Browsing by Subject "bridge"
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Item Improving seismic behaviour of bridges with lead rubber bearing in Iran(Видавництво Львівської політехніки, 2011) Golzar, M. J.; Azharian, M.; Behrouzyar, H. Kh.Construction of roads in Iran has received a considerable attention during these years. In this issue, the special geographic conditions of this country make bridge structures vital. Because of seismic location of Iran, attention to the reduction of risks is needed. Previous studies on seismic response of bridges prove the effective rules of isolators against the tremendous usage of elastomeric bearings in Iran. Lead rubber bearing (LRB) is one of the isolators that comprised of alternate layers of steel and vulcanized rubber with a central lead core. This paper describes the analytical study on seismic response of two concrete bridges with or without LRB based on a 3D time history nonlinear analysis using Sap2000 program. The models were subjected to strong seismic motions recorded near to the zone. Results show the beneficial effect of the isolation system in comparison with elastomeric bearing system on capability of energy dissipation. Not only, isolators reduce the base shear on bridges but also reduce shear force and bending moment of piers as well. According to this research deck displacement in isolated bridges reduces considerably whereas bent displacement is not effected practically in flexible bridges.Item One approach for computing simple polygons on a given point set in the plain(Lviv Polytechnic Publishing House, 2015) Fisunenko, Andriy; Taras Shevchenko National University of KyivWe consider the problem of computing all possible simple polygons embrasing every point of a given finite point set in the plane. The developed approach is based on topological analysis of mutual visibility graphs of all free points and end points of a constructed chain. We found several new necessary conditions for existence of simple polygonal chains which are based on checking collocations of articulation points, bridges and biconnected components of such graphs. These conditions can be effectively applied for reducing trees of exhaustive search for all possible polygons on the given point set or for their random generation.Item Ways of improvement of operational efficiency of hopper devices(Publishing House of Lviv Polytechnic National University, 2016) Koruniak, Petro; Shenbor, Vladyslav; Korendiy, Vitaliy; Bezpalov, Anatoliy; Brusentsov, VolodymyrThe operation of hopper devices, which are used in industry, civil engineering, agriculture and transport, is analyzed on the article. The external factors, which influence the process of charging, storing and discharging of loose cargo (freights) from hopper tanks, are overviewed. The subject of research of presented paper is the improvement of mechanisms of fracturing of products hangs-up (bridges) in hoppers at the stage of designing and setting up of hopper devices. In order to solve the stated problem the schemes of bridges fracturing and the structures of devices for debarment of products bridging and their uniform outflow from the hopper tank are proposed. The proposed schemes are based on the principles used in development of vibratory machinery with mechanical, cam and electromagnetic vibratory principles of structures forming. For cam spring device of bridges fracturing the technique of calculation of stiffness of elastic system and of the necessary forces for performing of technological process of bridges fracturing is presented and the recommendations for choosing of the stiffness of the system of elastic elements are suggested. For the hoppers with spring and electromagnetic blocks of bridges fracturing and of metered (batched) feeding of products the structural diagrams of devices are presented and the recommendations for usage of various modifications of devices are suggested. The influence of parameters of flat spring elements on the efficiency of devices operation is overviewed. The structural diagrams of devices with one-cycle and two-cycle electromagnetic vibration exciters and the modifications of elastic systems are considered. the structural diagram of the production prototype of the hopper feeder is presented. The materials of the article, the proposed structural diagrams, the operation scheme of the hopper feeder and the derived analytical formulas may be used by designers, researchers and technologists while improving of existent and developing of new devices.Item Визначення точності геодезичних робіт при будівництві мостових переходів шляхом моделювання напружено-деформованого стану конструкції(Видавництво Національного університету «Львівська політехніка», 2009) Старовєров, Володимир; Адаменко, ОлександрThe article contains the information about basic principles of accuracy surveying in geodetic engineering in the course of bridge crossings building using model analysis of structural stress strain behavior.Item Визначення точності геодезичних робіт при монтажі мостових переходів на основі теорії розмірних ланцюгів(Видавництво Національного університету «Львівська політехніка», 2009) Адаменко, ОлександрThe article contains the information about new principles of accuracy surveing in geodetic engineering in the course of bridge crossings building on the basis of dimension chain theory.Item Обгрунтування моделі прогнозу життєвого циклу залізобетонних елементів мостового переходу(Видавництво Національного університету "Львівська політехніка", 2010) Янчук, Л. Л.Моделюється життєвий цикл залізобетонних елементів мостів. Процес акумуляції пошкоджень описано аналітичною степеневою функцією. Запропонована модель обґрунтовується статистичними даними системи експлуатації мостів. This paper presents the service life modelling of bridges reinforced concrete elements of. The damage accumulation process is modelled using analytic degree function. The proposed model is substantiating by the real statistics of bridges maintenance.Item Розвиток методів динамічних випробувань автодорожніх мостів(Видавництво Національного університету "Львівська політехніка", 2010) Редченко В. П.Проаналізовано розвиток методів динамічних випробувань автодорожніх мостів в Україні та світі. Подано основні результати авторських досліджень з розроблення та впровадження нових методів динамічних випробувань.In the article the analysis of development of methods of dynamic tests of road bridges in Ukraine and world is stated. Main outcomes of researches by author on the given subjects are too.Item Теоретичні засади прогнозу ресурсу залізобетонних елементів мостів(Видавництво Національного університету "Львівська політехніка", 2010) Лантух-Лященко, А. І.Подано теоретичні засади моделювання життєвого циклу залізобетонних елементів мостів. Показано дві моделі деградації: детерміністична і стохастична. Розглянуто можливості наведених моделей. This paper presents an approach to the service life modelling of bridges reinforced concrete elements. Two degradation models are presented: deterministic and stochastic. The possibility of the proposed model is discussed.