المؤلفون: Freegah, Basim¹ (AUTHOR) basim.freegah@uomustansiriyah.edu.iq, Alhamdo, Mohammed Hamed¹ (AUTHOR) profmohamedh@uomustansiriyah.edu.iq, Falih, Abeer H.² (AUTHOR) abeerhashim@uomustansiriyah.edu.iq

المصدر: AIP Conference Proceedings. 2024, Vol. 3002 Issue 1, p1-13. 13p.

مصطلحات موضوعية: *RADIANT heating, *CONSTRUCTION slabs, *COMPUTATIONAL fluid dynamics, *WATER temperature, *HUMAN comfort, *TEMPERATURE effect, *HIGH temperatures

مستخلص: Radiant cooling-heating systems can be used to air-condition space in regions that are characterized by a high difference in temperature throughout the day. The principle of work of such systems is to reduce the thermal loads by using tubes inside the walls and the ceilings and passing through these tubes cooling or heating fluids. The effects of the temperature supply of the water and the pipe's diameter within the walls were investigated in the current study using computational fluid dynamics (CFD) analysis. The range of temperature supply used in the current study is (277K to 287K), while the range of pipe's diameter under study is (0.0127m to 0.0381m). The results showed that both the inlet temperature and the diameter of the pipe have a significant impact on the air-conditioned space. However, the inlet temperature of water has more effect on the air-condition space as compared to the diameter of the pipe. Furthermore, the results showed that the inner wall temperature decreased by 23.4% compared with the supply temperature, while the pipe diameter decreased by 18.32% in comparison with the traditional model (wall without pipes). In addition, an equation to predict the temperature of the air-conditioned space has been developed with about 89% accuracy. This equation is a function of temperature of the water, the pipe's diameter, and the wall thickness. Finally, it can be concluded that such systems can be used in an air-conditioned space to achieve human comfort. [ABSTRACT FROM AUTHOR]

المؤلفون: Cheng, Kai, Wu, Peng, Hu, Wenbo, Wu, Lifan, Guo, Xu, Guo, Sandong, Su, Yan

المصدر: Journal of Applied Physics; 5/28/2024, Vol. 135 Issue 20, p1-8, 8p

مصطلحات موضوعية: BINDING energy, ELECTRON traps, ENERGY bands, CONSTRUCTION slabs, SUBSTRATES (Materials science), HETEROSTRUCTURES

مستخلص: Loading of WS2 can greatly improve water splitting H2 generation efficiency of CdS in experiments. Here, we constructed WS2/CdS(100) and WS2/CdS(110) heterostructures with smaller mismatches and explored their interaction energy and band offset by first-principles calculations. Our calculation suggests that the WS2/CdS(100) interface with a stronger binding energy is more active in experiments, while the WS2/CdS(110) interface is metastable. The band alignment between CdS and WS2 is highly dependent on the orientation of the interfaces, and WS2/CdS(100) and WS2/CdS(110) belong to type-I and type-II band alignments, respectively. Therefore, a metal electrode and hole scavenger may be essential in experiments to help WS2/CdS(100) efficiently trap electrons, and a suitable substrate and an appropriate growth temperature are also needed to composite the CdS(110) surface to achieve a higher photocatalytic efficiency. In addition, we performed a detailed analysis of the macroscopic average potential and found that the calculated accuracy of potential difference across the heterostructures due to slab thickness is less than 80 meV at WS2/CdS interfaces. In total, our calculations not only explain the physical reasons for the increased efficiency of WS2/CdS, but also provide a detailed guideline for the design of a more efficient synergistic catalyst. [ABSTRACT FROM AUTHOR]

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المؤلفون: Su, Hang^1,2,3 (AUTHOR), Su, Qingtian^1,4 (AUTHOR), Casas, Joan R.² (AUTHOR) joan.ramon.casas@upc.edu, Wu, Huayong⁵ (AUTHOR), Liu, An⁶ (AUTHOR), Chen, Zhiquan⁷ (AUTHOR)

المصدر: Structure & Infrastructure Engineering: Maintenance, Management, Life-Cycle Design & Performance. Jul/Aug2024, Vol. 20 Issue 7/8, p1197-1212. 16p.

مصطلحات موضوعية: *STEEL-concrete composites, *CONSTRUCTION slabs, *COMPOSITE construction, *STRAIN gages, *FINITE element method, *TRAFFIC safety

مصطلحات جغرافية: CHINA

مستخلص: The project case of Qiwu Bridge using link slab action between simply supported composite spans is introduced. The 60 m-span girder of Qiwu Bridge is the longest and heaviest among the composite girders erected by bridge-erecting machine in China. Qiwu Bridge consists of a series of 3 simply supported spans built with composite girders and connected at the pier supports by a link slab. This solution has both advantages of (1) smooth driving condition and enhancement of durability by removing expansion joints and (2) clear structural behavior as simply supported spans. A finite element model was established to simulate and predict the mechanical response of this semi-continuous solution. Numerical results showed that the removal of the shear connection around the link slab decreased the stress level but also caused a stress mutation. Qiwu Bridge was also monitored by vibrating wire strain gages to follow its actual structural response. From preliminary monitoring data and numerical results, it can be concluded that the proposed construction method and the static scheme is safe for the 60-span composite girder with a large safety margin. Further experimental results will be obtained during the service stage of the bridge to validate the in-service performance of the proposed steel-concrete composite bridge with link slab. [ABSTRACT FROM AUTHOR]

المؤلفون: Ren, Juanjuan^1,2 (AUTHOR) jj.ren@home.swjtu.edu.cm, Qu, Changheng^1,2 (AUTHOR), Liang, Jie^1,2 (AUTHOR), Zhang, Peng³ (AUTHOR), Zhang, Kaiyao^1,2 (AUTHOR), Deng, Shijie^1,2 (AUTHOR)

المصدر: Archives of Civil & Mechanical Engineering (Elsevier Science). Jul2024, Vol. 24 Issue 3, p1-19. 19p.

مصطلحات موضوعية: *CONSTRUCTION slabs, *EXTREME weather, *DEBYE temperatures, *COLD (Temperature), *SOLAR radiation, *SUBDUCTION zones, *COLD adaptation, COLD regions

مستخلص: A long-term monitoring experiment was conducted to investigate the spatial and temporal variation rule of the slab track temperature in cold regions using statistical analysis methods. The sensitivity of track temperature to meteorological factors was analyzed using the finite element method. The study found that temperature, solar radiation intensity, and full-section temperature of the track structure exhibit a reciprocal change with a daily cycle. Additionally, the temperature change of each structural layer lags with increasing depth. The measured data showed that the maximum positive and negative temperature gradient of the track slab exceeded the standard design value (90 °C/m, − 45 °C/m), suggesting that the design value of positive and negative temperature gradient in cold regions should be 95 °C/m and − 55 °C/m, respectively. Furthermore, the finite element model analysis indicated that the overall temperature of the track slab is strongly influenced by the daily average temperature, the solar radiation intensity, and the wind speed, while the temperature gradient of the track slab is strongly influenced by the daily temperature amplitude and solar radiation intensity. The maximum positive temperature gradient warning value of the track slab under extreme high-temperature weather was found to be 100 °C/m. These findings can provide valuable insights for the optimization design and temperature effect research of CRTS III prefabricated slab tracks in cold regions. [ABSTRACT FROM AUTHOR]

المؤلفون: Vinutha, D.¹ (AUTHOR), Vidjeapriya, R.¹ (AUTHOR) vidjeapriya@annauniv.edu, Jaya, K. P.¹ (AUTHOR)

المصدر: Archives of Civil & Mechanical Engineering (Elsevier Science). Jul2024, Vol. 24 Issue 3, p1-25. 25p.

مصطلحات موضوعية: *CONSTRUCTION slabs, *STEEL framing, *CONCRETE joints, *TRANSVERSE reinforcements, *CYCLIC loads, *CONCRETE slabs, *ENERGY dissipation

مصطلحات جغرافية: NEW Zealand

مستخلص: This study evaluates the cyclic response of the Precast Hollow Core Slab (PHCS) to the beam connection by proposing a novel connection detail. The evaluation involved, three different connection details, namely, (1) Continuity rebar and U-type Core Rebar Discrete with 100 mm ledge width (CUCRD_100); (2) continuity rebar and Core Rebar Combined with 100 mm ledge width (CCRC_100); and (3) continuity rebar and Core Rebar Combined with Ties along with 100 mm ledge width (CCRCT_100) were experimentally validated. These were validated through experimental testing, comparing their performance with a reference specimen that adhered to New Zealand guidelines using Continuity rebar and Core Rebar Discrete with 100 mm ledge width (CCRD_100). Displacement controlled reverse cyclic loading, following the ACI T1.1–0.1 protocol, was applied to the end of a hollow core slab for the experimental testing. The structural performance of all four connections considered failure pattern, strength, hysteretic behaviour, energy dissipation, displacement ductility, stiffness degradation, and equivalent viscous damping. The overall seismic efficiency of the connections was assessed using ACI 374.1–05 approval criteria. The experimental results proved that the peak load-carrying capacity for CCRCT_100 specimen was observed to be greater in both directions of loading (positive and negative) when compared with the other connection detailing. The presence of transverse reinforcement enhanced the confining capacity of the concrete in the joint region which substantially increased the ductility and dissipation of energy in CCRCT_100 specimen. The seismic performance of every connection specimen was favourable, and they all met the ACI 374.1–05 approval standards. [ABSTRACT FROM AUTHOR]

المؤلفون: Liu, Daiwei^1,2 (AUTHOR) liudaiwei158@163.com, Zhang, Guifang¹ (AUTHOR) guifangzhang65@163.com, Zeng, Jianhua³ (AUTHOR) zengjianhua68@163.com, Xie, Xin³ (AUTHOR) xiexin@alu.cqu.edu.cn

المصدر: Materials (1996-1944). Jun2024, Vol. 17 Issue 11, p2721. 16p.

مصطلحات موضوعية: *CONSTRUCTION slabs, *CONTINUOUS casting, *COMPUTER simulation, *MASS transfer, *THREE-dimensional modeling, *SOLIDIFICATION, *CONCRETE slabs

مستخلص: Secondary cooling electromagnetic stirring (S-EMS) significantly impacts the internal quality of continuous casting slabs. In order to investigate the effects of S-EMS modes on segregation in slabs, a three-dimensional numerical model of the full-scale flow field, solidification, and mass transfer was established. A comparative analysis was conducted between continuous electromagnetic stirring and alternate stirring modes regarding their impacts on steel flow, solidification, and carbon segregation. The results indicated that adopting the alternate stirring mode was more advantageous for achieving uniform flow fields and reducing the disparity in solidification endpoints, thus mitigating carbon segregation. Specifically, the central carbon segregation index under continuous stirring at 320 A was 1.236, with an average of 1.247, while under alternate stirring, the central carbon segregation index decreased to 1.222 with an average of 1.227. [ABSTRACT FROM AUTHOR]

المؤلفون: Cheng, Mai-Li¹ (AUTHOR) 13619526551@163.com, Hu, Guo-Zhuang¹ (AUTHOR), Wang, Hong-Qi² (AUTHOR) wanghongqi001@126.com

المصدر: Materials (1996-1944). Jun2024, Vol. 17 Issue 11, p2591. 15p.

مصطلحات موضوعية: *SANDWICH construction (Materials), *CONSTRUCTION slabs, *STRAINS & stresses (Mechanics), *BENDING stresses, *STRESS concentration

مستخلص: In order to explore the flexural behavior of a concrete sandwich panel under concentrated boundary conditions, based on Kirachhoff's elastic thin plate theory in this paper, the geometric deformation, physical conditions, and equilibrium relationship of a sandwich panel are deduced by constructing the layered analysis model of the sandwich panel, the basic differential equation of the flexural deformation of the concrete sandwich thin plate is obtained, and the mathematical expression of the internal force and displacement under the boundary condition of concentrated support is given. Combined with an engineering example, the proposed calculation method is verified. The results show that, in the arrangement of reliable connectors for concrete sandwich panels, the concrete wythes bear the load while the contribution of the core layer to the bending capacity of the structure can be ignored. When subjected to a laterally distributed load, the sandwich panel mainly experiences out-of-plane bending deformation, and the bending normal stress in the concrete panel layer shows a linear non-uniform distribution along the thickness direction of the panel. The bending deformation performance and bearing efficiency of a concrete sandwich slab with the change in concentrated support position have significant effects, and the load transfer efficiency can be improved by optimizing the arrangement of supports. Except for small local areas near the supports, the bending stress distribution and deformation behavior of the concrete sandwich panel can be accurately analyzed by the calculation method established in this paper. [ABSTRACT FROM AUTHOR]

المؤلفون: Heckmann, Michael¹ (AUTHOR) michael.heckmann@rptu.de, Dernbach, Aaron¹ (AUTHOR) aaron.dernbach@rptu.de, Müller, Rebecca¹ (AUTHOR) rebecca.mueller@rptu.de, Glock, Christian¹ (AUTHOR) christian.glock@rptu.de

المصدر: Beton- Und Stahlbetonbau. Jun2024, Vol. 119 Issue 6, p410-419. 10p.

مصطلحات موضوعية: *CONSTRUCTION slabs, *CONCRETE slabs, *PRECAST concrete, *REINFORCED concrete, *DECONSTRUCTION, *MANUFACTURING industries

الملخص (بالإنجليزية): Investigations on deconstruction and reuse of prestressed hollow core slabs Prestressed hollow core slabs as precast elements show potential for efficient reuse in terms of circularity. Within this article, the results of a research project evaluating suitability for deconstruction and reusability of prestressed hollow core slabs are shown. For this purpose, comparative experimental studies were conducted on deconstructed slabs, having been subjected to defined loads, as well as not previously loaded slabs. By erecting a sample ceiling, the prestressed hollow core slabs were loaded for 69 d. The main challenge in deconstructing the ceiling appeared to be loosening the conventionally grouted longitudinal joints between the elements without damage. Alternatively considered design variants of the joints indicate the suitability to easily improve deconstruction. In 4‐point flexural tests deconstructed as well as non‐preloaded prestressed hollow core slabs displayed a uniform pattern of failure. However, the failure of deconstructed, previously loaded hollow core slabs occurred under lower loads and with less deflection. The fact that all elements exceeded the manufacturer's specifications for bending load‐bearing capacity nevertheless supports the assumption of a high reuse potential of prestressed hollow core slabs. [ABSTRACT FROM AUTHOR]

Abstract (German): Spannbetonhohldielen weisen als Fertigteile Potenzial zur effizienten Bauteilwiederverwendung im Sinne der Kreislaufwirtschaft auf. Im Rahmen dieses Beitrags werden die Ergebnisse eines Forschungsprojekts zur Evaluierung der Rückbau‐ und Wiederverwendbarkeit von Spannbetonhohldielen vorgestellt. Hierzu wurden vergleichende experimentelle Untersuchungen an zuvor unbelasteten als auch definiert belasteten rückgebauten Spannbetonhohldielen durchgeführt. Die Belastung erfolgte über 69 d an einer eigens errichteten Musterdeckenfläche. Bei deren Rückbau stellte sich das nicht beschädigungsfrei mögliche Trennen der konventionell vergossenen Deckenlängsfugen als wesentliche Herausforderung dar. Alternativ betrachtete Ausführungsvarianten der Längsfugen weisen auf einfache Maßnahmen zur Verbesserung der Rückbaubarkeit hin. In 4‐Punkt‐Biegeversuchen zeigten sowohl vorbelastete rückgebaute als auch nicht vorbelastete Spannbetonhohldielen ein einheitliches Versagensbild. Die vorbelasteten und rückgebauten Hohldielen versagten jedoch unter geringeren Lasten bei kleineren Durchbiegungen. Die Tatsache, dass sämtliche Elemente die Herstellerangaben zur Biegetragfähigkeit überschritten, stützt dennoch die Annahme eines hohen Wiederverwendungspotenzials von Spannbetonhohldielen. [ABSTRACT FROM AUTHOR]

المؤلفون: Kotsovos, Gerasimos¹ (AUTHOR), Vougioukas, Emmanouil² (AUTHOR), Kotsovos, Michael D.³ (AUTHOR) mkotsov@central.ntua.gr

المصدر: Proceedings of the Institution of Civil Engineers: Structures & Buildings. Jun2024, Vol. 177 Issue 6, p490-498. 9p.

مصطلحات موضوعية: *STEEL corrosion, *CONSTRUCTION slabs, *TEST validity, *REINFORCEMENT learning, *REINFORCED concrete, *BUILDING failures

مستخلص: Between 1997 and 2010, there was a small, yet unexpected, number of flat-slab car park buildings that collapsed under service loading. In all the cases, the collapse was preceded by loss of bond (LoB) between the concrete and flexural reinforcement. All investigations of the causes of these collapses have since been inconclusive, particularly as regards the effect of LoB. Yet, LoB due to yielding of the flexural reinforcement in tension had already been proposed as the main cause of punching, and failure criteria derived on the basis of this proposal were found to produce predictions that correlated closely with experimentally established values of the punching failure load. The aim of the present work was to extend the range of application of these criteria to the case of LoB due to steel corrosion and test their validity against the available information on the car park building collapses. [ABSTRACT FROM AUTHOR]

المؤلفون: Kanchanadevi, A¹ (AUTHOR) kanchana@serc.res.in, Ramanjaneyulu, K^2,3 (AUTHOR), Gandhi, P³ (AUTHOR)

المصدر: Sādhanā: Academy Proceedings in Engineering Sciences. Jun2024, Vol. 49 Issue 2, p1-16. 16p.

مصطلحات موضوعية: *CONSTRUCTION slabs, *SHEAR reinforcements, *CONCRETE slabs, *BRIDGE design & construction, *BUILDING design & construction, *DESIGN, *COHESION

مستخلص: Concrete composite slab system, comprised of two half-slabs connected integrally through shear connectors, has gained popularity due to fast-track construction of bridges and buildings. Flexural performance and level of composite action of composite slab system depend on its interface shear connection. In the present study, the behaviour of composite slab system with different levels of interface shear design is assessed through experimental and numerical investigations. From the investigations carried out on concrete composite slabs, it is clearly identified that the interface cohesion is an important parameter which contributes to the stiffness of the system. It is also observed that the concrete composite slabs showed load-displacement response similar to that of control full slab, irrespective of the number shear connectors provided, when the cohesion mobilised is sufficient to cater to the shear demand. It is also observed that in the absence of contribution from interface cohesion, full composite action cannot be achieved even when full shear connection design is provided based on shear friction alone. Furthermore, in the absence of the interface shear reinforcement, the displacement sustained by the composite slab is much lower and failed at lower ultimate displacement compared to that of the control full slab. [ABSTRACT FROM AUTHOR]