Papers by Keyword: Dome

Abstract: Many masonry domes in their lower portion are subjected to hoop tensile forces which mostly lead to vertical cracks appearing along the dome's meridian planes. A close inspection of any such dome reveals these hoop tension cracks. The dome stands as a series of arches with common key stone, with cracks as a matter of non-structural consequences. Different strategies have been considered historically to arrest these cracks. The provision of tension ring mechanism adds to the stability of these domes, and hence many masonry domes are retrofitted with the provision of the tension rings using steel and FRP rings. The challenge in such retrofitting will remain to analyze its effect on stability of these masonry domes, more specifically in absence of reliable mechanical properties of such masonry domes. This paper presents a simplified analysis procedure combining thrust line analysis with the finite element analysis called here as Finite Element Thrust Line Analysis (FETLA). The development of a new element suitable for masonry dome analysis to include the effect of hoop tension cracks is demonstrated. The orthotropic material properties are utilized for penalty approach to allow redistribution of the forces from meridian direction to the hooping rings, with thrust line approaching the extrados or intrados of the dome. The analysis results of FETLA are validated with the previously available results. The analysis method proposed in this paper gives the rational estimates for the failure load without utilizing inelastic properties of the material to model the hoop tension cracks and its propagation.

Abstract: The historic Hagia Sophia in Istanbul, which held the record as the world's largest domed building for about 800 years, is analyzed with a 3D finite element formulation, by using commercial FEA software ANSYS Workbench 14.5, to understand its structural behaviour under the action of static loading. Four different levels of structural systems are demonstrated and the their effects on the maximum values of the first principal stresses in the main dome are discussed.

Abstract: This paper investigated the failure mechanisms of the stone masonry dome constructed in the heritage site at Jerash. Jerash is the remains of a Roman ancient city and is located 48km north from Amman, Jordan. West Bath in Jerash had one main dome and two small domes. Domes were constructed from stone masonry. The structural characteristics of the remained small dome were investigated numerically by use of the finite element method. The foundation of the West Bath is under the conditions of a land sliding and was cut beside the dome pier. Therefore, assuming the several uneven settlements of the piers, the structural behavior of the dome was assessed. From the distributions of the cracking and the crushing of the stone, the failure mechanisms of the stone masonry were represented.

Abstract: A dome-covered house is an example of designing sustainable buildings by learning from the optimized biological forms from the nature. This paper presents the solar-thermal model for a transparent dome built above one of the several houses located in Montreal. The incident solar radiation on selected cells, the roof and wall surface are presented. The dome-covered helps to reduce the heating load by 79.3% on January 21^st with annual average reduction of 92.9% and if the house is located in Yellowknife, the annual heating load reduction would be 56.3%.

Abstract: In this paper, three different types of tail domes were designed based on the mechanism of reducing pressure drag between the front and rear of vans, and it takes the van without a dome as a comparison to discuss the drag reduction effects of three different sizes. The three-dimensional model of the van is established in PRO/E, and the pressure and velocity distribution of the van model were analyzed in Fluent; In addition, the wind resistance test of the van model is proceed in the variable speed motor wind resistance simulation test device. The results of CFD simulation have good consistency with the experimental test results, and it verifies the conclusion that the tail dome is good for drag reduction. It provides basis and reference for the optimization of drag reduction for the vans.

Abstract: This paper describes a modeling method for film thickness variation within plasma enhanced chemical vapour deposition (PECVD) processes. The model enables the identification and optimization of deposition process sensitivities to electrode configuration, deposition system design and gas flow distribution. An comparison between theory and experiment is provided for PECVD of diamond-like-carbon (DLC) deposition onto flat and curved substrate geometries. This process utilizes butane reactive feedstock with an argon carrier gas. Radio-frequency plasma is used. The PECVD deposition system is based on co-planar 300mm diameter electrodes with separate RF power matching to each electrode. The system has capability to adjust the electrode separation as a parameter to optimize uniformity. Vacuum is achieved using dry pumps with real time control of butterfly valve position for active pressure control. Deposited film thickness sensitivities to electrode geometry, plasma power density, and pressure and gas flow distribution are demonstrated. In addition to film thickness uniformity, optical, durability and environmental performance of resulting DLC on germanium substrate materialreported.

Abstract: In this paper we apply semi-geodesic trajectories to the creation of isotensoid domes for filament wound pressure vessels. The governing equations for the determination of the meridian shapes and related winding angle distributions of domes are derived using the netting analysis and the semi-geodesic winding law. The effects of the slippage coefficient on the geometry and fiber trajectories of the domes are respectively evaluated in terms of the resulting meridional curves and fiber angles. It is revealed that the semi-geodesic angles and the dome depth have an overall decrease with increasing the slippage coefficient. The results also demonstrate that the use of semi-geodesics significantly enlarge the design space for the geometry and adapted fiber trajectories of the domes. The present method can provide a significant reference for the design and production of the domes for semi-geodesically overwound pressure vessels.

Abstract: The large-scale steel dome construction method is studied in the paper. Combined with Shandong province museum of steel construction dome, the piecewise processing methods are determined. According to the type of weight component chose lifting equipment types and model, aiming at the actual situation of construction formulated the steel structure installation overall process, the stress of the bed-jig to install a performance is calculated, and the steel frame column installation method is studied. The engineering experience and research content in the paper can provide a reference for the similar engineering.

Abstract: The wind tunnel tests of some typical large roofs, including a saddle roof, pitched roof and domes, are carried out with various terrains which cover suburban and urban exposures. The wind pressure data of roofs are obtained by using the synchronous multi-pressure scanning technique. The wind pressure coefficient and local shape factors of the wind load was investigated. The effects of various terrains on wind pressures of roofs are discussed. From the results, we can see mean pressures of these roofs exposed to the mean pressures exposed to the suburban terrain are 2 or 3 times those exposed to the urban terrain. And the terrains are no directly influence to the wind pressure shape factors.

Abstract: During the process of super heavy oil exploitation in Tahe oil field, when mixing light oil, due to heavy oil and light oil entering into pump from separator directly, the existing ESP string leads to poor mixing and heavy oil coming into the pump, as a result, the pump detection period is greatly shorten; when water injection-production, the injected water can contact with electrical cable and motor directly, causing serious damage to the cable and motor, and the pump detection period is also greatly shorten. This paper designs a new type of ESP string, adding a ESP dome, a sieve tube, a mixing device, an intelligent switch and a direct flushing valve, which can improve the mixing effect of heavy oil and light oil, avoid the injected water directly contacting with electrical cable and motor, in order to protect the electrical cable and motor, improve their service life, extend the pump detection period and reduce production costs. Field test showed that the pump detection period has been prolonged after using the new ESP string, it is recommended to promote the use.