The international standard ISO 13822 provides procedures for the reliability assessment of existing structures including the application of probabilistic methods. Probabilistic approach facilitates to decide about new exploitation of existing structures. Application of probabilistic methods for the reliability assessment of existing structures is shown on the example of deteriorated balcony beams.
Reliability Assessment of Existing Concrete Bridges
The remaining working life of an existing reinforced concrete bridge is analysed considering the serviceability limit states of crack width. Two new models of crack width provided Eurocode EN 1992 and in the Model Code 2010 are applied. The probabilistic methods of structural reliability are used for assessing the crack width limits and remaining working life of existing concrete bridges. It appears that the initial reliability with respect to the serviceability requirements resulting from the original design of the bridge seems to satisfy the required target reliability level recommended in Eurocodes. However, the reliability index significantly decreases with the reduction of the reinforcement area due to corrosion.
Presently the new generation of Eurocodes is under development. It is expected that the basis of structural design given in current EN 1990 will be considerably revised including the format for load combinations in the Ultimate Limit States and new categorisation of consequence classes for construction works. It is expected that the partial factors for self-weight of structural members could be reduced and factors for variable loads more differentiated. Calibration of partial factors should be performed for actions and materials including also structural glass and FRP polymers.
The article deals with two wells in the country of Brno-district (Brčálka well and Well Olšová). The aim of work was monitoring of elementary parameters of water at regular monthly intervals to measure: water temperature, pH values, solubility oxygen and spring yield. According to the client's requirements (Lesy města Brno) laboratory analyzes of selected parameters were done twice a year and their results were compared with Ministry of Health Decree no. 252/2004 Coll.. These parameters: nitrate, chemical oxygen demand (COD), calcium and magnesium and its values are presented in graphs, for ammonium ions and nitrite in the table. Graphical interpretation of spring yields dependence on the monthly total rainfall and dependence of water temperature on ambient temperature was utilized. The most important features of wells include a water source, a landmark in the landscape, aesthetic element or resting and relaxing place. Maintaining wells is important in terms of future generations.
The assessment of existing components of power producing facilities is based on probabilistic methods of the theory of reliability provided in Eurocodes and ISO standards. An example of quickclosing valves in a selected hydroelectric power plant indicates the assessment of reliability and the prediction of the remaining working life of a structural component for the considered model of corrosion.
The contribution is focused on quantifying model uncertainty of crack width estimates for reinforced concrete beams. Predictions obtained by the model provided by the fib Model Code 2010 are compared with results of tests of beams having different longitudinal and shear reinforcement ratios and concrete cover. Trends of model uncertainty with basic variables are investigated.
The contribution is focused on reliability of balcony girders of a Czech national heritage monument. As preliminary reliability assessment suggests insufficient resistance, a series of nondestructive tests supplemented by a single tensile test are performed and evaluated by the statistical methods. Values of material properties, recommended in standards for historic materials, seem to be overly conservative and it is advised to specify properties of historic metallic materials by tests.
The paper is focused on the deterioration of industrial reinforced concrete chimneys caused by carbonation. It is considered that a chimney has to be repaired when more than 30% of its surface is affected by visible corrosion-induced cracks. An optimal maintenance strategy aims at the postponement of this state beyond the intended service life of the chimney with minimum maintenance costs.
Jana Jaďuďová, Iveta Marková, Jana Hroncová Vicianová, Anna Bohers and Ivan Murin
The authors of the article consider regional labeling as a marketing tool which can contribute to the development of regional activities. These are focused mainly on traditional regional products and products. Their general popularity in prosperous regions is an important source of income for the inhabitants. In the less developed regions, it represents a significant stimulating tool of development. By means of a Slovak region of Gemer-Malohont as an example, the authors bring quantitative findings related to the preference of regional brands. They took into consideration the indicators of age, gender, education, monthly income and locality in connection with preference of regional products. They pointed to the fact that regional labeling has a mobilizing function to link and then jointly present its local activities. The behaviour of the population from the regions is an important recommendation for small producers and producers from less developed regions of Central Europe.
The target reliability levels recommended in national and international documents vary within a broad range, while the reference to relevant costs and failure consequences is mentioned only very vaguely. In some documents the target reliability index is indicated for one or two reference periods (1 year, 50 years or life-time) without providing appropriate links to the design working life. This contribution attempts to clarify the relationship between the target reliability levels, costs of safety measures, failure consequences, reference periods and the design working life