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Buildings, Volume 11, Issue 2 (February 2021) – 44 articles

Cover Story (view full-size image): The presence of infill panels substantially modifies the seismic performances of reinforced concrete (RC) frames in terms of strength, stiffness, and energy dissipation. Despite several studies focused on the quantification of the effect of infill presence on the overall performances of infilled RC frames, the best strategy to simulate the presence of infill panels remains an open debate. This study investigates the effects of different infill constitutive models on the seismic performance of infilled RC buildings expressed in terms of engineering demand parameters, and on the generation of damage fragility curves. View this paper
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Open AccessArticle
Challenges and Barriers for Net‐Zero/Positive Energy Buildings and Districts—Empirical Evidence from the Smart City Project SPARCS
Buildings 2021, 11(2), 78; https://doi.org/10.3390/buildings11020078 - 23 Feb 2021
Viewed by 166
Abstract
Without decarbonizing cities energy and climate objectives cannot be achieved as cities account for approximately two thirds of energy consumption and emissions. This goal of decarbonizing cities has to be facilitated by promoting net-zero/positive energy buildings and districts and replicating them, driving cities [...] Read more.
Without decarbonizing cities energy and climate objectives cannot be achieved as cities account for approximately two thirds of energy consumption and emissions. This goal of decarbonizing cities has to be facilitated by promoting net-zero/positive energy buildings and districts and replicating them, driving cities towards sustainability goals. Many projects in smart cities demonstrate novel and groundbreaking low-carbon solutions in demonstration and lighthouse projects. However, as the historical, geographic, political, social and economic context of urban areas vary greatly, it is not always easy to repeat the solution in another city or even district. It is therefore important to look for the opportunities to scale up or repeat successful pilots. The purpose of this paper is to explore common trends in technologies and replication strategies for positive energy buildings or districts in smart city projects, based on the practical experience from a case study in Leipzig—one of the lighthouse cities in the project SPARCS. One of the key findings the paper has proven is the necessity of a profound replication modelling to deepen the understanding of upscaling processes. Three models analyzed in this article are able to provide a multidimensional representation of the solution to be replicated. Full article
(This article belongs to the Special Issue Net-Zero/Positive Energy Buildings and Districts)
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Open AccessArticle
Augmented Reality to Enable Users to Identify Deviations for Model Reconciliation
Buildings 2021, 11(2), 77; https://doi.org/10.3390/buildings11020077 - 23 Feb 2021
Viewed by 140
Abstract
Effective use of Building Information Modeling (BIM) during operation typically requires modeled content to accurately match the built spaces, which necessitates effective field verification techniques to ensure that BIM content matches the actual built conditions. Some contractors leverage laser scanning and other reality-capture [...] Read more.
Effective use of Building Information Modeling (BIM) during operation typically requires modeled content to accurately match the built spaces, which necessitates effective field verification techniques to ensure that BIM content matches the actual built conditions. Some contractors leverage laser scanning and other reality-capture technologies to verify modeled content prior to turnover, but these approaches can be time- and resource-intensive. Augmented reality (AR) enables users to view BIM content overlaid on their field of view of the built space. Research suggests potential for using AR for tasks related to field verification, but a study that systematically explores the specific types of deviations that can be detected with this technology is missing from the current literature. This paper tasks participants with using immersive AR to identify deviations from BIM in a ceiling plenum space that includes installed Mechanical, Electrical and Plumbing (MEP) components, which would typically be included in a coordinated BIM. The results suggest that AR can enable users to effectively identify large deviations and missing building elements. However, the results do not indicate that AR effectively enables users to identify small deviations and can potentially lead to identifying false positive observations, where accurately constructed elements are perceived as deviating from BIM. These results suggest that immersive AR can effectively be used to check whether recently built elements conform to the intended BIM in instances where speed of verification is more important than adhering to strict tolerances. For instances where accuracy (less than two inches) is critical, the results of this work suggest that AR can be used to help determine where in the building more accurate, but more resource-intensive, reality-capture technologies should be used. Full article
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Open AccessArticle
Effect of the Particle Size on TDA Shear Strength Parameters in Triaxial Tests
Buildings 2021, 11(2), 76; https://doi.org/10.3390/buildings11020076 - 23 Feb 2021
Viewed by 174
Abstract
Tire recycling and reuse in North America and worldwide have increased considerably, intending to reduce the harmful effects of scrap tires on the environment. Accordingly, the use of tire derived aggregates (TDA) as backfill material in civil engineering applications is on the rise [...] Read more.
Tire recycling and reuse in North America and worldwide have increased considerably, intending to reduce the harmful effects of scrap tires on the environment. Accordingly, the use of tire derived aggregates (TDA) as backfill material in civil engineering applications is on the rise at an unprecedented rate. However, to use TDA in the construction industry, its strength and stiffness parameters properties must be evaluated. One key factor that is known to influence the strength and stiffness of backfill material is the particle size of the used material. Hence, in this paper, a series of large-scale triaxial tests on five TDA samples with different maximum particle size, Dmax, of 19.05, 25.4, 38.1, 50.8 and 76.2 mm were conducted to investigate the effect of the particle size on the obtained results. The tests were done under consolidated drained conditions using three confining pressures of 50, 100, and 200 kPa. The results showed that the shear strength of TDA increase by increasing the maximum particle size while the cohesion did not show a specific trend. Moreover, the samples exhibited an increase in the secant elastic modulus by increasing the particle size. Full article
(This article belongs to the Special Issue Utilization of Waste Materials in Building Engineering)
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Open AccessArticle
Design for Maintainability of Basements and Wet Areas
Buildings 2021, 11(2), 75; https://doi.org/10.3390/buildings11020075 - 20 Feb 2021
Viewed by 283
Abstract
With the motto of “doing it right the first time”, this study focuses on spearheading the integration of designers, constructors, and facility mangers, at the outset of the planning/design stage, by providing easy-to-read tables summarising (1) knowledge learnt from past mistakes and (2) [...] Read more.
With the motto of “doing it right the first time”, this study focuses on spearheading the integration of designers, constructors, and facility mangers, at the outset of the planning/design stage, by providing easy-to-read tables summarising (1) knowledge learnt from past mistakes and (2) maintainability benchmarks, to ensure high maintainability for Basements and Wet Areas. The commonly occurring problems in Basements and Wet Areas of a total of 110 buildings comprising of commercial, hotels, industrial, institutions, healthcare facilities, and residential facilities were evaluated using case and field studies. Face-to-face interviews and workshops with the respective professionals involved in the design, construction, operation and maintenance (O&M) of the buildings were conducted for detailed investigation on each problem for their (a) problem types, (b) extent of problem, (c) failure mechanism, (d) good practices in design/construction/O&M/facilities management (FM), and (e) environmental issues. Easy-to-read tables of checklists based on a preventive/predictive performance-based approach, which defines acceptable standards in design, construction and O&M/FM practices, were derived. The checklists help enhance the integration of designers, constructors, and facilities managers (FM), ensuring high maintainability and productivity right at the outset of the planning/design stage. They also help professionals derive, customise, and validate their own Maintainable Design Appraisal System (MDAS) according to their own needs. Full article
(This article belongs to the Special Issue Recent Advances in Design, Construction, and Maintenance of Buildings)
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Open AccessArticle
Effect of Frequency Characteristics of Ground Motion on Response of Tuned Mass Damper Controlled Inelastic Concrete Frame
Buildings 2021, 11(2), 74; https://doi.org/10.3390/buildings11020074 - 20 Feb 2021
Viewed by 138
Abstract
This paper investigates the performance of tuned mass damper (TMD) and dynamic behavior of TMD-controlled concrete structure considering the ground motion (GM) characteristics based on frequency content. The effectiveness of TMD in reducing the structural response and probability of collapse of the building [...] Read more.
This paper investigates the performance of tuned mass damper (TMD) and dynamic behavior of TMD-controlled concrete structure considering the ground motion (GM) characteristics based on frequency content. The effectiveness of TMD in reducing the structural response and probability of collapse of the building frames are affected by the frequency characteristics of GMs. To attenuate the seismic vibration of the buildings, the TMD controlled building has been designed based on the modal analysis (modal frequencies and modal mass participation ratio). In this study, to investigate the performance of TMD, four different heights (i.e., 3, 5, 10, 20 stories) inelastic concrete moment-resisting frames equipped with TMDs are developed using an open-source finite element software. A series of numerical analyses have been conducted using sixty earthquakes classified into three categories corresponding to low, medium, and high-frequency characteristics of GMs. To evaluate the proposed strategy, peak lateral displacements, inter-story drift, and the probability of collapse using fragility analysis have been investigated through the structures equipped with and without TMD. The results appraise the effect of TMD and compare the seismic responses of earthquake frequency contents and the vibration control system of the inelastic building frames. Full article
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Open AccessReview
Multiple Dimensions of Smart Cities’ Infrastructure: A Review
Buildings 2021, 11(2), 73; https://doi.org/10.3390/buildings11020073 - 19 Feb 2021
Viewed by 302
Abstract
In recent years, there has been significant focus on smart cities, on how they operate and develop, and on their technical and social challenges. The importance of infrastructure as a major pillar of support in cities, in addition to the rapid developments in [...] Read more.
In recent years, there has been significant focus on smart cities, on how they operate and develop, and on their technical and social challenges. The importance of infrastructure as a major pillar of support in cities, in addition to the rapid developments in smart city research, necessitate an up-to-date review of smart cities’ infrastructure issues and challenges. Traditionally, a majority of studies have focused on traffic control and management, transport network design, smart grid initiatives, IoT (Internet of Things) integration, big data, land use development, and how urbanization processes impact land use in the long run. The work presented herein proposes a novel review framework that analyzes how smart city infrastructure is related to the urbanization process while presenting developments in IoT sensor networks, big data analysis of the generated information, and green construction. A classification framework was proposed to give insights on new initiatives regarding smart city infrastructure through answering the following questions: (i) What are the various dimensions on which smart city infrastructure research focuses? (ii) What are the themes and classes associated with these dimensions? (iii) What are the main shortcomings in current approaches, and what would be a good research agenda for the future? A bibliometric analysis was conducted, presenting cluster maps that can be used to understand different research trends and refine further searches. A bibliographic analysis was then followed, presenting a review of the most relevant studies over the last five years. The method proposed serves to stress where future research into understanding smart systems, their implementation and functionality would be best directed. This research concluded that future research on the topic should conceptualize smart cities as an emergent socio-techno phenomenon. Full article
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Open AccessCase Report
A Top-Down Digital Mapping of Spatial-Temporal Energy Use for Municipality-Owned Buildings: A Case Study in Borlänge, Sweden
Buildings 2021, 11(2), 72; https://doi.org/10.3390/buildings11020072 - 18 Feb 2021
Viewed by 221
Abstract
Urban energy mapping plays a crucial role in benchmarking the energy performance of buildings for many stakeholders. This study examined a set of buildings in the city of Borlänge, Sweden, owned by the municipality. The aim was to present a digital spatial map [...] Read more.
Urban energy mapping plays a crucial role in benchmarking the energy performance of buildings for many stakeholders. This study examined a set of buildings in the city of Borlänge, Sweden, owned by the municipality. The aim was to present a digital spatial map of both electricity use and district heating demand in the spatial–temporal dimension. A toolkit for top-down data processing and analysis was considered based on the energy performance database of municipality-owned buildings. The data were initially cleaned, transformed and geocoded using custom scripts and an application program interface (API) for OpenStreetMap and Google Maps. The dataset consisted of 228 and 105 geocoded addresses for, respectively, electricity and district heating monthly consumption for the year 2018. A number of extra parameters were manually incorporated to this data, i.e., the total floor area, the building year of construction and occupancy ratio. The electricity use and heating demand in the building samples were about 24.47 kWh/m2 and 268.78 kWh/m2, respectively, for which great potential for saving heating energy was observed. Compared to the electricity use, the district heating showed a more homogenous pattern following the changes of the seasons. The digital mapping revealed a spatial representation of identifiable hotspots for electricity uses in high-occupancy/density areas and for district heating needs in districts with buildings mostly constructed before 1980. These results provide a comprehensive means of understanding the existing energy distributions for stakeholders and energy advisors. They also facilitate strategy geared towards future energy planning in the city, such as energy benchmarking policies. Full article
(This article belongs to the Special Issue Net-Zero/Positive Energy Buildings and Districts)
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Open AccessArticle
Implementation of Pushover Analysis for Seismic Assessment of Masonry Towers: Issues and Practical Recommendations
Buildings 2021, 11(2), 71; https://doi.org/10.3390/buildings11020071 - 16 Feb 2021
Viewed by 249
Abstract
Seismic assessment is a paramount issue and a valuable instrument towards the conservation of vulnerable structures in seismic prone regions. The past seismic events have highlighted the vulnerability of masonry towers that is exhibited by severe structural and nonstructural damages or even collapses. [...] Read more.
Seismic assessment is a paramount issue and a valuable instrument towards the conservation of vulnerable structures in seismic prone regions. The past seismic events have highlighted the vulnerability of masonry towers that is exhibited by severe structural and nonstructural damages or even collapses. The preservation of existing structures, mainly focused on the built heritage, is emerging and imposing substantial enhancements of numerical methods, including pushover analysis approaches. The accuracy of the estimated seismic capacity for these structures is correlated with the assumed strategies and approximations made during the numerical modeling. The present paper concerns those aspects by exploring the limitations and possibilities of conceiving pushover analysis in the finite element method environment. The most crucial target is tracing in a pushover capacity curve the corresponding initiation of structural damages, maximum load-bearing capacity, and the ultimate displacement capacity. Different recommendations for achieving this target have been proposed and illustrated for practical utilization. Three representative geometrical towers, adopting three different materials and five different load patterns, are investigated in this study. The load pattern’s role and necessity of the displacement-like control approach for the pushover analysis are exploited. This paper highlights the load-bearing capacity overestimation when the force-controlled are implemented. The material model influences the achievement of softening branch with a distinguishable displacement capacity. Full article
(This article belongs to the Special Issue Structural Analysis for Earthquake-Resistant Design of Buildings)
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Open AccessArticle
Building Drainage System Design for Tall Buildings: Current Limitations and Public Health Implications
Buildings 2021, 11(2), 70; https://doi.org/10.3390/buildings11020070 - 16 Feb 2021
Viewed by 263
Abstract
National design guides provide essential guidance for the design of building drainage systems, which primarily ensure the basic objectives of preventing odor ingress and cross-transmission of disease through water-trap seal retention. Current building drainage system design guides only extend to buildings of 30 [...] Read more.
National design guides provide essential guidance for the design of building drainage systems, which primarily ensure the basic objectives of preventing odor ingress and cross-transmission of disease through water-trap seal retention. Current building drainage system design guides only extend to buildings of 30 floors, while modern tall buildings frequently extend to over 100 floors, exceeding the predictive capability of current design guides in terms of operating system conditions. However, the same design guides are being used for tall buildings as would be used for low-rise buildings. A complicating factor is the historic roots of current design guides and standards (including the interpretation of the governing fluid mechanics principles and margins of safety), causing many design differences to exist for the same conditions internationally, such as minimum trap seal retention requirements, stack-to-vent cross-vent spacing, and even stack diameter. The design guides also differ in the size and scale of the systems they cover, and most make no allowance for the specific building drainage system requirements of tall buildings. This paper assesses the limitations of applying current building drainage system design guides when applied to the case of tall buildings. Primarily, the assessments used in this research are based on codes from Europe, the USA and Australia/New Zealand as representative of the most common approaches and from which many other codes and standards are derived. The numerical simulation model, AIRNET, was used as the analysis tool. Our findings confirm that current design guides, which have been out of date for a number of decades, are now in urgent need of updating as code-compliant systems have been shown to be susceptible to water-trap seal depletion, a risk to cross-transmission of disease, which is a major public health concern, particularly in view of the current COVID-19 pandemic. Full article
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Open AccessArticle
Effects of the Earthquake Nonstationary Characteristics on the Structural Dynamic Response: Base on the BP Neural Networks Modified by the Genetic Algorithm
Buildings 2021, 11(2), 69; https://doi.org/10.3390/buildings11020069 - 16 Feb 2021
Viewed by 205
Abstract
The intensity non-stationarity is one of the basic characteristics of ground motions, the influences of which on the dynamic responses of structures is a pressing issue in the field of earthquake engineering. The BP neural network modified by the genetic algorithm was adopted [...] Read more.
The intensity non-stationarity is one of the basic characteristics of ground motions, the influences of which on the dynamic responses of structures is a pressing issue in the field of earthquake engineering. The BP neural network modified by the genetic algorithm was adopted in this research to investigate the influence of intensity nonstationary inputs on the structural dynamic responses from a new perspective. Firstly, many training data were generated from the prediction formula of dynamic response. The BP neural network was then pre-trained by sparsely selected data to optimize the initial weights and biases. Finally, the BP neural network was trained by all data, and the mean square error of predicted responses compared with the target response were less than 10−5. The calculation formula of sensitivity was also derived here to quantify the influence of the input change on the output. The presented method combines the advantages of neural networks in nonlinear multi-variable fitting and provides a new perspective for the study of earthquake nonstationary characteristics and their influence on the structural dynamic responses. Full article
(This article belongs to the Special Issue Structural Analysis for Earthquake-Resistant Design of Buildings)
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Open AccessArticle
Numerical Analysis of Bearing Capacity of a Ring Footing on Geogrid Reinforced Sand
Buildings 2021, 11(2), 68; https://doi.org/10.3390/buildings11020068 - 14 Feb 2021
Viewed by 282
Abstract
A ring footing is found to be of practical importance in supporting symmetrical constructions for example silos, oil storage container etc. In the present paper, numerical analysis was carried out with explicit code FLAC3D 7.0 to investigate bearing capacity of a ring footing [...] Read more.
A ring footing is found to be of practical importance in supporting symmetrical constructions for example silos, oil storage container etc. In the present paper, numerical analysis was carried out with explicit code FLAC3D 7.0 to investigate bearing capacity of a ring footing on geogrid reinforced sand. Effects of the ratio n of its inner/outer diameter (Di/D) of a ring footing, an optimum depth to lay the geogrid layer were examined. It was found that an intersection zone was developed in soil under inner-side (aisle) of ring footing, contributing to its bearing capacity. Substantial increase of bearing capacities could be realized if ratio n of a ring footing was around 0.6. Numerical results also showed that, bearing capacity of a ring footing could increase significantly if a single-layer geogrid was laid at a proper depth under the footing. Similar contribution was found if a double-layer geogrid was implemented. However, such increases appeared to be rather limited if a triple-layer geogrid or a four-layer geogrid was used. A double-layer geogrid was recommended to increase the bearing capacity of a ring footing; the depth to lay this double-layer geogrid was also discussed. Full article
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Open AccessArticle
Structural Performance of Reinforced Concrete Beams Incorporating Cathode-Ray Tube (CRT) Glass Waste
Buildings 2021, 11(2), 67; https://doi.org/10.3390/buildings11020067 - 13 Feb 2021
Viewed by 234
Abstract
The performance of reinforced concrete beams in the presence of cathode-ray tube (CRT) glass waste is examined. Four concrete mixes containing 0%, 10%, 20%, and 30% CRT glass waste as partial replacement of sand were prepared. The compressive and flexural strength as well [...] Read more.
The performance of reinforced concrete beams in the presence of cathode-ray tube (CRT) glass waste is examined. Four concrete mixes containing 0%, 10%, 20%, and 30% CRT glass waste as partial replacement of sand were prepared. The compressive and flexural strength as well as the modulus of elasticity of concrete were determined. Reinforced concrete beams with varying amounts of CRT glass were prepared and the three-point bending test was conducted. The load-deflection curve as well as the strain distribution along the depth of the beams were determined. Concrete containing CRT glass showed an increase in compressive strength, flexural strength, and modulus of elasticity especially at 10% replacement level. The load carrying capacity of reinforced concrete beam is higher when 10% of sand is replaced with CRT glass compared to the control beam and the beams with 20% and 30% CRT glass substitution. The failure mode of the reinforced concrete beams is flexural failure, and the failure pattern is similar for all beams. Strain distribution showed a better ductility at control beam where the deflection was higher than the other beams at the same load. Numerical analysis was conducted, and comparison was made with the experimental results. The comparison showed the accuracy of the software used, where the results of maximum load capacity and maximum deflection were very similar, and the difference did not exceed 5%. In addition, the tensile damage generated by the numerical analysis was very similar to that obtained by the experimental study. Full article
(This article belongs to the Special Issue Advanced Concrete Materials in Construction)
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Open AccessReview
Structural Optimization in Civil Engineering: A Literature Review
Buildings 2021, 11(2), 66; https://doi.org/10.3390/buildings11020066 - 13 Feb 2021
Viewed by 299
Abstract
Since tremendous resources are consumed in the architecture, engineering, and construction (AEC) industry, the sustainability and efficiency in this field have received increasing concern in the past few decades. With the advent and development of computational tools and information technologies, structural optimization based [...] Read more.
Since tremendous resources are consumed in the architecture, engineering, and construction (AEC) industry, the sustainability and efficiency in this field have received increasing concern in the past few decades. With the advent and development of computational tools and information technologies, structural optimization based on mathematical computation has become one of the most commonly used methods for the sustainable and efficient design in the field of civil engineering. However, despite the wide attention of researchers, there has not been a critical review of the recent research progresses on structural optimization yet. Therefore, the main objective of this paper is to comprehensively review the previous research on structural optimization, provide a thorough analysis on the optimization objectives and their temporal and spatial trends, optimization process, and summarize the current research limitations and recommendations of future work. The paper first introduces the significance of sustainability and efficiency in the AEC industry as well as the background of this review work. Then, relevant articles are retrieved and selected, followed by a statistical analysis of the selected articles. Thereafter, the selected articles are analyzed regarding the optimization objectives and their temporal and spatial trends. The four major steps in the structural optimization process, including structural analysis and modelling, formulation of optimization problems, optimization techniques, and computational tools and design platforms, are also reviewed and discussed in detail based on the collected articles. Finally, research gaps of the current works and potential directions of future works are proposed. This paper critically reviews the achievements and limitations of the current research on structural optimization, which provide guidelines for future research on structural optimization in the field of civil engineering. Full article
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Open AccessCase Report
Systemic Issues Influencing Technical Certainty in Social Housing Programmes in a Small Island Developing State
Buildings 2021, 11(2), 65; https://doi.org/10.3390/buildings11020065 - 12 Feb 2021
Viewed by 337
Abstract
Underestimating costs in major public sector social infrastructure development projects is a highly contested and problematic issue. Several gaps exist in the identification of root causes of cost overruns. Behavioural science academics advocate political and psychological explanations as root causes for cost overruns [...] Read more.
Underestimating costs in major public sector social infrastructure development projects is a highly contested and problematic issue. Several gaps exist in the identification of root causes of cost overruns. Behavioural science academics advocate political and psychological explanations as root causes for cost overruns against technical factors, such as errors and omissions by engineers, practitioners and scientists. Most studies in this field primarily concentrate on developed countries. Although some studies have been undertaken in developing countries, very little attention is given to the Small Island Developing States (SIDS). This paper presents a case study of public sector social housing construction programmes in a Caribbean SIDS to further understand the root causes of cost overruns. Primary and secondary data spanning across two different political cycles were collected to test the concepts of whether political influences or technical influences are the true root causes of cost overruns. It was found that political explanations based on the psycho-strategic concept are the leading sources of cost risks on the final estimated contract price. This study strengthens the argument and discusses how strategic decisions emanating from the political directorate outweigh and influence informed technical decisions formulated during the planning stages. Full article
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Open AccessArticle
Danish Dwellings with Cold Attics—Ventilation Rates and Air Exchange between Attic and Dwelling
Buildings 2021, 11(2), 64; https://doi.org/10.3390/buildings11020064 - 12 Feb 2021
Viewed by 266
Abstract
Naturally ventilated cold attics are traditional in many Danish single-family homes. The moisture balance of these attics is dependent on sufficient ventilation for removal of excess moisture. Moisture is generated in the dwelling below, and transported to attic spaces through convection and diffusion. [...] Read more.
Naturally ventilated cold attics are traditional in many Danish single-family homes. The moisture balance of these attics is dependent on sufficient ventilation for removal of excess moisture. Moisture is generated in the dwelling below, and transported to attic spaces through convection and diffusion. Therefore, airtight ceilings are vital for reduction of excess moisture, which may yield mould growth in the attic. If mould spores migrate to the dwelling it can cause risk of health concerns for occupants. The presents study includes analysis of tracer gas and temperature/relative humidity measurements, in 30 dwellings/attics. The measurements yielded results of both air change rates in attics and dwellings, as well as air exchange between the two zones. Four of 30 houses, met the recommended air change rate of 0.5 h−1, and only in summer. The air change rate in the attics was found to be higher, and with larger variation compared to the dwelling. Visible mould growth was found in three attics, which all exhibited low air change rates. Air exchange between zones occurred in houses both with and without vapour barriers. The downward air exchange in summer, was however slightly larger in cases without vapour barriers. These results highlight the importance of airtight ceilings for both dwelling and attic performance. Full article
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Open AccessArticle
Resistance of an Optimized Ultra-High Performance Fiber Reinforced Concrete to Projectile Impact
Buildings 2021, 11(2), 63; https://doi.org/10.3390/buildings11020063 - 11 Feb 2021
Viewed by 282
Abstract
The scope of this paper is to investigate the performance of ultra-high performance fiber reinforced concrete (UHPFRC) concrete slabs, under projectile impact. Mixture performance under impact loading was examined using bullets with 7.62 mm diameter and initial velocity 800 m/s. The UHPFRC, used [...] Read more.
The scope of this paper is to investigate the performance of ultra-high performance fiber reinforced concrete (UHPFRC) concrete slabs, under projectile impact. Mixture performance under impact loading was examined using bullets with 7.62 mm diameter and initial velocity 800 m/s. The UHPFRC, used in this study, consists of a combination of steel fibers of two lengths: 6 mm and 13 mm with the same diameter of 0.16 mm. Six composition mixtures were tested, four UHPFRC, one ultra-high performance concrete (UHPC), without steel fibers, and high strength concrete (HSC). Slabs with thicknesses of 15, 30, 50, and 70 mm were produced and subjected to real shotgun fire in the field. Penetration depth, material volume loss, and crater diameter were measured and analyzed. The test results show that the mixture with a combination of 3% 6 mm and 3% of 13 mm length of steel fibers exhibited the best resistance to projectile impact and only the slabs with 15 mm thickness had perforation. Empirical models that predict the depth of penetration were compared with the experimental results. This material can be used as an overlay to buildings or to construct small precast structures. Full article
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Open AccessArticle
Architectural Photovoltaic Applications: Lessons Learnt and Perceptions from Architects
Buildings 2021, 11(2), 62; https://doi.org/10.3390/buildings11020062 - 11 Feb 2021
Viewed by 337
Abstract
Researchers have reported that despite technological development in photovoltaic technology and substantial cost reduction, there is still a narrow interest in architectural photovoltaic applications (APA). Lack of interest is correlated to various bottlenecks, and one of them is a lack of knowledge among [...] Read more.
Researchers have reported that despite technological development in photovoltaic technology and substantial cost reduction, there is still a narrow interest in architectural photovoltaic applications (APA). Lack of interest is correlated to various bottlenecks, and one of them is a lack of knowledge among architects on the possibilities and approaches to adopt APA. In response to the issues mentioned, the aim of the research presented was collecting qualitative and quantitative information from architects as lessons learned and perceptions in regards to APA. In total, 30 architects with and without experience of using photovoltaics (PV) were invited and interviewed. They were asked about their experience, design and decision-making process with PV, their understanding of integration, and the decisive factors to use APA. The results showed apparent differences between the experiences and perceptions, and they highlighted the lessons learned from realized projects. The analysis of the visual implication of PV integration shows that, to the eyes of architects, integration of PV into architecture does not depend on the PV product used, but instead, that when PV is part of the design concept and design process, the outcome is seen as a meaningful integration. Full article
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Open AccessArticle
Construction Waste Audit in the Framework of Sustainable Waste Management in Construction Projects—Case Study
Buildings 2021, 11(2), 61; https://doi.org/10.3390/buildings11020061 - 11 Feb 2021
Viewed by 319
Abstract
The issue of sustainability has long been the subject of interest in architecture engineering and the construction sector. All three aspects of sustainability—economic, environmental, and social—can be affected through appropriate construction waste management. Construction and demolition waste (CDW) is one of the largest [...] Read more.
The issue of sustainability has long been the subject of interest in architecture engineering and the construction sector. All three aspects of sustainability—economic, environmental, and social—can be affected through appropriate construction waste management. Construction and demolition waste (CDW) is one of the largest worldwide waste streams, therefore, it is given great attention by all stakeholders (investors, contractors, authorities, etc.). Research studies show that one of the main barriers to insufficient CDW recovery is inadequate policies and legal frameworks to manage CDW. It is also one of European Union’s (EU) environmental priorities. The aim of the article was to confirm the economic potential of construction and demolition waste audit processing through a case study. A pre-demolition waste audit was processed for an unused shopping center building in the town Snina in Slovakia. Subsequently, a comparison of economic parameters (waste disposal costs and transport costs) of the recommended CDW management was performed. This comparison confirmed the economic benefits of environmentally friendly construction waste management methods according to the waste audit results, which would also increase the sustainability of construction projects. Additionally, the cost parameters of selected waste disposal methods could be another dimension of building information modeling. Full article
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Open AccessArticle
A Comparative Study on the Influence of Nano and Micro Particles on the Workability and Mechanical Properties of Mortar Supplemented with Fly Ash
Buildings 2021, 11(2), 60; https://doi.org/10.3390/buildings11020060 - 10 Feb 2021
Viewed by 276
Abstract
In this study, the effects of micro-Al2O3 (MA) and nano-Al2O3 (NA) on the mechanical properties and durability performance of a mortar containing fly ash (FA) were investigated. In the first step, MA and NA were added to [...] Read more.
In this study, the effects of micro-Al2O3 (MA) and nano-Al2O3 (NA) on the mechanical properties and durability performance of a mortar containing fly ash (FA) were investigated. In the first step, MA and NA were added to the mortar (as a cement replacement) at dosages of 0%, 5%, 10% and 15% by weight. The flowability of the mixture containing NA and MA showed a dosage-dependent behavior, and the addition of MA resulted in a higher flow spread compared with NA. The flow spread increased at 5% (for both NA and MA), and a further increase in the particle content to 10% and 15% decreased the flow spread value. Although the presence of MA and NA contributed to increasing the compressive strength as the particle content increased, the addition of NA resulted in a greater increase in compressive strength (40% increase when adding 15% of NA). The highest splitting tensile strength was obtained when 10% NA was used, and a further increase in the particle content decreased the splitting tensile strength. In the optimization step, the effect of a binder replacement with FA (10, 20 and 30%) in the presence of 10% NA as the optimum level of additive was investigated. Generally, the addition of FA decreased the compressive strength. The highest drop in compressive strength was noticed at early ages, and there was no significant difference in strength development from 14 days to 28 days. A decreasing trend in the splitting tensile strength was observed with the addition of FA content. Full article
(This article belongs to the Special Issue Sustainable Concrete Construction: Methods and Practices)
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Open AccessArticle
Energy Rating of Buildings to Promote Energy-Conscious Design in Israel
Buildings 2021, 11(2), 59; https://doi.org/10.3390/buildings11020059 - 08 Feb 2021
Viewed by 424
Abstract
Improving the energy efficiency of existing and new buildings is an important step towards achieving more sustainable environments. There are various methods for grading buildings that are required according to regulations in different places for green building certification. However, in new buildings, these [...] Read more.
Improving the energy efficiency of existing and new buildings is an important step towards achieving more sustainable environments. There are various methods for grading buildings that are required according to regulations in different places for green building certification. However, in new buildings, these rating systems are usually implemented at late design stages due to their complexity and lack of integration in the architectural design process, thus limiting the available options for improving their performance. In this paper, the model ENERGYui used for design and rating buildings in Israel is presented. One of its main advantages is that it can be used at any design stage, including the early ones. It requires information that is available at each stage only, as the additional necessary information is supplemented by the model. In this way, architects can design buildings in a way where they are aware of each design decision and its impact on their energy performance, while testing different design directions. ENERGYui rates the energy performance of each basic unit, as well as the entire building. The use of the model is demonstrated in two different scenarios: an office building in which basic architectural features such as form and orientation are tested from the very beginning, and a residential building in which the intervention focuses on its envelope, highlighting the possibilities of improving their design during the whole design process. Full article
(This article belongs to the Special Issue Buildings: 10th Anniversary)
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Open AccessArticle
Failure Analysis of Apennine Masonry Churches Severely Damaged during the 2016 Central Italy Seismic Sequence
Buildings 2021, 11(2), 58; https://doi.org/10.3390/buildings11020058 - 08 Feb 2021
Viewed by 319
Abstract
This paper presents a detailed study of the damages and collapses suffered by various masonry churches in the aftermath of the seismic sequence of Central Italy in 2016. The damages will first be analyzed and then compared with the numerical data obtained through [...] Read more.
This paper presents a detailed study of the damages and collapses suffered by various masonry churches in the aftermath of the seismic sequence of Central Italy in 2016. The damages will first be analyzed and then compared with the numerical data obtained through 3D simulations with eigenfrequency and then nonlinear static analyses (i.e., pushover). The main purposes of this study are: (i) to create an adequately consistent sensitivity study on several definite case studies to obtain an insight into the role played by geometry—which is always unique when referred to churches—and by irregularities; (ii) validate or address the applicability limits of the more widespread nonlinear approach, widely recommended by the Italian Technical Regulations. Pushover analyses are conducted assuming that the masonry behaves as a nonlinear material with different tensile and compressive strengths. The consistent number of case studies investigated will show how conventional static approaches can identify, albeit in a qualitative way, the most critical macro-elements that usually trigger both global and local collapses, underlining once again how the phenomena are affected by the geometry of stones and bricks, the texture of the wall face, and irregularities in the plan and elevation and in addition to hypotheses made on the continuity between orthogonal walls. Full article
(This article belongs to the Special Issue Non-linear Modelling and Analysis of Buildings)
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Open AccessArticle
Effect of Masonry Infill Constitutive Law on the Global Response of Infilled RC Buildings
Buildings 2021, 11(2), 57; https://doi.org/10.3390/buildings11020057 - 07 Feb 2021
Viewed by 354
Abstract
Masonry-infilled reinforced concrete frames represent a very common construction typology across the Mediterranean countries. The presence of infills substantially modifies the global seismic performances of buildings in terms of strength, stiffness, and energy dissipation. Although several research studies focused on the overall performances [...] Read more.
Masonry-infilled reinforced concrete frames represent a very common construction typology across the Mediterranean countries. The presence of infills substantially modifies the global seismic performances of buildings in terms of strength, stiffness, and energy dissipation. Although several research studies focused on the overall performances of infilled reinforced concrete frames, the modeling of infill panels remains an open issue due to the complex interaction between the infill and the frame and the uncertainties involved in the definition of the problem. In the present paper, an existing masonry-infilled RC frame designed according to obsolete seismic codes is chosen as a case study. A refined three-dimensional finite element model is built for performing nonlinear static and time-history analyses in order to investigate some significant aspects related to the modeling of infills. In particular, it is investigated the effect of different infill constitutive models on the seismic performance of infilled RC building expressed in terms of engineering demand parameters such as interstory drift ratios and peak floor accelerations, and on the generation of damage fragility curves. Full article
(This article belongs to the Special Issue Non-linear Modelling and Analysis of Buildings)
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Open AccessArticle
Damage Detection in Multiple RC Structures Based on Embedded Ultrasonic Sensors and Wavelet Transform
Buildings 2021, 11(2), 56; https://doi.org/10.3390/buildings11020056 - 07 Feb 2021
Viewed by 342
Abstract
This paper summarizes the results of research aimed at assessing cracks in reinforced concrete structures using embedded ultrasonic sensors. The diffuse ultrasonic waves were considered to evaluate the health status of the tested structures. There are different algorithms used to detect cracks in [...] Read more.
This paper summarizes the results of research aimed at assessing cracks in reinforced concrete structures using embedded ultrasonic sensors. The diffuse ultrasonic waves were considered to evaluate the health status of the tested structures. There are different algorithms used to detect cracks in the structure, but most studies have been performed on benchmark reinforced concrete (RC) structures and in laboratory conditions. Since there were difficulties with the validity of damage detection in real structures in the presence of environmental changes and noises, the application of advanced signal processing methods was necessary. Therefore, the wavelet transform was applied to process ultrasonic signals acquired from multiple civil structures. It is shown that the ultrasonic sensors with an applied wavelet transform algorithm on collected signals can successfully detect cracks in the laboratory as well as in a real environment. Experimental results showed a perfect match for detecting damage and quasi-static load in the presence of environmental changes. The results were confirmed with other techniques. In addition, designing an extra filter for removing noises can be avoided by using the applied algorithms. The obtained results confirmed that diffuse ultrasonic sensor methodology with the proposed algorithm is useful and effective in monitoring real RC structures, and it is better than traditional techniques. Full article
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Open AccessArticle
Office Distractions and the Productivity of Building Users: The Effect of Workgroup Sizes and Demographic Characteristics
Buildings 2021, 11(2), 55; https://doi.org/10.3390/buildings11020055 - 06 Feb 2021
Viewed by 279
Abstract
Knowledge workers are experiencing ever-increasing distractions or unwanted interruptions at workplaces. We explored the effect of unwanted interruptions on an individual’s perceived productivity in various building types, user groups and workgroups. A case study of 68 buildings and their 5149 occupants using the [...] Read more.
Knowledge workers are experiencing ever-increasing distractions or unwanted interruptions at workplaces. We explored the effect of unwanted interruptions on an individual’s perceived productivity in various building types, user groups and workgroups. A case study of 68 buildings and their 5149 occupants using the Building Use Studies methodology was employed in this study. The database contains information on the occupants’ perceptions of physical and environmental parameters, including unmined data on the frequency of unwanted interruptions. Pearson’s correlation was used to test the correlation between the variables. In order to determine whether there are any statistically significant differences between the means of two or more independent (unrelated) groups, one-way ANOVA was employed to examine the significance of differences in mean scores between various user groups and workgroups. The evidence of clear correlations between the frequency of unwanted interruptions and perceived productivity is detailed in various user groups and in multiple building types. The Pearson correlation coefficients were −0.361 and −0.348 for sustainable and conventional buildings, respectively, demonstrating a lower sensitivity to unwanted interruptions in sustainable buildings. Females and older participants were more sensitive to unwanted interruptions and their productivity levels were reduced much more by unwanted interruptions. Comparing different sized workgroups, the highest sensitivity to unwanted interruptions for occupants in offices shared with more than 8 people was found. The findings of this study contribute to the understanding of different user needs and preferences in the design of workplaces. Full article
(This article belongs to the Special Issue Buildings: 10th Anniversary)
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Open AccessArticle
Evaluation of Seismic Vulnerability of Hospitals in the Tehran Metropolitan Area
Buildings 2021, 11(2), 54; https://doi.org/10.3390/buildings11020054 - 05 Feb 2021
Viewed by 242
Abstract
The Tehran metropolitan area is extremely vulnerable to earthquakes due to the location of its active faults and its dense population. Assessing the probable damage of a high magnitude earthquake on buildings and facilities relies on a precise structural survey, which has an [...] Read more.
The Tehran metropolitan area is extremely vulnerable to earthquakes due to the location of its active faults and its dense population. Assessing the probable damage of a high magnitude earthquake on buildings and facilities relies on a precise structural survey, which has an empirical basis depending on historic ground motions. The probability of damage and failure in discrete limits based on different ground motions is estimated by fragility curves. Using the most matching fragility curves for buildings in Tehran, the vulnerability of the hospitals in the capital, as one of the most critical structures in crisis management of disasters, was investigated in this study. Subsequently, the existing fragility curves, developed for Tehran and the other seismic prone countries such as Japan and the United States, were compared considering the typology of Tehran’s hospitals. Finally, the possible damages for each hospital were calculated based on the most conservative fragility curve and the most pessimistic scenario, which were used to evaluate the seismic vulnerability of hospitals and health care systems for different damage states. After zoning the damage of therapeutic areas of Tehran, it was observed that at least 2% to 10% damage occurred in all hospitals of Tehran, and none of the healthcare centers would remain structurally undamaged after a strong earthquake with the moment magnitude of 7 or more. In addition, the healthcare buildings could be prone to significant structural damage, especially in southern parts, which necessitates proactive management plans for Tehran metropolitan area. Full article
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Open AccessArticle
Critical Analysis about Emerging Technologies for Building’s Façade Inspection
Buildings 2021, 11(2), 53; https://doi.org/10.3390/buildings11020053 - 04 Feb 2021
Viewed by 279
Abstract
The diagnosis of the building’s façades pathology is extremely important to support rational and technically informed decisions regarding maintenance and rehabilitation actions. With a reliable diagnosis, the probable causes of the anomalies can be correctly identified, and the correction measures adopted can be [...] Read more.
The diagnosis of the building’s façades pathology is extremely important to support rational and technically informed decisions regarding maintenance and rehabilitation actions. With a reliable diagnosis, the probable causes of the anomalies can be correctly identified, and the correction measures adopted can be more compatible with the existing elements, promoting the durability of the façades. Visual inspection is the most common approach to identify anomalies in a building’s façade and, in many cases, this technique is sufficient to support the decision to intervene. However, the pathological phenomenon is complex, and the anomalies observed may indicate the presence of other defects, or some anomalies may not be visible in a simple visual observation. This study intends to discuss the application of emerging technologies on the diagnosis and anamneses of building’s façade, in order to automatise the collection of reliable on-site data and, thus, reduce the uncertainty of the diagnosis. The use of these techniques can help existing inspection methodologies, already tested, based mainly on the visual assessment of the buildings’ elements degradation condition. Full article
(This article belongs to the Special Issue Assessment, Diagnosis and Service Life Prediction)
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Open AccessArticle
Mechanical Behavior and Frost-Resistance of Alkali-Activated Cement Concrete with Blended Binder at Ambient Curing Condition
Buildings 2021, 11(2), 52; https://doi.org/10.3390/buildings11020052 - 04 Feb 2021
Viewed by 226
Abstract
Concrete is the most commonly used construction material because of its various advantages, such as versatility, familiarity, strength, and durability, and it will continue to be in demand far into the future. However, with today’s sensitivity to environmental protection, this material faces unprecedented [...] Read more.
Concrete is the most commonly used construction material because of its various advantages, such as versatility, familiarity, strength, and durability, and it will continue to be in demand far into the future. However, with today’s sensitivity to environmental protection, this material faces unprecedented challenges because of its high greenhouse gas emissions, mainly during cement production. This paper investigates one of the promising cement replacement materials, alkali-activated cement (AAC) concrete. Being produced mainly from byproduct materials and having a comparable structural performance to conventional concrete, AAC concrete can transform the construction industry. Mechanical properties such as compressive and flexural strength and the relationship between them are studied. Different source materials such as fly ash (FA), ground granulated blast furnace slag (GGBS), silica fume (SF), and Metakaolin (MK) are used. The effect of the source materials and the activator solutions on the concrete performance is studied. Furthermore, the freeze-thaw resistance of the concrete is studied. The study results showed that the behavior of AAC depends highly on the source material combinations and type used. The effect of the alkaline solution is also dependent on the source material used. Mixes with higher GGBS content showed the highest strength, while mixes with MK showed the highest flexural strength. The freeze-thaw test results showed that proper design of AAC concrete with lower water content is critical to achieving a good resistance. Full article
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Open AccessArticle
Evaluation of the Legal Framework for Building Fire Safety Regulations in Spain
Buildings 2021, 11(2), 51; https://doi.org/10.3390/buildings11020051 - 04 Feb 2021
Viewed by 331
Abstract
There is a trend in Europe towards increasing the quality and performance of regulations. At the same time, regulatory failure has been observed in the area of building fire safety regulation in England and elsewhere. As a result, an analysis of the appropriateness [...] Read more.
There is a trend in Europe towards increasing the quality and performance of regulations. At the same time, regulatory failure has been observed in the area of building fire safety regulation in England and elsewhere. As a result, an analysis of the appropriateness of fire safety regulations in Spain is warranted, with the objective being to assess whether a suitable level of fire safety is currently being delivered. Three basic elements must be considered in such analysis: the legal and regulatory framework, the level of fire risk/safety of buildings that is expected and the level which actually results, and a suitable method of analysis. The focus of this paper is creating a legal and regulatory framework, in particular with respect to fire safety in buildings. Components of an ”ideal” building regulatory framework to adequately control fire risk are presented, the existing building regulatory framework is summarized, and an analysis of the gaps between the ideal and the existing systems is presented. It is concluded that the gaps between the ideal and the existing framework are significant, and that the current fire safety regulations are not appropriate for assuring delivery of the intended level of fire risk mitigation. Full article
(This article belongs to the Special Issue Performance-Based Design of Buildings)
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Open AccessArticle
Advanced Multi-Body Modelling of DCCSS Isolators: Geometrical Compatibility and Kinematics
Buildings 2021, 11(2), 50; https://doi.org/10.3390/buildings11020050 - 03 Feb 2021
Viewed by 272
Abstract
The effectiveness of Double Concave Curved Surface Sliders (DCCSS), which initially spread under the name of Double Friction Pendulum (DFP) isolators, was already widely proven by numerous experimental campaigns carried out worldwide. However, many aspects concerning their dynamical behavior still need to be [...] Read more.
The effectiveness of Double Concave Curved Surface Sliders (DCCSS), which initially spread under the name of Double Friction Pendulum (DFP) isolators, was already widely proven by numerous experimental campaigns carried out worldwide. However, many aspects concerning their dynamical behavior still need to be clarified and some details still require improvement and optimization. In particular, due to the boundary geometrical conditions, sliding along the coupled surfaces may not be compliant, where this adjective is adopted to indicate an even distribution of stresses and sliding contact. On the contrary, during an earthquake, the fulfillment of geometrical compatibility between the constitutive bodies naturally gives rise to a very peculiar dynamic behavior, composed of continuous alternation of sticking and slipping phases. Such behavior yields a temporary and cyclic change of topology. Since the constitutive elements can be modelled as rigid bodies, both approaches, namely Compliant Sliding and Stick-Slip, can be numerically modelled by means of techniques typically adopted for multi-body mechanical systems. With the objective of contributing to the understanding and further improvement of this technology, a topology-changing multi-body mechanical model was developed to simulate the DCCSS. In the present work, attention is focused on details regarding geometrical compatibility and kinematics, while the complete dynamics is presented in another work. In particular, for the sake of comparison, the kinematic equations are presented and applied not only for the proposed Stick-Slip approach, but also for the currently accepted Compliant Sliding approach. The main findings are presented and discussed. Full article
(This article belongs to the Special Issue Advanced Methods for Structural Rehabilitation)
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Open AccessArticle
Evaluation of Metaheuristic-Based Methods for Optimization of Truss Structures via Various Algorithms and Lèvy Flight Modification
Buildings 2021, 11(2), 49; https://doi.org/10.3390/buildings11020049 - 31 Jan 2021
Viewed by 288
Abstract
Truss structures are one of the major civil engineering members studied in the optimization research area. In this area, various optimization applications such as topology, size, cost, weight, material usage, etc., can be conducted for different truss structure types. In this scope with [...] Read more.
Truss structures are one of the major civil engineering members studied in the optimization research area. In this area, various optimization applications such as topology, size, cost, weight, material usage, etc., can be conducted for different truss structure types. In this scope with the present study, various optimization processes were carried out concerning two different large-scale space trusses to minimize the structural weight. According to this state, three structural models provided via two different truss structures, including 25 bar and 72 bar truss models, were handled for evaluation of six different metaheuristics together with the modification of Lèvy flight for three of the algorithms using swarm intelligence by considering both constant and variable populations, and different ranges for iterations, too. Additionally, the effects of the Lèvy flight function and whether it is successful or not in terms of the target of optimization were also investigated by comparing with some documented studies. In this regard, some statistical calculations were also realized to evaluate the optimization method performance and detection of optimum values for any data stably and successfully. According to the results, the Jaya algorithm can handle the optimization process successfully, including the case, without grouping truss members. The positive effect of Lèvy flight on swarm-based algorithms can be seen especially for the gray wolf algorithm. Full article
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