Research

19 pages, 7438 KiB

Open AccessArticle

Hygrothermal Performance of Thick PCM Mortar behind PV Panels in Energy-Activated ETICS Facades

by

,

,

,

,

and

Buildings 2023, 13(6), 1572; https://doi.org/10.3390/buildings13061572 - 20 Jun 2023

Viewed by 706

Abstract

The concept of integrating PV panels into traditional ETICS facades has been developing for several years. Problems concerning the options for passively controlling the temperatures of PV panels with PCM and directing excess moisture out of the wall via diffusion channels have been [...] Read more.

The concept of integrating PV panels into traditional ETICS facades has been developing for several years. Problems concerning the options for passively controlling the temperatures of PV panels with PCM and directing excess moisture out of the wall via diffusion channels have been previously studied theoretically. During this study, real wall-scale experiments were conducted to test the thermal and hygrothermal performance of the wall system in an extreme climatic environment, as well as in a real outdoor environment in Tallinn, Estonia. Finally, a simulation model was calibrated according to the measured data. It was found that in case of test walls with diffusion channels, it was possible to keep the moisture content of PCM mortar under 0.11 m³/m³. Excess water drained out via channels leading to the external environment. Without diffusion channels, the moisture content rose as high as 0.18 m³/m³. Both the experiments and hygrothermal modelling showed that the high moisture content of PCM mortar, caused by water leakage, dropped to 0.08 m³/m³ over 10 solar cycles as moisture escaped via the diffusion channels. PCM mortar with a moisture content of 0.08 m³/m³ endured extreme rain and freeze-thaw cycles without visual damage, and PV panels retained their electrical production capabilities. Full article

(This article belongs to the Special Issue Building Physics, Structural and Safety Engineering)

► Show Figures

Figure 1

16 pages, 2586 KiB

Open AccessArticle

An Approach to In Situ Evaluation of Timber Structures Based on Equalization of Non-Destructive and Mechanical Test Parameters

by

,

,

,

,

,

,

and

Buildings 2023, 13(6), 1405; https://doi.org/10.3390/buildings13061405 - 29 May 2023

Cited by 2 | Viewed by 844

Abstract

This paper addresses the challenges in evaluating the structural performance of built structures using non-destructive methods and in situ tests. Such an examination of structural properties, without their sampling, is a diagnostic improvement, especially for historical heritage buildings, where it is not allowed [...] Read more.

This paper addresses the challenges in evaluating the structural performance of built structures using non-destructive methods and in situ tests. Such an examination of structural properties, without their sampling, is a diagnostic improvement, especially for historical heritage buildings, where it is not allowed to violate their physical integrity. Therefore, the research proposes a non-destructive testing method based on the equalization of the mechanically and non-destructively determined parameters of the strength of built-in timber. The research included three phases: (1) a preliminary examination; (2) a calibration procedure of the non-destructive method, and (3) in situ application of the established non-destructive method. The preliminary examination involved testing specimens using X-rays and ultrasonic waves by directing them, analogous to mechanical testing, in the fibers’ longitudinal, radial, and tangential directions. In the second phase, it was shown that equalizing the parameters of mechanical and non-destructive testing using ultrasound and X-rays of timber was feasible. Furthermore, mechanical calibration was conducted to establish an applicable non-destructive in situ method. Finally, in the third phase, an in situ assessment of timber architectural elements confirms the effectiveness of the suggested non-destructive approach in diagnosing architectural structures. Full article

(This article belongs to the Special Issue Building Physics, Structural and Safety Engineering)

► Show Figures

Figure 1

20 pages, 17174 KiB

Open AccessArticle

Influence of Piloti Forms on Wind Comfort of Different Building Group Layouts by Large Eddy Simulation

by

,

,

,

,

,

and

Buildings 2023, 13(1), 234; https://doi.org/10.3390/buildings13010234 - 13 Jan 2023

Viewed by 1024

Abstract

This paper studies the influence of different piloti rates (0%, 20%, 40%, 60%, 80%, 100%) on outdoor wind comfort for three building groups, i.e., determinant type, point type, and enclosure type. LES (Large Eddy Simulation) is used to simulate the wind environment of [...] Read more.

This paper studies the influence of different piloti rates (0%, 20%, 40%, 60%, 80%, 100%) on outdoor wind comfort for three building groups, i.e., determinant type, point type, and enclosure type. LES (Large Eddy Simulation) is used to simulate the wind environment of three clusters at six different piloti rates. This paper mainly studies the effect of piloti rate on wind speed at pedestrian level (1.5 m). The outdoor wind environment was analyzed using the average wind speed ratio, and outdoor wind comfort was evaluated using the comfortable wind ratio. The following results were obtained: (1) The piloti setting has little influence on the overall wind speed in the target area, and even an inappropriate piloti rate setting may reduce the overall average wind speed in the target area. (2) A comprehensive comparison of the three building layouts shows that the comfortable wind ratio of the determinant layout is the highest when the piloti ratio is 80%. The results of this study can provide architects and urban planners with reference for piloti and urban layout settings. Full article

(This article belongs to the Special Issue Building Physics, Structural and Safety Engineering)

► Show Figures

Graphical abstract

23 pages, 7764 KiB

Open AccessArticle

An Experimental and Numerical Study on Fire Spread in a Furnished Room

by

Małgorzata Król

and

Aleksander Król

Buildings 2022, 12(12), 2189; https://doi.org/10.3390/buildings12122189 - 10 Dec 2022

Cited by 1 | Viewed by 1282

Abstract

The main objective of this research was to examine the development of fire in a furnished room in a typical high-rise building. This work was part of research on the fire safety of building occupants. It included two controlled fires in which a [...] Read more.

The main objective of this research was to examine the development of fire in a furnished room in a typical high-rise building. This work was part of research on the fire safety of building occupants. It included two controlled fires in which a standard sofa in a room was set on fire. Several thermocouple trees were arranged in the test room and the temperature was continuously recorded. Additionally, each fire test was videotaped for further analysis. Since an unexpected forepeak of the temperature course was observed, special attention was paid to explain this phenomenon. For this purpose, numerical models of fire development in a furnished room were built using the well-recognized software package, ANSYS Fluent and Fire Dynamic Simulator (FDS). The numerical research was focused on fire spread over a single piece of furniture, the sofa. The data recorded in real experiments were used to tune and validate the numerical models. The results of the Fluent numerical simulation were consistent with the recorded experimental data and proved that after the initial growth, there was a critical phase of fire development in which the fire might almost snuff or flare again. Meanwhile, the FDS results, despite being generally in accordance with the experiment, did not reproduce this critical phase of fire spreading. Full article

(This article belongs to the Special Issue Building Physics, Structural and Safety Engineering)

► Show Figures

Figure 1

15 pages, 7835 KiB

Open AccessArticle

Production of Low-Cost, High-Strength Concrete with Waste Glass as Fine Aggregates Replacement

by

Ali Jahami

,

Jamal Khatib

and

Rabab Raydan

Buildings 2022, 12(12), 2168; https://doi.org/10.3390/buildings12122168 - 08 Dec 2022

Cited by 9 | Viewed by 1656

Abstract

The world of building materials is constantly and rapidly developing. New technologies are needed to reduce the cost of producing these materials and to ensure better efficiency when the materials are used in various engineering projects. One of these materials is high-strength concrete. [...] Read more.

The world of building materials is constantly and rapidly developing. New technologies are needed to reduce the cost of producing these materials and to ensure better efficiency when the materials are used in various engineering projects. One of these materials is high-strength concrete. This paper investigates the production of low-cost, high-strength concrete by partially replacing fine aggregates (FA) with waste glass sand (WGS). Four concrete mixes were considered in this study with varying percentages of WGS (0%, 25%, 50%, and 75%). For each mix, cubic, cylindrical, and beam specimens were cast to study the workability and different mechanical properties of concrete-like density, elasticity modulus, compressive strength, ultrasonic pulse velocity (UPV), split tensile strength, and flexural strength. In addition, the cost of each mix was calculated to evaluate the cost reduction efficiency of concrete with WGS compared to normal concrete. Results showed that the workability of concrete enhanced as the percentage of WGS increased. In terms of concrete mechanical properties, it was shown that the elasticity modulus, compressive strength, split tensile strength, and flexure strength for a concrete mix with 50% WGS as FA replacement was increased by 7%, 27%, 9%, and 50%, respectively. Also, it was concluded that the presence of WGS in concrete mixes reduced the production cost by up to 30% for a 75% replacement level. The authors recommended the usage of 50% WGS as the optimum replacement percentage for low-cost, high-strength concrete. Full article

(This article belongs to the Special Issue Building Physics, Structural and Safety Engineering)

► Show Figures

Figure 1

18 pages, 9739 KiB

Open AccessArticle

Improving the Performance of Piled Raft Foundations Using Deformation Adjustors: A Case Study

by

,

,

,

,

,

and

Buildings 2022, 12(11), 1903; https://doi.org/10.3390/buildings12111903 - 06 Nov 2022

Cited by 2 | Viewed by 1434

Abstract

Complicated soil conditions are direct difficulties for high-rise building projects. A new device called a deformation adjustor, which is used to optimize the stiffness distribution in the piled raft system, has achieved good results for this challenge. This paper presents a case study [...] Read more.

Complicated soil conditions are direct difficulties for high-rise building projects. A new device called a deformation adjustor, which is used to optimize the stiffness distribution in the piled raft system, has achieved good results for this challenge. This paper presents a case study on the application of deformation adjustors to improve the performance of a piled raft foundation. This case study describes the preliminary design of pile-raft foundations with deformation adjustors, followed by numerical analysis. Based on the numerical study, the potential savings are demonstrated due to the good performance of soil bearing capacity. Comparing the numerical results with the monitoring results in raft settlements, earth pressures, deformation amount of deformation adjustors, pile top reactions, and load-sharing ratios between soils and piles, the accuracy of the design schemes with an aided numerical analysis is verified. Through a long-term monitoring, soils below the raft carried 63% of the total applied loads, while the piles bear 37% of the loads. This case study proved that a piled raft foundation with deformation adjustors was an effective and economical design scheme, which can make full use of the soil bearing capacity. It is of great significance to facilitate the design and construction of piled raft foundations in complicated soil conditions. Full article

(This article belongs to the Special Issue Building Physics, Structural and Safety Engineering)

► Show Figures

Figure 1

23 pages, 6099 KiB

Open AccessArticle

The Effect of Relative Humidity Dependent Thermal Conductivity on Building Insulation Layer Thickness Optimization

by

,

,

and

Buildings 2022, 12(11), 1864; https://doi.org/10.3390/buildings12111864 - 03 Nov 2022

Viewed by 1461

Abstract

Optimization of insulation layer thickness is a significant factor in energy-efficient building design. Accurate determination of the thickness of the insulation layer will contribute to building energy conservation. In this study, ten typical cities in five thermal zones were selected, and the external [...] Read more.

Optimization of insulation layer thickness is a significant factor in energy-efficient building design. Accurate determination of the thickness of the insulation layer will contribute to building energy conservation. In this study, ten typical cities in five thermal zones were selected, and the external thermal insulation of a typical residential building was taken as the research object. Using the degree day method and the economic model of full life cycle cost analysis, the optimal thickness of seven kinds of building insulation materials under absolute dry conditions, the lowest humidity and the highest humidity of the monthly average of the annual daily average were obtained. In addition, the carbon emission, energy saving and recovery period of materials under different working conditions were further obtained through numerical calculation. The results show that the optimum thickness of seven building insulation materials in ten typical cities under three working conditions is 18.21–346.05 mm. Their carbon emission change rate is between −2.7% and 38.6%, energy saving change rate is between −0.4% and 18.4%, and the payback period growth is within 1.5 years. Among them, polystyrene foam is the material least affected by humidity. It is recommended to be the main building insulation material in high humidity areas. Full article

(This article belongs to the Special Issue Building Physics, Structural and Safety Engineering)

► Show Figures

Figure 1

20 pages, 10388 KiB

Open AccessArticle

Structural Response Analysis of FPSO under Pool Fire

by

Dapeng Zhang

,

Bowen Zhao

and

Keqiang Zhu

Buildings 2022, 12(10), 1665; https://doi.org/10.3390/buildings12101665 - 12 Oct 2022

Viewed by 807

Abstract

There is a large proportion of pool fire occurrence on the upper part of offshore platforms. In order to reduce the occurrence of fire disasters, the fire risk assessment of FPSOs should be carried out. According to the temperature characteristics of offshore platform [...] Read more.

There is a large proportion of pool fire occurrence on the upper part of offshore platforms. In order to reduce the occurrence of fire disasters, the fire risk assessment of FPSOs should be carried out. According to the temperature characteristics of offshore platform fires based on computational fluid dynamics, the temperature field of the superstructure of the offshore platform under pool fire has been analyzed, the regularities of the distribution of the wall temperature of the platform of FPSO under different wind speeds are studied, and research on the distribution of heat radiation flux of different fire is made. Based on the finite element method, the structural response of the platform structure in different fire scenarios has been made. In consideration of the pool fires caused by liquid leakage of the upper part of the platform structure, with the basis of the changes of temperature field and radiation field being obtained by CFD, a structural response analysis of the offshore platform structure using the finite element method and a risk assessment method based on quantitative analysis for pool fires caused by liquid leakage is proposed. Full article

(This article belongs to the Special Issue Building Physics, Structural and Safety Engineering)

► Show Figures

Figure 1

20 pages, 5819 KiB

Open AccessArticle

Shaking Table Tests of a Novel Flat Slab-Flanged Wall (FSFW) Coupled System with Embedded Concrete-Filled-Steel-Tubes in Wall Piers

by

,

,

and

Buildings 2022, 12(9), 1441; https://doi.org/10.3390/buildings12091441 - 13 Sep 2022

Cited by 1 | Viewed by 936

Abstract

The flat slab-flanged wall (FSFW) coupled system has gained popularity in recent years; however, its seismic performance remains an issue, as beams and columns in it are commonly eliminated. To tackle this problem, embedding concrete-filled steel tubes (CFSTs) in wall piers has been [...] Read more.

The flat slab-flanged wall (FSFW) coupled system has gained popularity in recent years; however, its seismic performance remains an issue, as beams and columns in it are commonly eliminated. To tackle this problem, embedding concrete-filled steel tubes (CFSTs) in wall piers has been proposed to strengthen the system; the viability of this approach has been verified at the member level. Along this line, this study embarks on a shaking table testing of a 1/8-scale five-story FSFW structure equipped with CFSTs in walls, with an aim to understand the overall seismic behavior of such an enhanced system. As with the practice in many countries, the plan layout of the test structure consisted of four rows of wall piers, thus presenting a ‘fish-bone’ floor configuration that relied only upon the walls to resist gravity and lateral loads. The structure was subjected to a suite of input ground motions along with white-noise excitations. By so doing, its damage progression, pattern and dynamic characteristics were clearly identified. Furthermore, a non-linear time history analysis was conducted using PERFORM-3D, and the goodness-of-fit of the computed responses to the experimental records was examined. Findings indicated that the application of CFSTs was instrumental in resisting the simulated earthquake loads acting on the FSFW system, hence the global response limits required by codes of practice were met, even in the case of extremely strong earthquakes. Nevertheless, the junction between the shear walls and floor slabs was found to be the weakest links in the whole system. Designers are thus cautioned to implement proper detailing in those regions to prevent local distress, though it did not appear to acutely impair the system’s collapse-resisting capacity. Full article

(This article belongs to the Special Issue Building Physics, Structural and Safety Engineering)

► Show Figures

Figure 1

19 pages, 6562 KiB

Open AccessArticle

Freezing Effect of Enhancing Tubes in a Freeze-Sealing Pipe Roof Method Based on the Unsteady-State Conjugate Heat Transfer Model

by

,

,

,

,

and

Buildings 2022, 12(9), 1373; https://doi.org/10.3390/buildings12091373 - 02 Sep 2022

Cited by 1 | Viewed by 1103

Abstract

The freeze-sealing pipe roof (FSPR) method was applied as an innovative construction technology to the Gongbei Tunnel of the Hong Kong–Zhuhai–Macau Bridge. A freezing scheme involving master freezing tubes, enhancing freezing tubes, and limiting freezing tubes is the key component of the freezing [...] Read more.

The freeze-sealing pipe roof (FSPR) method was applied as an innovative construction technology to the Gongbei Tunnel of the Hong Kong–Zhuhai–Macau Bridge. A freezing scheme involving master freezing tubes, enhancing freezing tubes, and limiting freezing tubes is the key component of the freezing effect of the FSPR method during the construction process under various working conditions. This is related to whether the thickness and temperature of the frozen soil meet the design requirements under various complex working conditions, and it is also related to frost heave control and energy saving. Based on the unsteady-state conjugate heat transfer model, different freezing schemes of enhancing freezing tubes—that is, the shape, layout, operating duration, and heat preservation—were simulated to analyze the freezing effect, which can be measured by the thickness of frozen soil around the steel pipes and the average temperature of the frozen soil curtain. The results show that the greater the contact area between the enhancing tube and the inner wall of the steel pipe, the better the freezing effect, and that the semicircle enhancing freezing tube scheme is superior to the other three shapes of freezing tubes. The arrangement of enhancing freezing tubes far away from the excavation surface, without heat preservation measures, has a better freezing effect due to the function of the hollow pipe as a freezing pipe. Moreover, the enhancing freezing tube can be operated intermittently to control frost heave. Our research simulated the temperature fields of different media—such as steel pipes, frozen soil, and air—providing a design basis for similar projects, such as the combination of the pipe-roofing method and artificial freezing method. Full article

(This article belongs to the Special Issue Building Physics, Structural and Safety Engineering)

► Show Figures

Figure 1

18 pages, 4757 KiB

Open AccessArticle

Unsteady-State Conjugate Heat Transfer Model of Freeze-Sealing Pipe Roof Method and Sensitivity Analysis of Influencing Factors of Freezing Effect

by

,

,

,

,

,

and

Buildings 2022, 12(9), 1370; https://doi.org/10.3390/buildings12091370 - 02 Sep 2022

Viewed by 978

Abstract

The freeze-sealing pipe roof (FSPR) method has been applied to the Gongbei tunnel of the Hongkong–Zhuhai–Macau Bridge, which is the first application of this method in the world. The purpose of the ground-freezing method is soil waterproofing. Temperature is an important indicator for [...] Read more.

The freeze-sealing pipe roof (FSPR) method has been applied to the Gongbei tunnel of the Hongkong–Zhuhai–Macau Bridge, which is the first application of this method in the world. The purpose of the ground-freezing method is soil waterproofing. Temperature is an important indicator for measuring the freezing effect; however, the FSPR method involves unsteady-state conjugate heat transfer between frozen soil, steel pipes, concrete, air, and other media. This paper proposes an unsteady-state conjugate heat transfer model and establishes a global solution algorithm of a strong coupling governing equation based on the virtual density method. Then, a calculation based on COMSOL software is realized and validated. The sensitivity of different factors such as initial formation temperature, different soil layers, and brine temperature on the freezing effect was studied by simulating the FSPR model. It is concluded that the brine temperature had a greater impact on the freezing effect, followed by the soil layer, whereas the formation temperature had the least impact. For muddy silty clay, if the brine temperature is −20 °C, it takes 44 days to meet the design requirements of 2 m. If the brine temperature is −30 °C, 27 days is enough. When the formation temperature is 20 °C, it takes 20 days for medium gravel sand to reach the thickness of the freezing curtain, and 32 days for muddy silty clay. Compared to other soil layers, the freezing effect of the medium gravel sand is relatively better. This research has a certain impetus to similar multimedia freezing heat transfer issues. Full article

(This article belongs to the Special Issue Building Physics, Structural and Safety Engineering)

► Show Figures

Figure 1

13 pages, 1166 KiB

Open AccessArticle

Resistance Characteristic Parameters Estimation of Hydraulic Model in Heating Networks Based on Real-Time Operation Data

by

,

,

,

and

Buildings 2022, 12(6), 743; https://doi.org/10.3390/buildings12060743 - 30 May 2022

Viewed by 1033

Abstract

Heating systems are essential municipal infrastructure in winter, especially in severe cold cities of China. The safety and efficiency of heating systems greatly affect building energy efficiency and indoor thermal comfort. Heating networks (HNs), playing the role of transportation, are the key parts [...] Read more.

Heating systems are essential municipal infrastructure in winter, especially in severe cold cities of China. The safety and efficiency of heating systems greatly affect building energy efficiency and indoor thermal comfort. Heating networks (HNs), playing the role of transportation, are the key parts of heating systems. In HNs, hydraulic models could be affected by the accuracy of resistance characteristic parameters, which are expressed by pipe friction parameters (PFPs) in this paper. As the uniqueness of the estimation results of PFPs has not been discussed in previous studies, this paper builds an estimation method of PFPs by dividing two types of pipes, substituting variables and establishing a split-step linearization method. Combining with the theory of matrix equations, the decision conditions and solution methods for obtaining the unique estimation results of PFPs are determined. Theoretical analysis and case study results show that estimation values of PFPs can be obtained by utilizing measured data under multiple hydraulic conditions. In the example of DN and the simple actual HN, the average estimation deviation of PFPs is 1.42% and 1.86%, which are accurate enough for actual engineering. Estimation results of PFPs obtained by this method guarantee the accuracy of analysis and regulation in heating systems and improve social energy utilization efficiency. Full article

(This article belongs to the Special Issue Building Physics, Structural and Safety Engineering)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Special Issue "Building Physics, Structural and Safety Engineering"

Share This Special Issue

Special Issue Editors

Special Issue Information

Published Papers (12 papers)

Research

Further Information

Guidelines

MDPI Initiatives

Follow MDPI