Buildings — Open Access Journal

Date palm midribs enjoy a long heritage among rural builders and craftsmen in Egypt for their abundance and low-cost. This familiarity encouraged previous studies to tackle the question of using date palm midribs in wide-span construction to provide simple, quick, cost efficient shaded structures. The design of tri-arched space truss was aimed to utilize date palm midribs in cost-efficient wide-span construction with minimal processing and maximum structural efficiency. However, the validated mechanical properties, the workability, the short-term and the long-term structural behaviors of the system are yet to be investigated. This paper investigates the structural behavior of a proposed tri-arched system using 1:3 scale specimens. The long-term environmental effects are also studied in one of the specimens. The specimens experienced high flexibility and gradual failure. A finite element model was created to predict the behavior of the specimens. The validated model was used to determine the structural behavior of the system with 12 m span. The system was found to be safe under the loads of wind and roofing. This paper is a part of a continuous process of validation that aims to utilize date palm midribs in contemporary wide-span construction to match the spirit of the youth in rural communities. Full article

The aim of this work is the evaluation of the inhibition effect of tartrate ions with respect to the localized corrosion of steel reinforcements in alkaline solution as a function of the concentration of chlorides ions. Weight loss tests and electrochemical tests were carried out in saturated Ca(OH)₂ solution with NaOH at pH 12.7 and 13.2. The results only evidence a slight inhibition effect at pH 12.7, whereas at pH 13.2 the pitting onset is inhibited also for chloride concentration up to 3 M. Tartaric acid is a dicarboxylic acid with nucleophile substituents, which can act as a chelating agent both adsorbing on the surface of the passive film and forming a soluble complex with ferrous and ferric ions. Tartrate causes an increase in the passive current density but it prevents the depassivation of carbon steel due to the action of chlorides, thus preventing pitting initiation due to the competitive adsorption on metal surface. Full article

(1) Background: On the Internet, we can find the guidelines for homemade air purifiers. One of the solutions includes the use of a low-cost ozone generator to decrease the level of odors and biological contaminants. However, the authors do not notify about hazardous effects of ozone generation on human health; (2) Methods: We elaborated our test results on the bacterial and fungal aerosol reduction by the use of two technical solutions of homemade air purifiers. First, including a mesh filter and ozone generator, second including an ozone generator, mesh filter, and carbon filter. (4) Conclusions: After 20 minutes of ozone generation, the concentration of bacteria decreased by 78% and 48% without and with a carbon filter, while fungi concentration was reduced in the lower range 63% and 40%, respectively. Based on our test results, we proposed a precise periodical operation of homemade air purifier to maintain the permissible level of ozone for the occupants. Full article

Near surface mounted (NSM) carbon fibers reinforced polymer (CFRP) reinforcement is one of the techniques for reinforcing masonry structures and is considered to provide significant advantages. This paper is composed of two parts. The first part presents the experimental study of brick masonry walls reinforced with NSM CFRP strips under combined shear-compression loads. Masonry walls have been tested under vertical compression, with different bed joint orientations 90° and 45° relative to the loading direction. Different reinforcement orientations were used including vertical, horizontal, and a combination of both sides of the wall. The second part of this paper comprises a numerical analysis of unreinforced brick masonry (URM) walls using the detailed micro-modelling approach (DMM) by means of ABAQUS software. In this analysis, the non-linearity behavior of brick and mortar was simulated using the concrete damaged plasticity (CDP) constitutive laws. The results proved that the application of the NSM-CFRP strips on the masonry wall influences significantly strength, ductility, and post-peak behavior, as well as changing the failure modes. The adopted DMM model provides a good interface to predict the post peak behavior and failure mode of unreinforced brick masonry walls. Full article

Renovation of existing buildings is an indispensable part of achieving European efficiency and environmental targets. This paper applies different assessment methodologies to find optimal renovation, given different evaluation criteria. The performed literature study identifies the cost-optimal methodology employing Life Cycle Cost (LCC) calculation as one of the most common assessment methods. This paper proposes a new renovation assessment method targeted to the early design phases of specific building projects. The method has a simple structure, and can be used as a roadmap of necessary activities for obtaining solid building knowledge and required energy and cost calculations. The methodology is based on linking economic and energy efficiency parameters into defined cost-effective value, calculated for all investigated renovation actions. The cost-effectiveness value is used for ranking and selecting the most appropriate single renovation actions to form renovation packages, which can be further examined in detail (for example, with LCC). To demonstrate the method, evaluate the strengths, and identify the weaknesses, it is applied to case study buildings in Denmark and Switzerland. The results show that, in the initial stage, the proposed cost-effectiveness representation can be used successfully to compare and evaluate different envelope elements and systems. Cost-effectiveness also provides rational results on a package level. Further work is still required in the area of evaluation of energy supply and renewable energy production systems. Full article

Geopolymer Concrete (GPC) as a cement-less construction material has attracted worldwide attention due to its lower carbon footprint. There are numerous studies reported on GPC made using different by-products including fly-ash. However, since the use of bottom-ash is comparatively limited, making potassium-based GPC using this waste can be an alternative to Portland Cement Concrete (PCC). In this study, two methods of accelerated curing were used to determine the influence of elevated temperature on the compressive strength of GPC, composed of 50% bottom-ash and 50% fly-ash. GPC specimens were cured using various temperatures including ambient, 30 °C, 45 °C, 60 °C, and 80 °C for 24 h, all followed by 28 days of ambient curing. The highest compressive strength was obtained with steam curing at a temperature of 80 °C for a duration of 24 h. It is of great significance to evaluate elastic modulus of the concrete mixture so that the short-term rigidity of structures subjected to elongation, bending, or compression can be predicted. In this study, a longitudinal Resonant Frequency Test (RFT) as a non-destructive test (NDT) was used to calculate the elastic modulus of both GPC and a comparative PCC mix. Based on the results, PCC had higher resonant frequency (by about 1000 Hz) compared to GPC. A review of empirical models for predicting GPC’s elastic modulus showed that all of the predicted elastic modulus values were lower than experimental values. Full article

The majority of the single-family houses in Sweden are affected by deteriorations in building envelopes as well as heating, ventilation and air conditioning systems. These dwellings are, therefore, in need of extensive renovation, which provides an excellent opportunity to install renewable energy supply systems to reduce the total energy consumption. The high investment costs of the renewable energy supply systems were previously distinguished as the main barrier in the installation of these systems in Sweden. House-owners should, therefore, compare the profitability of the energy supply systems and select the one, which will allow them to reduce their operational costs. This study analyses the profitability of a ground source heat pump, photovoltaic solar panels and an integrated ground source heat pump with a photovoltaic system, as three energy supply systems for a single-family house in Sweden. The profitability of the supply systems was analysed by calculating the payback period (PBP) and internal rate of return (IRR) for these systems. Three different energy prices, three different interest rates, and two different lifespans were considered when calculating the IRR and PBP. In addition, the profitability of the supply systems was analysed for four Swedish climate zones. The analyses of results show that the ground source heat pump system was the most profitable energy supply system since it provided a short PBP and high IRR in all climate zones when compared with the other energy supply systems. Additionally, results show that increasing the energy price improved the profitability of the supply systems in all climate zones. Full article

Time-dependent reliability assessment is a crucial aspect of the decision process for rehabilitation of existing reinforced concrete structures. Since the assessment strongly depends on degradation of materials with time, the paper focuses on the influence of corrosion in reinforcing steel on time-reliability curves of relevant reinforced concrete (r.c.) structures, built in Italy in the 1960s, belonging to different building categories. To realistically represent the probability distribution functions (pdfs) of the relevant properties of reinforcing steel and concrete commonly adopted in the 1960s, stochastic models for steel yielding and concrete compressive strength have been derived, by means of a suitable cluster analysis, from secondary databases of test results gathered at that time in Italy on concrete and steel rebar specimens. This cluster analysis, based on Gaussian mixture models, provides a powerful tool to “objectively” extract material classes and associated probability density functions from databases of experimental test results. In the study, different degradation conditions and several reinforcing steel and concrete classes are considered, also aiming to scrutinize their influence on the time-dependent reliability curves. Finally, to stress the significance of the study, the time-dependent reliability curves so obtained are critically examined and discussed also in comparison with the target reliability levels currently adopted in the Eurocodes. Full article

In recent years, the use of new technologies is rapidly transforming the way working activities are managed and carried out. In the construction industry, in particular, the use of Building Information Modelling (BIM) is ever increasing as a means to improve the performances of numerous activities. In such a context, several studies have proposed BIM as a key process to augment occupational safety effectively, considering that the construction industry still remains one of the most hazardous working sectors. The purpose of the present study is to investigate the recent research addressing the use of BIM to improve construction safety. A systematic review was performed considering journal papers that appeared in literature in the last decade. The results showed that the most viable and promising research directions concern knowledge-based solutions, design for safety improvement through BIM solutions, transversal applications of BIM, and dynamic visualization and feedback. The findings of this study also indicated that more practical BIM applications are needed, especially focusing on safety training and education, the use of BIM to augment safety climate and resilience, and the development of quantitative risk analysis to better support safety management. Overall, the study provided a comprehensive research synthesis augmenting knowledge on the role of BIM-based tools in construction safety, which can be considered a reference framework to enhance workers’ safety by means of these new technologies. Full article

The aim of the article is to analyze three variants of modernization and reconstruction of a road intersection, which in practice is the cause of numerous collisions and accidents. Detailed design solutions are presented for them. The aim of the analyses is to indicate an effective solution that, taking into account technical modifications of the road system elements, will ensure the functionality of the road system to the highest degree and significantly reduce the number of road incidents. To indicate the optimal solution, quantitative data (cost and duration of activities for three options) and qualitative data (determined based on the own experience and knowledge of road industry experts) is analyzed. The authors refer to many criteria of various natures (e.g., economic, technical, functional, environmental, social), which allow for comprehensive consideration of the current requirements of road users and changing circumstances, among others a steady increase in the number of vehicles and growing social expectations in terms of road parameters. Considering the presented analyses and arguments, the authors recommend option 1 as optimal. This is the most expensive solution among those analyzed and with the longest implementation time, however, taking into account the long-term prognosis of the direction and scope of changes to the existing standards and requirements for road infrastructure, it can be stated that option 1 meets them to the highest degree, and also has the greatest potential. The envisaged solution ensures high standards of the quality of road infrastructure use in terms of functionality, capacity, technical parameters, as well as the safety of traffic participants related to the smoothness of the journey, reduction of the number of collisions and accidents. Full article

Small UAVs (unmanned aerial vehicle) can be used in many sectors such as the acquisition of images or the transport of objects. Small UAVs have also been used for terrorist activities or to disturb the flight of airplanes. Due to the small size and the presence of only rotating parts, drones escape traditional controls and therefore represent a danger. This paper reports a methodology for identifying the presence of small UAVs inside a closed environment by measuring the noise emitted during the flight. Acoustic measurements of the noise emitted by a drone inside a large environment (12.0 × 30.0 × 12.0 m) were performed. The noise was measured with a sound level meter placed at different distances (5, 10, and 15 m), to characterize the noise in the absence of anthropic noise. In this configuration, a typical tonal component of drone noise is highlighted at the frequency of one-third of an octave at 5000 Hz due to the rotation of the blades. This component is also present 15 m away from the source point. Subsequent measurements were performed by introducing into the environment, through a loudspeaker, the anthropogenic noise produced by the buzz of people and background music. It is possible to distinguish the typical tonal component of UAV noise at the frequency of 5000 Hz even when the level of recording of anthropogenic noise emitted by the loudspeaker is at the maximum power tested. It is therefore possible to search for the presence of small UAVs inside a specific closed environment with only acoustic measurements, paying attention to the typical frequency of noise emission equal to 5000 Hz. Full article

This study examined a method to reduce energy consumption in office buildings. Correspondingly, an optimal control method was proposed for heating, ventilation, and air conditioning (HVAC) systems via two control algorithms that considered the indoor thermal environment. The control algorithms were developed by considering temperature and humidity as the factors of the indoor thermal environment that influence the control of HVAC systems and the predicted mean vote comfort ranges. Furthermore, an experiment was performed using office equipment that incorporated the two control algorithms for HVAC systems, and the correlation between changes in the thermal environment within the office and the occupant’s comfort levels was estimated via an actual survey. The results demonstrated that the proposed control method for HVAC systems, which considered the comfort ranges of temperature and humidity and the thermal adaptation capability, can efficiently maintain the occupant’s comfort with lower energy usage compared with conventional HVAC systems. Thus, the use of the control method contributes to the reduction of total energy consumption in buildings with HVAC systems. Full article

Society and the business world are paying more and more attention to the Circular Economy (CE) principles. The construction industry is no stranger to this issue, and the companies are transitioning towards sustainable production models. However, it is not easy to predict when and to what extent a company implements the CE. To measure this process, a scorecard, that includes the main Key Performance Indicators (KPIs) of the construction industry, related to the CE, was designed. Thus, the objective of this article is to design and test the CE-dashboard applicable to the construction industry. To do it, firstly, a literature review is performed. The next step is the selection of the KPIs collected in the literature, more suitable for reporting information about CE. Afterwards, a simulation based on the Monte Carlo technique performs. After multiple iterations, this method establishes the most probable KPI values as a result, which will be confronted with the limits used in the scorecard. With all this information, the dashboard emerges in Qlik software. Finally, a test of this dashboard takes place according to the information about KPIs from one of the leading Spanish companies (General Contractor (GC) building company). This step brings the validity of the created measurement instrument. Full article

The Global South, much of it in warm tropical latitudes, is expected to double its total energy demand by 2050. In addition to increased mean demand, greater demand for space cooling during external temperature peaks will exacerbate the strain on already fragile energy networks. Recent anecdotal evidence that a proportion of the increase in cooling demand is driven by cold—rather than warm—indoor thermal discomfort, suggests the imposition of an unnecessary cooling energy cost. Here, we investigate the impact of this cost on the expanding Global South using field data from four cities in India, Philippines, and Thailand. We observe that mean cold discomfort across the four cities is roughly 45 percentage points higher than warm discomfort, suggesting warmer indoor temperatures would not only lower overall discomfort but also reduce cooling energy demand. Computer simulations using a calibrated building model reveal that average savings of 10%/Kelvin and peak reductions of 3%–19%, would be feasible across the expected external temperature range in these cities. This suggests that more climatically appropriate indoor thermal comfort standards in the Global South would not only significantly counteract the expected rise in energy demand, but also produce more comfortable indoor conditions and reduce peak demand. Full article

Wood is one of the most popular renewable natural materials. Nowadays, raw wood is hardly ever used in the construction industry. It has been substituted by glued laminated wood that is processed with the use of high-tech methods, thus eliminating the principal flaws and defects of the natural material. The deformability of glued laminated beams with combined reinforcement has been studied, under which the steel reinforcement of the periodic profile was placed in the dappings of the upper compressed zone, while ribbon-reinforced composite was glued to the bottom of the stretched zone. The graphical charts for the layer change of the deformations of wood, steel, and composite reinforcement from the beginning of the loading application to the moment of destruction are presented. Full article

The evaluation of the maximum and cumulative response is an important issue for the seismic design of new base-isolated buildings. This study predicts the maximum and cumulative response of a 14-story reinforced concrete base-isolated building using a set of pushover analyses. In the proposed pushover analysis method, the maximum and cumulative responses of the first and higher modes are evaluated from the nonlinear analysis of equivalent single-degree-of-freedom (SDOF) models. Then, the maximum local responses are predicted by enveloping the two pushover analysis results by referring to the contribution of the first and higher modal responses, while the cumulative strain energies of the lead-rubber bearings and steel dampers are predicted from the cumulative response of the first mode. The results reveal that the responses predicted by the proposed set of pushover analyses have satisfactory accuracy. Full article

Following the observation of severe damage to structurally isolated non-structural reinforced concrete walls after major earthquakes, researchers began to reassess the effectiveness and connection detail of non-structural walls to moment-resisting frames. A method to control damages to the non-structural wall, is to cast exterior non-structural concrete wall elements to be monolithic with frame elements, without anchoring the wall longitudinal bar. The non-anchorage of the wall longitudinal bar significantly increases the drift capacity of the wall and decreases damage. Using an experimental approach, this study assesses the influence of reinforcement detailing and quantity of the transverse reinforcements on the strength and drift capacity of the non-structural hanging wall. This study further evaluates the workability mechanism of the transverse reinforcements and reinforcement detailing with concrete. The non-anchorage of hanging walls, having boundary confinements, was found to exhibit a higher drift and strength capacity than similar walls with the anchored detailing without boundary confinements. The strength capacity of the anchored detailing hanging walls with minimum amounts of reinforcements was higher than that of the non-anchored specimen. The boundary confinements were found to be more influential on the capability of the hanging wall when placed along with non-anchored detailing reinforcement. Full article

Operational uncertainties play a critical role in determining potential pathways to reduce the building energy footprint in the Global South. This paper presents the application of a non-dominated sorting genetic (NSGA II) algorithm for multi-objective building design optimization under operational uncertainties. A residential building situated in a mid-latitude steppe and desert region (Köppen climate classification: BSh) in the Global South has been selected for our investigation. The annual building energy consumption and the total number of cooling setpoint unmet hours (h) were assessed over 13,122 different energy efficiency measures. Six Pareto optimal solutions were identified by the NSGA II algorithm. Robustness of Pareto solutions was evaluated by comparing their performance sensitivity over 162 uncertain operational scenarios. The final selection for the most optimal energy efficiency measure was achieved by formulating a robust multi-criteria decision function by incorporating performance, user preference, and reliability criteria. Results from this robust approach were compared with those obtained using a deterministic approach. The most optimal energy efficiency measure resulted in 9.24% lower annual energy consumption and a 45% lower number of cooling setpoint unmet h as compared to the base case. Full article