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Fatigue of reinforced concrete is often not considered for civil engineering structures since the self-weights of reinforced concrete structures are very high (in case of normal strength concrete) while live loads are relatively small, which leads to very small stress variations during service duration of the structure. However, particularly for bridge structures with increased use of high strength concrete and increase in traffic loads, this scenario is reversed and fatigue verification becomes much more important for the safety. This paper presents a probabilistic approach for reliability assessment of existing bridges along with reliability-based calibration of fatigue-design-factors based on the S-N approach, calibration of S-N approach with fracture-mechanics approach and reliability updating using inspections along with a case study for the Crêt de l'Anneau viaduct in Switzerland. It has been observed that, a designer needs to design the structure for fatigue life of 3.5–4.5 times the planned service life, in order to achieve the target annual reliability index of 3.7 at the end of the service life. Further, the presented framework can easily be extended to any other viaducts to estimate the fatigue reliability and maintain the safety level throughout the entire service duration. [ABSTRACT FROM AUTHOR]

Damage detection of civil engineering structures is usually carried out by analysing the changes in vibration properties of the structures due to the effects of damage. However, these vibration properties are also affected by the environmental and operational conditions the structures face, which can create false alerts. To tackle these effects, it is proposed to consider damage detection as an outlier analysis case study in this paper. The observations obtained from the damaged condition of the structures have abnormal values of measurements (e.g. abnormal values of natural frequencies) and do not follow the pattern of the undamaged measurements obtained under different environmental and operational conditions. These damaged observations are similar to the outlier measurements. Both types of measurements do not follow the pattern of the normal observations. The COVRATIO statistic, which is usually used to identify outlier measurements, is proposed to be used in this paper to detect damage. The identified outlier measurements are then the damaged observations in this paper. A beam structure and the Z24 Bridge in Switzerland are analysed using the proposed method. The traditional regression damage detection method is also applied to both structures, and it is found that better results are obtained using the method proposed in this paper. 10% and 87% more damaged cases are detected in the beam structure and the Z24 Bridge using the proposed method, respectively. • Damage detection is affected by the environmental and operational conditions. • Damage detection is considered as an outlier analysis case study. • A method using the COVRATIO statistic is proposed for damage detection. • The proposed method successfully classified between undamaged and damaged cases. • The proposed method has better performance than the traditional regression method. [ABSTRACT FROM AUTHOR]

Rocks containing clay and anhydrite exhibit the property of increasing their volume by absorbing water. The paper first discusses the mechanisms causing swelling and outlines their effects on tunnels. Next the hazard scenario of heaving of the tunnel tube as a whole, the structural consequences of this and the concept of the Modular Yielding System for tunnelling in stretches where heave is unavoidable are discussed. Taking the case of the Chienberg road tunnel in Switzerland, the paper also reports on experience during construction and field measurements after putting the repaired sections into operation. Special attention is given to the technical aspects of yielding supports with cement as a basic constituent for loads up to 10 MN and a yielding capacity of up to 50 %. Ton- und anhydritführende Gesteine haben die Eigenschaft, ihr Volumen durch Aufnahme von Wasser zu vermehren. Der Beitrag behandelt einleitend die Mechanismen, die den Quellvorgang auslösen und die Auswirkungen des Quellvorgangs auf Tunnel. Anschließend wird das Gefährdungsbild der Hebungen der Tunnelröhre als Ganzes, deren Folgen auf die Tragkonstruktion und das Konzept des modularen Knautschsystems] für den Tunnelbau in unvermeidbaren Hebungsstrecken erörtert. Am Beispiel des Chienbergtunnels in der Schweiz wird auch über Bauerfahrung und Feldmessungen nach der Inbetriebnahme der sanierten Strecken berichtet. Besondere Aufmerksamkeit wird den technischen Merkmalen von Knautschkörpern auf Zementbasis für Belastungen von bis zu 10 MN und einem Stauchvermögen von bis zu 50 % gewidmet. [ABSTRACT FROM AUTHOR]

The construction of check dams is a common practice around the world where the aim is to reduce the damage by flooding events through mountain streams. However, quantifying the effectiveness of such engineering structures has remained very challenging and requires well-selected case studies, since the outcome of such an evaluation depends on site-specific geometric, geologic and climatic conditions. Conventionally, the check dams' effectiveness has been estimated using information about how the bedload sediment flux in the stream changes after the check dams are constructed. A permanent lowering of the bedload flux not only points to a success in reducing the probability of sediment transport occurrence but also implies that the sediment input through the system is likely to decrease. Here, we applied a method for data acquisition and two different equations (Meyer-Peter–Müller and Recking approach) to estimate and compare the sediment transport in a mountain stream in Switzerland under engineered and non-engineered conditions. Whereas the first equation is derived from a classical approach that is based on flume experiment data with a slope of less than 0.02 m m -1 , the second equation (Recking) has been derived based on a bedload field dataset comprising active mountain streams under steeper conditions. We selected the Guerbe (Gürbe) River situated in the Swiss Alps as a case study, which has been engineered since the end of the 19th century. This has resulted in more than 110 check dams along a ca. 5 km reach where sediment has continuously been supplied from adjacent hillslopes, primarily by landsliding. We measured the riverbed grain size, topographic gradients and river widths within selected segments along this reach. Additionally, a gauging station downstream of the reach engineered with check dams yielded information to calibrate the hydroclimatic situation for the study reach, thus offering ideal conditions for our catchment-scale experiment. Using the acquired data and the dataset about historical runoff covering the time interval between 2009 and 2021 and considering the current engineered conditions, we estimated a mean annual volume of transported bedload which ranges from 900 to 6000 m 3 yr -1. We then envisaged possible channel geometries before the check dams were constructed. We inferred (1) higher energy gradients which we averaged over the length of several check dams and which we considered a proxy for the steeper river slope under natural conditions; (2) channel widths that are smaller than those measured today, thereby anticipating that the channel was more confined in the past; and (3) larger grain size percentiles, which we consider to be similar to the values measured from preserved landslides in the region. Using such potential non-engineered scenarios as constraints, the two equations both point towards a larger sediment flux compared to the engineered state, although the results of these equations differed significantly in magnitude. Whereas the Recking approach returned estimates where the bedload sediment flux is ca. 10 times larger in comparison with the current situation, the use of the Meyer-Peter–Müller equation predicts an increase of ca. 100 times in bedload fluxes for a state without check dams. These results suggest that the check dams in the Guerbe River are highly efficient not only in regulating sediment transport by decreasing the probability of high sediment flux occurrence during torrential conditions but also in stabilizing the channel bed by avoiding incision. The most likely consequence is a stabilization of the terrain around such structures by reducing the activation of landslides. [ABSTRACT FROM AUTHOR]

Bridge managers, as other infrastructure managers, are increasingly required to justify the financial resources they need to perform preventative maintenance on bridges. This requires a demonstration of the current state of their bridges and the consequences if the preventative maintenance is not performed. The consequences can be expressed in terms of additional costs to the owner if unacceptable levels of failure risk are avoided. These demonstrations are complicated by the fact that many managers have only basic data with respect to the condition of their bridges, how deterioration processes will affect their bridges and on the type, cost and effectiveness of the interventions that will need to be performed on their bridges in the future. This, in many cases, makes it difficult to show that optimal intervention strategies are being followed and results in a less than convincing argument for the use of taxpayers' money. When less than the required funding is received, managers are forced to follow less than optimal intervention strategies, i.e. short term savings are exchanged for, often unknown, increased future costs. In this paper a general methodology is given that is currently being used in practice in Switzerland and France to determine the lowest cost intervention strategies of bridges with respect to gradual deterioration processes, their financial needs and the consequences, in terms of condition, if they are not followed. It is used when either sufficient detailed element level information or tools are not available to conduct such an analysis based on element level data. At a minimum, the methodology provides a way for managers to structure their technical knowledge and make logical, sound and repetitive estimates of required future financial resources. Additionally, however, it can be used to verify the base assumptions, e.g. speed of deterioration, used to make the estimates. As opposed to other methodologies used in similar situations, this methodology allows consideration of the uncertainty in the input parameters. An example is used to illustrate the type of results obtained using this methodology with normally existing data, as well as some potential uses of the results. [ABSTRACT FROM AUTHOR]

Since extreme values of climatic actions are commonly derived assuming the climate being stationary over time, engineering structures and infrastructures are designed considering design actions derived under this assumption. Owing to the increased relevance of the expected climate change effects and the correlated variations of climate actions extremes, ad hoc strategies for future adaption of design loads are needed. Moreover, as current European maps for climatic actions are generally based on observations collected more than 20 years ago, they should be updated. By a suitable elaboration of the projections of future climate changes, the evolution over time of climatic actions can be assessed; this basic and crucial information allows us to facilitate future adaptations of climatic load maps, thus improving the climate resilience of structures and infrastructures. In this paper, current trends of climatic actions in Europe, daily maximum and minimum temperatures, daily precipitation, and ground snow loads, are investigated based on available gridded datasets of observations (E-OBS) and regional reanalysis (Uncertainties in Ensembles of Regional Re-Analyses, UERRA), to assess their suitability to be used in the elaboration of maps for climatic actions. The results indicate that the E-OBS gridded datasets reproduce trends in extreme temperatures and precipitation well in the investigated regions, while reanalysis data, which include snow water equivalent, show biases in the assessment of ground snow load modifications over the years in comparison with measurements. As far as climate change effects are concerned, trends of variation of climatic actions are estimated considering subsequent time windows, 40 years in duration, covering the period 1950–2020. Results, in terms of factors of change, are critically discussed, also in comparison with the elaborations of reliable datasets of real observations, considering a case study covering Germany and Switzerland. [ABSTRACT FROM AUTHOR]

• Environmental conditions may not be available for damage detection of structures. • A regression-based damage detection method is proposed. • Natural frequencies of structures are used as the independent and dependent variables. • The proposed method can classify between damaged and undamaged states. • The proposed method has better performances than the traditional regression method. Damage detection of civil engineering structures during the past decade has focused on eliminating the effects of the changing environmental and operational conditions, from the effects of damage. In the literature, a regression analysis has been adopted to construct a model between the vibration properties of structures, and the environmental and operational parameters to represent the undamaged state of the structures, for damage detection. However, using the environmental and operational parameters in the analysis has several limitations. For example, these parameters are not always available which may affect the performances of the damage detection methods. Regression between the vibration properties only has also been proposed in the literature where multivariate statistical tools have been adopted to extract the relationships among the properties. However, these methods have the problem that it is more difficult to detect damage in the multivariate situations and a regression target is usually needed, which is difficult to determine. Therefore, a damage detection method which uses the simple regression analysis, is developed in this paper. The vibration properties of structures are used as both the independent and dependent variables in the developed method. This has the advantages that the environmental and operational conditions are not needed and the multivariate statistical tools are not required for data processing. The developed method is applied to a beam structure model and the Z24 Bridge, in Switzerland, and the results obtained demonstrate that the method can successfully classify between undamaged and damaged states. The traditional regression analysis method is also applied to the two structures and it was found that better results are obtained using the method developed in this paper. [ABSTRACT FROM AUTHOR]

This paper aims to employ a 2D thermo-mechanical multi-scale ASR model for the analysis of a concrete gravity dam in Western Switzerland. Simulation results are compared to the field measurements and observations. Analysis of the results reveals negligible effect of temperature variation on the ASR advancement. The difference in length between the upstream and the downstream faces is identified as the main source for the upstream drift at the level of the crest. Study of the structural effects reveals ASR-related expansion anisotropy and cracks alignment being more pronounced along the upstream part and the foundation. If the former is explained by the transmission of the self-weight, the latter is attributed to the constraining effect of the underlying rock. • Multi-scale numerical model for ASR-affected engineering structures is presented. • ASR-expansion rate at the meso-scale is made dependent on the temperature values. • A model of concrete Salanfe dam in Switzerland is calibrated with the field measurements. • The model shows low dependence of the ASR expansion rate on the temperature variation. • Anisotropic macroscopic deformations correlate with crack patterns at the meso-scale. [ABSTRACT FROM AUTHOR]

• Local out-of-plane buckling failures were observed for both specimens. • Out-of-plane displacements of 10–15% of the thickness could be sustained. • Global failure was caused by concrete crushing in the web for both specimens. • A small twist was applied to one specimen to determine torsional stiffness. • Rate of decay of torsional stiffness is equivalent to translational when centered. Reinforced concrete walls are commonly used to resist the lateral loading induced by wind and earthquake actions. While most walls include two vertical reinforcement layers, some regions of the world construct slender, non-rectangular concrete walls with a single vertical layer of reinforcement. The seismic performance of such elements is largely unknown given the paucity of experimental research. This paper presents the results of two slender reinforced concrete U-shaped walls tested at the Earthquake Engineering and Structural Dynamics Laboratory (EESD Lab), École Polytechnique Fédérale de Lausanne (EPFL) in Switzerland. Both wall specimens, designed similar to construction practice in Colombia, were tested using quasi-static cyclic loading to observe if out-of-plane instability would develop when deformations were limited to prevent the flange boundary ends crushing. Initial failure of both wall specimens corresponded with local out-of-plane buckling in the boundary ends of the flanges occurring on load reversal. The buckling lengths were approximately 700–800 mm, which corresponded to 44–50 bar diameters. The crack patterns were observed to be steepest in the web of the walls, demonstrating the increased shear demand in comparison to that of a rectangular wall. Both wall specimens reached ultimate drifts larger than 2.5–3.0% before global failure occurring in the web-flange intersection due to crushing. A small twist was subjected to one of the walls when centered and loaded diagonally, which showed that the decay in torsional stiffness is proportional to the decay in translational stiffness. [ABSTRACT FROM AUTHOR]

The article presents information related to the sixth CEB and fib International PhD Symposia in Civil Engineering organized by the Institute of Structural Engineering, Zurich, Switzerland, held from August 23 to 26, 2006. 121 contributions out of 140 abstracts submitted were admitted. Finally, eight-page paper were submitted by 81 of them. All participants had received a three day ticket for all public transport in the Zurich area.

The article offers information on the activities of the European Structural Integrity Society (ESIS) in 2008-2009. It states that the 17th European Conference on Fracture (ECF17) was held on September 2-5, 2009, in Brno, Czech Republic which was organized by ESIS Czech Chapter. It mentions that Griffith Medal was presented to Professor A. Carpinteri during the Social Dinner. It adds that the ESIS TC4 meeting on Polymers, Adhesives and Composites was held on September 11-12, 2008 in Switzerland.