well but have deficiencies in simulating the dynamic behavior of bearings. In this paper, the experimental observations of previous dynamic bearing tests were investigated. The simulation capacity of existing macroscopic models was checked by comparison with the test data. The results show that the calculated axial load and hysteresis loops exhibit undesired oscillations under dynamic excitation. The intrinsic deficiency of existing models in simulating the dynamic response of a bearing was identified as the coupling or off-diagonal terms in the tangent stiffness matrix and the variation of vertical stiffness of the model. Motivated from this key observation, a new macroscopic model was developed to account for the dynamic behavior of bearings, followed by the suggestion of its numerical implementation. Through the introduction of a new axial load expression, the tangent stiffness matrix of the new model was semidecoupled, and the vertical stiffness of the new model remains unchanged, which reduced the interaction between the horizontal and vertical behavior. The simulation capacity of the new model was then validated by comparison with previous test data. The results show that the new model effectively captures the axial load variation and hysteresis loop of the bearings under dynamic excitations. Moreover, it was found that the consideration of the bearing height improved the simulation accuracy, and the size effect of the bearing is critical for isolated structures with large bearing-to-superstructure-height ratio, such as low- to medium-span bridges. [ABSTRACT FROM AUTHOR]

This paper investigates experimentally and numerically the buckling behavior of three-layered cross-laminated timber (CLT) panels under in-plane axial compression. The main aim is to assess the panels' ultimate limit load and their typical failure mechanisms. A total of 14 specimens were tested. Seven of them were homogeneous (HO series), entirely made of beech, whereas the others were hybrid (HB series), made of beech (outer layers) and Corsican pine (inner layer). The tests gave evidence of a rather stable column buckling capacity for CLT panels, with evidence of major failure mode due to bending. In some cases, rolling shear and delamination were highlighted as additional failure mechanisms. Finally, further assessment of experimental evidence is provided by extended analytical calculations (based on existing formulations, including the Eurocode 5 approach) and even finite-element (FE) numerical analyses for the examined three-layer CLT compositions. Comparative results are discussed in terms of structural performance, capacity, and weakness of analytical models for CLT solutions. [ABSTRACT FROM AUTHOR]

Shape memory alloys (SMAs) show great potential in self-centering structures because of their appealing superelastic feature and good energy dissipation capability. The mechanical properties of SMA bars have been extensively studied over the past decades. However, the characteristics of smooth surface and poor machinability of the SMA bars, especially the widely used nickel–titanium SMAs, bring challenges to the anchorage systems in practical applications. This existing limitation is especially prominent for SMA bars designed to be used at the critical deformation locations of structural members or in seismic devices experiencing extreme working conditions. For this reason, this paper develops a novel hybrid threaded-swaged anchorage system to overcome the limitations of the current SMA mechanical splices. The uniaxial behavior of the threaded-swaged anchorage systems under different loading conditions was investigated experimentally with emphasis on the seismic application-oriented responses. Furthermore, the influence of eccentricity on the anchorage system was also considered to evaluate the SMA bars with large end rotation induced by the rocking behavior of the self-centering structures during earthquake shaking. Test results reveal that the performance of the proposed anchorage system is satisfactory with stable behavior under different loading conditions, which can provide a promising anchorage solution for SMA bars used in seismic resilient design. Moreover, a practical design method for this anchorage system is proposed for implementation in seismic applications. [ABSTRACT FROM AUTHOR]

This correction notice addresses errors in the article "Collapse Resistance of Reinforced Concrete Frame Beams under Sustained Loads" by Ghazaleh M. Laleh, Ying Tian, and Sarah L. Orton. The errors occurred when converting imperial units to metric units in the "Bending Moment" section of the paper. The correction involves dividing the numbers on the horizontal axes of Figures 16 and 17, as well as the vertical axis of Figure 18, by 12. Additionally, two values in the last paragraph of this section need to be changed. The corrected figures are provided in the erratum. The purpose of this correction is to ensure the accuracy of the published version. [Extracted from the article]

• Prior work through continuum finite-element studies on steel columns ([7]; [24]) demonstrates that the preceding findings are substantiated even in cases where axial load demands on steel columns remain low. Pertinent data for steel columns specifically on collapse have been presented in prior work ([6]; and the original paper), whereas for RC beams and columns the reader is referred to other pertinent work ([19]; [16]; [15]). Unlike prior testing programs on steel columns ([18]), the original paper considered as part of their testing program the fact that there is axial load deterioration due to redistribution of axial forces once an end column is damaged. [Extracted from the article]

This paper develops a horizontal displacement estimation framework for wind-excited high-rise buildings based on limited measurements of accelerations and strains and applies it to reconstruct the displacement responses of a 600-m-high skyscraper in Shenzhen, China, during Super Typhoon Mangkhut on September 16, 2018. A field measurement study was conducted to verify the reliability and effectiveness of the framework based on the acceleration and strain responses of the skyscraper during Typhoon Kompasu. Then, the horizontal displacements of the skyscraper during the passage of Mangkhut were reconstructed by the framework based on the measurements of accelerations at one floor and strain responses at four floors, and the accuracy of the reconstructed displacement responses was subsequently validated in both time and frequency domains. In the final, the along-wind and across-wind responses as well as the resonant and background components of the reconstructed displacements during the extreme typhoon event were investigated. This paper aims to provide useful information for structural health monitoring and wind-resistant design of supertall buildings in tropical cyclone-prone regions. [ABSTRACT FROM AUTHOR]

This paper presents an improved design approach based on the direct strength method (DSM) in American Iron and Steel Institute (AISI) design specification S100 for cold-formed steel (CFS) built-up closed cross-section columns subjected to local, global, and local–global interaction buckling modes. Initially, the failure mode and load data corresponding to various design parameters such as intermediate fastener connection spacing, boundary conditions, material properties, slenderness, and cross sections from various researchers are collected, including the authors' test results. The design predictions using the current DSM design provisions are compared with the collected test results. The results show that the current DSM approach requires improvisation to adequately predict the axial compression load. The data are then analyzed to understand the behavioral features of the built-up closed cross-section column such as limit for interaction buckling, erosion of strength due to arrant interaction buckling, and increase in strength due to flange or web overlapping effect. The interpretation methods used to improve the current design approach are presented. The original DSM design procedure is improved by failure mode classification and modified slenderness to account for increase and erosion in strength. Finally, the safety (accuracy and reliability) of the design predictions from the improved DSM-based approach is assessed using the large amount of data collected. Since the introduction of the direct strength method to the North American Specification for the Design of Cold-Formed Steel Structural Members (AISI S100) in 2001, it has gained traction among design engineers due to its simplicity, advantages over other design methods, and specific design curves for individual buckling modes. To implement the DSM for CFS built-up members, several researchers have proposed different design approaches, and research is still happening. This study is also aimed toward the same objective but is specific to the local–global interaction in built-up members. It is demonstrated why the DSM prediction is unsafe for CFS built-up members with larger intermediate fastener connection spacing and excessively safe for CFS built-up members with closer intermediate fastener connection spacing. An intermediate fastener connection spacing limit that separates the local–global interaction buckling and element overlapping effect is determined. A design proposal for limiting the interaction buckling mode and considering the overlapping effect of elements in the DSM design method is suggested. More specifically, the proposed design method is in line with the current AISI approach so the designer need not confuse how to use this new design approach in practice. Therefore, for further ease of understanding, two design examples for built-up closed cross-section columns—(1) subjected to local–global interaction buckling; and (2) subjected to element overlapping effect—are included in this paper. It is also recommended that future research may focus on further classifying the AISI main specification sections, E2 and F2 (simple classifications based on the global failure modes), based on the interaction buckling modes in built-up cross-section members. [ABSTRACT FROM AUTHOR]

In wind engineering, to accurately estimate the nonlinear dynamic response of structures while considering uncertainties of hurricanes, a suite of wind records representing the hurricane hazards of a given location is of great interest. Such a suite generally consists of a large number of hurricane wind records, which may lead to highly computational cost for structural analysis. To reduce the computational demand while still preserving the accuracy of the uncertainty quantification process, this paper proposes a machine learning approach to select a representative subset of all collected hurricane wind records for a location. First, hurricane wind records, which are expressed as time series with information that includes both wind speed and direction, are collected from a synthetic hurricane catalog. The high dimensional hurricane wind records are then compressed into a set of low dimensional latent feature vectors using an artificial neural network, designated as an autoencoder. The latent feature vectors represent the important patterns of wind records such as duration, magnitude, and the changing of wind speeds and directions over time. The wind records are then clustered by applying the k -means algorithm on the latent features, and a subset of records is selected from each cluster. The wind records selected from each cluster are those whose latent feature points are closest to the centroid of all latent feature points in that cluster. In order to do regional analysis while taking into account that the hurricane wind records are site-specific, this paper suggests that a region can be discretized into a set of grids, with the proposed hurricane selection approach applied to each grid. This procedure is demonstrated using Massachusetts as a testbed. [ABSTRACT FROM AUTHOR]

Six of these papers focus on ultrahigh-performance concrete (UHPC) while five papers focus on high-strength concrete (HSC) or high-strength reinforcing (HSR) steel materials. Yang and Okumus ([11]) describe a parametric numerical investigation on the seismic behavior of UHPC rectangular hollow bridge columns with HSR steel for confinement. In this paper, the results from seven column test specimens demonstrate that the ductility capacity of UHPC-jacketed columns can be increased through textile reinforcing. [Extracted from the article]

A steel brace is effective to retrofit old reinforcement concrete (RC) buildings by increasing the horizontal load capacity of structures. However, concrete cracks that easily occur in the surrounding RC members under tension initiate early strength degradation, so this research aimed to develop a new self-centering brace (SCB) with the compression-only capacity such that no tension force is developed in the brace or to the adjoining RC members. Original SCBs have been developed to reduce the residual deformation of structures with a symmetrically flag-shaped hysteretic response. By altering the force transfer mechanism in the original SCB, a compression-only self-centering brace (C-SCB) can be developed under a symmetrically reversed cyclic loading, providing an alternative for the RC building retrofit. This paper first introduces the mechanics and deformation mechanism of the proposed C-SCB. A test program is then conducted on the cyclic tests of a buckling-restrained energy dissipating bar (EDB) to evaluate the energy dissipation. A 3,695-mm-long C-SCB is composed of posttensioning high-strength steel tendons, steel compression members, and buckling-restrained EDBs for the energy dissipation. The C-SCB in tests showed a good compression-only self-centering capability up to an axial displacement of 31 mm, with a maximum axial force of 1,530 kN. No damage of the steel tendons, compression members, or EDBs was found after three phase tests. Finite element analysis further validated the compression-only hysteretic response and mechanics of the C-SCB in a symmetrically reversed cyclic loading. [ABSTRACT FROM AUTHOR]

Four different composite coupling beam-to-composite plate shear wall (CPSW/CF) connection details were developed and proposed. Six large-scale specimens representing the four connections were designed, fabricated, and tested. The connections were subassemblies of coupled composite plate shear walls/concrete filled (CC-PSW/CF) subjected to cyclic lateral loading. The coupling beams were designed to be flexure-critical with clear span-to-depth (Lb/d) ratios of 3.5 or 5.1. This paper presents the experimental program, capacities, and detailed behavioral observations of all six specimens. The effects of connection type and Lb/d ratio on the ultimate strength, stiffness, ductility, and failure modes are evaluated. Major limit states and events included yielding of the steel plates comprising the coupling beam, followed by local inelastic buckling, fracture initiation in the base metal (near the weld toes), and fracture propagation through the beam flange and web plates, leading to loss of flexural strength and failure. All the connections were able to develop and transfer the flexural capacity of the composite beam section. The composite coupling beams developed flexural capacities (10%–50%) greater than those calculated using the plastic stress distribution method. The underlying reasons for this overstrength are evaluated. The AISC flexural stiffness equation for filled composite sections could reasonably estimate the stiffness of the composite coupling beam sections. A fiber-based model of the cross-section was used to calculate the section moment–curvature response of the filled composite beam sections. The calculated flexural capacities were consistent with those calculated by the plastic stress distribution method but lower than the experimentally observed values. The flexural stiffness values were slightly higher than the experimental results. For more accurate comparisons with experimental results, a numerical model is needed to estimate the cyclic lateral load-deformation response while accounting for the effects of local buckling, low cycle fatigue, and fracture. [ABSTRACT FROM AUTHOR]