Buildings, Volume 10, Issue 11 (November 2020) – 23 articles

While continuous reinforced concrete deep beams with fixed and hinged support conditions are every so often found in structures, little research has focused on their performance. This, in part, can be attributed to the demanding nature of ensuring fixed supports in experimentally testing such members. Nonetheless, conducting numerical analysis in comparison with experimental study has been a typical technique for producing a reliable numerical model as an alternative to destructive tests. This paper is aimed at numerically investigating the impact of different support conditions in the performance of two-span continuous reinforced concrete deep beams. A numerical model of three experimentally tested beams with two exterior rollers and interior hinge support conditions was generated. Good comparison, with an acceptable variation between numerical and experimental results, was achieved by tuning a few parameters in the numerical model, including element type, mesh size, and material constitutive relations. The refined numerical model was used as an alternative to destructive tests to conduct a parametric study to further investigate the impact of different sets of support conditions in the performance of two-span continuous reinforced concrete deep beams. This study highlights the potentially serious consequences of the support conditions in the performance of such deep beams. Full article

Modern heritage buildings designed in the 1950s and 1960s often feature poor seismic performance capacities and may require significant retrofit interventions. A representative case study in Florence, i.e., the edifice housing the Automobile Club Headquarters, is examined here. The building was designed in 1959 with an articulated reinforced concrete structure and presents some enterprising solutions for the time, including suspended floors accommodating large glazed curtain wall façades in the main halls. The original design documentation was collected with accurate record research and checked with detailed on-site surveys. Based on the information gained on the structural system by this preliminary investigation, a time-history assessment analysis was carried out. Remarkable strength deficiencies in most members and severe pounding conditions between the two constituting wings, which are separated by a narrow technical gap, were found. As a result, a base isolation retrofit hypothesis is proposed in order to improve the seismic response capacities of the building without altering its elegant architectural appearance, being characterized by large free internal spaces and well-balanced proportions of the main structural members. A substantial performance improvement is obtained thanks to this rehabilitation strategy, as assessed by the achievement of non-pounding response conditions and safe stress states for all members up to the maximum considered normative earthquake level. Furthermore, the very low peak inter-storey drifts evaluated in retrofitted conditions help in preventing damage to the glazed façades and the remaining drift-sensitive non-structural components. Full article

The seismic assessment of existing school buildings is an important issue in earthquake prone regions; such is the case of the Algarve, which is the southern region of Portugal mainland. Having this problem in mind, the PERSISTAH project (Projetos de Escolas Resilientes aos SISmos no Território do Algarve e de Huelva, in Portuguese) aimed to develop a computational approach enabling the damage evaluation of a large number of individual school buildings. One of the school typologies assessed was the so-called “P3” schools. This typology is composed of several different modules that are combined in different manners depending on the number of students. Each module was built in accordance with architectural standardised designs. For this reason, there are many replicas of these modules all over the Algarve region. The structural system of each module is composed of a frame of reinforced concrete (RC) elements. Nonlinear static seismic analysis procedures were adopted to evaluate the structural seismic behaviour, namely by using the new concept of performance curve. Based on the obtained results, it was possible to conclude that the seismic safety of this type of school building is mainly ruled by the shear capacity of the columns. This study also shows the difficulties of carrying out accurate seismic assessments of existing buildings using the methods of analysis that are established in the Eurocode 8. Full article

During the summer, the environmental impact of building operations can be reduced by optimizing ventilation and preventing heat from entering the building. Shades are used to create a comfortable temperature state in interiors without operating mechanical equipment or using low-power systems. The most significant factor in reducing energy consumption would be if the spatial delimitation of buildings utilizes solar energy in a passive or active way. At the same time, limiting the energy entering through windows reduces the temperature of interiors and the amount of energy used for cooling; thus, the phenomenon of the urban heat island would be less exacerbated. In the case of existing historical buildings, there are limited possibilities to reduce the energy consumption of the building and to protect the buildings against excessive summer heating, especially in connection with the structural appearance of the doors and windows on the façade. This paper presents the preparation of a large-scale reconstruction project based on a newly developed combined window that can significantly reduce indoor summer overheating. Designing steps of the complex retrofitting of a traditional box-type window are highlighted based on the results of closely connected literature pertaining to thermal, ventilation, shading, and acoustical phenomena. The result is a detailed structural and technological design of the reconstruction for the historical window in a combined way, as the frame, glazing, ventilation, and shading are simultaneously developed and calculated approximately; moreover, active shading is integrated. One aim of this desktop study was to demonstrate that in the case of historical buildings, it is possible and necessary to reduce heat losses during the heating season and to minimize the risk of summer overheating, and to show that the surface of the façade could be converted into an energy producer. Full article

Trapezoidal-shaped thin-walled metallic profiled sheets are used in composite floor construction to enable rapid construction and reduce reinforcement and formwork requirements in concrete casting. However, relevant literature reported the early failure of steel sections due to the buckling and shear of existing trapezoidal and re-entrant decking profiles. There are also limitations regarding design rules for composite flooring systems. Current work aims to develop a new type of composite top-hat section for possible use in composite slim-floor construction. Sinusoidal metallic corrugated sheets that are widely used in building construction were utilized and a new bending technique was used to produce deck components, in which transverse corrugations were introduced along the main direction of the corrugated profile. This paper investigates the structural response of these new sections for several loading and support conditions using a pilot experimental scheme. The developed top-hat sections demonstrated considerable resistance to bending as well as buckling through effective stress re-distributions under considered construction stage loading for single span and continuous span conditions. Currently available design equations recommended by Australian Standards for a similar type of corrugated decks were used to predict the design strength and to compare it with those obtained experimentally. It was concluded that the expressions proposed by the code were inadequate for single span loading cases and would require modifications before being applied to the new profile. Full article

Sustainable Project Management (SPM) is a novel theme in construction industries of developing countries and very little is known (so far) about the sustainability performance of construction projects in those settings. Accordingly, the quantitative measurement of SPM as a higher-order construct is not well established and lacks a holistic approach and homogenous taxonomy of indicators. This study explores the SPM practices of construction firms by validating SPM as a second-order construct in the Pakistani construction industry. Data were obtained from 146 construction firms, which were then analyzed using partial least square structure equation modeling. Results of the first and second level measurement model assessments showed that construction firms practice SPM, with varying degrees of attention paid to three sustainability aspects. Environmental dimension surfaced as the most important, in-terms of practice and social sustainability as least. The analysis of the second-order measurement model yielded significant results, thus, validating the higher-order structure of SPM. This study contributes to the field by presenting one of the first studies of its kind by focusing on the sustainability practices of construction firms by using a higher-order design of SPM construct within the context of developing countries. Full article

Windows account for a significant proportion of the total energy lost in buildings. The interaction of window type, Window-to-Wall Ratio (WWR) scheduled and window placement height influence natural lighting and heat transfer through windows. This is a pressing issue for nontropical regions considering their high emissions and distinct climatic characteristics. A limitation exists in the adoption of common simulation-based optimisation approaches in the literature, which are hardly accessible to practitioners. This article develops a numerical-based window design optimisation model using a common Building Information Modelling (BIM) platform adopted throughout the industry, focusing on nontropical regions of Australia. Three objective functions are proposed; the first objective is to maximise the available daylight, and the other two emphasize undesirable heat transfer through windows in summer and winter. The developed model is tested on a case study located in Sydney, Australia, and a set of Pareto-optimum solutions is obtained. Through the use of the proposed model, energy savings of up to 8.57% are achieved. Full article

In countries with high heating demand, waste heat from industrial processes should be carefully utilized in buildings. Finland already has an extensive district heating grid and large amounts of combined heat and power generation. However, despite the average climate, there is little use for excess heat in summer. Waste incineration plants need to be running regardless of weather, so long-term storage of heat requires consideration. However, no seasonal energy storage systems are currently in operation in connection with Finnish waste incineration plants. This study used dynamic energy simulation performed with the TRNSYS 17 software to analyze the case of utilizing excess heat from waste incineration to supplement conventional district heating of a new residential area. Seasonal energy storage was utilized through a borehole thermal energy storage (BTES) system. Parametric runs using 36 different storage configurations were performed to find out the cost and performance range of such plans. Annual energy storage efficiencies from 48% to 69% were obtained for the BTES. Waste heat could generate 37–89% of the annual heat demand. Cost estimations of waste heat storage using BTES are not available in the literature. As an important finding in this study, a levelized cost of heat of 10.5–23.5 €/MWh was obtained for various BTES configurations used for incineration waste heat storage. In the three most effective cases, the stored heat reduced annual CO₂ emissions of the residential area by 42%, 64% and 86%. Thus, the solution shows great potential for reducing carbon emissions of district heating in grids connected to waste incineration plants. Full article

Off-site construction (OSC) is known as an efficient construction method that could save time and cost, reduce waste of resources, and improve the overall productivity of projects. Coupled with digital technologies associated with the Industry 4.0 concept, OSC can offer a higher rate of productivity and safety. While there is a rich literature focusing on both OSC and Industry 4.0, the implementation of associated digital technologies in the OSC context has not been fully evaluated. This paper intends to evaluate the current literature of digital technology applications in OSC. Scientometric analyses and a systematic review were carried out evaluating fifteen typical digital technologies adopted by OSC projects, including building information modelling (BIM), radio frequency identification devices (RFID), global positioning systems (GPS), the Internet of Things (IoT), geographic information systems (GIS), sensors, augmented reality (AR), virtual reality (VR), photogrammetry, laser scanning, artificial intelligence (AI), 3D printing, robotics, big data, and blockchain. This review formulates a clear picture of the current practice of these digital technologies and summarizes the main area of application and limitations of each technology when utilized in OSC. The review also points out their potential and how they can be better adopted to improve OSC practice in the future. Full article

This study is devoted to experimentally investigate the seismic behaviour of reinforced concrete (RC) wide beam–column joints equipped with a steel jacketing seismic strengthening solution. To this end, three identical full-scale specimens have been tested under cyclic loading, one in the as-built condition and two after the application of the strengthening solutions. Details of selected solutions are described in the paper along with the experimental results which confirm how the application of simple and feasible steel interventions can effectively improve the seismic capacity of wide beam–column connections in RC frames, especially in terms of lateral load carrying capacity and energy dissipation. Full article

Conservation of heritage buildings has become a very important issue in many countries, as it is in Italy, where a great number of existing buildings of historical–artistic importance are seismically vulnerable. To improve existing building behavior, researchers focus on the design of retrofit interventions. This paper presents the application of energy dissipation devices in the retrofit of two existing Reinforced Concrete (RC) buildings, both irregular in plan and along their heights, designed for gravitational loads only. These buildings are representative of Italian public housing built in the 1960s and early 1970s. Technical information and mechanical properties of materials are presented, and non-linear analyses are carried out to evaluate the buildings’ behavior under earthquake loads. Many of their structural members do not satisfy the verifications required by the Italian Building Code. Retrofit interventions with buckling-restrained axial dampers in one building and viscous fluid dampers in the other are proposed. The verifications of the retrofitted buildings and the amount of the energy absorbed by the devices with respect to that absorbed by the unretrofitted buildings show the effectiveness of the proposed interventions. Moreover, it is demonstrated that adequate dispositions of the dissipative devices in plan and along the height increase the torsional stiffness of the buildings, improving their structural response under seismic action. Full article

The use of generative design has been suggested to be a novel approach that allows designers to take advantage of computers’ computational capabilities in the exploration of design alternatives. However, the field is still sparsely explored. Therefore, this study aimed to investigate the potential use of generative design in an architectural design context. A framework was iteratively developed alongside a prototype, which was eventually demonstrated in a case study to evaluate its applicability. The development of a residential block in the northern parts of Sweden served as the case. The findings of this study further highlight the potential of generative design and its promise in an architectural context. Compared to previous studies, the presented framework is open to other generative algorithms than mainly genetic algorithms and other evaluation models than, for instance, energy performance models. The paper also presents a general technical view on the functionality of the generative design system, as well as elaborating on how to explore the solution space in a top-down fashion. This paper moves the field of generative design further by presenting a generic framework for architectural design exploration. Future research needs to focus on detailing how generative design should be applied and when in the design process. Full article

Improving the energy efficiency of existing buildings by implementing building automation control strategies (BACS) besides building envelope and energy system retrofitting has been recommended by the Energy Performance of Buildings Directive (EPBD) 2018. This paper investigated this recommendation by conducting a simulation-based optimization to explore cost-effective retrofitting combinations of building envelope, energy systems and BACS measures in-line with automation standard EN 15232. Two cases (i.e., a typical single-family house and apartment block) were modeled and simulated using IDA Indoor Climate and Energy (IDA-ICE). The built-in optimization tool, GenOpt, was used to minimize energy consumption as the single objective function. The associated difference in life cycle cost, compared to the reference design, was calculated for each optimization iteration. Thermal comfort of the optimized solutions was assessed to verify the thermal comfort acceptability. Installing an air source heat pump had a greater energy-saving potential than reducing heat losses through the building envelope. Implementing BACS achieved cost-effective energy savings up to 24%. Energy savings up to 57% were estimated when BACS was combined with the other retrofitting measures. Particularly for compact buildings, where the potential of reducing heat losses through the envelope is limited, the impact of BACS increased. BACS also improved the thermal comfort. Full article

Several authors have studied construction defects, but no studies were found implementing best practices and control strategies through the implementation of continuous improvement projects. This article shows a procedure based on Continuous Improvement Projects, which can be used in building constructions, and it is structured into four phases: Plan, Do, Check, Act, following the PDCA Quality Cycle. In addition, the method developed was specified for ceramic tiling execution and was further implemented in three building projects of Spain. The results obtained concluded that the proposed Procedure can be used by construction professionals who are concerned about improving the quality of construction. In addition, the implementation of the Procedure managed to reduce around 45% the costs derived from the defects caused during the ceramic tiling execution, due to the best practices incorporated in the Procedure. A slight increase in the number of defects was also found, motivated by the thorough inspection conducted when the Procedure was applied. Therefore, the Procedure (incorporating the lessons learned) must be implemented so that by learning, gaining experience, and incorporating best practices, the goal of zero defects can be achieved. Full article

With the constant expansion of the building sector as a major energy consumer in the modern world, the significance of energy-efficient building systems cannot be more emphasized. Most of the buildings are now equipped with an electric dashboard to record consumption data which presents a significant scope of research by utilizing those data in energy modeling. This paper investigates conventional regression modeling in building energy estimation and proposes three models with data classifications to improve their performance. The proposed models are regression models and an artificial neural network model with data classification for predicting hourly or sub-hourly energy usage in four different buildings. Energy data is collected from a building energy simulation program and existing buildings to develop the models for detailed analysis. Data classification is recommended according to the system operating schedules of the buildings and models are tested for their performance in capturing the data trends resulting from those schedules. Proposed regression models and an ANN model with the recommended classification show very accurate results in estimating energy demand compared to conventional regression models. Correlation coefficient and root mean squared error values improve noticeably for the proposed models and they can potentially be utilized for energy conservation purposes and energy savings in the buildings. Full article

Although base isolation is nowadays a well-established seismic-protection technique for both buildings and bridges, and several issues are still open and attract the interest of the research community. Among them, the formulation of computationally efficient and accurate analysis methods is a relevant aspect in structural design of seismic-isolated buildings. In fact, codes and guidelines currently in force in various parts of the world generally include the possibility for designers to utilize linear-elastic analysis methods based on equivalent linearization of the non-linear force-displacement response of isolators. This paper proposes a formula for defining the force distribution in height that should be considered in linear-static analyses to obtain a more accurate approximation of the actual structural response, supposedly simulated by means of non-linear time history analysis. To do that, it summarizes the results of a wide parametric analysis carried out on a batch of structures characterized by three different heights and various properties of base isolators. The reported results highlight that the equivalent static force distribution provided by both Italian and European codes tend to underestimate the actual seismic lateral forces acting on base-isolated buildings, whereas the inverted triangular distribution, proposed in various American codes and standards, is often conservative. Full article

The present paper reports an experimental study coupled with a numerical modelling approach to simulate masonry walls strengthened with textile-reinforced mortar (TRM). This innovative reinforcing technique is based on high-strength fibre grids embedded into inorganic matrices, and it has recently been promoted for the seismic retrofitting of historical masonry buildings. In the experimental campaign presented here, two different commercial TRM systems are applied to single-leaf clay masonry panels. The specimens are then subjected to diagonal compression tests in order to evaluate the effects of TRM on the structural performance. The proposed finite element (FE) model, based on an original multiscale approach, is employed to simulate the diagonal compression tests. The numerical results show a very good agreement with the experimental data, including in terms of failure mode. In particular, the approach reproduces the macroscopic behaviour of the masonry panels as regards the force-displacement response, and it allows for the possibility of simulating bed joint sliding and TRM layer debonding. Full article

Optimizing the operating conditions and control set points of the heating, ventilation, and air-conditioning (HVAC) system in a building is one of the most effective ways to save energy and improve the building’s energy performance. Here, we optimized different control variables using a genetic algorithm. We constructed and evaluated three optimal control scenarios (cases) to compare the energy savings of each by varying the setting and number and type of the optimized control variables. Case 1 used only air-side control variables and achieved an energy savings rate of about 5.72%; case 2 used only water-side control variables and achieved an energy savings rate of 16.98%; and case 3, which combined all the control variables, achieved 25.14% energy savings. The energy savings percentages differed depending on the setting and type of the control variables. The results show that, when multiple control set points are optimized simultaneously in an HVAC system, the energy savings efficiency becomes more effective. It was also confirmed that the control characteristics and energy saving rate change depending on the location and number of control variables when optimizing using the same algorithm. Full article

The paper introduces a new semi-probabilistic methodology for the definition of energy fragility curves suitable for a macro-classification of building stock inspired to and coupled with the widely adopted method of seismic fragility curves. The approach is applied to the reinforced concrete residential buildings of the Italian stock. Starting from a classification according to the climatic zone and the construction period, some reference buildings in terms of building envelope typologies have been defined and simulated by means of dynamic modeling tools. Then, cumulative distributions of the probability that the primary energy consumption for heating was comparable with certain threshold values are defined according to the climatic conditions expressed with the heating degree days, which constitute the intensity measure for the fragility curves. Finally, by focusing on the interaction points between structural and energetic aspects, it is shown how these curves can be useful for decision-makers with regards to definition of importance and or the level of intervention to be made to the building envelope for improving its seismic safety and the energy quality. Indeed, non-integrated interventions are more expensive and less efficient. Full article

The 21st century abounds in modern electronic-information technologies, which are applied in many areas of life. Amongst many modern technologies there is also the Internet of Things (IoT) that is the concept of incorporating objects and devices equipped with a communication interface into the telecommunication and IT networks. This particular feature makes IoT a paradigm that can be successfully applied to measurement systems used in research in civil engineering, especially using a wireless sensor network deployed in scattered research locations. In turn, technological progress in the miniaturization of sensors and controllers allows the construction of very efficient and low-cost systems for monitoring the physical parameters of buildings, which are safety indicators. The main purpose of this paper is to present the concept of wireless network of MEMS-based sensors with particular emphasis on its application in monitoring of structural safety including the author’s own system based on Long Range (LoRa) technology. The exact novelty of the proposed concept is the synergistic synthesis of solutions in the field of electronics, micromechanics and computer science, applied for civil engineering purposes. The system consists of MEMS accelerometers based on MPU6050 chips and A1302 Hall-effect sensors supported by AVR microcontrollers and LoRa transceivers based on RF98 chips operating at 433 MHz. The prototype of the measuring network was installed in a selected university building in which structural discontinuities (wall cracks) were noted. Sample results of measurements of the impact of service loads on the building structure behavior were presented in the form of accelerograms. Full article

Climate change and global warming have triggered a global increase in the use of renewable energy for various purposes. In recent years, the photovoltaic (PV)-system has become one of the most popular renewable energy technologies that captures solar energy for different applications. Despite its popularity, its adoption is still facing enormous challenges, especially in developing countries. Experience from research and practice has revealed that installed PV-systems significantly underperform. This has been one of the major barriers to PV-system adoption, yet it has received very little attention. The poor performance of installed PV-systems means they do not generate the required electric energy output they have been designed to produce. Performance assessment parameters such as performance yields and performance ratio (PR) help to provide mathematical accounts of the expected energy output of PV-systems. Many reasons have been advanced for the disparity in the performance of PV-systems. This study aims to analyze the factors that affect the performance of installed PV-systems, such as geographical location, solar irradiance, dust, and shading. Other factors such as multiplicity of PV-system components in the market and the complexity of the permutations of these components, their types, efficiencies, and their different performance indicators are poorly understood, thus making it difficult to optimize the efficiency of the system as a whole. Furthermore, mathematical computations are presented to prove that the different design methods often used for the design of PV-systems lead to results with significant differences due to different assumptions often made early on. The methods for the design of PV-systems are critically appraised. There is a paucity of literature about the different methods of designing PV-systems, their disparities, and the outcomes of each method. The rationale behind this review is to analyze the variations in designs and offer far-reaching recommendations for future studies so that researchers can come up with more standardized design approaches. Full article

Volatile organic compound (VOC) emissions from indoor sources are large determinants of the indoor air quality (IAQ) and occupant health. Cross-laminated timber (CLT) is a panelized engineered wood product often left exposed as an interior surface finish. As a certified structural building product, CLT is currently exempt from meeting VOC emission limits for composite wood products and confirming emissions through California Department of Public Health (CDPH) Standard Method testing. In this study, small chamber testing was conducted to evaluate VOC emissions from three laboratory-produced CLT samples: One bonded with a new soy-based cold-set adhesive; a second bonded with a commercially available polyurethane (PUR) adhesive; and the third assembled without adhesive using dowels. A fourth commercially-produced eight-month-old sample bonded with melamine formaldehyde (MF) adhesive was also tested. All four samples were produced with Douglas-fir. The test results for the three laboratory-produced samples demonstrated VOC emissions compliance with the reference standard. The commercially-produced and aged CLT sample bonded with MF adhesive did not meet the acceptance criterion for formaldehyde of ≤9.0 µg/m³. The estimated indoor air concentration of formaldehyde in an office with the MF sample was 54.4 µg/m³; the results for the soy, PUR, and dowel samples were all at or below 2.5 µg/m³. Full article

Clay brick is a commonly used building material in China. Due to the enormous land destruction and excessive consumption of resources, such as materials and energy in the manufacture of clay brick, it is important to study its overall sustainability, i.e., in terms of impact on the environment, services, and economy. In this study, emergy analysis is employed, which offers a holistic perspective, unlike typical environmental studies. A series of emergy indices such as renewability rate (R%), nonrenewability rate (N%), unit emergy values (UEVs), emergy yield ratio (EYR), environmental loading ratio (ELR), and emergy sustainability index (ESI) were used to study manufacturing of clay brick. In addition to calculating UEVs of clay brick manufacturing in China (7.18 × 10¹² sej/kg), our detailed analysis shows that the nonrenewable resources and imported energy have a dominant impact on the emergy contribution (50.6%) and within the nonrenewable resources, clay is the foremost item, accounting for 33.5% of local emergy inputs. Given different electricity UEVs, the change ranges of clay brick system UEVs are 14.9% (scenario 1), 7.24% (scenario 2), 8.91% (scenario 3), and 6.94% (scenario 4). Furthermore, several policy suggestions are discussed for improving the sustainability of the evaluated system, involving the energy structure adjustment, recycling material replacement, and promotion of energy-saving systems. Full article