Pub Date : 2024-10-11DOI: 10.1016/j.jobe.2024.111024
Alkali-silica reaction (ASR) poses a critical damage to concrete structures, which will lead to a serious reduction for the service life of concrete. This study investigated the mitigation of ASR using glass powder (GP) through accelerated mortar bar tests (AMBT), with fly ash (FA) and ground granulated blast-furnace slag (GGBS) setting as control groups, and the replacement ratio of GP, FA and GGBS is 0, 5 %, 10 %, 20 %, 30 % and 40 % respectively. The results reveal that both FA and GGBS can mitigate the possibility of ASR: GGBS can significantly mitigate ASR only when its content reaches up to 40 % and FA effectively suppressed ASR with a dosage of 20 %. For the GP, particles larger than 75 μm will increase the risk of ASR, and as evidenced by the clear presence of ASR-gel and cracks in the mortar bars observed. Conversely, GP with particle sizes smaller than 75 μm effectively mitigated ASR, achieving significant suppression at a content of 20 %. The possible mitigation mechanism of GP could be attributed to the pozzolanic reaction between the GP and the alkali in the concrete, which reduces the alkali in the cement. This work might offer some reference to ASR risk control in concrete.
碱硅反应（ASR）会对混凝土结构造成严重破坏，导致混凝土的使用寿命严重缩短。本研究通过加速砂浆棒试验（AMBT），以粉煤灰（FA）和磨细高炉矿渣（GGBS）为对照组，研究了使用玻璃粉（GP）缓解 ASR 的情况，GP、FA 和 GGBS 的替代率分别为 0%、5%、10%、20%、30% 和 40%。结果表明，FA 和 GGBS 都能减轻 ASR 的可能性：GGBS 只有在含量达到 40% 时才能显著减轻 ASR，而 FA 在用量为 20% 时能有效抑制 ASR。对于 GP 而言，大于 75 μm 的颗粒会增加 ASR 的风险，从观察到的砂浆条中明显存在 ASR 凝胶和裂缝就可以看出这一点。相反，粒径小于 75 μm 的 GP 可有效缓解 ASR，在含量为 20% 时可显著抑制 ASR。GP 的可能缓解机制可归因于 GP 与混凝土中的碱之间的胶凝反应，从而减少了水泥中的碱。这项工作可为混凝土中的 ASR 风险控制提供一些参考。
{"title":"Effect of glass powder on alkali-silica reaction mitigation for tunnel waste rock slag in concrete","authors":"","doi":"10.1016/j.jobe.2024.111024","DOIUrl":"10.1016/j.jobe.2024.111024","url":null,"abstract":"<div><div>Alkali-silica reaction (ASR) poses a critical damage to concrete structures, which will lead to a serious reduction for the service life of concrete. This study investigated the mitigation of ASR using glass powder (GP) through accelerated mortar bar tests (AMBT), with fly ash (FA) and ground granulated blast-furnace slag (GGBS) setting as control groups, and the replacement ratio of GP, FA and GGBS is 0, 5 %, 10 %, 20 %, 30 % and 40 % respectively. The results reveal that both FA and GGBS can mitigate the possibility of ASR: GGBS can significantly mitigate ASR only when its content reaches up to 40 % and FA effectively suppressed ASR with a dosage of 20 %. For the GP, particles larger than 75 μm will increase the risk of ASR, and as evidenced by the clear presence of ASR-gel and cracks in the mortar bars observed. Conversely, GP with particle sizes smaller than 75 μm effectively mitigated ASR, achieving significant suppression at a content of 20 %. The possible mitigation mechanism of GP could be attributed to the pozzolanic reaction between the GP and the alkali in the concrete, which reduces the alkali in the cement. This work might offer some reference to ASR risk control in concrete.</div></div>","PeriodicalId":15064,"journal":{"name":"Journal of building engineering","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142446897","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-11DOI: 10.1016/j.jobe.2024.111023
While guided wave-based techniques have been extensively developed for various engineering materials, their application to ultra-high performance concrete (UHPC), particularly in thin-walled structures, remains underexplored. This paper presents a shear horizontal (SH) guided wave technique for the nondestructive assessment of thin-shaped UHPC, specifically mimicking pipeline components. The proposed technique leverages SH mode guided waves for two key purposes: (1) the quantitative evaluation of mechanical properties and (2) the precise estimation of defect geometry. An 8 mm-thick UHPC plate sample was used to investigate the detection of frontal defect shapes and acoustic properties by utilizing the dispersive traits of SH mode waves. The results confirm the nondispersive nature of SH wave propagation at frequencies between 120 and 150 kHz, ensuring accurate measurements of wave velocity and attenuation coefficients for UHPC. This study also compares the short-time Fourier transform (STFT) method employed for signal processing with the conventional Hilbert envelope (HE) method, identifying 140 kHz as the optimal frequency for effective defect localization and shape characterization in the UHPC sample. The findings from this preliminary study can contribute to establishing new maintenance guidelines for thin UHPC structures, with potential applications in hyperloop systems and complex architectural designs.
虽然基于导波的技术已广泛应用于各种工程材料，但其在超高性能混凝土（UHPC），尤其是薄壁结构中的应用仍未得到充分开发。本文提出了一种水平剪切 (SH) 导波技术，用于对薄型超高性能混凝土（特别是模拟管道组件）进行无损评估。所提出的技术利用 SH 模式导波实现两个关键目的：(1) 机械性能的定量评估和 (2) 缺陷几何形状的精确估算。利用 SH 模式波的色散特性，使用 8 毫米厚的 UHPC 板样品研究了正面缺陷形状和声学特性的检测。结果证实了 SH 波在 120 至 150 kHz 频率范围内传播的非分散性，从而确保了对超高强度混凝土波速和衰减系数的精确测量。本研究还比较了用于信号处理的短时傅立叶变换 (STFT) 方法和传统的希尔伯特包络 (HE) 方法，确定 140 kHz 为有效定位 UHPC 样品缺陷和形状特征的最佳频率。这项初步研究的结果有助于为超高强度混凝土薄结构制定新的维护准则，并有可能应用于超高速轨道系统和复杂的建筑设计中。
{"title":"Application of shear horizontal guided waves for nondestructive damage detection in thin-walled ultra-high performance concrete","authors":"","doi":"10.1016/j.jobe.2024.111023","DOIUrl":"10.1016/j.jobe.2024.111023","url":null,"abstract":"<div><div>While guided wave-based techniques have been extensively developed for various engineering materials, their application to ultra-high performance concrete (UHPC), particularly in thin-walled structures, remains underexplored. This paper presents a shear horizontal (SH) guided wave technique for the nondestructive assessment of thin-shaped UHPC, specifically mimicking pipeline components. The proposed technique leverages SH mode guided waves for two key purposes: (1) the quantitative evaluation of mechanical properties and (2) the precise estimation of defect geometry. An 8 mm-thick UHPC plate sample was used to investigate the detection of frontal defect shapes and acoustic properties by utilizing the dispersive traits of SH mode waves. The results confirm the nondispersive nature of SH wave propagation at frequencies between 120 and 150 kHz, ensuring accurate measurements of wave velocity and attenuation coefficients for UHPC. This study also compares the short-time Fourier transform (STFT) method employed for signal processing with the conventional Hilbert envelope (HE) method, identifying 140 kHz as the optimal frequency for effective defect localization and shape characterization in the UHPC sample. The findings from this preliminary study can contribute to establishing new maintenance guidelines for thin UHPC structures, with potential applications in hyperloop systems and complex architectural designs.</div></div>","PeriodicalId":15064,"journal":{"name":"Journal of building engineering","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142441677","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-11DOI: 10.1016/j.jobe.2024.111035
Permafrost degradation poses significant environmental and geological challenges in Arctic and subarctic regions, particularly in areas like Umiujaq, Canada. The warming climate leads to thawing permafrost, causing ground instability, disrupting hydrology, and impacting local built environment. This study evaluates the use of Ground Source Heat Pump (GSHP) operation for mitigating ground subsidence in a permafrost region using a two-dimensional Thermo-Hydro-Mechanical (THM) coupled finite element analysis considering the ground poro-elastic and poro-plastic responses. The research uses a single-well scenario to demonstrate the interactions among thermal, hydraulic, and mechanical processes. The impact of GSHP operation under different temperature management strategies, including a scenario with a constant GSHP temperature of −5 °C throughout the year is numerically investigated. Results indicate that GSHP operation exacerbates ground deformation near the borehole, particularly during winter months. However, maintaining GSHP operation throughout the entire year can mitigate extreme subsidence fluctuations, leading to a more stable subsurface environment. While GSHP systems provide effective thermal regulation, their operation can introduce mechanical stresses that potentially disturb the ground close to the borehole. Therefore, careful design, operation, and further research are essential to balance thermal benefits with ground stability in permafrost regions.
{"title":"Numerical evaluation of ground source heat pumps in a thawing permafrost region","authors":"","doi":"10.1016/j.jobe.2024.111035","DOIUrl":"10.1016/j.jobe.2024.111035","url":null,"abstract":"<div><div>Permafrost degradation poses significant environmental and geological challenges in Arctic and subarctic regions, particularly in areas like Umiujaq, Canada. The warming climate leads to thawing permafrost, causing ground instability, disrupting hydrology, and impacting local built environment. This study evaluates the use of Ground Source Heat Pump (GSHP) operation for mitigating ground subsidence in a permafrost region using a two-dimensional Thermo-Hydro-Mechanical (THM) coupled finite element analysis considering the ground poro-elastic and poro-plastic responses. The research uses a single-well scenario to demonstrate the interactions among thermal, hydraulic, and mechanical processes. The impact of GSHP operation under different temperature management strategies, including a scenario with a constant GSHP temperature of −5 °C throughout the year is numerically investigated. Results indicate that GSHP operation exacerbates ground deformation near the borehole, particularly during winter months. However, maintaining GSHP operation throughout the entire year can mitigate extreme subsidence fluctuations, leading to a more stable subsurface environment. While GSHP systems provide effective thermal regulation, their operation can introduce mechanical stresses that potentially disturb the ground close to the borehole. Therefore, careful design, operation, and further research are essential to balance thermal benefits with ground stability in permafrost regions.</div></div>","PeriodicalId":15064,"journal":{"name":"Journal of building engineering","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142432699","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-11DOI: 10.1016/j.jobe.2024.111038
Short circuit failures in building cables exposed to incidental heat are a significant cause of major electrical fires. However, the scientific understanding of how applied voltage influences the occurrence of such faults remains limited. This study investigates short circuits in cables exposed to a cone heater with a radiant heat flux of 20 kW m−2, focusing primarily on the effects of applied voltages ranging from 20 to 380 V alternating current (VAC). The results indicate that at voltages below 140 VAC, a physical short circuit typically occurs, characterized by a single arc that lacks ignition capability. As the voltage increases between 140 and 260 VAC, an arcing short circuit with multiple arcs is more likely, presenting a higher risk of ignition. For voltages exceeding 280 VAC, only physical short circuits with excessively intense arcs are observed, which can immediately ignite fires and trip circuit breakers. Additionally, the time to failure decreases as applied voltage increases. Through an analysis of time-to-failure, arc energy, surface temperature of the thermally degraded cable, and arc bead characteristics, this paper also explains the formation mechanisms of both physical and arcing short circuits across different voltages. This study enhances the understanding of the complex influence of applied voltage on the occurrence and ignition potential of short circuits in heated cables.
{"title":"Effects of applied voltages on the occurrence features of short circuits in building cables exposed to constant radiation heat","authors":"","doi":"10.1016/j.jobe.2024.111038","DOIUrl":"10.1016/j.jobe.2024.111038","url":null,"abstract":"<div><div>Short circuit failures in building cables exposed to incidental heat are a significant cause of major electrical fires. However, the scientific understanding of how applied voltage influences the occurrence of such faults remains limited. This study investigates short circuits in cables exposed to a cone heater with a radiant heat flux of 20 kW m<sup>−2</sup>, focusing primarily on the effects of applied voltages ranging from 20 to 380 V alternating current (VAC). The results indicate that at voltages below 140 VAC, a physical short circuit typically occurs, characterized by a single arc that lacks ignition capability. As the voltage increases between 140 and 260 VAC, an arcing short circuit with multiple arcs is more likely, presenting a higher risk of ignition. For voltages exceeding 280 VAC, only physical short circuits with excessively intense arcs are observed, which can immediately ignite fires and trip circuit breakers. Additionally, the time to failure decreases as applied voltage increases. Through an analysis of time-to-failure, arc energy, surface temperature of the thermally degraded cable, and arc bead characteristics, this paper also explains the formation mechanisms of both physical and arcing short circuits across different voltages. This study enhances the understanding of the complex influence of applied voltage on the occurrence and ignition potential of short circuits in heated cables.</div></div>","PeriodicalId":15064,"journal":{"name":"Journal of building engineering","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142441637","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-11DOI: 10.1016/j.jobe.2024.111003
The high cost of robust UHPC of a proprietary nature and expensive constituents hinders mass production and expansion into full structural applications. This study provides experimental research and validation to support new initiatives in scalable, economical UHPC of a semi-proprietary nature that leverages local and sustainable materials and explores the use of raw recycled tire fibers. The study provides comprehensive material trials and mechanical characterization validated through the fabrication and testing of five full-scale axial UHPC columns with varying reinforcement ratios, fiber ratios, and types of fibers. Overall, the result shows that incorporating local and sustainable components into proprietary mixtures does not compromise the mechanical properties of UHPC with compressive strength of more than 150 MPa and modulus of elasticity ranging from 41.8 to 43.4 GPa. In addition, the axial strength capacity of economical UHPC columns, designed accordingly with ACI, performed better than non-ACI-compliant columns by up to 26.8 %.
{"title":"Economic and sustainable UHPC at scale: Material variability study and application to axial columns","authors":"","doi":"10.1016/j.jobe.2024.111003","DOIUrl":"10.1016/j.jobe.2024.111003","url":null,"abstract":"<div><div>The high cost of robust UHPC of a proprietary nature and expensive constituents hinders mass production and expansion into full structural applications. This study provides experimental research and validation to support new initiatives in scalable, economical UHPC of a semi-proprietary nature that leverages local and sustainable materials and explores the use of raw recycled tire fibers. The study provides comprehensive material trials and mechanical characterization validated through the fabrication and testing of five full-scale axial UHPC columns with varying reinforcement ratios, fiber ratios, and types of fibers. Overall, the result shows that incorporating local and sustainable components into proprietary mixtures does not compromise the mechanical properties of UHPC with compressive strength of more than 150 MPa and modulus of elasticity ranging from 41.8 to 43.4 GPa. In addition, the axial strength capacity of economical UHPC columns, designed accordingly with ACI, performed better than non-ACI-compliant columns by up to 26.8 %.</div></div>","PeriodicalId":15064,"journal":{"name":"Journal of building engineering","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142441678","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-10DOI: 10.1016/j.jobe.2024.111019
Radiant temperature asymmetry as one of the criteria for local thermal discomfort has an influence on the practical design of the heating system, as people are most sensitive to the radiant heating of the top of the head. The paper presents the determination of the allowable surface temperature of the heated ceiling based on the theoretical calculation using the angle factors and taking into account the allowable the radiant temperature asymmetry according to the standard values of 5 and 7 K. In practice, the radiation temperature asymmetry is determined by measuring two radiant temperatures. In this paper, the measurement of radiant temperature asymmetry is measured in an experimental room with a heated ceiling and the results are compared with the theoretical calculation procedure. The paper points out the differences between the measured and calculated values of the radiant temperature asymmetry. Based on the analyses, the allowable ceiling temperatures for radiant heating have been determined for different room geometries so that the radiant temperature asymmetry for thermal comfort categories A, B is actually observed. A new correlation has been established to determine the allowable surface temperature of the radiant ceiling as a function of the angle factor between the small plane element and the ceiling. For practical use, the correlation has been adjusted for typical geometric cases without the need for calculation of angle factors. Maximum ceiling surface temperatures are graphically displayed without causing thermal discomfort. Conversely, in large rooms with a heated ceiling, the ceiling surface temperature is severely limited, precisely because of the potential for thermal discomfort due to radiant temperature asymmetry.
辐射温度不对称作为局部热不适的标准之一，对加热系统的实际设计有影响，因为人们对头顶的辐射加热最为敏感。本文介绍了在使用角度系数进行理论计算的基础上，根据 5 和 7 K 的标准值并考虑到允许的辐射温度不对称，确定加热天花板的允许表面温度。本文在一个带有加热天花板的实验房间内对辐射温度不对称进行了测量，并将测量结果与理论计算程序进行了比较。本文指出了辐射温度不对称测量值和计算值之间的差异。根据分析结果，确定了不同房间几何形状的辐射供暖允许天花板温度，从而实际观察到热舒适度类别 A、B 的辐射温度不对称。我们建立了一种新的相关关系，以确定辐射天花板的允许表面温度与小平面元件和天花板之间的角度系数的函数关系。为便于实际使用，已针对典型的几何情况对相关性进行了调整，而无需计算角度系数。天花板表面的最高温度以图形显示，不会造成热不适。相反，在有加热天花板的大房间中，天花板表面温度受到严格限制，这正是因为辐射温度不对称可能导致热不适。
{"title":"Allowable surface temperature of ceiling heating based on radiant temperature asymmetry","authors":"","doi":"10.1016/j.jobe.2024.111019","DOIUrl":"10.1016/j.jobe.2024.111019","url":null,"abstract":"<div><div>Radiant temperature asymmetry as one of the criteria for local thermal discomfort has an influence on the practical design of the heating system, as people are most sensitive to the radiant heating of the top of the head. The paper presents the determination of the allowable surface temperature of the heated ceiling based on the theoretical calculation using the angle factors and taking into account the allowable the radiant temperature asymmetry according to the standard values of 5 and 7 K. In practice, the radiation temperature asymmetry is determined by measuring two radiant temperatures. In this paper, the measurement of radiant temperature asymmetry is measured in an experimental room with a heated ceiling and the results are compared with the theoretical calculation procedure. The paper points out the differences between the measured and calculated values of the radiant temperature asymmetry. Based on the analyses, the allowable ceiling temperatures for radiant heating have been determined for different room geometries so that the radiant temperature asymmetry for thermal comfort categories A, B is actually observed. A new correlation has been established to determine the allowable surface temperature of the radiant ceiling as a function of the angle factor between the small plane element and the ceiling. For practical use, the correlation has been adjusted for typical geometric cases without the need for calculation of angle factors. Maximum ceiling surface temperatures are graphically displayed without causing thermal discomfort. Conversely, in large rooms with a heated ceiling, the ceiling surface temperature is severely limited, precisely because of the potential for thermal discomfort due to radiant temperature asymmetry.</div></div>","PeriodicalId":15064,"journal":{"name":"Journal of building engineering","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142535272","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-10DOI: 10.1016/j.jobe.2024.110958
This study investigates the effectiveness of equivalent linear air spring stiffness in a Vertical Tuned Liquid Column Gas Damper (VTLCGD) for reducing vertical structural vibrations, particularly considering different sealing conditions. The VTLCGD system, designed with a single sealed vertical air column, allows flexible frequency tuning by adjusting the air spring stiffness. It aims to be used in low-frequency structures where conventional VTLCGD designs with two sealed ends are less efficient. The geometric configuration and working principle of the VTLCGD are first described. The equation of motion is derived using liquid dynamic equilibrium and the pressure-volume relationship, with expressions for natural frequency and control force validated through shaking table tests conducted with varying VTLCGD lengths. Experimental investigations are conducted to examine the parameters affecting damper performance using pressure data. The system's vibration reduction performance is then numerically evaluated on a cantilevered floor subjected to human walking. The numerical results, based on the equation of motion for liquid displacement and natural frequency, show good agreement with experimental data, which confirms the effectiveness of using linearized air spring stiffness for frequency tuning. The effects of total liquid length and height difference on control force are further investigated, and a polytropic index of 1.2 is determined for the VTLCGD frequency formula. The VTLCGD system achieves a maximum vibration reduction of 52.63 % in acceleration response on the cantilevered floor compared to the uncontrolled case. Moreover, the variation in stiffness due to changes in the sealing condition is presented to validate the damper's adaptability over a wide frequency range.
{"title":"Theoretical and experimental investigation of flexible air spring stiffness in a tuned liquid column gas damper for vertical vibration control","authors":"","doi":"10.1016/j.jobe.2024.110958","DOIUrl":"10.1016/j.jobe.2024.110958","url":null,"abstract":"<div><div>This study investigates the effectiveness of equivalent linear air spring stiffness in a Vertical Tuned Liquid Column Gas Damper (VTLCGD) for reducing vertical structural vibrations, particularly considering different sealing conditions. The VTLCGD system, designed with a single sealed vertical air column, allows flexible frequency tuning by adjusting the air spring stiffness. It aims to be used in low-frequency structures where conventional VTLCGD designs with two sealed ends are less efficient. The geometric configuration and working principle of the VTLCGD are first described. The equation of motion is derived using liquid dynamic equilibrium and the pressure-volume relationship, with expressions for natural frequency and control force validated through shaking table tests conducted with varying VTLCGD lengths. Experimental investigations are conducted to examine the parameters affecting damper performance using pressure data. The system's vibration reduction performance is then numerically evaluated on a cantilevered floor subjected to human walking. The numerical results, based on the equation of motion for liquid displacement and natural frequency, show good agreement with experimental data, which confirms the effectiveness of using linearized air spring stiffness for frequency tuning. The effects of total liquid length and height difference on control force are further investigated, and a polytropic index of 1.2 is determined for the VTLCGD frequency formula. The VTLCGD system achieves a maximum vibration reduction of 52.63 % in acceleration response on the cantilevered floor compared to the uncontrolled case. Moreover, the variation in stiffness due to changes in the sealing condition is presented to validate the damper's adaptability over a wide frequency range.</div></div>","PeriodicalId":15064,"journal":{"name":"Journal of building engineering","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142446898","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-10DOI: 10.1016/j.jobe.2024.111000
<div><div>The substitution of Ba<sup>2+</sup> for Ca<sup>2+</sup> in both dicalcium silicate (C<sub>2</sub>S) and ye'elimite (C<sub>4</sub>A<sub>3</sub>$) has the potential to stimulate the development of early hydration activity of high belite sulfoaluminate cement (HBSAC). To relieve the emission pressure of CO<sub>2</sub> in the cement industry and promote the early compressive strength development of HBSAC, the C<sub>2</sub>S-C<sub>4</sub>A<sub>3</sub>$ binary system with different amounts of Ba<sup>2+</sup> substitution for Ca<sup>2+</sup> was synthesized and investigated in this study. The SEM-EDS and XRD test methods confirmed the stoichiometric composition of Ba-bearing C<sub>2</sub>S-C<sub>4</sub>A<sub>3</sub>$ binary systems. The results showed that Ba<sup>2+</sup> tends to preferentially replace Ca<sup>2+</sup> in C<sub>4</sub>A<sub>3</sub>$ compared to replacing Ca<sup>2+</sup> in C<sub>2</sub>S, resulting in more substitution amount of Ba<sup>2+</sup> in C<sub>4</sub>A<sub>3</sub>$ mineral, as the designed substitution amount of barium increased from 25 wt.% to 55 wt.%, the stoichiometric formula of Ba-bearing C<sub>2</sub>S was transformed from Ca<sub>1.66</sub>Ba<sub>0.34</sub>SiO<sub>4</sub> to Ca<sub>1.45</sub>Ba<sub>0.55</sub>SiO<sub>4</sub>, and the stoichiometric formula of Ba-bearing C<sub>4</sub>A<sub>3</sub>$ was transformed from Ca<sub>2.29</sub>Ba<sub>1.71</sub>Al<sub>6</sub>SO<sub>16</sub> to Ca<sub>0.86</sub>Ba<sub>3.14</sub>Al<sub>6</sub>SO<sub>16</sub>. While excessive amount of barium (more than 45 wt.%) resulted in the increased content of by-products, such as BaSO<sub>4</sub> and BaAl<sub>2</sub>O<sub>4</sub>, as well as the formation of C<sub>3</sub>S. The hydration properties of each group of synthetic clinker were investigated, including compressive strength, qualitative and quantitative analyses of the hydration products, leaching solution environment, and micromorphological analysis. The hydration products including C-(A)-S-H and AH<sub>3</sub>, as well as hydroxide (Ca(OH)<sub>2</sub> and Ba(OH)<sub>2</sub>·8H<sub>2</sub>O), which can be carbonated to form carbonates (BaCO<sub>3</sub> and CaCO<sub>3</sub>) by CO<sub>2</sub> in the air. As the substitution amount of Ba<sup>2+</sup> increased from 25 wt. % to 35 wt. %, the hydration degree of Ba-bearing α′<sub>L</sub>-C<sub>2</sub>S was promoted in the early stage, and the presence of C<sub>3</sub>S may affected the increase of early hydration activity of Ba-bearing α′<sub>L</sub>-C<sub>2</sub>S, however, the hydration degree of α′<sub>L</sub>-C<sub>2</sub>S with the most amount doping of barium in A055 samples exhibited the highest hydration degree of 88.0 % after hydration for 90 days. The compressive strength of high belite C<sub>2</sub>S-C<sub>4</sub>A<sub>3</sub>$ binary system of 3-day displayed a rapid increase from 8.6 MPa to 16.1 MPa, with the amount of barium increased from 25 wt. % to 55 wt. %. The compressive strength of A025 and A035 after hydratio
{"title":"Effect of different amounts of barium substitution for calcium on the hydraulic activity of the high belite binary C2S-C4A3$ system","authors":"","doi":"10.1016/j.jobe.2024.111000","DOIUrl":"10.1016/j.jobe.2024.111000","url":null,"abstract":"<div><div>The substitution of Ba<sup>2+</sup> for Ca<sup>2+</sup> in both dicalcium silicate (C<sub>2</sub>S) and ye'elimite (C<sub>4</sub>A<sub>3</sub>$) has the potential to stimulate the development of early hydration activity of high belite sulfoaluminate cement (HBSAC). To relieve the emission pressure of CO<sub>2</sub> in the cement industry and promote the early compressive strength development of HBSAC, the C<sub>2</sub>S-C<sub>4</sub>A<sub>3</sub>$ binary system with different amounts of Ba<sup>2+</sup> substitution for Ca<sup>2+</sup> was synthesized and investigated in this study. The SEM-EDS and XRD test methods confirmed the stoichiometric composition of Ba-bearing C<sub>2</sub>S-C<sub>4</sub>A<sub>3</sub>$ binary systems. The results showed that Ba<sup>2+</sup> tends to preferentially replace Ca<sup>2+</sup> in C<sub>4</sub>A<sub>3</sub>$ compared to replacing Ca<sup>2+</sup> in C<sub>2</sub>S, resulting in more substitution amount of Ba<sup>2+</sup> in C<sub>4</sub>A<sub>3</sub>$ mineral, as the designed substitution amount of barium increased from 25 wt.% to 55 wt.%, the stoichiometric formula of Ba-bearing C<sub>2</sub>S was transformed from Ca<sub>1.66</sub>Ba<sub>0.34</sub>SiO<sub>4</sub> to Ca<sub>1.45</sub>Ba<sub>0.55</sub>SiO<sub>4</sub>, and the stoichiometric formula of Ba-bearing C<sub>4</sub>A<sub>3</sub>$ was transformed from Ca<sub>2.29</sub>Ba<sub>1.71</sub>Al<sub>6</sub>SO<sub>16</sub> to Ca<sub>0.86</sub>Ba<sub>3.14</sub>Al<sub>6</sub>SO<sub>16</sub>. While excessive amount of barium (more than 45 wt.%) resulted in the increased content of by-products, such as BaSO<sub>4</sub> and BaAl<sub>2</sub>O<sub>4</sub>, as well as the formation of C<sub>3</sub>S. The hydration properties of each group of synthetic clinker were investigated, including compressive strength, qualitative and quantitative analyses of the hydration products, leaching solution environment, and micromorphological analysis. The hydration products including C-(A)-S-H and AH<sub>3</sub>, as well as hydroxide (Ca(OH)<sub>2</sub> and Ba(OH)<sub>2</sub>·8H<sub>2</sub>O), which can be carbonated to form carbonates (BaCO<sub>3</sub> and CaCO<sub>3</sub>) by CO<sub>2</sub> in the air. As the substitution amount of Ba<sup>2+</sup> increased from 25 wt. % to 35 wt. %, the hydration degree of Ba-bearing α′<sub>L</sub>-C<sub>2</sub>S was promoted in the early stage, and the presence of C<sub>3</sub>S may affected the increase of early hydration activity of Ba-bearing α′<sub>L</sub>-C<sub>2</sub>S, however, the hydration degree of α′<sub>L</sub>-C<sub>2</sub>S with the most amount doping of barium in A055 samples exhibited the highest hydration degree of 88.0 % after hydration for 90 days. The compressive strength of high belite C<sub>2</sub>S-C<sub>4</sub>A<sub>3</sub>$ binary system of 3-day displayed a rapid increase from 8.6 MPa to 16.1 MPa, with the amount of barium increased from 25 wt. % to 55 wt. %. The compressive strength of A025 and A035 after hydratio","PeriodicalId":15064,"journal":{"name":"Journal of building engineering","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142441682","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-10DOI: 10.1016/j.jobe.2024.110953
This study applies Particle Swarm Optimization (PSO) to enhance the energy efficiency of a multi-chiller system in a large office building, with a focus on optimizing capacity configuration and load distribution. Given the rising demand for sustainable energy solutions in buildings, where HVAC systems, particularly chillers, account for a significant portion of energy consumption, this research aims to reduce energy use and improve system performance. EnergyPlus simulations, based on Baltimore weather data and a reference large office model, were conducted to build a baseline dataset. This dataset was then used in Python to calculate energy consumption and optimize load distribution and capacity configuration. PSO was applied in three stages: optimizing capacity configuration using five built-in EnergyPlus algorithms, optimizing load distribution, and simultaneously optimizing both. The results showed that optimizing capacity configuration alone improved performance, even using traditional load distribution methods. Load distribution optimization outperformed other algorithms and converged at a 0.7 Part Load Ratio (PLR) for staging. The integrated PSO application achieved an 11.3 % reduction in energy consumption, a 21.5 % improvement in Coefficient of Performance (COP), and a 12.8 % increase in the Seasonal Energy Efficiency Ratio (SEER) by precise operation of 15 different combinations throughout the entire load range. These results demonstrate the potential of PSO to significantly enhance the efficiency of multi-chiller systems, providing a novel approach to optimizing both capacity configuration and load distribution. This research contributes to a robust framework for improving energy performance in building systems and offers valuable insights for future sustainable energy solutions.
{"title":"Particle Swarm Optimization for multi-chiller system: Capacity configuration and load distribution","authors":"","doi":"10.1016/j.jobe.2024.110953","DOIUrl":"10.1016/j.jobe.2024.110953","url":null,"abstract":"<div><div>This study applies Particle Swarm Optimization (PSO) to enhance the energy efficiency of a multi-chiller system in a large office building, with a focus on optimizing capacity configuration and load distribution. Given the rising demand for sustainable energy solutions in buildings, where HVAC systems, particularly chillers, account for a significant portion of energy consumption, this research aims to reduce energy use and improve system performance. EnergyPlus simulations, based on Baltimore weather data and a reference large office model, were conducted to build a baseline dataset. This dataset was then used in Python to calculate energy consumption and optimize load distribution and capacity configuration. PSO was applied in three stages: optimizing capacity configuration using five built-in EnergyPlus algorithms, optimizing load distribution, and simultaneously optimizing both. The results showed that optimizing capacity configuration alone improved performance, even using traditional load distribution methods. Load distribution optimization outperformed other algorithms and converged at a 0.7 Part Load Ratio (PLR) for staging. The integrated PSO application achieved an 11.3 % reduction in energy consumption, a 21.5 % improvement in Coefficient of Performance (COP), and a 12.8 % increase in the Seasonal Energy Efficiency Ratio (SEER) by precise operation of 15 different combinations throughout the entire load range. These results demonstrate the potential of PSO to significantly enhance the efficiency of multi-chiller systems, providing a novel approach to optimizing both capacity configuration and load distribution. This research contributes to a robust framework for improving energy performance in building systems and offers valuable insights for future sustainable energy solutions.</div></div>","PeriodicalId":15064,"journal":{"name":"Journal of building engineering","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142446894","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-10DOI: 10.1016/j.jobe.2024.111013
Bamboo scrimber, as a renewable and sustainable material engineered from bamboo, is inevitably subjected to impact loadings in engineering applications. To study the dynamic behaviour and failure mechanism of bamboo scrimber panels under low-velocity impact, a series of drop hammer impact tests were conducted on 36 panels. The peak force, deformation and energy absorption of bamboo scrimber panels were obtained and analysed. The influence of impact energy, impactor shape and impact angle on the dynamic behaviour of panels was quantitatively characterised. Besides, based on test observations and microscopic views, the failure mechanism of bamboo scrimber panels under different impact types was revealed, including the energy absorption mechanism through fibre fracture, fibre debonding, fibre pull-out and matrix failure. Test results showed that with increasing impact energy, the peak force of panels impacted by the spherical and flat impactors increased, while that of panels impacted by the wedge impactor did not vary significantly. The deformation and energy absorption of panels also increased with increasing impact energy. Notably, the impactor shape obviously influenced the dynamic behaviour of panels, causing a higher peak force of panels impacted by the flat impactor and a larger deformation of panels impacted by the wedge impactor. The failure mechanism of panels depended highly on the impact energy and the impactor shape. Finally, a comparative study of single versus repeated impacts revealed that the deformation of bamboo scrimber panels under repeated impacts was less than that of panels under a single impact when the same amount of energy was imposed to the panel. This study provided a basis for the use of bamboo scrimber to resist impact loadings.
{"title":"Dynamic behaviour and failure mechanism of bamboo scrimber panels under single and repeated impacts: Experimental tests","authors":"","doi":"10.1016/j.jobe.2024.111013","DOIUrl":"10.1016/j.jobe.2024.111013","url":null,"abstract":"<div><div>Bamboo scrimber, as a renewable and sustainable material engineered from bamboo, is inevitably subjected to impact loadings in engineering applications. To study the dynamic behaviour and failure mechanism of bamboo scrimber panels under low-velocity impact, a series of drop hammer impact tests were conducted on 36 panels. The peak force, deformation and energy absorption of bamboo scrimber panels were obtained and analysed. The influence of impact energy, impactor shape and impact angle on the dynamic behaviour of panels was quantitatively characterised. Besides, based on test observations and microscopic views, the failure mechanism of bamboo scrimber panels under different impact types was revealed, including the energy absorption mechanism through fibre fracture, fibre debonding, fibre pull-out and matrix failure. Test results showed that with increasing impact energy, the peak force of panels impacted by the spherical and flat impactors increased, while that of panels impacted by the wedge impactor did not vary significantly. The deformation and energy absorption of panels also increased with increasing impact energy. Notably, the impactor shape obviously influenced the dynamic behaviour of panels, causing a higher peak force of panels impacted by the flat impactor and a larger deformation of panels impacted by the wedge impactor. The failure mechanism of panels depended highly on the impact energy and the impactor shape. Finally, a comparative study of single versus repeated impacts revealed that the deformation of bamboo scrimber panels under repeated impacts was less than that of panels under a single impact when the same amount of energy was imposed to the panel. This study provided a basis for the use of bamboo scrimber to resist impact loadings.</div></div>","PeriodicalId":15064,"journal":{"name":"Journal of building engineering","volume":null,"pages":null},"PeriodicalIF":6.7,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142441674","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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