Data science

F - 16 Numerical investigation of shear cracking in concrete beams

Task
1 Objectives

The maintenance and assessment of bridge infrastructure is critical to the economy, as these structures are vital for transportation and commerce Many concrete bridges are aging and may not comply with modern technical standards due to outdated design methods and increased traffic loads. One of the failing mechanisms detected when recalculating existing bridges in accordance with the recalculation guidelines is insufficient shear load-bearing capacity, leading to the premature demolition of numerous bridges.

This project aims to model concrete beams with varying lengths and reinforcement ratios using ATENA software to simulate and analyze shear cracking behavior. The objective is to develop a reliable numerical model that accurately predicts shear cracking, providing a foundation for future experimental testing.

2 Working program
Based on the key aspects, the following tasks should be solved:

• Literature review on shear cracking in concrete.
• Literature review on ATENA software and shear modeling parameters.
• Development of a numerical model with ATENA software
• Evaluation of shear cracking patterns
• Perform parametric studies
• Summarize all the results to draw conclusions and outlooks.

Contact person:
Kleo Lila, M.Sc.
Phone: +49 351 463-40471
E-Mail:

F - 15 Measurement of crack propagation in cyclic loaded, repaired steel components

For the repair of fatigue cracks in steel components, adhesively bonded laminates made of carbon fiber-reinforced plastic (CFRP) offer particular potential due to their high stiffness and weight-specific strength. To strengthen trust in this innovative repair method, it is necessary to monitor crack propagation in the repaired component on the real structure and replicate it in the laboratory. However, the problem is that the steel component surface is covered by the CFRP laminate and therefore not accessible. This is where the work comes in.

As part of the work, strategies for tracking crack propagation under both laboratory conditions and application on a real structure will be developed and experimentally investigated. The accuracy, reliability, and consistency of the measurement and analysis methods will be highlighted through method validation. The objectives of the work are to derive a preferred methodology for the detection of crack propagation in repaired steel components, experimentally test the influencing factors for this variant, and create a procedural instruction for the optimal application of the measurement methodology.

Details of the task will be specified prior to commencement.

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

F - 14 Einfluss der Messdatenqualität auf die messwertgestützte Nachweisführung

Durch sensorische Überwachung von Brückenbauwerken können Tragfähigkeiten und Einwirkungen realitätsnäher abgebildet und damit rechnerische Sicherheitsdefizite vermieden werden. Jedoch fehlen in den Regelwerken konkrete Empfehlungen für die Durchführung messwertgestützter Nachweise. Auch der Umgang mit Messunsicherheiten in Kombination mit dem Sicherheitskonzept ist nicht geregelt. Im Rahmen der Diplomarbeit sind Anforderungen an die Messdaten für ihre Weiterverwendung in der Nachweisführung zu spezifizieren. Sowohl die Datenqualität als auch der Messumfang können einen erheblichen Einfluss auf die Nachweisführung haben. So können bspw. ungenau oder fehlerhaft arbeitende Sensoren den Tragsicherheitsnachweis beeinflussen. Es muss definiert werden, welche Qualitätskriterien für Nachweise erforderlich sind und wie diese beschrieben werden können, sodass eine Berücksichtigung der Messdatenqualität im darauffolgenden Berechnungsprozess erfolgen kann.

Folgende Teilaufgaben können in Projekt- und Diplomarbeiten bearbeitet werden:

• Recherche möglicher Qualitätskriterien für Messdaten an Brücken
• Recherche gängiger Methoden und Algorithmen für die automatisierte Bewertung der Daten hinsichtlich ihrer Qualität
• Validierung der Qualitätskriterien und ausgewählter Algorithmen anhand von realen Messdaten
• Prüfung der Auswirkungen der variierenden Messdatenqualität und des Messumfangs auf Nachweisergebnisse für ein Versagensmechanismus
• Prüfung der Kompatibilität entwickelter Konzepte mit den bestehenden Normen und Regelwerken.

Die konkrete Aufgabenstellung wird nach Rücksprache individuell ausgearbeitet.

Ansprechpartnerin:
Dipl.-Ing. Maria Walker
Tel.: +49 351 463 39820
E-Mail:

F - 13 Measuring multi-dimensional tension and strain fields in concrete structures with distributed fiber optic sensors

Fiber optic sensors make quasi-continuous strain measurements possible. Therefore, this measurement technique has a great potential for monitoring the behavior of structures, such as global deformations. By mounting those linear sensors in a mesh-like manner, the three-dimensional deformation state of the structure can be detected.
Hence, approaches to estimate two- and three-dimensional strain, stress and deformation fields from linear strain data are to be developed in this thesis (Projekt- and/or Diplomarbeit/master’s thesis). The algorithms are to be implemented into a Python software framework and validated by means of experimental data.

The work consists of the following tasks:

• Literature research regarding distributed fiber optic sensors and efficient mapping approaches
• Implementation of (geo-referenced) localization and orientation of the fiber optic sensor in three-dimensional space
• Linking the sensor to virtual models of the structure
• Reconstruction of the strain field of the structure by means of interpolation or numerical deformation calculations
• Calculation of the stress field and deformation state by means of analytical or numerical methods
• Implementation of the (analytical) algorithms into the Python software framework
• Validation of the developed methods using experimental data

Details of the task will be refined prior and while working on the project. Interest/experience in software development/programming is advantageous.

Contact Person:
Dipl.-Ing. Bertram Richter
Phone: +49 351 463-32822
E-Mail:

F - 12 Development of strain transmission model for distributed fiber optic sensor data on concrete structures

Fiber optic sensors make quasi-continuous strain measurements possible. Therefore, the interest in deployment of this measurement technique grows for structural health monitoring, especially for crack width monitoring. Concrete shows long-term load induced and load independend behaviour. Real structures are subject to temperature fields. These influences alter measured strain signals and need to be compensated for a monitoring from the first hour.

Hence, approaches to compensate alduterating influences are to be developed in this thesis (Projekt- and/or Diplomarbeit/master’s thesis). The algorithms are to be implemented into a Python software framework and validated by means of experimental data.

The work consists of the following tasks:

• Literature research regarding long-term and temperature behavior of distributed fiber optic sensors and concrete
• Development of a numerical model to investigate the temperature fields and long-term behavior of a concrete structure
• Development of compensation approaches
• Implementation of the algorithms into the Python software framework
• Validation of the developed methods using experimental data and the numerical model

Details of the task will be refined prior and while working on the project. Interest/experience in software development/programming is advantageous.

Contact Person:
Dipl.-Ing. Bertram Richter
Phone: +49 351 463-32822
E-Mail:

F - 11 Development of optimal gage distance for distributed fiber optic sensors

Fiber optic sensors make quasi-continuous strain measurements possible. Therefore, the interest in deployment of this measurement technique grows for structural health monitoring, especially for crack width monitoring. The density of the virtual measurement points influences the data quality and is suspected to have an optimum. Small distances result in large data amounts and increased noise. Larger distances make missing out data more likely and the detectability of cracks might decrease due to smearing. The optimal resolution is dependent on several factors (e.g., sensor type, application method, expected loading of the specimen).

Hence, approaches to estimate the optimal resolution are to be developed in this thesis (Projekt- and/or Diplomarbeit/master’s thesis). The algorithms are to be implemented into a Python software framework and validated by means of experimental data.

The work consists of the following tasks:

• Literature research regarding distributed fiber optic sensors
• Investigation of the relation of crack widths and maximum of the according strain peak
• Development of strain peak approximation with suitable function types taking influencing parameters into account
• Development of an estimator for the optimal measurement resolution
• Implementation of the algorithms into the Python software framework
• Validation of the developed methods using experimental data

Details of the task will be refined prior and while working on the project. Interest/experience in software development/programming is advantageous.

Contact Person:
Dipl.-Ing. Bertram Richter
Phone: +49 351 463-32822
E-Mail:

F - 10 Quality measures for distributed fiber optic sensor data

Fiber optic sensors make quasi-continuous strain measurements possible. Therefore, the interest in deployment of this measurement technique grows for structural health monitoring, especially for crack width monitoring. The quality of the resulting data depends on several faktors (sensor type, application method, measurement settings, etc.). Different sensor applications and their fitners for crack width monitoring were investigated. Due to missing quality measures, objective assessments are not yet possible.

Hence, such quality measures for fiber optic sensor data are to be developed in this thesis (Projekt- and/or Diplomarbeit/master’s thesis). The algorithms are to be implemented into a Python software framework and validated by means of experimental data.

The work consists of the following tasks:

• Literature research regarding distributed fiber optic sensors and data quality measures
• Discussion of existing approaches for quality assessment and development of own approaches
• Development of quality measure for technical disturbances (noise, errors, missing data)
• Development of quality measure for strain peaks (detectability, stability)
• Implementation of the algorithms into the Python software framework
• Validation of the developed methods using experimental data
• Analysis of the experiments regarding data qualtity and deriving setup recommendations

Details of the task will be refined prior and while working on the project. Interest/experience in software development/programming is advantageous.

Contact Person:
Dipl.-Ing. Bertram Richter
Phone: +49 351 463-32822
E-Mail:

F - 9 Preprocessing of distributed fiber optic sensor data

Fiber optic sensors make quasi-continuous strain measurements possible. Therefore, the interest in deployment of this measurement technique grows for structural health monitoring, especially for crack width monitoring. However, the resulting data is distorted by three different technological disturbances. These need to be cured before proceeding with further calculations (eg., crack width estimation). Especially under extrem loading, those disturbances accumulate up to the point, where the data becomes unusable.
Hence, approaches to cure those disturbances are to be developed in this thesis (Projekt- and/or Diplomarbeit/master’s thesis). The algorithms are to be implemented into a Python software framework and validated by means of experimental data.

The work consists of the following tasks:

• Literature research regarding distributed fiber optic sensors and signal processing
• Discussion of existing approaches for anomaly detection and development of own approaches
• Discussion of existing approaches for reconstructing missing data and development of own approaches
• Implementation of the algorithms into the Python software framework
• Validation of the developed methods using experimental data

Details of the task will be refined prior and while working on the project. Interest/experience in software development/programming is advantageous.

Contact Person:
Dipl.-Ing. Bertram Richter
Phone: +49 351 463-32822
E-Mail:

F - 8 Investigations on near-crack bonding of distributed fiber optic sensors

Fiber optic sensors make quasi-continuous strain measurements possible. Therefore, the interest in deployment of this measurement technique grows for structural health monitoring, especially for crack width monitoring. The bonding behavior in the vicinity of concrete cracks is essential for a correct calculation. Initial crack formation with isolated, solitary cracks and final crack state with seamlessly neighboring crack differ fundamentally. For the latter, approaches with good results already exist in a Python software framework. However, determination of the integration limits for solitary cracks is yet to be developed.

Goal of the thesis (Projekt- and/or Diplomarbeit/master’s thesis) is the investigation of the bonding behavior of fiber optic sensors to concrete near cracks. An approach for the transfer length estimation, which works for both initial crack formation and final crack state shall developed. Compensatory measures for the tension stiffening in this transfer length are further developed. The algorithms are to be implemented into the Python software framework and validated by means of experimental data.

The work consists of the following tasks:

• Literature research regarding distributed fiber optic sensors and the their bonding behavior
• Development of a numerical model to investigate the strain transfer from the concrete into the sensor’s core
• Development of transfer length estimation for concrete cracks
• Investigation of tension stiffening near the crack’s surface and development of compensatory measures
• Implementation of the algorithms into the Python software framework
• Validation of the developed methods using experimental data

Details of the task will be refined prior and while working on the project. Interest/experience in software development/programming is advantageous.

Contact Person:
Dipl.-Ing. Bertram Richter
Phone: +49 351 463-32822
E-Mail:

F - 7 AI based design assistant für early stage bridge design

The thesis can be of different scope: (bachelor thesis), project thesis, diploma thesis or a combination. Detailing and structuring of the task will be done before the start of the project with the student depending on the individual interests. The work is integrated into the institute's internal research on the topic of "parametrization" and "artificial intelligence" in bridge design.

Generally, Bridge design is a creative process with multiple requirements and constraints. The design process is often manual and without (partially) automated support processes. Accordingly, it can be optimized and this is particularly important in times of high demand for new construc-tion and growing sustainability requirements. Bridge design takes place within given, multiple boundary conditions. In the "preliminary design" phase, a preferred variant must be found, taking into account important boundary conditions such as topography and the road profile. Methods of Artificial Intelligence (AI) and Machine Learning (ML) enable nowadays design assistance for general design methods and also for bridge design. Data from built bridges can be taken into account and new design proposals can be derived from them. However, built bridges may not always be optimized or the reasons for the design determination may be manifold and therefore not always explainable.

The aim of this work is to develop a digital design assistant for the preliminary design of a frame bridge using AI methods that suggests possible bridge variants for given boundary conditions.

The thesis is to be worked on in the following steps:

• Research and categorisation of AI methods for the design process
• Development of a parametric FEM optimisation model
• (Software: Grasshopper+Karamba+ e.g. Galapogos)
• Development of a data set of synthetic and real bridge designs of superstructures
• Analysing the synthetic database of optimised bridges for existing bridges (software: OrangeDataScience). For this purpose, a cluster analysis is to detect statical and constructive correlations. A correlation analysis should explain the correlations with the target variables for certain design parameters in more detail.

• Training of existing regression algorithms and evaluation of their reliability

Contact person:
Jakob Grave, M.Sc.
Phone: +49 30 2207-7774
E-Mail:

F - 6 Literature research on ageing phenomena in structural health monitoring systems

Metrological monitoring for infrastructure structures will play an increasingly important role in the future, as it enables continuous monitoring of the structure and the provision of information for digitalisation in the construction industry. Structures are nowadays monitored with so-called structural health monitoring systems. However, it is problematic that not only the structure but also the measuring system itself is subject to an ageing process, which reduces the measuring accuracy and thus the reliability of such systems. The difficulty lies in the fact that the measuring systems do not fail completely, but provide seemingly plausible, but faulty data.

Within the scope of a project or diploma thesis, a literature research on existing national and international research findings on ageing phenomena in measurement systems is to be carried out. Based on this, an experimental programme should be developed that takes into account different environmental influences such as temperature or humidity.

Contact person:
Jan-Hauke Bartels, M. Sc.
Phone: +49 351 463-36399
E-Mail:

F - 3 Literature research on the digital inventory methods of large infrastructure structures (applies to project work)

In the scope of the Priority Program 2388 "Hundred plus", the Nibelungen Bridge Worms has been selected as a validation structure. Accordingly, a monitoring system will be deployed on this bridge. In addition, a digital twin is to be developed.

As the central object of a digital twin, an accurate 3D model of the structure is very important. To create the 3D model of an existing structure, there are many optical technologies such as laser scanning, infrared scanning, and digital image correlation etc. In this project work, the state of the art in this field will be investigated and summarized. In addition, the different methods will be compared regarding their advantages and disadvantages, their time consumption, and their economic expenditure.

For more information on the 100+ priority program, please follow this link:
https://tu-dresden.de/bu/bauingenieurwesen/imb/forschung/spp-2388?set_language=en

Contact person:
Dr.-Ing. Chongjie Kang
Phone: +49 351 463-37305
E-mail:

F - 2 Description of ageing processes in strain gauges in structural monitoring systems

In the course of digitalisation in the construction industry, the digital twin is taking on an increasingly important role. This virtual image of the real structure enables, in addition to dimensioning, above all monitoring during the use phase. Since this phase takes up the largest part of the building's life, information about the condition of the building must be collected continuously. Monitoring systems that guarantee a lifelong link between the real and virtual systems are suitable for this purpose. Over time, the real supporting structure will change (e.g. due to ageing). This change must be reliably recorded by monitoring and transferred to the digital twin. However, monitoring systems are also subject to an ageing process. The quality of the monitoring system deteriorates significantly over the lifetime of the real structure in terms of data quantity and quality. One difficulty is that components of the measuring system do not immediately fail completely, but the system still delivers seemingly plausible, but erroneous data.

In the course of the student work, it is to be shown how the functioning of monitoring system components (strain gauges, cables, measuring amplifiers, A/D converters) can be physically described. Which measuring system components are subject to a notable ageing process? What are useful methods for describing these ageing processes? Which signal analyses are suitable for measurement data evaluation? In order to answer these questions, different signal analysis procedures for ageing-related changes in the measured values of strain gauges are to be investigated.

Depending on the progress of the project and the interests of the students, the following subtasks can be worked on:

• Evaluation of time-independent laboratory tests with different influencing parameters such as cable length and temperature as well as the physical description of the measurement system components.
• Evaluation of time-dependent, mechanically unloaded laboratory tests with different influencing parameters such as time, cable length, humidity, etc.

Evaluation of time-dependent, mechanically loaded laboratory tests with different influencing parameters such as time, cable length, force, air humidity etc.

Contact person:
Jan-Hauke Bartels, M. Sc.
Phone: +49 351 463-36399
E-Mail:

F - 1 Damage assessment of cyclically loaded concrete structures with ultrasonic measurements

Concrete structures under a given load do not fail because they abruptly change from a "normal" state to a fracture state, but because the degradation process progresses with increasing load until material failure occurs. When subjected to mechanical loads, stresses first concentrate around material defects or interfaces at the microscale, destroying bonds between individual molecules. With increasing mechanical load, the microcracks then grow and unite, leading to the formation of macrocracks. During this process, the lattice structure of the material, which serves as a propagation medium for the stress waves of an ultrasonic pulse, is progressively changed and in this way the damage can be detected.

The objective of this thesis is to relate ultrasonic measurements of degradation evolution from concrete specimens and beams subjected to cyclic loading to hypotheses of damage accumulation. From these correlations and using concepts of robustness and redundancy, safety factors will be determined and the remaining useful life will be evaluated.

Contact person:
Raúl Enrique Beltrán Gutiérrez, M. Sc.
Phone: +49 351 463-33675
E-Mail: