Dall'Italia al Lussemburgo. Storia della mia famiglia

Book published by Metauro Edizioni (2011)

Damage assessment of a gradually damaged pre-stressed concrete bridge using static load tests and non-linear vibration characteristic

in International Conference on Noise and Vibration Engineering (2008)

Damage Assessment of Civil Engineering Structures by the Observation of Non-linear Dynamic Behaviour

in Proceedings of the International Conference on Experimental Vibration Analysis for Civil Engineering Structures (2007)

Damage assessment of concrete structures through dynamic testing methods. Part 1 - Laboartory Test

in Journal of Engineering Structures (2012), 34

The present paper is split into two parts: Part 1 is about laboratory tests whereas the second part deals with experiments on real bridges. This article aims at summarizing several experimental dynamic ... [more ▼]

The present paper is split into two parts: Part 1 is about laboratory tests whereas the second part deals with experiments on real bridges. This article aims at summarizing several experimental dynamic testing methods with different damage indicators to evaluate the state of prestressed as well as of passively reinforced concrete structures. First the differences between prestressed and passively reinforced concrete are repeated for static behavior, before the transition to dynamics is made. As it will be proved in the following that the amount of nonlinearities increases with damage, harmonic excitation is favorable to realize good testing conditions. It is applied to visualize variations in linear as well as in non-linear structural characteristics, which are subsequently used as damage indicators, e.g. the drop of the eigenfrequencies, the changes in damping and modeshapes, the occurrence of higher harmonics and a varying dependency of the eigenfrequency on excitation force amplitude. These different indicators will be used on passively reinforced beam elements and industrially produced prestressed slabs in the first part and on two real post-tensioned bridges in the second part. All these structures were in good order and condition before artificial damage was applied in multiple steps and the sensitivity of each damage indicator was analyzed. [less ▲]

Damage detection for bridge structures based on dynamic and static measurements

Scientific Conference (2016, March)

Some results of damage detection for real bridge structures are reported in the present paper based on both dynamic and static measurements. Dynamic analysis relates to the identification of modal ... [more ▼]

Some results of damage detection for real bridge structures are reported in the present paper based on both dynamic and static measurements. Dynamic analysis relates to the identification of modal parameters and deduced variables… The processing of static data is based on the analyses of deflection line and its derivatives, i.e. slope and curvature. Detection methods were applied in several real concrete bridges in Luxembourg. The results are encouraging and useful for Structural Health Monitoring in civil engineering structures. [less ▲]

Damage detection in prestressed concrete bridges based on static load testing, sagging and modal parameters, using measurements and model updating

Doctoral thesis (2017)

Bridges are an essential part of nowadays infrastructure to cross natural and artificial obstacles like rivers, valleys or other roads and railways. Many concrete bridges were built in the last 70 years ... [more ▼]

Bridges are an essential part of nowadays infrastructure to cross natural and artificial obstacles like rivers, valleys or other roads and railways. Many concrete bridges were built in the last 70 years. The traffic density has increased immensely over the last decades and the bridges are suffering from corrosion and wear. Nevertheless, the safety of the infrastructure has to be guaranteed and therefore it is very important to find efficient methods for structural health monitoring. For this purpose, visual inspections are the most widely adopted in reality today. Considering the size of most bridge structures, it is understandable that these tests are generally very time-consuming and many personnel are needed, so they are cost-intensive. However, it is not always guaranteed that all damage can be found as only the surface is accessible. For instance, internal damage, such as corrosion of passive reinforcements or prestressed tendons, is difficult to detect. In addition, small cracks can remain undetected when covered by paints or dirt. Therefore, it is important to complement the standard methods with advanced alternatives. The aim is therefore not necessarily to replace visual inspections, but rather to find efficient methods for amendment. An idea being vigorously discussed in the scientific community is based on vibration measurements of a structure to assess its dynamic behaviour. The occurrence of damage will change the system properties, as it changes above all the stiffness distribution. So the system identification process in principle allows detection of changes of eigenfrequencies and hence stiffness. The main problem in practice on real bridges is that the robustness of a method is often insufficient, as the measured parameters are often also influenced by temperature changes. It will be shown that the impact of temperature change, e.g. between night and day, on the system properties is much higher than the influence of small damage. Furthermore, changes in soil and bearing conditions between different seasons can play a role. These environmental effects have to be taken into account while performing measurements for damage assessment. For this purpose, strategies are proposed to compensate environmental effects. Therefore, this thesis focuses on measurements under real environmental conditions, outside a laboratory. Different methods for damage assessment or stiffness tracking based on measured static and on dynamic properties of structures are deployed. Finally, the measured and analysed physical properties of the bridges in this thesis are: eigenfrequencies, mode shapes, sagging under own weight and the deflection line under a static test-loading. These quantities are tracked and artificial damage is introduced stepwise to a test-beam of a real bridge. Damage assessment and localisation is tried directly with the measured quantities but also by model-updating of a finite element model. This solid model is divided in a special way in different slices. It is possible to change the stiffness distribution along the axis of the simulated beam by varying the Young’s moduli of these slices. Furthermore, to reduce the number of free parameters for the subsequent up-dating process, an exponential damage function is introduced that describes the stiffness distribution. At first, the model was designed to fit a healthy reference state. Now measurement data from the artificially damaged test-beam are introduced and the model is updated by changing the Young’s moduli of the slices to minimise a special objective function containing the measured and simulated physical quantities. The comparison of initial and updated model allows a quantification and localisation of damage. Finally, the slice width is reduced around the identified damage region to improve the process. [less ▲]

Damage Identification and Localisation Using Changes in Modal Parameters for Civil Engineering Structures

in Proceedings of the International Conference on Noise and Vibration Engineering (2012)

Damage tolerance assessment directly from CAD: (extended) isogeometric boundary element methods (XIGABEM)

Scientific Conference (2014)

DaMAT: A Data-driven Mutation Analysis Tool

in Proceedings of the 45th International Conference on Software Engineering (ICSE ’23) (in press)

We present DaMAT, a tool that implements data- driven mutation analysis. In contrast to traditional code-driven mutation analysis tools it mutates (i.e., modifies) the data ex- changed by components ... [more ▼]

We present DaMAT, a tool that implements data- driven mutation analysis. In contrast to traditional code-driven mutation analysis tools it mutates (i.e., modifies) the data ex- changed by components instead of the source of the software under test. Such an approach helps ensure that test suites appropriately exercise components interoperability — essential for safety-critical cyber-physical systems. A user-provided fault model drives the mutation process. We have successfully evalu- ated DaMAT on software controlling a microsatellite and a set of libraries used in deployed CubeSats. A demo video of DaMAT is available at https://youtu.be/s5M52xWCj84 [less ▲]

Damnation et salut babélique dans le théâtre luxembourgeois

in Synergies Pays Germanophones (2015)

La situation sociolinguistique du Grand-Duché du Luxembourg n’est pas sans laisser de trace dans son champ littéraire. Trois langues y sont utilisées quotidiennement et simultanément. L’écrivain ... [more ▼]

La situation sociolinguistique du Grand-Duché du Luxembourg n’est pas sans laisser de trace dans son champ littéraire. Trois langues y sont utilisées quotidiennement et simultanément. L’écrivain luxembourgeois a le choix d’écrire dans l’une des trois langues, de les alterner ou de les mélanger à l’intérieur d’un même texte. Nous analyserons, dans cette brève étude, trois pièces de théâtre luxembourgeoises qui brassent les langues et déterminerons la fonction de cette polyglossie caractéristique du Luxembourg : de la mise en évidence de l’étrangéité d’un personnage, jusqu’à la mise en question d’une entente harmonieuse de différentes nations européennes dans une bousculade culturelle babélique. [less ▲]