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The editorial introduces the August 2024 edition of the journal "Structures and Buildings," which is one of the oldest journals in the field of structures and buildings. The issue includes six papers covering a range of topics and materials from researchers and designers across four continents. The papers discuss various subjects such as the flexural strength of steel girders, non-linear dynamic behavior of bridge piers, analysis of carbon-fiber-reinforced polymer-wrapped steel box sections, limit state design of earthquake-resisting systems, seismic resilience of Kath-Kuni structures, and the moment-curvature relationship of coal gangue concrete beams. The editorial encourages readers to engage in discussions and welcomes their comments. [Extracted from the article]

Structural engineers, whether they are designers, contractors or academics, are frequently faced with the problem of introducing innovation into practice through research, such as for the development of new structures or the use of new materials such as fibre reinforced polymer. Hence, research is pivotal to the introduction of innovation. How research is applied is invariably a very complex and often costly problem and consequently needs careful examination to be effective. All engineers do research but by the very nature of research we all do research in different ways. This paper is the author's reflections on research procedures and approaches often used in structural engineering. These approaches are then illustrated using the author's research particularly on developing a generic failure model for reinforced concrete which can be applied to the seemingly disparate reinforced concrete problems of moment-rotation, shear capacity and the effect of confinement. Numerous concepts are introduced in this paper such as: the use of empirical modelling in plugging the gaps in the structural mechanics models; the elusive concept that is pivotal to understanding and should not be confused with the illusive concept; and categorisation of researchers to help sort out the mass of information available. [ABSTRACT FROM AUTHOR]

This paper presents the finite-element procedure for fatigue evaluation of reinforced concrete bridge deck under the application of truck wheel load. The approach is based on the smeared crack concept with the introduction of the fatigue tests of concrete and reinforcing steel available in the literature and the Palmgren-Miner linear criterion of cumulative damage in the analysis. The models are validated with the fatigue test of 1/6.6-scale AASHTO bridge deck under the application of fixed-point repetitive loading presented in previous study. Results are in good agreement. Significant contribution of the developed approach to the fatigue evaluation of bridge deck is a series of S-N relations which can be simulated at any desired levels of damage. This permits the investigation of the deterioration of bridge deck which is appeared to be useful information for highway agencies to prolong the life of their bridge decks. S-N relations are simulated at crack areas of 10%, 20%, 30%, and 40% of the bottom surface area of the deck slab to represent the propagation of crack. Deterioration of bridge deck subjected to passages of five-axle double-unit trucks in Thailand is investigated to demonstrate the application of the simulated S-N relations. [ABSTRACT FROM AUTHOR]

An experimental study was conducted to investigate the structural behavior and performance of deep beams reinforced in shear with a honeycomb steel mesh (HSM). A series of four-point loading tests on five simply supported deep beams were carried out. The control beam was substantially deficient in shear strength, another beam was fully reinforced in shear by stirrups, and four other beams were reinforced with various configurations of HSM. The primary variables were the diagonal cell width and welding condition of the HSM. The shear behavior and performance of deep beams reinforced with various configurations of HSM were compared with those of the control beam and the beam reinforced in shear by stirrups. In this study, all of the tested deep beams failed in shear. Crack patterns and failure modes of the specimens were explained on the basis of the arch action. It was found from the test results that HSM was effective in reinforcing deep beams in shear. Further, the butt- welded HSM with a diagonal cell width of 100 mm was shown to be most effective in terms of stiffness, load carrying, and energy absorption capacities. [ABSTRACT FROM AUTHOR]

This document is a guest editorial from the journal "Advances in Structural Engineering" discussing the challenges faced by concrete infrastructure, such as sustainability, corrosion damage, alkali-aggregate reaction damage, and resilience. The editorial highlights the development of a new class of advanced materials called Ultra-High Performance Concrete (UHPC) and Ultra-High Performance Fiber Reinforced Cementitious Composite (UHPFRC), which offer high mechanical performance and durability. The special issue of the journal includes thirteen papers on UHPC, covering topics such as material-level performance, innovative design of UHPC structures, and the fundamental behavior of UHPC structures. The editors express gratitude to the authors and reviewers for their contributions to the special issue. [Extracted from the article]

The corrosion of steel rebars is a prevalent factor leading to the diminished durability of reinforced concrete structures, posing a significant challenge to the safety of structural engineering. To tackle this issue, extensive research has been conducted, yielding a variety of theoretical insights and remedial measures. This review paper offers an exhaustive analysis of the passivation processes and corrosion mechanisms affecting steel rebars in reinforced concrete. It identifies key factors such as chloride ion penetration and concrete carbonization that primarily influence rebar corrosion. Furthermore, this paper discusses a suite of strategies designed to enhance the longevity of reinforced concrete structures. These include improving the concrete protective layer's quality and bolstering the rebars' corrosion resistance. As corrosion testing is essential for evaluating steel rebars' resistance, this paper also details natural and accelerated corrosion testing methods applicable to rebars in concrete environments. Additionally, this paper deeply presents an exploration of the use of X-ray computed tomography (X-CT) technology for analyzing the corrosion byproducts and the interface characteristics of steel bars. Recognizing the close relationship between steel bar corrosion research and microstructural properties, this paper highlights the pivotal role of X-CT in advancing this field of study. In conclusion, this paper synthesizes the current state of knowledge and provides a prospective outlook on future research directions on the corrosion of steel rebars within reinforced concrete structures. [ABSTRACT FROM AUTHOR]

This paper presents mechanics-based modeling methodologies to predict the shear strength of squat walls incorporating boundary elements. Developed with the intention of surmounting the limitations of empirical models that are prevalent in the structural engineering community, these approaches are composed of an iterative analytical method and simplified design equations. Conforming to experimental observations, a failure criterion is established to determine the web crushing and shear compression of each wall component. Upon validating the methodologies against 123 test data compiled from the literature, detailed responses of the wall system are examined to comprehend the behavior of the web and the compression and tension boundary elements subjected to lateral loading. Model outcomes indicate that the overall strength of the squat walls is distributed to the web and the boundary elements by 58% and 42%, respectively, signifying that the contribution of the boundary elements should not be ignored, unlike the case of most customary models. In contrast to the provision of published design specifications, both horizontal and vertical reinforcing bars affect the shear strength of the web concrete. The growth of compressive principal strains, which dominate the failure of the members, is a function of the reinforcement ratio. According to statistical evaluations, the proposed models outperform existing models in terms of capacity prediction. The effects of major parameters are articulated from a practical standpoint. [ABSTRACT FROM AUTHOR]

Numerous studies revealed optimization techniques' applicability in minimizing the costs of reinforced concrete buildings. However, the existing literature has narrowly focused on optimizing buildings with a single function, such as residential or office buildings, hindering the generalization of the results. This paper aims to bridge the gap between optimization and structural engineering by obtaining the minimum-cost design of flat slab buildings with different intended functions. In this context, the optimal designs of 120 alternatives were obtained, considering various spans (4–8 m), live loads (2–10 kPa), and concrete compressive strength (25–40 MPa). The optimization was executed using the evolutionary algorithm provided in Microsoft Excel's Solver tool. The optimization model permits the utilization of drop panels to resist punching stresses developed from the slab-column interaction. The objective function is the cost of materials and labor involved in constructing floors and columns. The decision variables are the floor dimensions and column configurations in dimensions and reinforcement. The structural constraints were applied per the Egyptian design code (ECP203-2020). Eventually, guidelines were developed to help the designers choose the economic floor system and quantities of materials based on the building's intended function. [ABSTRACT FROM AUTHOR]

Estimating the shear strength of a fiber-reinforced polymer (FRP)–reinforced-concrete (RC) beam is a complex task that depends on multiple design variables. The use of FRP bars has emerged as a promising alternative to diminish the corrosion problems that are associated with steel reinforcement in adverse environments; however, an accurate and reliable method of shear strength prediction is needed to ensure the economical use of materials and robust designs. Several optimized design equations are available in the literature; however, when utilizing these equations a substantial difference is observed between the predicted outcome (Vpred) and the experimental shear strength (Vexp) result. Therefore, this paper presented a novel approach toward implementing machine learning (ML) algorithms to accurately estimate the shear strength of FRP–RC beams. A large database that consisted of 302 shear test results on FRP-reinforced slender concrete beams without stirrup was collected from the literature to formulate the most efficient prediction model. The performance of each ML algorithm model was compared with the existing design provisions and models. The model interpretation was performed through feature importance analysis to explain the model output compared with a black box. The proposed data-driven ML models demonstrated a high level of accuracy and excellent performance and were superior to the existing shear strength models. In addition, a simple graphical user interface (GUI) was developed to aid practicing engineers when estimating shear strength without the need for complicated design procedures. The shear strength of FRP–RC beams is calculated using various design codes and guidelines that are heuristically developed based on previous test results. In general, the developed equations are either mechanics-based or empirical. However, this paper demonstrated that data-driven ML algorithms could generate a more reliable and appropriate prediction of the shear strength of FRP–RC beams. Furthermore, as the database increases, it could be automatically updated, which would result in more accurate and reliable results. Designers and practitioners could conveniently use the developed algorithms for the reliable and quick prediction of the shear strength of FRP–RC beams. In addition, the developed GUI is innovative and user-friendly. It allows users to determine the design shear strength without referring to an existing code by employing ML in conjunction with a large, reliable, and authenticated database to ensure accuracy. This could be important for the structural engineering community when assessing the shear capacity of existing FRP–RC beams. [ABSTRACT FROM AUTHOR]

BIM‐based assessment of sustainable maintenance measures for existing building structures In Germany, around 70 % of all building construction work is done on existing buildings. This high proportion emphasizes the need for the maintenance management of buildings. For this purpose, digital methods and technologies are combined with integrating sustainability aspects for optimized decision‐making. In this paper, a holistic method for the building maintenance is developed by using the BIM‐method in combination with the integration of sustainability aspects. Different digital technologies are combined within a semi‐automated workflow. In the first step, the status quo of digital maintenance on reinforced concrete structures is analyzed in a literature review. Subsequently, the process‐related and data‐technical basics are defined. Based on this, the concept development and validation are carried out by holding the steps ‐ data acquisition, an algorithmic data process and sustainability analysis as well as data provision via augmented reality and a common data environment. At the end, the process steps are validated using a real demonstrator. The result of the article demonstrates a semi‐automated process chain and decision support for resource‐efficient maintenance management of reinforced concrete structures. [ABSTRACT FROM AUTHOR]

The booming growth of computational abilities in the 21st century has led to its assimilation and benefit in all horizons of engineering. For civil engineers, these advancements have led to groundbreaking technologies such as BIM, automation, and optimization. Unfortunately, even in an era of dwindling resources and dire need for sustainability, optimization has failed to attract implementation in practice. Despite an exponential growth as an area of research interest, the optimization of engineering structures such as reinforced concrete (RC) is still a complex task that requires multidisciplinary knowledge, hindering its practicability. Although past review papers have delved into this topic, they have only been able to cover the breadth of information available by covering broader aspects of optimization of structures. This study on the other hand aims to cover this topic in depth to uncover problem specific trends and issues, by focusing only on optimization of RC cantilever retaining walls. Although there is an abundance of research studies on this topic, there is an absence of any critical review to tie them up, and concurrently with its broader scope, it suffers the same lack of applicability in the field. The in-depth review presents a summarization of all the online publications including research articles, conference papers, and theses to the best of authors' knowledge on the topic of RC cantilever retaining wall optimization. Geographical trends, regional developments, and prominent journals have been identified. The design codes, problem formulation, objectives, constraints, variables, and their optimization techniques are tabulated for ease of understanding. Unique areas of development investigated by the different researchers have been highlighted. Lastly, comprehensive recommendations for future works have been detailed with a focus on improving its applicability and assimilation into the construction industry. [ABSTRACT FROM AUTHOR]

The vision for fib MC2020 is to go beyond the point reached by fib MC2010, recent ISO codes, such as ISO 16311, and the current Eurocode activities to extend the application of Eurocodes to existing structures. The contents of fib MC2020 suit these forward‐looking objectives, dealing both with the design of new structures and all the activities associated with the life‐cycle management of existing concrete structures including matters, such as in‐service assessment and interventions upon them, including situations where new structural members are incorporated as parts of existing structures. With the fib MC2020 adaptations taking sustainability as a fundamental requirement, defining implications for subsidiary performance requirements critical to structural design and assessment procedures, it is logical that Model Code 2020 explicitly introduces and consequently seeks to make use of performance‐based concepts. A focus on performance provides a potential way to better align the interests of owners, users, technical consultants (such as structural engineers, material engineers, etc.), contractors, as well as material suppliers and manufacturers. It is envisaged that implementing the concept of the performance‐based approach in design and assessment will encourage rational design and technological progress which will facilitate the creation of superior structures for future generations, by removing constraints to the use of novel types of concrete and reinforcing materials and offering possibilities for optimization of solutions that better fit the needs of stakeholders. This paper addresses the principles of the performance‐based approach to design and assessment and discusses the manner in which it has been introduced in fib MC2020. The benefits and burdens associated with the performance‐based approach and the traditional prescriptive approach to engineering specification are discussed, both from a technical and process/commercial/contractual point of view, to describe the overall benefits of the performance‐based approach. Finally, the future outlook for a coherent integration of the performance‐based approach in design and assessment is addressed, paving the way for further work on standardization for sustainable concrete structures. [ABSTRACT FROM AUTHOR]

Mobilisation of alternate load path (ALP) mechanisms in three-dimensional (3D) beam–slab systems is a key factor in designing structures against progressive collapse. Existing analytical methods on 3D beam–slab systems focusing on limited load-resisting mechanisms often lead to uneconomical and unrealistic design, while finite element models with 3D solid elements are too complicated and time-consuming for 3D beam–slab systems. To address these shortcomings, this paper aims to provide structural engineers with two simple but effective and reliable approaches to predict the structural behaviour of 3D beam–slab systems. They include (i) an analytical method and (ii) a simplified finite element model based on strip method and grillage analysis. Both approaches are validated against published test results for 3D beam–slab systems. Compared to existing approaches on 3D beam–slab systems, these two proposed methods incorporate all the load-resisting mechanisms in both the beams and slabs, giving more accurate and realistic predictions of load–displacement curves for the sub-structures considered. In addition, parametric studies on the analytical approach are presented to shed light on the role of boundary conditions and the contribution of slabs to the load resistance capacity of 3D beam–slab structures against progressive collapse. [ABSTRACT FROM AUTHOR]

Reinforced concrete (RC) is a widely used construction material due to its superior characteristics compared to steel and timber. It is commonly used in various civil engineering structures such as bridges, dams, and residential buildings. The mechanical behavior of reinforced concrete under different loading conditions remains a challenge, despite extensive research. This special issue explores theoretical, experimental, and numerical studies on the mechanical properties of reinforced concrete materials, including topics such as dynamic characteristics, antiknock performance, structural behavior, bond behavior, and modification of concrete aggregates. The research papers included in this special issue highlight the importance of global collaborations in advancing our understanding of reinforced concrete materials. [Extracted from the article]

Simplicity and optimality are commonly associated with the particle swarm optimization (PSO) algorithm. As a result, numerous variants and hybrids of PSO have been developed and implemented to address structural optimization problems. The undeniable importance of the initialization technique in determining the overall performance of a given optimization algorithm cannot be overstated. Optimization algorithms, such as PSO, typically rely on a random, uniformly distributed initialization. Through multiple iterations and updates, these algorithms aim to achieve optimal results. The underlying assumption behind such an initialization approach is that a fair or reasonable arrangement of particles is best accomplished through randomization, and thus the entire optimization process is iterated based on this assumption. However, this initialization technique raises concerns regarding the attainment of optimality and convergence, leaving room for further examination. In this paper, we challenge this assumption by introducing a priority concept. The key idea is that particles should not be initialized randomly since randomness alone does not guarantee a reasonable allocation of design variable values in iterative optimization. This can lead to misguided velocity updates and ultimately, a time-consuming pursuit of optimality. To address this issue, we formulate priority criteria (PC) and propose an enhanced PSO variant called Priority Criteria PSO (PCPSO). The PC can be incorporated into any PSO variant or hybrid without impacting the parameter settings, constraints, and penalty approaches of the respective algorithms. A case study involving 2D reinforced concrete frames was conducted to compare the performance of the ordinary PSO algorithm with the PCPSO. The results clearly demonstrate that the introduction of the PC leads to a significant cost reduction when compared to PSO with an inertia damping factor. Additionally, the PCPSO algorithm exhibits accelerated convergence. Furthermore, to alleviate the computational burden associated with structural analysis at each iteration, a reanalysis approach called Combined Approximations (CA) is mathematically formulated and implemented. [ABSTRACT FROM AUTHOR]

In recent years, substantial efforts have been made to incorporate the nonlinear behavior of joints in frame analysis. In this regard, a well-established component-based model (CBM) is provided in EN 1993-1-8 to capture the nonlinear moment–rotation curve of steel beam-column joints. In this paper, to extend the design approach in EN 1993-1-8 to steel beam-to-reinforced concrete column (RCS) joints, a simple mechanical model is first developed to determine the moment resistance of RCS joints. The proposed model can predict two different failure modes of RCS joints and yields better accuracy and consistency compared to the current design method for such joints. After determining the joint moment resistance, an appropriate CBM is developed to simulate the nonlinear moment–rotation response of RCS joints. The proposed CBM can capture the moment–rotation behavior of RCS joints at elastic, transitional, and ultimate states. The initial rotational stiffness of RCS joints can be easily calculated based on the proposed CBM. This is particularly important in the frame analysis as the beam-column joint can be classified as a rigid, semirigid, or pinned joint based on the initial rotational stiffness. The derivations are discussed in detail, followed by verifications of the proposed CBM. Compared to the experimental results, the proposed CBM shows reasonable accuracy in predicting the moment–rotation behavior of RCS joints. Most importantly, the numerical procedure of the proposed CBM can be implemented by a spreadsheet method, which provides a simple and robust means for structural engineers to obtain the mechanical properties of RCS joints. [ABSTRACT FROM AUTHOR]

Copyright of Mechanika is the property of Mechanika 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.)

In the recent two decades, the progressive collapse of reinforced concrete (RC) frame structures attracted unprecedented research interests in the structural engineering community. Experiments are regarded as an essential method in this field since actual cases can barely provide sufficient and effective data to support rigorous research. In this paper, prevailing experimental assumptions and configurations among over 100 series of experiments are quantitatively revealed by a bibliometric collection based on systematic search in an academic database. Since numerous experiments have been reported on the progressive collapse of RC frame structures, this paper subsequently presents a state-of-the-art review summarizing both experimental consensuses and controversies constituted by three main aspects: (a) static mechanisms, (b) dynamic behavior, and (c) threat-dependent research. The significance of secondary mechanisms, existing problems of dynamic effects, and potential flaws of the threat-independent assumption are discussed in detail with experimental findings. Future needs are emphasized on research targets, correlations between experiments and design, dynamic effects, threat-dependent issues, and retrofitting. These recommendations might help researchers or designers realize a more reliable and realistic progressive collapse design of RC frame structures in the future. [ABSTRACT FROM AUTHOR]

Copyright of Bulletin of the Polytechnic Institute of Iasi - Construction & Architecture Section is the property of Sciendo 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.)

The vulnerability of Reinforced Concrete (RC) building systems to progressive collapse has turned out to be a challenging task for professional structural engineers looking to prevent total failure on account of nearby damage. The paper estimates the behavior of such buildings under several scenarios of misplaced columns at different floor stages and their capacity for progressive collapse. The study has been conducted following the General Services Administration (GSA) guidelines for progressive collapse evaluation and design. The progressive collapse of a 10-story structure subjected to the simplest gravity load is taken into consideration and the column is eliminated at one place to evaluate the damage spread; columns at diagnosed crucial locations (corner, middle and interior) are removed in line with the GSA guidelines. Static analysis is done using ETABS. For each case, the consequences are considered in terms of Demand Capacity Ratio (DCR) at critical sections, and the structure is assessed for its susceptibility to progressive collapse. The shear wall is made available on the component where collapse occurred and DCR values are mentioned. By providing the shear wall to the structure, the progressive collapse of a structure due to accidental load may be controlled. [ABSTRACT FROM AUTHOR]

The implementation of structural health monitoring (SHM) systems in existing civil engineering structures could contribute to a safer and more resilient infrastructure as well as important savings. Due to their light weight, small size, and high resistance to the environment, distributed optical fibre sensors (DOFS) stand out as a very promising technology for damage detection and quantification in reinforced concrete (RC) structures. In this paper, the performance of DOFS featuring an external polymeric cladding with rough surface, to accurately assess deflection and crack width of a stainless-steel RC beam subjected to four-point bending is investigated. Several sensor positions, both embedded in the concrete and attached to the surface, are investigated in a multi-layer configuration. The study revealed that embedded sensors yield very accurate results regardless of the sensor position and the load level, that is, service or ultimate loads, being the sensor glued in a premade groove on the steel bar the most reliable solution for high-load levels. Conversely, externally deployed sensors for the assessment of existing structures, described attenuated values for the measured deflections, and, to some extent also the crack width, due to a loss of bond between the sensor and the surrounding concrete, already for service loads. Corrective methods to further use the obtained data are presented, yet the clad DOFS attached to the concrete surface described a significant drop of performance with increasing load levels, showing an important loss of data at 80% of the ultimate load. [ABSTRACT FROM AUTHOR]

The concept of concrete-encased concrete-filled steel tube (CE-CFST) columns was conceived during the quest to enhance the safety of structures in high seismic regions. Over the past two decades, researchers have extensively investigated the performance of CE-CFST columns under a range of loading conditions using experimental, analytical, and numerical methods. Previous research has shown that integrating outer RC and encasing steel tubes into concrete-encased concrete-filled steel tube columns boosts their structural performance under a wide diversity of loading conditions. This paper aims to provide a comprehensive analysis of various models proposed by researchers in different regions and summarize all results that have been breakthroughs in the last decade. Researchers revealed that this type of structure only uses less than 85% of its flexural capacity. There are still significant research gaps in depicting these structures' behavior under diverse loading conditions, both analytical, numerical and experimental. The authors show the highlights of CE-CFST columns' performance and give a detailed review of the corresponding reinforced concrete (RC) columns and concrete-filled steel tube (CFST) columns. The highlights for further researches on CE-CFST are provided for elaborating other mechanical properties. To sum up, the CE-CFST composite columns provide resilient and sustainability in structure during engineering applications. [ABSTRACT FROM AUTHOR]