Добірка наукової літератури з теми "Lateral building separation"

This paper presents an analytical investigation on the required separations between adjacent buildings to avoid pounding during earthquakes. Five wall buildings, having 3, 6, 10, 15, and 25 storeys, were designed for three different seismic zones in Canada: Montreal, Vancouver, and Prince Rupert. For each zone, an ensemble of code compatible ground motions was identified. Nonlinear time-step dynamic analyses were performed to determine the separations to avoid pounding between each building pair under each earthquake. The required separations, obtained by subtracting the time-histories of lateral displacements between adjacent floor levels, were compared with the requirements of the static method of the National Building Code of Canada. The results indicate that the static method of the code grossly overestimates the required separations. This is to be expected, since the static code procedure does not take full account of the intervening variables (periods, responses, and phases between building motions) which characterize the ground motion and building properties when determining the separation distances. A simplified spectral difference procedure is proposed for inclusion in future editions of the code. Key words: dynamics, earthquake, gap, pounding, seismic, separations.

Various vapour intrusion (VI) models have been proposed in order to predict indoor concentration of Volatile Organic Compounds (VOCs) in buildings. However, these models tend to be conservative, and overestimate or underestimate vapour flux emissions due to several assumptions. Particularly, most of these VI models only consider an infinite uniform contaminated groundwater as the principal source of VOCs in the soil, and lateral pollution source in the vadose zone are disregarded. It has been shown that ignoring the lateral source position may lead to uncertainties on the estimations. In this paper, a numerical model is developed in order to better understand the relationship between the lateral source position in the soil, including both a source in the vadose zone and a source located at the groundwater level, and the resulting indoor air concentration. Results show that source position plays a significant role on vapour intrusion attenuation. In fact, indoor concentration of VOCs decreases with increasing lateral separation. Finally, it is shown that considering the source position can significantly improve the quality of VI predictions.

This research discusses the feasibility of using the required minimum separation distance based on SBC 301-2007. Moment resistance frames were designed with expansion joints requiring 400mm separation distance. Nonlinear response history analysis was conducted with four ground motions selected and scaled to match the risk-targeted response spectrum of NEOM city based on ASCE 7-16 provisions. An equivalent spring constant value based on floor lateral stiffness was selected as a gap link stiffness. Finally, an evaluation for the pounding response of adjacent blocks is presented along with the conclusions.

Due to the high cost and less availability of land, the buildings are constructed adjacent to each other with a significantly smaller separation gap. Whenever seismic forces act on adjacent structures, they collide and cause significant structural and architectural damage. Soil-Structure Interaction (SSI) effects cause more complications in the adjacent structures. This paper assesses the gap distance between RC bare frame adjacent structures of varying heights in medium and soft soil with and without SSI to avoid the pounding effect of an earthquake. The main objectives are to find the separation distance between adjacent buildings by the provisions of FEMA 356, IS 1893 (Part 1):2002, IS 1893 (Part 1):2016 and EN 1998-1:2004. The separation gap between different codes was then compared to determine the minimum separation required to prevent pounding between the structures. The maximum lateral displacement on the roof and the time period of the adjacent buildings are compared with and without SSI. There is a significant increase in lateral displacement, separation distance, and time period considering SSI. It is found that the Indian code overestimates the separation distance. Thus, this study guides structural engineers to maintain a minimum separation distance between buildings erected on medium and soft soils in high seismic zones of India. Doi: 10.28991/CEJ-2022-08-02-09 Full Text: PDF

In a framed-tube tall building, shear wall systems are the most efficient structural systems for increasing the lateral load resistance. A novel and simple mathematical model is developed herein which calculates the natural frequencies of such tall buildings. The analyses are based on a continuous model, in which a tall building structure is replaced by an idealized cantilever beam that embodies all relevant structural characteristics. Governing equations and the corresponding eigen-problem are derived based on the energy method and Hamilton’s principle. Solutions are obtained for three examples; using the separation of variables technique implemented in MATLAB. The results are compared to SAP2000 full model analysis; and they indicate reasonable accuracy. The computed natural frequencies for structures 50, 60 and 70 storey buildings were over-estimate 7, 11 and 14 percent respectively. The computed errors indicate that the proposed method has acceptable accuracy; and can be used during the initial stages of designing of tall buildings; it is fast and low cost computational process.

One of the possibilities to prevent building pounding between two adjacent structures is to consider appropriate in-between separation distance. Another approach might be focused on controlling the relative displacements during seismic excitations. Although the majority of building codes around the world recommend the use of some equations of various distances between structures to avoid pounding; a lot of reports after earthquakes have obviously shown that safety situation or economic consideration is not always provided due to the collisions between buildings and high cost of land; respectively. The aim of the present paper is to focus the analysis on the properties of structures and conduct an in-depth analysis of available methods to control interstory deflections so as to prevent pounding. For this purpose, a numerical lumped mass model of the five-story building has been considered and its response under different earthquake records has been investigated. Firstly, the influence of the change in structural properties (story stiffness; mass and damping) has been examined. Then the application of tuned mass damper, base isolation and base isolation with rubber bumpers has been considered. The results of comparative analyses clearly indicate that using base isolation, with the addition of bumpers, can be selected as the best method to control building deflections and decrease absolute lateral displacement between two buildings so as to prevent their pounding during earthquakes

Biological membranes exhibit a great deal of compositional and phase heterogeneity due to hundreds of chemically distinct components. As a result, phase separation processes in cell membranes are extremely difficult to study, especially at the molecular level. It is currently believed that the lateral membrane heterogeneity and the formation of domains, or rafts, are driven by lipid–lipid and lipid–protein interactions. Nevertheless, the underlying mechanisms regulating membrane heterogeneity remain poorly understood. In the present work, we combine inelastic X-ray scattering with molecular dynamics simulations to provide direct evidence for the existence of strongly coupled transient lipid pairs. These lipid pairs manifest themselves experimentally through optical vibrational (a.k.a. phononic) modes observed in binary (1,2-dipalmitoyl-sn-glycero-3-phosphocholine [DPPC]–cholesterol) and ternary (DPPC–1,2-dioleoyl-sn-glycero-3-phosphocholine/1-palmitoyl-2-oleoyl-glycero-3-phosphocholine [DOPC/POPC]–cholesterol) systems. The existence of a phononic gap in these vibrational modes is a direct result of the finite size of patches formed by these lipid pairs. The observation of lipid pairs provides a spatial (subnanometer) and temporal (subnanosecond) window into the lipid–lipid interactions in complex mixtures of saturated/unsaturated lipids and cholesterol. Our findings represent a step toward understanding the lateral organization and dynamics of membrane domains using a well-validated probe with a high spatial and temporal resolution.

Currently, the steel plate shear wall (SPSW) is commonly used in high-rise steel buildings as a lateral load-resisting system due to its several advantages such as its lightweight and high ductility and strength. The SPSW consists of two main parts, i.e., the boundary frame and infill plate, which are connected by welding. The objective of this work is to study the effect of the infill plate weld separation on the seismic behavior of the SPSWs. A numerical method was proposed to have a comprehensive comparison of seismic behaviors of different separation characteristics. The model was validated by using previously published experimental works. Key parameters, such as load-carrying capacity, stiffness, and energy-dissipation capacity, were discussed extensively. The unstiffened SPSW (USPSW) system is more sensitive to the plate–beam separation than the plate–column one, especially the corner plate–beam separation. When plate–column welding separation occurs, the initial stiffness and the energy dissipation capacity are reduced by approximately 21% and 14%, respectively; however, the reductions are 36% and 20.5% in the case of beam welding separation.

Les sites pollués (sol ou eaux souterraines) représentent un potentiel de risque pour la santé humaine et l’environnement. Il existe des outils d’aide à la gestion, en complément des mesures in-situ, qui permettent d’estimer rapidement et à moindre coût les risques sanitaires associés à l’exposition des polluants gazeux du sol dans les espaces intérieurs afin d’établir des mesures de prévention et/ou correction. Cependant, et malgré leur intérêt, il a été montré dans la littérature qu’il existe des différences importantes entre les concentrations intérieures mesurées et les estimations des outils existants. Ces incertitudes reposent principalement sur trois aspects : une mauvaise caractérisation du site, une modélisation incomplète des voies et mécanismes de transfert, ou bien du fait de négliger l’influence de certains paramètres sur le transfert. Par exemple, le fait de négliger la latéralité de la source reste une explication plausible des limites des modèles classiques de transfert. Les auteurs conviennent que la migration latérale joue un rôle important sur l’atténuation de la concentration intérieure en polluant, contrairement aux scénarios de source homogène ou continue, où les vapeurs migrent uniquement de manière verticale vers le bâtiment. Ainsi, lorsque la source est latéralement décalée vis-à-vis du bâtiment, les vapeurs vont migrer préférentiellement vers l’atmosphère et moins vers le bâtiment générant une atténuation plus importante de la concentration intérieure. Dans ce contexte, l’objectif principal de ces travaux de thèse est la contribution à l’amélioration des outils d’aide à la gestion afin d’élargir leur plage d’application. Pour ce faire, des nouveaux modèles ont été développés permettant de tenir compte de la latéralité de la source dans l’estimation de la concentration intérieure en polluant. Le développement de ces modèles est réalisé à partir de l’expérimentation numérique et l’analyse adimensionnelle sur la base des outils existants (modèles semi-empiriques construits en considérant une source continue). La combinaison de ces deux approches permet d’une part, de garder la capacité des modèles source continue de tenir compte des propriétés physiques du sol (perméabilité, coefficient de diffusion, …) et des caractéristiques du bâtiment (typologie de soubassement, dépression, volume, …), et d’une autre part, de mieux préciser la position de la source dans le sol en considérant l’influence de sa latéralité dans les estimations. Ces nouveaux modèles ont été issus d’une analyse comparative permettant de vérifier la cohérence et la précision des estimations vis-à-vis d’un modèle numérique (CFD), de données expérimentales et de modèles existants dans la littérature. Finalement, ces expressions ont été intégrées dans un code de ventilation (MATHIS-QAI) permettant de mieux préciser les caractéristiques des environnements intérieurs (système de ventilation, perméabilité à l’air de l’enveloppe, volume du bâtiment, …) et de réaliser des estimations des niveaux de concentration en fonction des variations temporelles (vitesse du vent, température extérieure, …) au cours du temps. À partir d’une étude paramétrique il a été montré que malgré l’impact non-négligeable des caractéristiques du bâtiment, l’influence de la latéralité de la source sur l’atténuation de la concentration intérieure en polluant reste prédominante (atténuation de plusieurs ordres de grandeur quand la source est décalée latéralement du bâtiment en comparaison à une source continue). Cependant, préciser les caractéristiques du bâtiment (soubassement, système de ventilation, perméabilité à l’air de l’enveloppe,…), ainsi que les conditions météorologiques uniques de chaque projet de construction, permet d’augmenter la précision des estimations en évitant la mise en œuvre de solutions extrêmes ou bien encore, de mesures inadaptées
Polluted sites and most precisely vapor intrusion represents a potential risk for human health and its environment. Various screening-level and analytical models have been proposed in order to evaluate vapor intrusion and provide assessment tools for exposure risk. However, some in situ investigations show significant differences between predicted and measured indoor concentrations leading eventually to misleading conclusions and inappropriate solution implementations. These uncertainties are mainly associated with a poor characterization of the site, an incomplete modeling of transfer pathways and mechanisms, or by neglecting certain influencing parameters on this transfer. For example, ignoring the lateral source/building separation may serve as possible explanation of the uncertainties presented by the conventional models based on a homogeneous source distribution assumption. The authors agree that lateral migration plays an important role in the attenuation of the indoor concentration. In homogeneous or continuous source scenarios vapors may migrate mainly vertically towards the building. However, lateral source may promote lateral migration to the atmosphere and less into the building generating a greater attenuation of the indoor concentration. In this context, the main objective of this thesis work is to contribute to the improvement of the assessment and management risk tools in order to improve the accuracy of their estimations and increase their range of application. To do this, new vapor intrusion models are developed considering the lateral source/building separation. These models are built on a numerical experimentation and dimensionless analysis based on existing models (semi-empirical models considering a homogeneous source distribution). The combination of these two approaches allows, on the one hand, to maintain the aptitude of the existing models to consider the physical properties of the soil (permeability, diffusion coefficient, …) and the characteristics of the building (type of construction, building depression, volume,…), and on the other hand, to better precise the position of the source in the soil taking into account the influence of the lateral source/building separation in the estimations. From a comparative analysis, the accuracy of these new expressions is verified comparing to the proposed numerical model (CFD), experimental data and existing models in the literature. Finally, the proposed expressions were coupled with a ventilation code (MATHIS-QAI) allowing to better specify indoor characteristics (ventilation system, air permeability of the envelope, volume of the building, …) and estimate indoor air concentration levels as a function of environmental variations (wind speed, outside temperature, …) over time. From a parametric study it was shown that despite the significant impact of the characteristics of the building, the influence of the lateral source/building separation remains predominant on the attenuation of the indoor concentration (attenuation of several orders of magnitude when the source is laterally offset of the building compared to a homogeneous source). However, specifying the characteristics of the building (construction type, ventilation system, air permeability, …) and weather conditions may increase the accuracy of the estimation avoiding the implementation of extreme solutions or insufficient actions

This chapter considers the possibility of building a maritime monarchy and how the Anglo-Dutch Revolution achieved this. Early modern Europe was governed by territorial monarchies and small, sometimes maritime, republics and/or cities. The former were culturally and socially aristocratic, and the latter mercantile. But in the later seventeenth century, a new European great power emerged that was a territorial monarchy within which a landed aristocracy, enriched by the economic changes of the period, beginning with those revolutionizing agricultural productivity, became fully participant in its new commercial economy. The way in which Britain's ruling class in both Houses of Parliament intertwined hereditary nobility and a mercantile, manufacturing, and financial oligarchy had no European parallel. The strict separation of the world of work from socially mandated aristocratic idleness which applied elsewhere had disappeared.

Tectonism is the science of Earth movements and the rocks and structures involved therein. These movements build the structural framework that supports the stage on which surface processes, plants, animals and, most recently, people pursue their various roles under an atmospheric canopy. An appreciation of this tectonic framework is thus a desirable starting point for understanding the physical geography of South America, from its roots in the distant past through the many and varied changes that have shaped the landscapes visible today. Tectonic science recognizes that Earth’s lithosphere comprises rocks of varying density that mobilize as relatively rigid plates, some continental in origin, some oceanic, and some, like the South American plate, amalgams of both continental and oceanic rocks. These plates shift in response to deep-seated forces, such as convection in the upper mantle, and crustal forces involving push and pull mechanics between plates. Crustal motions, augmented by magmatism, erosion, and deposition, in turn generate complex three-dimensional patterns. Although plate architecture has changed over geologic time, Earth’s lithosphere is presently organized into seven major plates, including the South American plate, and numerous smaller plates and slivers. The crustal mobility implicit in plate tectonics often focuses more attention on plate margins than on plate interiors. In this respect, it is usual to distinguish between passive margins, where plates are rifting and diverging, and active margins, where plates are either converging or shearing laterally alongside one another. At passive or divergent margins, such as the present eastern margin of the South American plate, severe crustal deformation is rare but crustal flexuring (epeirogeny), faulting, and volcanism occur as plates shift away from spreading centers, such as the Mid-Atlantic Ridge, where new crust is forming. Despite this lack of severe postrift deformation, however, passive margins commonly involve the separation of highly deformed rocks and structures that were involved in the earlier assembly of continental plates, as shown by similar structural legacies in the facing continental margins of eastern South America and western Africa. At active convergent margins, mountain building (orogeny) commonly results from subduction of oceanic plates, collision of continental plates, or accretion of displaced terranes.

Abstract Separators can over the length of field life be exposed to operating conditions outside the set design conditions, which can cause operating issues in terms of separator efficiency, operating expenditures and potential need for frequent maintenance and/or retrofitting new internals. In mature operations with heavy oils, there can be severe issues with Water-in-Oil and Oil-in-Water emulsion layers. In late life operations, enhanced oil recovery (EOR) efforts with polymer injection can also take place to produce more, but at the same time making the separator function in terms of phase separation even more complex. Emulsion thickness and residence time optimization in separators and tanks are key issues in the oil and gas operations. Real-time data of the full level profiling is complicated and has been based on instruments with varying reliability and performance. Operations have been relying on other process parameters and bottle tests. However, in this work, separator profiler utilizing electrical tomography was used for monitoring separator content online, especially fluid interface levels as well as emulsion and foam layer thicknesses. In addition, effect of polymer injection to the wells is investigated. From the single profiler, data for the separator fluid levels, emulsion and foam thicknesses can be derived. The profiler used is a safe-to-use non-radioactive probe-type measurement sensor which is installed through an existing separator nozzle. The actual separator profiler with dimensions 5 cm diameter and 3 m length was installed downstream of the inlet cyclones and the flow distribution baffles in the three-phase separator located at one of the production fields in the Middle East. Water-oil interface, turbulent water-in-oil dispersion band, oil-gas interface and foam layer thickness were monitored continuously for several months with varying flowrates and operation conditions. Later, effect of polymer injection was also investigated. Interface level and layer monitoring results will be given and discussed. The results show that the profiler is highly useful for monitoring the separator fluid distribution online, building a rigid data analytics model over time that can be utilized by the operations to improve and optimize the performance. This paper shares novel information on operational experience of data analytics used for three-phase separators operating in a heavy oil field with polymer injection. The sensor type used is novel to the industry with high robustness and reliability generating multiple data points per second, enabling a highly detailed analytics model generating new possibilities for operational optimization through digitalization. In addition, commissioning and monitoring of the sensor was done remotely during covid-19 shutdown without the need of external personnel entering the field demonstrating remote commissioning and digital oil field concepts.

The deconstruction of steel-concrete composite structures in buildings and the later separation of the materials is a labour- and cost intensive work. This is due to the fact, that the shear studs are welded on the steel beam, and a large amount of cutting work gets necessary. As a result, recycling is difficult and the potential for reusing entire elements is lost. The carbon footprint of composite structures could be decreased by the application of the principles of “design for deconstruction and reuse”. This paper presents a study with its respective laboratory experiments on demountable shear connectors that facilitate recyclability and even offer the potential for reusing elements in their entirety. In the Laboratory of Steel and Composite Structures of the University of Luxembourg 15 push-out tests have been carried out using different bolted connection systems suitable for multiple uses in order to verify their performance characteristics by means of shear strength, stiffness, slip capacity, ductility and ability of demounting. The investigated systems included pre-stressed and epoxy resin injection bolts, solid slabs and composite slabs with profiled decking. The results showed that the tested demountable shear connections could provide higher shear resistance than conventional shear connections in some cases. The connection failure happened in the bolts, while there was no or minor visible damage observed on the connected members. Most of the tested connections could fulfil the ductility requirement given by Eurocode 4. The application of epoxy resin in the hole clearance resulted in lower slip capacity. The outcome will provide an important basis for the calibration of the forthcoming enhancement and numerical simulation of the demountable shear connections. The failure behaviour, the observed damages and the resulting ability of the elements for later re-use are discussed in detail.