Anwendung des Penetrationsmodells von Chlorid bei der Beurteilung des Zustands beim Brückenmanagement

Although there is a large number of established Bridge Management Systems worldwide, there seems to be a lack of those that utilise the knowledge on material properties and environmental loading. Hence, as a supplement to current practice, the paper examines the use of the chloride ingress model, supported by the International Federation for Structural Concrete, for preliminary assessment in bridge management. The focus is set on analysing application of the model in realistic situations on existing concrete bridges for which the information on material and environmental properties is lacking.Iako se danas diljem svijeta primjenjuju brojni sustavi za gospodarenje mostovima, čini se da ipak nema dovoljno sustava u kojima bi se koristilo znanje o svojstvima materijala i opterećenju iz okoliša. U ovom se radu, kao doprinos sadašnjoj praksi, analizira primjena modela prodora klorida, što podržava Međunarodni savez za betonske konstrukcije, a koristi se za preliminarno ocjenjivanje u okviru gospodarenja mostovima. Prije svega, analizira se primjena modela u realnim situacijama za ocjenu postojećih betonskih mostova za koje ne postoje podaci o materijalima i svojstvima okoliša.Obwohl heute weltweit zahlreiche Brückenmanagementsysteme angewendet werden, scheint es jedoch nicht ausreichend Systeme zu geben, in denen die Kenntnisse über die Materialeigenschaften und die Umweltbelastung angewendet werden. In dieser Abhandlung wird als Beitrag zur aktuellen Praxis die Anwendung des Penetrationsmodells von Chlorid analysiert, was vom Internationalen Verband für Betonkonstruktionen unterstützt wird, und wird als vorläufige Beurteilung im Rahmen des Brückenmanagements angewendet. Zunächst wird die Anwendung des Modells unter realen Bedingungen für die Beurteilung der bestehenden Betonbrücken analysiert, zu denen Daten über die Materialien und die Umwelteigenschaften vorliegen.The authors would like to show their gratitude for the support received during the project “Life – Cycle Assessment for Railway Structures”, funded by the ÖBB-Infrastruktur Bau AG, Vienna. For the support in the analysis of existing standards, authors would like to express special appreciation to Smart Minerals GmbH

Inspection and lifetime assessment for arch bridges

Arch bridges made from nature stone nowadays are the oldest structures which are still in use on road and railway lines. With an average age of more than hundred years, these structures often are seen as historical important buildings. Most of them had been constructed during the great building period of roads and railways from the 1840ies to 1900. Lots of the considered nature stone bridges are constructed as circle or three center curve, some of them also in a parabolic form or catenaries or cycloide. The height of the apex cover varies in a large range. If masomy was appropriated, usually sand, chalkstone or clay bricks were used. For most bridges no observations of the material parameter are available, as a result the stone and the mortar strengths are unknown. Under the usage of the German railway company, there are more than 8000 arch bridges yet, although at local roads there is an additional unknown number of them. In Austria, the railway network, especially along the Southern railway line has around 1000 arch bridges in usage. In whole Europe, the stock of masomy railway bridges is estimated with around 70.000. In the course of route expansion plans in the past especially arch bridges have been replaced by new steel or reinforced concrete structures. Considerations of preservation, the budgetary situation of the rail and road operators, as well as a sustainable, resource efficiënt usage of resources and existing infrastructure are motivations to maintain and - if necessary - toughen up existing arch bridges. Therefore, the issues of sustainability, durability and serviceability become more important

Applied and research based performance indicator database for highway bridges across Europe

Publicado em "Life-cycle of engineering systems: emphasis on sustainable civil infrastructure: proceedings of the Fifth International Symposium on Life-Cycle Civil Engineering (IALCCE 2016), ISBN 978-1-138-02847-0"Structural codes provide several practical principles and application rules such as the use of protective systems for material exposed in aggressive environment, the construction detailing aimed at avoiding the initiation of degradation, the maintenance actions to be regularly performed. Each construction, during its life cycle, will face with deterioration depending on several factors such as the environmental condition, the natural aging, the quality of the material, the execution of works and the planned maintenance. Therefore, several design procedures based on the prediction of the deterioration that will likely act on the structure will be developed in the framework of the international research. In addition, performance indicators for the present and future structural conditions on deterministic and probabilistic level will be defined and determined. It is extremely important to analyse such indicators in terms of used assessment frameworks, and in terms of the quantification procedure itself.COST (European Cooperation in Science and Technology

Measurement of corrosion rates on reinforcement using the field test

Reinforcement corrosion is a phenomenon that affects not only the durability and serviceability of the structure itself but the economy of the countries, as well. In many cases, structures and bridges must be repaired or reconstructed as a result of corrosion of the reinforcement. In extreme cases, when maintenance is neglected, it is necessary to completely replace the structures with new ones, even if their planned service lifetime has not been reached - it is not enough to strengthen them or it is economically inefficient. Corrosion of the reinforcement primarily causes a reduction in the cross-sectional resistance of the load-bearing elements by reducing the cross-sectional area of the reinforcement, which means a reduction in the force in the reinforcement that it transmits. For this reason, it is necessary to know the rate of corrosion over time depending on the environment in which the element is located. The paper is focused on the experimental measurements of corrosion losses due to atmospheric corrosion on reinforcement samples using the field test. As a part of experimental measurements, corrosion rates on reinforcements of four diameters (diameters 6, 10, 14, and 25 mm) of steel for reinforcement, grade B 500B, are monitored at measuring stations and bridges in various aggressive environments.This research was supported by Research Projects No. 1/0623/21 of the Slovak Grant Agency

Value of information (VoI) for the chloride content in reinforced concrete bridges

The corrosion of reinforcement caused by chloride ingress significantly reduces the length of the service life of reinforced concrete bridges. Therefore, the condition of bridges is periodically inspected by specially trained engineers regarding the possible occurrence of reinforcement corrosion. Their main goal is to ensure that the structure can resist mechanical and environmental loads and offer a satisfactory level of safety and serviceability. In the course of assessment, measuring the chloride content, through which corrosion could be anticipated and prevented, presents a possible alternative to visual inspections and corrosion tests that can only indicate already existing corrosion. It is hard to determine the cost-effectiveness and actual value of chloride content measurements in a simple and straightforward way. Thus, the main aim of the paper was to study the value of newly gained information, which is obtained when a chloride content in reinforced concrete bridges is measured. This value was here analyzed through the pre-posterior analysis of the cost of measurement and repair, taking into account different types of exposure and material properties for a general case. The research focus was set on the initiation phase in which there are no visible damages. A relative comparison of costs is presented, where the cost of possible reactive/proactive repair was compared with the maximum cost of measurement, while the measurement is still cost effective. The analysis showed a high influence of the initial probability of depassivation on the maximum cost of the cost-effective measurement, as well as a nonreciprocal relation of the minimum cost of cost-effective reactive repair with the measurement accuracy.The author would like to acknowledge the financial and educational support from the COST TU 1402 Action (www.cost-tu1402.eu), received through the Training School grant

Gamma prediction models capturing the long term creep shrinkage performance of segmentally-erected prestressed box girder bridges

For creep-sensitive structures like statically in determined large bridges, it is essential to implement an efficient and realistic creep model for example in 3D Finite element considerations. Concrete creep, characterized by the gradual strain growth with time under a unit sustained stress applied at age t’, is generally calculated based on the given compliance function J(t, t’), where t is the current time. For stress level within the designed service strength, the concrete creep is assumed to follow the constitutive law of ageing linear viscoelasticity. In order to systematically study the main influence factors on bridge deflection measurements, which are known to show large scatter, a probabilistic analysis can be performed. Due to the associated computational costs such investigation are limited. The predictions based on these large-scattering basic variables (model inputs) are fraught with uncertainties and accordingly there is interest in alternative prediction models decoupled from complex analytical and numerical models, using measured structural responses. Gamma process considerations are such alternative methods. These approaches are suitable for capturing the structural behavior, like crack formation, bending, and surface strain, as well as previously mentioned long term creep shrinkage performance (can also be captured by traditional inspection and/or monitoring methods). The objective of this contribution is to illustrate the use of gamma process approaches for the prediction of the creep shrinkage performance of complex pre-stressed concrete bridges that incorporates uncertainties and makes predictions in terms of load rating and system-level more reliable with the help of structural health monitoring (SHM) data. The creep-shrinkage response of a statically in determined three span boxgirder bridge extracted (a) from a complex finite-element (FE) model, which is based on the gradual strain growth concrete creep, and (b) from structural health monitoring data, serves for the calibration and verification of the considered gamma process approaches. Finally, The ability of the Gamma process approaches to capture complex creep shrinkage processes in complex statically in determined will be critically examined

Probability and sensitivity analysis of strain measurements in FRP

Monitoring is an important issue for FRP strengthening systems in order to control their health state. Strain gauges are often used for this aim, but the measures to be utilised can be affected by various factors. In this paper the influence of various factors is taken into account, such as the characteristics of resin coating, the type of glue and the gauge length. The theoretical approach developed in previous work performed on a deterministic basis is extended here to the probabilistic field. The objective is to make a sensitivity analysis of the basic variables which can cause errors in strain measurements. Additionally, the effect of the deviation of the direction of the gauges from the longitudinal direction of the FRP sheets is considered and the existing approach is extended to take this into account. Copyright © 2004 John Wiley & Sons, Ltd

El parentesco: textos fundamentales

En el conjunto de trabajos compilados se encuentran todos los problemas empíricos y teóricos capitales de los estudios del parentesco: su relación con la organización social (Tylor, Durkheim, Rivers); el análisis de las terminologías (Kroeber, Lounsbury); la relación de las mismas con las formas sociales (Kroeber, Rivers); la teoría extensionista (Evans-Pritchard); la del linaje (Goody) y la de la alianza (Lévi-Strauss, Needham), son los más importantes. Asimismo, están representadas la mayoría de las regiones del planeta: Oceanía (Durkheim, Needham), Asia (Dumont, Radcliffe-Brown), África (EvansPritchard, Goody) y las Américas (Kroeber, Eggan, Radcliffe-Brown, LéviStrauss, Lounsbury)

fib models for modeling of chloride ion ingress and concrete carbonation: Levels of assessment of input parameters

Degradation processes affecting structural materials, such as chloride ion ingress, concrete carbonation, and the subsequent corrosion of reinforcement, are limiting factors for the service life of reinforced concrete structures and/or structural elements. The objective of a structural condition assessment is to determine the current state and estimate the future performance of a structure with a maximum degree of accuracy and a minimum of effort. There is therefore a need for advanced methodologies and predictive deterioration models for the assessment of structures/structural elements over time. In the paper, the focus is on the widely accepted models for modeling of chloride ion ingress into concrete and concrete carbonation process incorporated in the fib Model Code 2010. Three levels of assessment of input parameters are presented, starting with simple quantification based on codes/literature recommendations and progressing to higher levels of assessment using design documentation and visual inspection data, additional on-site measurements, and/or laboratory tests