Other topics

H - 10 Nachrechnung und Bewertung historischer Bemessungen von Festen Fahrbahnkonstruktionen

Die Feste Fahrbahn wird allgemein als bevorzugte Option für den Bau neuer Hochgeschwindigkeitsstrecken betrachtet. Die über 50-jährige Entwicklung dieser Technologie hat zu zufriedenstellenden Ergebnissen bei den derzeit eingesetzten Bauformen geführt. In der Entwicklungsgeschichte haben sich jedoch nicht alle Varianten als dauerhaft bewährt – in einigen Fällen kam es zu Schäden. Im Rahmen von Instandhaltungsmaßnahmen sind daher statische Nachrechnungen bestehender Konstruktionen erforderlich. Dafür müssen auch historische Bemessungsmethoden analysiert und nachvollzogen werden. Daraus ergeben sich folgende Themen und Aufgabenstellungen für Projekt- und Abschlussarbeiten (Master und Diplom), die individuell mit den Studierenden abgestimmt werden können:

• Literaturrecherche zur historischen Bemessung der Festen Fahrbahn (Deutschkenntnisse erforderlich)
• Parameterstudie zur Bemessung der Festen Fahrbahn gemäß DIN EN 16432-2 und Betonkalender 2015
• Nachrechnung historischer Feste-Fahrbahn-Konstruktionen
• Vergleichsstudie: Bemessung der Festen Fahrbahn nach DIN EN 16432 im Vergleich zu anderen Normen (z. B. Eurocode oder Model Code)

Ansprechpartner:
Dipl.-Ing. Franz Grützmacher
+49 351 463-40412

H - 8 Modeling of the thermal expansion of a concrete slab of a slab track structure

Slab track has established itself as the preferred option for the construction of new high-speed lines. The development of this technology over a period of more than 50 years has led to satisfactory results with the designs in use today. However, not every design has aged equally successfully during the development period. Some slab track designs show numerous damages or are in a condition that makes a replacement investment worth considering. In this context, the effect of temperature on the concrete base layer in particular is to be investigated in more detail. The determination of the thermal expansion is of particular interest as well as the occurrence of possible peak stresses.              

The present thesis deals with the following work packages:

• Comprehensive literature review on slab track structures and on thermal expansion or temperature effects
• Modeling of various slab track designs using different modeling approaches
• Implementation of the actions in the models
• Performing rough hand calculations to determine the magnitude of the action and checking them
• Comparison of the different modeling approaches and interpretation of the results

This investigation is carried out by means of software.

Contact person:
Dipl.-Ing. Franz Grützmacher
+49 351 463-40412

H - 6 Numerical study on different influences on fiber optic sensors

Full title: Numerical calculation on the influence of creep, shrinkage and pre-stressing on the measurement with fiber optic sensors

Unlike conventional strain gages, distributed fiber optic sensors (DFOS) enable quasi-continuous strain measurement along the sensor length. Due to the wide range of applications, e.g., to determine crack widths, prestressing losses, deflections, etc., DFOS offer enormous potential in structural health monitoring and can contribute to the preservation of aging infrastructure. For monitoring of existing structures, DFOS can be subsequently installed on the concrete surface. The crack widths can be determined by integrating the strain curve. In the case of subsequently applied DFOS, it must be clarified how initial strains from prestressing, creep and shrinkage can be considered in the methodology of crack width calculation.

Within the scope of the student work, numerical calculations are carried out on reinforced concrete and prestressed concrete components, taking into account the nonlinear and time-dependent material behavior of concrete. Based on the models, conclusions can be drawn about the influencing factors mentioned and suggestions for their compensation can be derived. The use of the FE software ATENA is recommended for the analysis.

Contact person:
Max Herbers, M.Sc.
+49 351 463-39620

H - 5 Influencing parameters for acoustic signals' transmission

Full title: Investigation of different influencing parameters for the transmission of acoustic signals in acoustic emission analysis (SEA)

Acoustic signals are everywhere in our life. In everyday life they can be processed by our brain to get the needed information, e.g. from a conversation. In construction, they can also be used in combination with various measurement techniques for building diagnostics. Sound emission analysis (SEA) is a non-destructive testing method that can draw conclusions about a change in the condition of the structure based on the analysis of the sound waves emitted by the structure.

For a successful building diagnosis, the quality of the measured signals is crucial, which can be influenced by many parameters. These parameters can basically be divided into three groups, the sound source in the building component, the propagation path of the acoustic signals from the source to the sensor, and the measurement system. While the first two depend on the material properties of the component, parameters from the last group, e.g. the coupling of the measurement sensor, can be influenced by the measurement setup. A good coupling not only ensures a good signal quality, but also the reproducibility of the measurements.

Within the scope of the project work, various influencing parameters such as coupling means, the contact pressure of the measuring sensor with respect to the sensor coupling are to be investigated by means of tests on small-format specimens.

Details of the task will be specified during the processing time.

Contact person:
Dipl.-Ing. Ronghua Xu
0351 463-33776