Preliminary Evaluation of the Impact of Eurocode 8 Draft Revision on the Seismic Zonation of Romania

This study is focused on the impact of the Eurocode 8 draft revision on the seismic zonation of Romania, one of the countries with the highest hazard levels in Europe. In this study, the design response spectra are evaluated for a number of sites in Romania for which both shear wave velocity profiles and ground motion recordings are available. The impact of the proposed changes on the structural design for structures situated in the southern part of Romania is also discussed. The results show considerable differences between the design response spectra computed according to the Eurocode 8 draft revision and the design response spectra from the current Romanian seismic code P100-1/2013. The differences are larger in the case of the sites situated in the southern part of Romania and those which have large design values for the control period TC. In Bucharest, for instance, it was found that the maximum design spectral accelerations would correspond to those from the 2006 version of the code while the maximum design spectral displacements would be significantly smaller than the levels produced by the 1981 or 1992 versions of the code. The results presented herein show that the differences in the seismic hazard and design ground motions are mainly due to the effects of local soil and site conditions and the associated site amplification proposed in the current Romanian seismic code and EC8 draft revision. Moreover, it has been shown that more analyses are needed to apply the seismic actions proposed in Eurocode 8 revision specifically for the sites in Romania under the influence of Vrancea intermediate-depth earthquakes so as to ensure an increased level of seismic safety for structures designed and built in the future.

Multi-level designing structures in tsunami-prone areas

The paper proposes a two-level approach to the calculation of structures for the tsunami effect. The concept of the design tsunami and the maximum design tsunami and their corresponding limit states is introduced. The estimated loads on the bridge piers from the design and maximum design tsunami are estimated, depending on the territory danger and the bridge responsibility. At the same time, bridges, in accordance with the approach adopted in transport construction, are divided according to their degree of responsibility into four categories. A formula is obtained to estimate the design splash value for the design and maximum design tsunami, depending on the bridge category. In addition, graphs are provided showing the frequency of the tsunami and the calculated wave height corresponding to this frequency. To estimate the combination coefficient of wind and tsunami loads, their equally probable pairs are considered. At the same time, the Weibull distribution is used to set the wind load, and for the tsunami load, the distribution given in the Code of Rules for Ensuring Tsunami Safety is used. Taking into account such load pairs is relevant for bridges with high piers, when the height of the splash does not exceed the pier height and there is a high probability of a simultaneous combination of wind and tsunami loads. The paper presents the calculations of surges for two types of tsunamis: the design one with a repeatability of once in 50 years and the maximum design one with a repeatability of once in 500 years for the Kamchatka region and the Kuril Islands for bridges of the first and second categories. Studies show that for the design tsunami and the maximum design tsunami, the coefficients of combinations with wind load differ significantly.

Іmprovement of driving-speed properties improvement of the method for selecting the parameters of the motor-transmission unit car

Aerodynamic characteristics have a major impact on the energy efficiency and traction and speed properties of the vehicle. In this article, based on previous studies of the aerodynamic characteristics of various car models, we propose an improved method for selecting engine and transmission parameters at the design stage. The aim of the study is to improve the dynamic properties of the car by improving the method of selecting the main parameters of the engine-transmission unit by refining the calculation of aerodynamic drag. To achieve it, the following tasks must be solved: to specify the method of selecting the maximum effective engine power; to specify a technique of definition of the maximum constructive speed of the car; to develop a technique for selecting gear ratios. The aerodynamic resistance to the movement of the vehicle is determined by the frontal coefficient of the specified resistance, the density of the air, the area of the frontal resistance and the speed of the vehicle. It is known from classical works on the aerodynamics of a car that in the range of vehicle speeds from 20 m / s to 80 m / s, taking the law of squares when assessing the force of air resistance, it is necessary to change the coefficient of frontal aerodynamic drag depending on the speed of the car. However, when carrying out calculations, this coefficient is taken constant, which leads to obtaining large values of the air resistance force at high speeds and lower at low speeds. There are two possible ways to improve the dynamic properties and energy efficiency of the car during its modernization (increasing the maximum design speed of the car by reducing the gear ratio in higher gear; reducing the maximum efficiency of the engine while maintaining the previous gear ratio in higher gear). As a result of the study, the method of selection (maximum effective engine power; maximum design speed of the car; gear ratios) at the design stage of the parameters of the motor-transmission unit of the car has been improved.

Experimental research of the air permeability of concrete in the compressed zone of the containment for power units no. 1, 2 of the South-Ukrainian NPP

The determination of the air permeability of concrete in the compressed zone of NPP’s containment under conditions of excessive air pressure in the subshell space of the reactor compartment under a maximum design basis accident is necessary to confirm the localizing functions of the containment when extending the lifetime of power units. Approaches to determining the localizing ability (air permeability) of concrete in the compressed zone of the containment of NPPs with WWER-1000 type reactors under the impact of excessive air pressure under conditions of maximum design basis accident are discussed in the article. The designed testing installation for experimental studies of the air permeability of concrete by the method of stationary radial filtration is described and the results of experimental researches of the air permeability on the installation are presented for samples simulating the composition of concrete used under construction of the containment for Power Units No. 1, 2 (series B-302 and B-338, respectively) SD “South-Ukrainian NPP”. A comparative analysis of the results of abovementioned experimental researches with the results of experimental and theoretical work on the study of air permeability of the similar samples-imitators of concrete by the method of stationary linear filtration, as well as the results of measurements for samples of concrete sampled directly from the compressed zone of containment for Power Unit No. 2 of SD “South-Ukrainian NPP” was fulfilled. The results are explained by processes of compaction of the concrete structure under a complex stress state that occurs under specific hardening conditions and during longtime compression by pre-stressed reinforcing ropes, which takes place under conditions of real containment operation. It was concluded that the simulators made according to the currently accepted technology cannot provide a correct determination of the localizing ability of the NPP’s containment, since the conditions and time of containment concrete hardening, as well as the longtime constant compressive action of reinforcing ropes, cannot be correctly modeled in full under the formation of samples-imitators. The issue of the containment concrete samplesimitators creating in laboratory conditions requires additional study, improvement of technology and the development of new approaches with maximum physical modeling of the conditions characteristic of the operation of the NPP containment.

Results of Structural Analysis of WWER-1000/320 Containment Behavior under Severe Accidents

The paper presents the review and evaluation of the containment prestressing system within reinforced concrete structures under seismic loads and severe accidents. Given the complex design of the containment, the detailed finite element model has been developed and used to describe real containment behavior. Containment stress and strain state was calculated by modern LIRA software. The first stage analyzed the results of WWER-1000/320 containment stress and strain state calculation under a combination of loads caused by maximum design basis accident (MDBA) and safe shutdown earthquake (SSE) and defined minimum acceptable tension of tendons. The research determines the minimum acceptable tension of tendons in the containment prestressing system, and evaluates the strength and reliability of containment structures under a combination of loads in normal operation + design-basis accident + maximum design earthquake (NO + DBA + MDE). The verification calculations have been performed using tendon tension of 780 ton-force in the cylindrical part of the containment and 760 ton-force in the containment dome. The second stage covered the analysis of severe accident parameters (pressure and temperature) and the results of calculation. Stress and strain state in ZNPP-1 containment has been calculated, parameters (pressure and temperature) under which the containment can loss its protective and isolation functions have been identified, calculation results have been analysed and conclusions of containment structural integrity and ensuring the implementation of the design confining functions have been made. Based on the calculation results, it can be concluded that strength of the containment cylindrical part during a beyond design-basis accident cannot be ensured under parameters t (temperature) = 120°С, p (pressure) = 0.6 MPa.

Повышение энергоэффективности систем ультрафиолетового обеззараживания воды

Проанализирована производительность ряда представленных на рынке систем ультрафиолетового обеззараживания воды в сравнении с системами с максимальной производительностью, полученной в результате теоретических исследований, при одинаковом энергопотреблении. Показано, что максимальные значения производительности, заявленные производителями систем, в 1,12 раза меньше, чем можно было бы получить для тех же конструкций при обеспечении однородности облучения обрабатываемого потока. Предложено техническое решение, позволяющее обеспечить однородность облучения за счет формирования распределения скорости потока, убывающего с расстоянием от лампы пропорционально убыванию средней по длине лампы интенсивности облучения. Такое решение позволяет существенно приблизиться к максимальной расчетной производительности при незначительных изменениях в конструкции и минимальных затратах. Исследовано распределение потоков обрабатываемой воды в системе с диафрагмами-рассекателями, формирующими необходимое направление потока. Показано, что для корпуса-реактора длиной до 50 см можно ограничиться одной диафрагмой, а для корпусов большей длины вопрос решается установкой дополнительных рассекателей. Показана возможность применения предложенного решения для любых систем с продольным потоком относительно расположения УФ-ламп.The performance of a number of ultraviolet water disinfection systems available on the market is analyzed in comparison with systems of the maximum capacity reached as a result of theoretical studies, at the same energy consumption. It is demonstrated that the maximum performance values declared by the system manufacturers are 1.12 times less than could be obtained for the same designs, provided the irradiation uniformity of the treated flow is ensured. A technical solution is proposed that provides for the uniform exposure due to the flow velocity distribution that decreases with the distance from the lamp in proportion to a decrease in the average irradiation intensity along the length of the lamp. This solution allows approaching significantly the maximum design performance with the minimal cost and minor changes in the design. The distribution of treated water flows in a system with diaphragms-spreaders that ensure the required flow direction, is investigated. It is demonstrated that for a reactor vessel up to 50 cm long one diaphragm is enough, whereas for larger vessels installing additional flow spreaders can solve the problem. Possible use of the proposed solution for any systems with a longitudinal flow relative to the location of the UV lamps is shown.

Недостатки типового проектирования автоматических установок пожаротушения. Часть 2. Проектный пожар и безопасность применения

Критерий «максимальный проектный пожар» может использоваться для обоснования эффективности автоматической установки пожаротушения (АУП). Он выбирается из анализа сценариев и динамики развития пожара, представляет собой пожар, наиболее сложный для пожаротушения с помощью АУП. Безопасность огнетушащих газов зависит от их свойств. СО и хладон 114В2 являются наиболее опасными огнетушащими газами. Типовое проектирование АУП не учитывает специфические особенности объектов защиты. Обоснованный выбор АУП должен осуществлять только высококвалифицированный специалист, прошедший соответствующее обучение.The criterion «maximum design fire» is used to justify the effectiveness of automatic fire extinguishing installation (AUP). It is based on the analysis of fire development scenarios and found the most difficult fire for fire-extinguishing with AUP. The safety of extinguishing gases depends on their properties. CO and freon 114B2 are the most dangerous fire extinguishing gases. Typical design of AUP does not take into account the specific features of objects of protection. Reasonable choice of AUP should be made only by a highly qualified specialist after the appropriate training.

ESTUDO DA CAPACIDADE DE REGULARIZAÇÃO DE VAZÃO NA BACIA DO RIBEIRÃO SÃO BARTOLOMEU VISANDO ABASTECIMENTO PÚBLICO

O objetivo do presente trabalho foi avaliar a viabilidade de implantação de novos reservatórios de regularização de vazões na bacia do ribeirão São Bartolomeu, Minas Gerais, Brasil. Foram estudadas duas regiões para implementação de novos reservatórios. O cálculo da capacidade máxima de regularização foi realizado com base na metodologia conhecida como diagrama de massas. Para o dimensionamento da estrutura de emergência, foi realizado o cálculo da vazão máxima de projeto a partir do método racional modificado. A vazão média evaporada do período de estudo resultou em 4,5 L s-1 e 1,0 L s-1 para os reservatórios. Foram obtidos volumes úteis de 375.216 m³ e 66.596 m³ e profundidades máximas de 16,2 m e 17,7 m. As áreas dos espelhos de água equivaleram a 93.348 m² e 18.041 m². Tendo em vista o quadro de escassez hídrica no município de Viçosa, recomenda-se a implantação de um dos reservatórios, com aumento da disponibilidade hídrica para fins de abastecimento público. Entretanto, são necessários maiores estudos em relação à potencialidade de aumento dos conflitos por recursos hídricos na bacia. Adicionalmente, ressalta-se a necessidade da avaliação de potenciais alterações na qualidade da água do rio a jusante dos reservatórios propostos.Palavras-chave: disponibilidade hídrica; ponto de captação; reservatórios. STUDY OF FLOW REGULATION CAPACITY IN THE SÃO BARTOLOMEU RIVER BASIN FOR WATER SUPPLY ABSTRACT: This paper aimed to evaluate the viability of the implementation of new reservoirs to regulate flow in the São Bartolomeu river basin, Minas Gerais, Brazil. Two regions were studied. The maximum regularization capacity was calculated based on the methodology known as mass diagram. For the dimensioning of the emergency structure, the maximum design flow was calculated from the modified rational method. The mean evaporated flow of the study period resulted in 4.5 L s-1 and 1.0 L s-1. Useful volumes of 375,216 m³ and 66,596 m³ and maximum depths of 16.2 m and 17.7 m were obtained. The water mirrors areas obtained for the new dams amounted to 93,348 m² and 18,041 m². Considering the situation of water scarcity in the municipality of Viçosa, it is recommended to install one of the proposed reservoirs, with increased availability of water for public supply. However, further studies are needed regarding the potential for increasing conflicts over water resources in the basin. In addition, the need to evaluate changes in river water quality downstream the proposed reservoirs is emphasized.Keywords: water availability; catchment point; reservoirs.

Genetic Algorithm Coupled with the Krawczyk Method for Multi-Objective Design Parameters Optimization of the 3-UPU Manipulator

SUMMARYIn this paper, a multi-objective design optimization of the 3-UPU translational parallel manipulator is presented. Based on a new algorithm, which combines the genetic algorithms and the Krawczyk operator, the robot position error is minimized and the robot design parameters tolerances are maximized, simultaneously. The results show that the designer can maintain the manipulator accuracy by using a specific size of the base, and can restrict its tolerance even by enlarging the actuators’ tolerance intervals. This algorithm is also used to determine the maximum design parameters tolerances for an allowable robot position error. The proposed algorithm can be extended to optimize other types of robots.