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Determination of Subgrade Reaction Coefficients and Spring Stiffnesses for a Combined Pile Raft Foundation (CPRF) by Means of a Cluster Analysis 基于聚类分析的组合桩筏基础地基反力系数和弹簧刚度的确定
IF 0.4 Pub Date : 2021-06-01 DOI: 10.2478/sjce-2021-0010
Szilárd Kanizsár
Abstract An analysis of combined piled raft foundations could be performed by means of a special geotechnical finite element software that utilizes 3D modeling and advanced constitutive models for the soil. However, a foundation is generally included in the structural models in a structural design program. The least advanced part of finite element software that has been developed for structural FEM modeling are the tools used for modeling behaviour. A method is required with which the input parameters of the structural design software that are used for modeling the soil structure interaction as well could be determined so that the results calculated by means of a geo-technical software that approximates realistic soil behaviour the best can be reproduced by structural design software as well. The procedure outlined in this paper by means of a cluster analysis provides a tool for a substantial and innovative improvement in subsoil modeling, to which not enough attention is generally paid in the structural FEM software, thereby resulting in a reduced amount of work associated with the task of inputting data.
摘要:利用三维建模和先进的土本构模型的特殊岩土有限元软件,可以对组合桩筏基础进行分析。然而,在结构设计方案中,基础通常包含在结构模型中。已经开发的用于结构有限元建模的有限元软件中最不先进的部分是用于建模行为的工具。需要一种方法来确定用于模拟土壤结构相互作用的结构设计软件的输入参数,以便通过最接近实际土壤行为的岩土技术软件计算出的结果也可以由结构设计软件复制。本文通过聚类分析概述的过程为地基建模提供了一个实质性的创新改进工具,这在结构有限元软件中通常没有得到足够的重视,从而减少了与输入数据任务相关的工作量。
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引用次数: 0
Aerodynamic Study of the Wind Flow in the Area of the R2 Expressway in Slovakia 斯洛伐克R2高速公路区域气流的空气动力学研究
IF 0.4 Pub Date : 2021-06-01 DOI: 10.2478/sjce-2021-0014
O. Hubová, M. Macák, Alžbeta Grmanová
Abstract Our calculation of wind effects was based on the specific wind situation of the planned R2 expressway. Given the topography and the prevailing wind directions, it was necessary to analyse the speeds for winds that could cause vehicles with trailers to be pushed off the roadway, as has been observed in recent years. Using a CFD simulation in the ANSYS FLUENT program, we analysed the entire section of the planned R2 expressway in order to evaluate the wind speeds at the level of the centre of gravity of truck trailers. Statistical turbulence models based on a time-averaging method, i.e., the RANS-Reynolds Averaged Navier-Stokes equations, of turbulent flow quantities and the time-averaging procedure of balance equations are suitable for solving the engineering tasks. In numerical simulations, the Realizable k - ε model was used in which the calculation of the turbulent dynamic viscosity in the equation for Boussinesque’s hypothesis was solved using two transport equations. Plotting and comparing the wind speeds for significant wind directions allowed us to design protection in the dangerous areas using protective walls.
摘要我们的风效应计算是基于规划的R2高速公路的具体风况。鉴于地形和主要风向,有必要分析可能导致带拖车的车辆被推离道路的风速,正如近年来观察到的那样。使用ANSYS FLUENT程序中的CFD模拟,我们分析了计划中的R2高速公路的整个路段,以评估卡车拖车重心水平的风速。基于时间平均法(即RANS Reynolds Averaged Navier-Stokes方程)的湍流统计模型和平衡方程的时间平均程序适用于解决工程任务。在数值模拟中,使用了可实现的k-ε模型,其中使用两个输运方程求解Boussinsque假设方程中湍流动态粘度的计算。绘制和比较重要风向的风速,使我们能够在危险区域使用防护墙进行防护设计。
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引用次数: 0
Non-Hydrostatic Transitional Open-Channel Flows from a Supercritical to a Subcritical State 从超临界状态到亚临界状态的非静水过渡明渠流
IF 0.4 Pub Date : 2021-06-01 DOI: 10.2478/sjce-2021-0012
Y. Zerihun
Abstract In this study, a depth-averaged numerical model was employed to investigate the two-dimensional flow features of transitional open-channel flows from a supercritical to a subcritical state. Compared to a shallow-water model, the proposed model incorporates supplementary terms to account for the effects of non-uniform velocity and non-hydrostatic pressure distributions. The model equation was solved numerically by means of the Adams–Bashforth–Moulton scheme. A wide variety of transitional open-channel flow problems such as hydraulic jumps was considered for assessing the suitability of the numerical model. The results of the model for the free-surface profile, pressure distribution, and characteristics of the first wave of an undular jump were compared with the experimental data, and the agreement was found to be satisfactory. Despite the effects of the three-dimensional characteristics of the flow and the bulking of the flow caused by air entrainment, the model performed reasonably well with respect to the simulations of the mean flow characteristics of the curvilinear turbulent flow problems. Furthermore, the results of this investigation confirmed that the model is more suitable for analyzing near-critical turbulent flow problems without cross-channel shock waves.
摘要在本研究中,采用深度平均数值模型研究了明渠从超临界状态过渡到亚临界状态的二维流动特征。与浅水模型相比,所提出的模型包含了补充项,以考虑非均匀速度和非静水压力分布的影响。采用Adams–Bashforth–Moulton格式对模型方程进行了数值求解。为了评估数值模型的适用性,考虑了各种各样的过渡明渠流动问题,如水跃。将该模型的自由表面轮廓、压力分布和第一波波动特性的结果与实验数据进行了比较,结果令人满意。尽管存在流动的三维特性和空气夹带引起的流动膨胀的影响,但该模型在模拟曲线湍流问题的平均流动特性方面表现相当好。此外,研究结果证实,该模型更适合于分析没有跨通道冲击波的近临界湍流问题。
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引用次数: 1
Thermaly Active Interior Panels with an Integrated Active Area 具有集成活动区域的热活动内部面板
IF 0.4 Pub Date : 2021-03-01 DOI: 10.2478/sjce-2021-0007
D. Kalús, Mária Kurčová, Z. Straková, Matej Kubica
Abstract Panels with an integrated active area can be used for interior applications for walls, ceilings and floor heating, and alternatively as a wet or dry type of construction. At present, most panels with an integrated active area are made of gypsum boards with milled channels and embedded pipes. Some manufacturers already supply these panels with thermal insulation (Radwan et al., 2021; Zhang et al., 2020). Certain limitations, mainly regarding the diameter and material of the pipes, apply to the panels with channels milled in the gypsum board and embedded pipes. These limitations are closely related to the high cost of such panels and to the limited heat/cooling output. The disadvantages of these panels are eliminated by the construction of a thermal insulation panel with active thermal protection for application with an active heat transfer control system (indoor thermally active panel (ITAP)) in accordance with European Patent No. EP 2 572 057 B1 (Kalús, 2011).
具有集成活动区域的面板可用于墙壁,天花板和地板供暖的室内应用,也可作为湿式或干式建筑。目前,大多数具有集成活动区的面板都是由石膏板制成的,带有铣槽和嵌入式管道。一些制造商已经为这些面板提供隔热材料(Radwan et al., 2021;Zhang等人,2020)。在石膏板上铣槽的面板和预埋管有一定的限制,主要是管材的直径和材质。这些限制与这种面板的高成本和有限的热/冷输出密切相关。根据欧洲专利号(ITAP),这些面板的缺点通过具有主动热保护的隔热面板的构造来消除,该隔热面板适用于主动传热控制系统(室内热活动面板(ITAP))。EP 2 572 057 B1 (Kalús, 2011)。
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引用次数: 0
Evaluation of the Cohesive Properties of SBS-Modified Binders at Low Temperatures sbs改性粘结剂的低温粘结性能评价
IF 0.4 Pub Date : 2021-03-01 DOI: 10.2478/sjce-2021-0005
B. Kök, Yunus Erkuş, M. Yılmaz
Abstract The durability, fatigue resistance, and low-temperature behavior of asphalt layers are greatly affected by the properties of bitumen. Therefore, the composition of bitumen is frequently modified to improve the performance of asphalt mixtures. Sty-rene-butadiene-styrene (SBS) has been the most often used additive recently. Researchers are trying to improve the cohesive and adhesive properties of binders by such polymer-based additives. In this study, 160/220 penetration grade bitumen and Kraton D 1101 SBS were used. The present study contains a new evaluation for determining the cohesive behavior of SBS-modified binders at -1°C, -3°C, and -5°C. The results of this evaluation were compared to conventional and rheological test results. Penetration, softening point, viscosity, dynamic shear rheometer, and bending beam rheometer tests were therefore conducted. Finally, the results of a low-temperature tensile test were found to be consistent with the results of the other tests; hence, they also confirm the cohesive behavior of SBS-modified binders at low temperatures.
摘要沥青的性能对沥青层的耐久性、抗疲劳性能和低温性能有很大的影响。因此,经常对沥青的成分进行改性,以改善沥青混合料的性能。丁烯苯乙烯(SBS)是近年来应用最广泛的添加剂。研究人员正试图通过这种聚合物基添加剂来改善粘合剂的内聚性和粘合性能。本研究采用160/220渗透级沥青和Kraton D 1101 SBS。本研究包含了一种新的评估,用于确定sbs改性粘合剂在-1°C, -3°C和-5°C下的内聚行为。该评价结果与常规和流变试验结果进行了比较。因此进行了渗透、软化点、粘度、动态剪切流变仪和弯曲梁流变仪试验。最后,发现低温拉伸试验的结果与其他试验的结果一致;因此,它们也证实了sbs改性粘合剂在低温下的内聚行为。
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引用次数: 2
Simulation Modelling of Aerial Works and Its Role in the Preparation of Construction 航空工程仿真建模及其在施工准备中的作用
IF 0.4 Pub Date : 2021-03-01 DOI: 10.2478/sjce-2021-0004
A. Bisták, Z. Hulínová, Michal Neštiak
Abstract The construction process is characterized by a diverse technological composition and the use of a wide range of construction machinery and mechanization. The amount of machinery increases with the complexity of the construction, which increases the demands concerning the preparation and overall organisation of the construction. The preparation of construction processes carried out by helicopters (aerial work) must respect the effect of randomly changing construction conditions as well as the specific working conditions of helicopters. The complexity of such a system can be modelled using simulation models. In the work presented, we designed and practically tested a simulation model of aerial work in the MATLAB software environment. An essential part of the simulation model is an algorithm designed on the basis of commercial numerical weather prediction models. We consider the outputs of the simulation to be reliable, because they are very close to the actual results achieved in the case of the implementation of construction of this type. The concept of the simulation model enables its wider use not only in the construction sector, but also in other branches of industry.
摘要施工过程的特点是技术组成多样化,使用范围广泛的施工机械和机械化。机械数量随着施工的复杂性而增加,这增加了对施工准备和整体组织的要求。直升机(高空作业)施工过程的准备必须考虑随机变化的施工条件以及直升机的具体工作条件的影响。这种系统的复杂性可以使用仿真模型来建模。在所介绍的工作中,我们在MATLAB软件环境中设计并实际测试了一个高空作业的仿真模型。模拟模型的一个重要部分是在商业数值天气预测模型的基础上设计的算法。我们认为模拟的输出是可靠的,因为它们非常接近在实施这种类型的构造的情况下所获得的实际结果。模拟模型的概念使其不仅在建筑行业,而且在其他行业中得到更广泛的应用。
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引用次数: 2
Sound Absorption Properties of Materials Based on Recycled Plastic Granule Mixtures 基于再生塑料颗粒混合物的材料吸声性能研究
IF 0.4 Pub Date : 2021-03-01 DOI: 10.2478/sjce-2021-0003
Andrea Biskupičová, M. Ledererová, S. Unčík, C. Glorieux, M. Rychtáriková
Abstract This article reports on impedance tube measurements of the sound absorption coefficient α (-) of selected recycled foam plastics, i.e., ethylene-vinyl acetate (EVA), polyvinyl chloride (PVC), polystyrene (PS), and polypropylene (PP), in different mixtures with a binding adhesive. The effect of the thickness of the sample on the sound absorption spectrum as well as the variability in absorption across the different samples of the same composition and thickness are discussed. For the EVA/ PP and PS/PP mixtures, the spectrum is characterized by two peaks that shift as the thickness is changing. These mixtures were also found to be the most absorbent across the whole audible frequency range.
摘要本文报道了用阻抗管测量再生泡沫塑料,即乙酸乙烯乙烯(EVA)、聚氯乙烯(PVC)、聚苯乙烯(PS)和聚丙烯(PP)在不同混合物中与粘合剂的吸声系数α(-)。讨论了样品厚度对声吸收光谱的影响,以及相同成分和厚度的不同样品的吸收变异性。对于EVA/ PP和PS/PP混合物,光谱的特征是两个峰随着厚度的变化而移动。这些混合物也被发现在整个可听频率范围内是最吸收的。
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引用次数: 5
Effects of Interference on Local Peak Pressures Between Two Buildings with an Elliptical Cross-Section 干涉对两个椭圆截面建筑物间局部峰值压力的影响
IF 0.4 Pub Date : 2021-03-01 DOI: 10.2478/sjce-2021-0006
M. Franek, M. Macák
Abstract The interference effects on the distribution of external wind pressure coefficient between two high-rise buildings with an elliptical cross section were studied experimentally at the Boundary Layer Wind Tunnel (BLWT) at the Faculty of Civil Engineering STU in Bratislava, Slovakia. Various arrangements of models, which were derived from the breadth ratio, were investigated. The peak value of the external wind pressure coefficient for a stand-alone model was measured and compared with the peak value in the case of interference. The measurements showed that the wind loads on buildings in a close vicinity are considerably different from those on a stand-alone building. The interference effects significantly affect negative pressure zones. The optimal and critical arrangements of buildings were evaluated. The elimination of peak negative external wind pressure coefficients can be reduced by half. On the other hand, the interference effects had a strong impact on increasing the peak value of the negative external wind pressure coefficient, which can be more than roughly double compared to an isolated building.
摘要在斯洛伐克布拉迪斯拉发STU土木工程学院边界层风洞(BLWT)试验研究了干扰对两栋椭圆形截面高层建筑外部风压系数分布的影响。研究了从宽度比导出的各种模型排列。测量了独立模型的外部风压系数的峰值,并与干扰情况下的峰值进行了比较。测量结果表明,附近建筑物的风荷载与独立建筑物的风载荷有很大不同。干扰效应显著影响负压区。对建筑物的最佳和关键布置进行了评估。峰值负外部风压系数的消除可以减少一半。另一方面,干扰效应对负外部风压系数峰值的增加有很大影响,与孤立建筑相比,负外部风压的峰值可能大约增加一倍以上。
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引用次数: 0
Analysis of a Topsoil Moisture Regime Through an Effective Precipitation Index for the Locality of Nitra, Slovakia 利用有效降水指数分析斯洛伐克尼特拉地区表层土壤水分状况
IF 0.4 Pub Date : 2021-03-01 DOI: 10.2478/sjce-2021-0002
P. Rončák, P. Šurda, J. Vitková
Abstract The aim of this work was to analyze and statistically confirm the relationship between the computed daily values of the Effective Precipitation Index (EP365) and the measured moisture content of the topsoil of a research site near Nitra, Slovakia. The statistical analysis (coefficients of determination) confirmed the strong correlation. Subsequently each day’s mean of EP365 (MEP) was used to quantify the long-term deficit or surplus of the soil water supply in the individual years. The daily values of the EP365 index provide a more detailed view of the development of the topsoil’s moisture regime. According to the deviation of EP (DEP) from the 14-year MEP, the most extreme dry periods prevailed during the years 2015, 2017 and 2018. Therefore, the 2012–2018period was evaluated as dry, and the topsoil moisture regime described through the MEP index was compared with the course of the MEP index from the normal (slightly humid) period of the years 2005 – 2011.
摘要这项工作的目的是分析和统计确认有效降水指数(EP365)的每日计算值与斯洛伐克尼特拉附近研究地点表层土的实测含水量之间的关系。统计分析(决定系数)证实了这种强烈的相关性。随后,使用EP365(MEP)的每日平均值来量化各个年份土壤水供应的长期短缺或过剩。EP365指数的日值提供了表层土水分状况发展的更详细视图。根据EP(DEP)与14年MEP的偏差,最极端的干旱期出现在2015年、2017年和2018年。因此,2012-2018年期间被评估为干燥,通过MEP指数描述的表层土水分状况与2005-2001年正常(轻度潮湿)期间MEP指数的过程进行了比较。
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引用次数: 5
Effect of the Temperature on the Modal Properties of a Steel Railroad Bridge 温度对钢轨桥梁模态特性的影响
IF 0.4 Pub Date : 2021-03-01 DOI: 10.2478/sjce-2021-0001
M. Venglár, K. Lamperová
Abstract The article is devoted to a study of the impact of various environmental conditions on modal parameters, such as natural frequencies and damping ratios. The modal analysis has been performed using the Stochastic Subspace Identification (SSI) method of measuring data every month on the same steel bridge structures located on an important railroad route from Prague (the Czech Republic) to Košice (Slovakia). The structure is approximately 60 m long, and the bearing structure is formed by two arch trusses. The bridge was exposed to ambient vibrations as well as to vibrations caused by a train passage. Accelerations and temperatures (the temperature of the air and the structure) were logged during the measurements. Natural frequencies were obtained from these acceleration data using the SSI method and processed into graphs of the dependencies between the natural frequencies and temperatures. Some statistical procedures were also applied.
本文研究了各种环境条件对固有频率和阻尼比等模态参数的影响。模态分析采用随机子空间识别(SSI)方法,每个月对位于从布拉格(捷克共和国)到Košice(斯洛伐克)的重要铁路线上的同一钢桥结构进行测量数据。该结构长约60 m,承重结构由两个拱桁架构成。这座桥暴露在环境振动和火车通道引起的振动下。在测量过程中记录了加速度和温度(空气和结构的温度)。利用SSI方法从这些加速度数据中获得固有频率,并将其处理成固有频率与温度之间的依赖关系图。还采用了一些统计程序。
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引用次数: 4
期刊
Slovak Journal of Civil Engineering
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