Search

This article compares the results of estimating the buckling capacity of steel spherical shells using simple engineering formulas with the results of selected experimental studies that have been conducted over the past 70 years. It is worth noting that these studies were conducted by research centers from all over the world, and the tested coatings differed in material, manufacturing method, radius R, and thickness t. The test methods, procedures, and measurement tools were also different. The convergence of the results obtained between the proposed simple engineering approach, which is based on the provisions of EN-1993-1-6 and the recommendations in EDR5th, and the experimental studies is satisfactory, and in many cases the results obtained are almost identical. Therefore, it is possible to practically apply the developed algorithms for estimating the buckling capacity of steel spherical shells without worrying too much about the capacity reserve. [ABSTRACT FROM AUTHOR]

A positive user experience is crucial for enhancing user adherence throughout the utilization of lumbar-support-assistive devices (LSAD). However, there is a lack of research for optimal user experience with LSAD in the existing literature. Therefore, this study aims to explore how patients with lower-back pain use LSAD and assess their satisfaction and overall experience. Based on this, we aim to provide design improvement recommendations for LSAD to researchers in the relevant field. Through in-depth interviews with 14 LSAD users, key themes were identified using reflexive thematic analysis. The results indicate that participants were "somewhat satisfied" with the overall experience with their LSAD. The key factors influencing the LSAD-wearing experience were: (1) key design challenges in improving LSAD (stability, fit and, comfort), (2) providing necessary assistance (potential barriers and prompts), and (3) individualizing needs and balance of design (aesthetics, dimensions, safety, and cleanliness). All participants reported that poor stability, fit, and comfort of LSAD were the main reasons for an adverse experience. It is worth noting that users may encounter potential barriers when initially using LSAD. Furthermore, younger participants perceived pressure related to appearance and expressed concerns about the exposure of their health privacy during social interactions involving the LSAD. Based on these findings, we have proposed a set of comprehensive LSAD design-improvement recommendations, which serve as a foundational reference for future improvements. [ABSTRACT FROM AUTHOR]

This paper primarily presents an investigation into rectangular hollow section (RHS) cross- (or X-) connections with the branches fully laterally offset and loaded in axial tension. A set of 10 full-scale experimental specimens, carefully fabricated with noncritical welds, are tested in the laboratory, and the results are used to validate nonlinear finite-element models. To enhance the range of available data, the calibrated models are varied in an expanded parametric numerical study. A chord failure limit-state model based on a yield-line mechanism, which was identified in prior research on branch compression loading, is verified herein for branch tension loading. Furthermore, the limit state of branch failure is investigated by means of the combined experimental and numerical database produced. Design recommendations for laterally offset cross-connections loaded under branch tension, based on chord and branch failure modes, are presented. The application of current design recommendations for traditional cross-connections (with centered branches) to connections with full-width branches and laterally offset branches is also evaluated. [ABSTRACT FROM AUTHOR]

While it is common for blind and visually impaired (BVI) users to use mobile devices to search for information, little research has explored the accessibility issues they encounter in their interactions with information retrieval systems, in particular digital libraries (DLs). This study represents one of the most comprehensive research projects, investigating accessibility issues, especially help-seeking situations BVI users face in their DL search processes. One hundred and twenty BVI users were recruited to search for information in six DLs on four types of mobile devices (iPhone, iPad, Android phone, and Android tablet), and multiple data collection methods were employed: questionnaires, think-aloud protocols, transaction logs, and interviews. This paper reports part of a large-scale study, including the categories of help-seeking situations BVI users face in their interactions with DLs, focusing on seven types of help-seeking situations related to visual interactions on mobile platforms: difficulty finding a toggle-based search feature, difficulty understanding a video feature, difficulty navigating items on paginated sections, difficulty distinguishing collection labels from thumbnails, difficulty recognizing the content of images, difficulty recognizing the content of graphs, and difficulty interacting with multilayered windows. Moreover, corresponding design recommendations are also proposed: placing meaningful labels for icon-based features in an easy-to-access location, offering intuitive and informative video descriptions for video players, providing structure information about a paginated section, separating collection/item titles from thumbnail descriptions, incorporating artificial intelligence image/graph recognition mechanisms, and limiting screen reader interactions to active windows. Additionally, the limitations of the study and future research are discussed. [ABSTRACT FROM AUTHOR]

In this paper, a novel corrugated steel sheet central sheathed cold-formed steel (CCS-CFS) shear wall is proposed. This shear wall can address the problems of low shear strength and ductility in conventional cold-formed steel (CFS) shear walls caused by screw connection failure and eccentric sheet arrangement. A numerical simulation method for the novel shear wall was developed and verified through cyclic loading test results of two full-size shear wall specimens. Parameter analysis was then conducted to investigate the effects of screw spacing, sheet thickness ratio, and aspect ratio on the seismic performance of these shear walls, accompanied by design recommendations. The results indicated that this innovative shear wall configuration can effectively resolve the connection failure between the frame and the sheet. Furthermore, the CCS-CFS shear wall can effectively improve shear strength, energy dissipation capacity, and ductility. The developed numerical simulation method can accurately capture the hysteretic properties and failure modes of shear walls. In addition, it can address the shortcomings in conventional models that neglect the mixed hardening characteristic of steel and metal damage criteria, resulting in inaccurate simulation results and unrealistic buckling modes. The principal failure modes observed in the novel shear wall were identified as the plastic buckling of corrugated steel sheathing and the distortional buckling of the end stud. Reducing the screw spacing has a limited impact on its shear strength. It is recommended that the sheet thickness ratio of the CCS-CFS shear wall should be greater than 2.0, while the aspect ratio can be relaxed to 10:4. [ABSTRACT FROM AUTHOR]

While reinforcing bar lap splicing is inevitable in reinforced concrete (RC) structures, it critically affects structural behavior, especially in structures subjected to seismic load. That notwithstanding, current North American design standards do not provide any recommendations or equations for lap-spliced glass fiber-reinforced polymer (GFRP) reinforcing bars under seismic load. This study tested six full-scale RC columns measuring 1850 mm (73 in.) in height and 400 x 400 mm (16 x 16 in.) in cross section under constant axial load and incremental reversed cyclic lateral loading. Four columns were reinforced with GFRP bars, and two were reinforced with steel bars for comparison. The test parameters included lap-splice length and type of reinforcement. The structural performance of the specimens was evaluated based on the cracking behavior, failure mechanism, hysteretic response, load-carrying capacity, dissipated energy, stiffness degradation, and strain behavior. Afterward, available models in North American design standards for the splice length of GFRP reinforcing bars under monotonic loading were evaluated based on the experimental results. According to the results, providing adequate splice length can secure satisfactory structural performance in spliced GFRP-RC columns. The splice length determined based on the North American design standards for monotonic loading cannot, however, be directly used to achieve the required drift capacity in GFRP-RC columns under reversed cyclic lateral loading. [ABSTRACT FROM AUTHOR]

Introduction: Acquired brain injuries pose significant societal and individual challenges worldwide. The adoption of XR technologies presents an opportunity to enhance current rehabilitation procedures. However, a comprehensive understanding of the specific requirements of different user groups in XR-based rehabilitation remains incomplete. Our objective was to identify design recommendations for designers and researchers of XR-based exergames for motor rehabilitation for lower-limb motor recovery at home. Methods: After initially conducting a mini-literature review and brief market analysis, we used a human-centered design process, interviewing central stakeholders to understand their perspectives and using thematic analysis to identify recurring themes and insights related to XR-based rehabilitation. Results: The resulting eight key themes for integrating XR-based exergames into acquired brain injuries (ABI) rehabilitation were safety, flexibility, efficacy, usability, technology, motivation, ownership, and social factors. Conclusion: By addressing technical and user-oriented demands, our resulting design recommendations aid designers in developing meaningful XR-based rehabilitation exercises. [ABSTRACT FROM AUTHOR]

Background: Informal caregivers, often family members or friends, play a crucial role in supporting individuals with chronic illnesses, disabilities, or age-related needs. However, the demands of caregiving can be overwhelming, leading to stress, burnout, and negative impacts on caregivers' well-being. IT applications have emerged as potential solutions to support informal caregivers, but their design and evaluation often lack a comprehensive understanding of caregivers' needs and preferences. By understanding caregivers' perspectives on these issues, this review aimed to inform the development of more effective and user-centered IT solutions that truly support caregivers' needs. Objective: The purpose of this study was to conduct a scoping review to outline design recommendations for IT applications gathered from informal caregivers. In addition, this study presents evaluations of the use of IT applications by informal caregivers. Methods: A five-step scoping review methodology was used to map relevant literature in the following manner: (1) research question identification, (2) relevant study identification, (3) selection of pertinent studies for review, (4) data charting from the selected literature, and (5) summarization and reporting of results. A structured search was conducted across the PubMed, Scopus, IEEE Xplore Digital Library, Web of Science, and ACM Digital Library databases. In addition, reference list hand searches and keyword searches in Google Scholar were undertaken. The inclusion criteria comprised research articles (journal and conference) focusing on IT applications tailored for informal caregivers, primarily qualitative studies. Two reviewers independently identified articles for review and extracted the data. Conflicts were resolved through discussion, with a third reviewer consulted if consensus could not be attained. Thematic analysis was used to analyze the data. Results: A total of 82 articles were selected for the scoping review—44 (54%) related to design and 39 (48%) related to evaluation of IT applications. Six overarching themes emerged related to designing IT applications: information access, support systems, streamlining care-related tasks, fostering informal caregivers' well-being, communication with formal health care professionals, and task support. Furthermore, 3 broad themes emerged related to the evaluation of IT applications for informal caregivers: facilitators of using IT applications, barriers to using IT applications, and suggestions for improving IT applications for informal caregivers. Conclusions: To our knowledge, this is the first study to map the literature on the design and evaluation of IT applications for informal caregivers. This scoping review outlines current practices and recommendations for designing and evaluating the use of IT applications for informal caregivers. It identifies 6 key design themes and 3 evaluation themes, offering valuable insights for future development in this field. These findings provide a road map for enhancing user-centric IT solutions in informal caregiver support technologies. International Registered Report Identifier (IRRID): RR2-10.2196/47650 [ABSTRACT FROM AUTHOR]

While it is common for blind and visually impaired (BVI) users to use mobile devices to search for information, little research has explored the accessibility issues they encounter in their interactions with information retrieval systems, in particular digital libraries (DLs). This study represents one of the most comprehensive research projects, investigating accessibility issues, especially help-seeking situations BVI users face in their DL search processes. One hundred and twenty BVI users were recruited to search for information in six DLs on four types of mobile devices (iPhone, iPad, Android phone, and Android tablet), and multiple data collection methods were employed: questionnaires, think-aloud protocols, transaction logs, and interviews. This paper reports part of a large-scale study, including the categories of help-seeking situations BVI users face in their interactions with DLs, focusing on seven types of help-seeking situations related to visual interactions on mobile platforms: difficulty finding a toggle-based search feature, difficulty understanding a video feature, difficulty navigating items on paginated sections, difficulty distinguishing collection labels from thumbnails, difficulty recognizing the content of images, difficulty recognizing the content of graphs, and difficulty interacting with multilayered windows. Moreover, corresponding design recommendations are also proposed: placing meaningful labels for icon-based features in an easy-to-access location, offering intuitive and informative video descriptions for video players, providing structure information about a paginated section, separating collection/item titles from thumbnail descriptions, incorporating artificial intelligence image/graph recognition mechanisms, and limiting screen reader interactions to active windows. Additionally, the limitations of the study and future research are discussed.

A positive user experience is crucial for enhancing user adherence throughout the utilization of lumbar-support-assistive devices (LSAD). However, there is a lack of research for optimal user experience with LSAD in the existing literature. Therefore, this study aims to explore how patients with lower-back pain use LSAD and assess their satisfaction and overall experience. Based on this, we aim to provide design improvement recommendations for LSAD to researchers in the relevant field. Through in-depth interviews with 14 LSAD users, key themes were identified using reflexive thematic analysis. The results indicate that participants were “somewhat satisfied” with the overall experience with their LSAD. The key factors influencing the LSAD-wearing experience were: (1) key design challenges in improving LSAD (stability, fit and, comfort), (2) providing necessary assistance (potential barriers and prompts), and (3) individualizing needs and balance of design (aesthetics, dimensions, safety, and cleanliness). All participants reported that poor stability, fit, and comfort of LSAD were the main reasons for an adverse experience. It is worth noting that users may encounter potential barriers when initially using LSAD. Furthermore, younger participants perceived pressure related to appearance and expressed concerns about the exposure of their health privacy during social interactions involving the LSAD. Based on these findings, we have proposed a set of comprehensive LSAD design-improvement recommendations, which serve as a foundational reference for future improvements.

In this paper, a novel corrugated steel sheet central sheathed cold-formed steel (CCS-CFS) shear wall is proposed. This shear wall can address the problems of low shear strength and ductility in conventional cold-formed steel (CFS) shear walls caused by screw connection failure and eccentric sheet arrangement. A numerical simulation method for the novel shear wall was developed and verified through cyclic loading test results of two full-size shear wall specimens. Parameter analysis was then conducted to investigate the effects of screw spacing, sheet thickness ratio, and aspect ratio on the seismic performance of these shear walls, accompanied by design recommendations. The results indicated that this innovative shear wall configuration can effectively resolve the connection failure between the frame and the sheet. Furthermore, the CCS-CFS shear wall can effectively improve shear strength, energy dissipation capacity, and ductility. The developed numerical simulation method can accurately capture the hysteretic properties and failure modes of shear walls. In addition, it can address the shortcomings in conventional models that neglect the mixed hardening characteristic of steel and metal damage criteria, resulting in inaccurate simulation results and unrealistic buckling modes. The principal failure modes observed in the novel shear wall were identified as the plastic buckling of corrugated steel sheathing and the distortional buckling of the end stud. Reducing the screw spacing has a limited impact on its shear strength. It is recommended that the sheet thickness ratio of the CCS-CFS shear wall should be greater than 2.0, while the aspect ratio can be relaxed to 10:4.

This paper investigates the mechanical properties of a traditional welded rigid joint with a weakened panel zone under seismic load. The created finite element model is calibrated by the high-strength steel joint test, carried out by the team in the early stage, and the effectiveness of the finite element method was verified. The finite element software ABAQUS is used to investigate the influence of different joint web thicknesses on the mechanical properties of middle column joints under a low-cyclic-loading test. Supported by a validated numerical model, the ductility, energy dissipation, and other properties of different thicknesses of panel zone column webs are carefully analyzed. The results indicate that the thickness of the web plate in the panel zone significantly affects the location of the joint plastic hinge. The ultimate loading capacity of the joints increased significantly with an increase in the thickness of the webs in the panel zones. Compared with the joint with a weakened panel zone, the hysteresis curve of the strengthened joint is fuller; meanwhile, it cannot alleviate the stress concentration at the weld holes of the web. When the thickness of the joint domain web is too weak, excessive deformation in the joint domain will lead to a decrease in the bearing capacity of the joint, causing damage. The stiffness degradation coefficient of the web-thickened specimen was found to be dominated and controlled by the stiffness of the beam; however, with an increase in the thickness of the web, the stiffness degradation coefficient remained basically unchanged. Finally, a recommendation for weakened beam–column interior joints based on the steel frame panel zone is made, which will lay a foundation for the simulation and analysis of the seismic performance of this structure. [ABSTRACT FROM AUTHOR]

Most research on circular hollow section (CHS) flange-plate connections deals with axial tension loading, yet bending action is a common load case. Prior researchers have studied both ring and blank-flange-plate connections, using a four-point-bending setup, generating a database of 10 experimental tests and five numerical models on bolted blank-flange-plate connections under pure bending. This limited data is extended herein by two large-scale laboratory tests with blank-flange-plate connections having a large span-to-tube diameter ratio, and 120 numerical models. Flange-plate plastification and bolt fracture are the valid failure modes for this splice, so all data was meticulously assessed to exclude experimental tests or numerical models not governed by connection failure. Existing design models for calculating the connection capacity under pure bending are evaluated and revised. Moreover, based on rectangular flange-plate connections, a novel method is proposed to design its circular counterpart under pure bending. For all methods, the difference in using the ultimate stress for flange-plate moment capacity—instead of the conventional yield stress—is also analyzed. Lastly, a reliability analysis is conducted to support the proposed design method. [ABSTRACT FROM AUTHOR]

This paper aims to evaluate the web crippling capacities of cold-formed Z-sections under two-flange load cases defined in the AISI Specification. The design specification provides an empirical equation to determine the web crippling strength. However, the results from this equation for different loading and support conditions are not consistent as it predicts unconservative for certain cases and over-conservative for some other cases. In this study, web crippling capacities of Z-sections are determined using validated finite element models and compared with the AISI Specification. The comparison showed that the empirical equation predicts adequate strength for fastened support conditions and conservative strength for unfastened support conditions under End-Two-Flange (ETF) load case. For the Interior-Two-Flange (ITF) load case, the empirical equation predicts unconservative strength for fastened support conditions and over-conservative strength for unfastened support conditions. Therefore, a detailed numerical study is carried out to recommend new web crippling coefficients using a parametric study under both loading cases for fastened and unfastened support conditions. The parametric study is based on 540 finite element models. Based on the results of this study new web crippling design equations are proposed for both load cases and support conditions using the direct strength method. [ABSTRACT FROM AUTHOR]

Maintenance of reinforced concrete (RC) structures has become a global issue due to the problems associated with the corrosion of steel reinforcement. Corrosion of RC structures results in severe serviceability and strength issues, which in turn necessitates major repair works. Though it is difficult to eliminate the risk of corrosion in RC structures, appropriate retrofitting procedures can be implemented to restore the lost strength. This paper presents a detailed analysis of the mechanism of corrosion in RC members and the procedure for retrofitting corrosion-damaged RC members subjected to different loading conditions. Moreover, the efficiency of existing strengthening techniques, such as steel jacketing, fiber-reinforced polymer (FRP) composites, engineered cementitious composites (ECCs), ferrocement jacketing, fabric-reinforced cementitious composites (FRCMs) and ultra-high-toughness cementitious composites (UHTCCs), are evaluated and compared in relation to restoring/enhancing the performance of corrosion-damaged RC members under different loading scenarios. Moreover, the paper provides a detailed comparison of the effects of different parameters governing the corrosion mechanism and suggests suitable design recommendations for improving the overall performance of corrosion-damaged RC members. [ABSTRACT FROM AUTHOR]

The effects of hidden toe welds on the static behavior and strength of rectangular hollow sections to rectangular hollow sections (RHS-to-RHS) overlapped K-connections is investigated. Five full-scale welded specimens with a high overlap ratio were fabricated and tested under quasistatic loading in a universal testing machine, with the existence of hidden toe welds and branch loading condition varied. The experimental results were used to validate corresponding numerical models, and a parametric study was performed thereafter. The experimental and numerical results indicate that the overlapped K-connection capacity is affected by the presence of a hidden toe weld and the branch load case but remains within a reasonable range of the capacity predicted by certain codes and guides. Considering all the branch load cases studied, the hidden toe in a partially overlapped K-connection can be left unwelded, while some modifications are suggested to current design recommendations to account for this. A new method for calculating the branch local failure limit state is proposed, which can be used to accurately predict the capacity of overlapped RHS K-connections, without considering hidden toe welds in partially overlapped K-connections. [ABSTRACT FROM AUTHOR]

Self-esteem is a concept that refers to a person's self-evaluation that can be related to the person’s success in interacting with other people and the world around them. The self-esteem of a person is built over a lifetime, influenced by experiences, social interactions, and sense-making about the world based on self-perception of life. As people, technology and society are increasingly connected, technology may also influence its user’s self-esteem. In this paper, we investigate the subject through the lens of the Self-determination Theory, by analyzing literature work addressing the relation between technology design and self-esteem impact. Based on a meta-analysis of 21 papers previously selected from literature, we present, as result, 18 design recommendations to digital and physical artefact solutions; these recommendations are classified according to their main content, purpose, and aspect (personal, social, and technical). We could verify the recommendations completeness and analyze how they encompass the capacity of influencing self-esteem in four systems raised from literature and in one system developed considering these recommendations. With results of this work, we aim at providing technical support to guide designers in improving their system towards users’ motivation and self-esteem, favoring a designer’s reflection about how the systems they develop may affect the user’s life.

Balcony-slab joints (BSs) are common in residential buildings. Integrating thermal break systems (TBSs) can reduce the energy loss resulting from thermal bridging. However, the mechanical performance of BSs equipped with TBSs against shear and bending remains hardly explored in design and experimentation. The aim of this study is to evaluate the mechanical behavior of BS joints under combined shear and bending actions, taking into account the presence of TBSs. Seven large-scale balcony-slab specimens were fabricated and tested under vertical loading with different moment-shear ratios (M/V). The BSs are equipped with TBSs comprising steel bars and shear profiles. A simplified finite element (FE) model was then developed using the ABAQUS software. The FE model employs spring-like elements to simulate the bond and contact behavior between concrete and steel, reproducing both the resistance and stiffness of the tested specimens. On the basis of the experimental and FE results, a resistance model consistent with the Eurocode design guidelines was drawn. Finally, moment-shear (M-V) interaction curves for balcony-slab joints were generated at the ultimate (ULS) and serviceability (SLS) levels, considering the impact of horizontal loading to achieve comprehensive design insights. The tests and FE results showed that the moment-shear ratio (M/V) significantly influences the shear capacity of the BS joints. The steel profiles effectively acted as shear keys connecting the balcony and the slab. A strength reduction coefficient of 0.701 was introduced for the design. • Balcony-slab joints insulated with thermal break systems (SLABE) were investigated. • A simplified finite element (FE) spring-model was developed using ABAQUS software. • Design model and strength reduction factor were proposed. • Moment-shear interaction curves for design at SLS and ULS for joints with shear keys were introduced. • The impact of lateral forces on the M-V curves of joints with shear keys/TBS was investigated. [ABSTRACT FROM AUTHOR]

This paper presents an algorithm for the optimization of the design of reinforced concrete (RC) road bridges, taking into account the current conditions in Cuba. The use of RC is chosen over the common solutions due to the current high economic cost of prestressing steel. The optimization problem is formulated to find the minimum direct cost, defining constraints based on the AASTHO-LRFD 2014 and NC-207:2019 standards. The algorithm is created to properly obtain practical solutions from the engineering point of view, involving the use of discrete variables. The optimization method used is Biogeography-Based Optimization. A sensitivity analysis of the parameters of this method is performed. The results indicate that the typical projects currently used can be considerably improved to enhance their economic indexes. Based on these results, some specific design recommendations are given. In addition, future research lines are suggested based on the deficiencies of the proposed methodology.

Copyright of Dyna is the property of Universidad Nacional de Colombia, Medellin, Facultad de Minas and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper investigates the mechanical properties of a traditional welded rigid joint with a weakened panel zone under seismic load. The created finite element model is calibrated by the high-strength steel joint test, carried out by the team in the early stage, and the effectiveness of the finite element method was verified. The finite element software ABAQUS is used to investigate the influence of different joint web thicknesses on the mechanical properties of middle column joints under a low-cyclic-loading test. Supported by a validated numerical model, the ductility, energy dissipation, and other properties of different thicknesses of panel zone column webs are carefully analyzed. The results indicate that the thickness of the web plate in the panel zone significantly affects the location of the joint plastic hinge. The ultimate loading capacity of the joints increased significantly with an increase in the thickness of the webs in the panel zones. Compared with the joint with a weakened panel zone, the hysteresis curve of the strengthened joint is fuller; meanwhile, it cannot alleviate the stress concentration at the weld holes of the web. When the thickness of the joint domain web is too weak, excessive deformation in the joint domain will lead to a decrease in the bearing capacity of the joint, causing damage. The stiffness degradation coefficient of the web-thickened specimen was found to be dominated and controlled by the stiffness of the beam; however, with an increase in the thickness of the web, the stiffness degradation coefficient remained basically unchanged. Finally, a recommendation for weakened beam–column interior joints based on the steel frame panel zone is made, which will lay a foundation for the simulation and analysis of the seismic performance of this structure.

Acknowledging the potential of system‐based design approaches, most international design standards for steel structures include preliminary versions of such alternative design methods. The Direct Design Method (DDM) is one of these approaches, which allows designing steel structures directly using advanced numerical analyses without requiring further member checks. This paper presents the DDM design (and verification) procedure and summarizes the key aspects of the advanced finite element model necessary for the determination of the system strength, with an emphasis on cold‐formed stainless steel portal frames. Through the design of two frames, the DDM design procedure is illustrated and the resulting cross‐sections are compared with those derived using the traditional two‐step design approach in the Eurocode and ASCE design frameworks. The results demonstrate that the DDM verification process is simpler and more direct, and that lighter structures are obtained when designing using the DDM for strength considerations. Finally, this paper also highlights that allowing larger deformations in the ultimate limit state design for the DDM does not have additional negative effects on the serviceability requirements if compared to the traditional two‐step design approach. [ABSTRACT FROM AUTHOR]

The replacement of rear-view mirrors with camera-monitor systems introduces new opportunities for design, such as altering the image quality and the rearward field-of-view. We investigated how the image quality and field-of-view might affect the distance and time-to-contact estimation of other vehicles. Eighty-six subjects estimated either their egocentric distance to a stationary vehicle (Experiment I) or the time-to-contact to an approaching vehicle (Experiment II). Throughout the experiments, the pixel density and either the field-of-view or the viewing condition varied. A larger field-of-view increased distance estimation accuracy and confidence. Reduced pixel density led to larger estimates. In contrast, reduced pixel density and simulated dirt shortened time-to-contact estimates. This is compatible with a safety strategy applied under conditions of impaired vision. Moreover, a limited benefit was observed for higher pixel densities. Therefore, camera-monitor systems with large field-of-view and a pixel density of around 300 ppi could ensure accurate TTC and distance estimation. Practitioner summary: A camera's field-of-view and image quality are important parameters for camera-monitor systems. In two experiments, we investigated the effects of these two parameters on rearward distance and time-to-contact estimation. Whereas a larger field-of-view improved distance estimation accuracy, increasing the pixel density had a limited effect in the estimation of time-to-contact. [ABSTRACT FROM AUTHOR]

The design of a rectangular hollow-section K-connection in which the branches are welded toe-to-toe to the chord is not permitted at present in design guides and codes. To illustrate the feasibility of such connections, two full-scale cold-formed welded rectangular hollow-section K-connection laboratory tests, including one control specimen and one zero-gap specimen, are presented. A new chord face shear analytical model based on a yield-line mechanism is proposed for such connections, and its validity was evaluated against the experiments. Nonlinear finite-element connection models were built and validated against the laboratory tests, and a numerical parametric study was performed on similar connections with a broader range of parameters. From the results of the finite-element study, an empirical connection strength model was also generated by regression curve-fitting. Based on the experimental and numerical data, the proposed chord face shear analytical model is recommended for design of rectangular hollow-section zero-gap K-connections. The gap size can also be increased up to the summation of the two branch thicknesses. [ABSTRACT FROM AUTHOR]

Maintenance of reinforced concrete (RC) structures has become a global issue due to the problems associated with the corrosion of steel reinforcement. Corrosion of RC structures results in severe serviceability and strength issues, which in turn necessitates major repair works. Though it is difficult to eliminate the risk of corrosion in RC structures, appropriate retrofitting procedures can be implemented to restore the lost strength. This paper presents a detailed analysis of the mechanism of corrosion in RC members and the procedure for retrofitting corrosion-damaged RC members subjected to different loading conditions. Moreover, the efficiency of existing strengthening techniques, such as steel jacketing, fiber-reinforced polymer (FRP) composites, engineered cementitious composites (ECCs), ferrocement jacketing, fabric-reinforced cementitious composites (FRCMs) and ultra-high-toughness cementitious composites (UHTCCs), are evaluated and compared in relation to restoring/enhancing the performance of corrosion-damaged RC members under different loading scenarios. Moreover, the paper provides a detailed comparison of the effects of different parameters governing the corrosion mechanism and suggests suitable design recommendations for improving the overall performance of corrosion-damaged RC members.