Buildings

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EISSN : 2075-5309
Published by: MDPI (10.3390)
Total articles ≅ 1,447
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Published: 23 September 2021
by MDPI
Abstract:
The risks associated with extreme weather events induced by climate change are increasingly being recognized, and must be addressed through each country’s construction regulations, building codes, and standards. Ensuring that buildings and cities are resilient against disasters is becoming more important. Few studies have analyzed the impact of global polices and frameworks in reducing disaster risks and increasing resilience in built environments. This research reviews disasters associated with climate change in the Sendai Framework for Disaster Risk Reduction 2015–2030, analyzing how Australia’s National Construction Code is aligned with the framework and the potential implications for reducing disaster risk. Decision-makers in construction companies in Sydney, Australia, were surveyed. The results show there is a statistically significant link among the National Construction Code, the Sendai Framework, and building resilience. The Sendai Framework is an effective mediator in this three-pronged relationship that can further enhance building resilience in Australia. Stakeholders in the construction industry will need to incorporate disaster risk reduction practices, especially authorities, such as local governments, building commissioners, and building certifiers that are responsible for the approval, quality, and defects mitigation of development applications and best practices. Overall, implementation of the Sendai Framework will help develop more regulations and standards for resilient buildings, set targets, and make improvements over time in the Australian construction industry.
Published: 23 September 2021
by MDPI
Abstract:
In the context of global climate change, urban morphology is closely related to thermal comfort and contributes to sustainable urban development. Academics started to pay attention to related topics and carried out many studies during the last decades. This paper aims to summarize the research achievements and the development track for future studies. The Web of Science database and CiteSpace were used in this paper to conduct a bibliometric analysis of 556 studies in related fields from 1993 to 2020. Using a three-level co-occurrence analysis of 446 keywords, 1187 cocited literature clusters, and 15 landmark studies, the research topics and mainstream research frameworks were identified. The results show that with the increasing participation of disciplines such as computer science, ecology, and chemistry, the purpose of future research will shift to a focus on anthropogenic heat emissions, energy consumption, air pollution, and other aspects, and new research tools will be needed. In addition to building-scale and block-scale morphology, urban-scale morphology and green infrastructure will become the focus in the future. This study provides a systematic review of research about urban morphology and thermal comfort, which can inspire other researchers and policy makers.
Published: 23 September 2021
by MDPI
Abstract:
Wood-frame walls in cold climates are traditional constructed with a vapour barrier that also constitutes the air-tightness layer. Polyethylene foil as a vapour barrier is likely used; however, other building materials can be used to obtain correspondingly sufficient properties. 1D hygrothermal simulations were conducted for a wood-frame structure to investigate the wind–vapour barrier ratio, and if the vapour barrier of polyethylene foil could be omitted and replaced by other materials. The results were postprocessed using the VTT mould model. The results showed how wood-frame walls can be designed with respect to internal humidity class and diffusion resistance divided into three categories: no risk for mould growth, needs further investigation, and is not performing well as the risk for mould growth is present. For internal humidity classes 1–3, the ratio between wind and vapour barrier must be about 1:5, and 1:10 for classes 4 and 5 to be on the safe side. Simulations were performed for the climate of Lund, Sweden, which were used to simulate climate in Denmark too. Nevertheless, the results are related to climate data and, thus, the location.
Published: 22 September 2021
by MDPI
Abstract:
Many studies concerning the precision manufacturing of freeform concrete panels have been conducted, however, this process remains labor intensive taking significant amounts of time and cost. In particular, the precision in the shape of the panels produced tends to be low because of the manual work involved in producing the curves of those panels. This study documents the development of mold production technologies that can be used to produce precise curved surfaces on the upper and lower parts of a mold for freeform concrete panels. A double-sided multipoint press CNC (computer numerical control) produces curved upper and lower surfaces of a mold without the need for manual work, while the operational technology we developed to control this tool enhances the precision of the curves created. The precision of these technologies was verified through experiments. The difference between the shapes designed and those produced were found using 3D scans and quality inspections. Unpredictable errors can occur due to the size of certain curvatures, the elasticity of the silicone plate, and the rotational angle of the joints of the rods supporting the surfaces. To minimize errors, shape compensation was carried out through reverse engineering, leading to a maximum error of 2.887 mm, which is within the allowable error. The results achieved in this study are a significant step toward technologies that will produce increasingly precise freeform concrete panels.
Published: 22 September 2021
by MDPI
Abstract:
Corrosion of reinforcement is one of the main problems related to the durability of reinforced concrete structures. This can cause cracks and a separation of the protective layer, as well as reducing strength and structural stiffness, which can result in numerous human casualties. Visual inspection is a standard method of assessing the condition of reinforced concrete structures whose limitations, such as time, interpretability, accessibility, etc., may affect its effectiveness. Therefore, damage determination methods based on dynamic parameters are becoming more and more prominent in the assessment of damage to reinforced concrete structures. The aim of this paper is to review the literature regarding the determination of corrosion of reinforcement by methods based on dynamic parameters, and to identify future research to develop a method that would detect corrosion problems in time through a continuous system of structural health monitoring.
Published: 21 September 2021
by MDPI
Abstract:
The rural residences of Northwest China are characterized by a state of high energy consumption and low comfort due to the limited economic level and awareness of energy-saving compared with the urban residences. To remedy this, appropriate passive design strategies should be adopted first, in order to provide a design mode with low energy consumption and low cost for rural residences under the premise of thermal comfort. In this paper, taking Hanzhong region (Shaanxi Province, China) as an example, we establish a benchmark model based on a field survey and develop an optimization process by combining EnergyPlus simulation software, the MOBO optimization engine, and weighted sum method. The action mechanisms of passive design parameters, including the building orientation, length–width ratio, building envelope parameters, external shading system, and window–wall ratio, on heating, cooling, and total energy consumption are analyzed, and the quantitative relationships between single-parameter and energy consumption are established. Then, the mutually restricted indices of total energy consumption and initial investment cost are taken as optimization objectives, and 17 design parameters are selected as the optimization variables. The NSGA-II algorithm is adopted to conduct the multi-parameter, multi-objective optimization design for rural houses in Hanzhong area, through coupling of the EnergyPlus and MOBO software. In this way, Pareto solutions are obtained and the value distributions of the multi-objectives and design parameters are analyzed. Based on the actual requirements of decision-makers and using the weight method, three design schemes focusing on different performance tendencies are proposed. The results indicate that by using the proposed optimization process, the building energy consumption can be significantly reduced while taking initial investment costs into account, where the energy-saving rate is in the range of 31.9%–61.5%. When the EC/IC ratio is 1:1, 2:1, and 1:2, the energy-saving rate can reach 51.5%, 57.8%, and 43.5%, respectively. It can provide a beneficial pattern for the energy-saving design and renovation of rural residences in Hanzhong area of China.
Published: 21 September 2021
by MDPI
Abstract:
Cementitious and recycled materials that have the potential to improve various properties of concrete have attracted the attention of many researchers recently. Different types of cementitious and recycled materials seem to possess certain unique properties to change cement concrete. This experimental study aims to investigate the impact of ground granulated blast furnace slag (GGBFS) and corn cob ash (CCA) as a partial replacement material for Portland cement (PC) and fine aggregate (FA), respectively, on fresh and hardened concrete properties, as well as the embodied carbon of concrete. The concrete mix was blended with 5-20% of GGBFS and 10-40% of corn cob ash, both individually and combined. A total of 300 concrete specimens were made to achieve the targeted strength of 25 MPa at a 0.50 water/cement ratio and cured at 28 days. It is observed that the workability of fresh concrete is lowered as the dosages of GGBFS and CCA increase in the mixture. Moreover, the compressive and split tensile strengths are augmented by 10.94% and 9.15%, respectively, at 10% of GGBFS by the weight of PC at 28 days. Similarly, the compressive and split tensile strengths are augmented by 11.62% and 10.56%, respectively, at 30% of CCA by the weight of FA at 28 days. Moreover, the combined use of 10% of GGBFS as a cementitious ingredient along with 30% of fine aggregate replaced with CCA in concrete provides the highest compressive and splitting tensile strength, with 16.98% and 13.38% at 28 days, respectively. Furthermore, the density and water absorption of concrete were reduced with increasing dosages of GGBFS and FA in concrete at 28 days. In addition, the embodied carbon and energy were also reduced as the replacement content of GGBFS along with CCA increased in concrete. It is concluded that 10% of GGBFS and 30% of CCA are the optimum percentages for structural applications to reduce the use of cement as well as the cost of the project.
Published: 21 September 2021
by MDPI
Abstract:
Results of an experimental investigation aimed at studying the effect of steel fibers on the shear behavior of concrete deep beams made with a 100% recycled concrete aggregate (RCA) are presented in this paper. The study comprised testing of seven concrete deep beam specimens with a shear span-to-depth ratio (a/h) of 1.6. Two beams were made of natural aggregates (NAs) without steel fibers, two beams were made of a 100% RCA without steel fibers, and three beams were made of RCA-based concrete with steel fibers at volume fractions (vf) of 1, 2, and 3%. Two of the beams without steel fibers included a minimum shear reinforcement. Test results showed that the beam with a 100% RCA without steel fibers exhibited a lower post-cracking stiffness, reduced shear cracking load, and lower shear capacity than those of the NA-based control beam. The detrimental effect of the RCA on the shear response was less pronounced in the presence of the minimum shear reinforcement. The addition of steel fibers significantly improved the shear response of the RCA-based beams. The post-cracking stiffness of the RCA-based concrete beams with steel fibers coincided with that of a similar beam without fibers containing the minimum shear reinforcement. The use of steel fibers in RCA beams at vf of 1 and 2% restored 80 and 90% of the shear capacity, respectively, of a similar beam with the minimum shear reinforcement. The response of the RCA specimen with vf of 3% outperformed that of the NA-based control beam with the minimum shear reinforcement, indicating that steel fibers can be used in RCA deep beams as a substitution to the minimum shear reinforcement. The shear capacities obtained from the tests were compared with predictions of published analytical models.
Published: 21 September 2021
by MDPI
Abstract:
Concrete beams reinforced with FRP rebars have greater durability than standard steel reinforced elements. The main disadvantage of using FRP rebars is the low ductility of elements which may be unacceptable in certain situations. There are several different ways of increasing the ductility of concrete elements, which are analyzed in this paper. They are compared based on efficiency, influence on durability and ease of construction. Less analyzed and tested methods are given more attention to try and expand the current knowledge and possibilities. For methods that lack experimental data, theoretical analysis is undertaken to assess the possible influence of that method on the increase in ductility. Ductility was obtained by calculating bending moment–curvature diagrams of cross sections for different reinforcement layouts. One method that lacks experimental data is confining the compressive area of beams with tensile FRP reinforcement. Theoretical analysis showed that confining the compressive area of concrete can significantly increase the ductility and bending capacity of beams. Since experimental data of beams reinforced with FRP rebars in tension and confined compressive area is sparse, some suggestions on the possible test setups are given to validate this theoretical analysis. Concrete beams reinforced with FRP can be detailed in such a way that they have sufficient ductility, but additional experimental research is needed.
Published: 19 September 2021
by MDPI
Abstract:
Although studies have been performed on the recycled aggregate made of waste concrete for the production of new concrete, the new concrete with 100% recycled coarse aggregate and manufactured sand (abbreviated as RAMC) still needs to be researched for structural applications. In this paper, an experimental study was performed on seven groups, including fourteen reinforced RAMC beams under the simply supported four-point loading test, considering the factors of the strength of RAMC and the reinforcement ratio of longitudinal tensile rebars. Based on the test results, the cracking resistance, the bearing capacity, the crack width, the flexural stiffness and the mid-span deflection of reinforced RAMC beams in bending are discussed and examined by using the formulas of conventional reinforced concrete beams. Results show that an obvious effect of reinforcement ratio was present, while less so was that of the strength of RAMC. With the comparison of predicted values by the formulas of conventional reinforced concrete beams, the reinforced RAMC beams decreased cracking resistance by about 20%, increased crack width by about 15% and increased mid-span deflection by about 10%, although the same bearing capacity can be reached. The results directly relate to the lower tensile strength of RAMC which should be further improved.
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