@article{ChowdhuryZabel, author = {Chowdhury, Sharmistha and Zabel, Volkmar}, title = {Influence of loading sequence on wind induced fatigue assessment of bolts in TV-tower connection block}, series = {Results in Engineering}, volume = {2022}, journal = {Results in Engineering}, number = {Volume 16, article 100603}, publisher = {Elsevier}, address = {Amsterdam}, doi = {10.1016/j.rineng.2022.100603}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20221028-47303}, pages = {1 -- 18}, abstract = {Bolted connections are widely employed in structures like transmission poles, wind turbines, and television (TV) towers. The behaviour of bolted connections is often complex and plays a significant role in the overall dynamic characteristics of the structure. The goal of this work is to conduct a fatigue lifecycle assessment of such a bolted connection block of a 193 m tall TV tower, for which 205 days of real measurement data have been obtained from the installed monitoring devices. Based on the recorded data, the best-fit stochastic wind distribution for 50 years, the decisive wind action, and the locations to carry out the fatigue analysis have been decided. A 3D beam model of the entire tower is developed to extract the nodal forces corresponding to the connection block location under various mean wind speeds, which is later coupled with a detailed complex finite element model of the connection block, with over three million degrees of freedom, for acquiring stress histories on some pre-selected bolts. The random stress histories are analysed using the rainflow counting algorithm (RCA) and the damage is estimated using Palmgren-Miner's damage accumulation law. A modification is proposed to integrate the loading sequence effect into the RCA, which otherwise is ignored, and the differences between the two RCAs are investigated in terms of the accumulated damage.}, subject = {Schadensakkumulation}, language = {en} } @article{HarirchianIsik, author = {Harirchian, Ehsan and Isik, Ercan}, title = {A Comparative Probabilistic Seismic Hazard Analysis for Eastern Turkey (Bitlis) Based on Updated Hazard Map and Its Effect on Regular RC Structures}, series = {Buildings}, volume = {2022}, journal = {Buildings}, number = {Volume 12, issue 10, article 1573}, publisher = {MDPI}, address = {Basel}, doi = {10.3390/buildings12101573}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20221028-47283}, pages = {1 -- 19}, abstract = {Determining the earthquake hazard of any settlement is one of the primary studies for reducing earthquake damage. Therefore, earthquake hazard maps used for this purpose must be renewed over time. Turkey Earthquake Hazard Map has been used instead of Turkey Earthquake Zones Map since 2019. A probabilistic seismic hazard was performed by using these last two maps and different attenuation relationships for Bitlis Province (Eastern Turkey) were located in the Lake Van Basin, which has a high seismic risk. The earthquake parameters were determined by considering all districts and neighborhoods in the province. Probabilistic seismic hazard analyses were carried out for these settlements using seismic sources and four different attenuation relationships. The obtained values are compared with the design spectrum stated in the last two earthquake maps. Significant differences exist between the design spectrum obtained according to the different exceedance probabilities. In this study, adaptive pushover analyses of sample-reinforced concrete buildings were performed using the design ground motion level. Structural analyses were carried out using three different design spectra, as given in the last two seismic design codes and the mean spectrum obtained from attenuation relationships. Different design spectra significantly change the target displacements predicted for the performance levels of the buildings.}, subject = {Erbeben}, language = {en} } @article{MaiwaldSchwarzKaufmannetal., author = {Maiwald, Holger and Schwarz, Jochen and Kaufmann, Christian and Langhammer, Tobias and Golz, Sebastian and Wehner, Theresa}, title = {Innovative Vulnerability and Risk Assessment of Urban Areas against Flood Events: Prognosis of Structural Damage with a New Approach Considering Flow Velocity}, series = {Water}, volume = {2022}, journal = {Water}, number = {Volume 14, issue 18, article 2793}, publisher = {MDPI}, address = {Basel}, doi = {10.3390/w14182793}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20221012-47254}, pages = {1 -- 28}, abstract = {The floods in 2002 and 2013, as well as the recent flood of 2021, caused billions Euros worth of property damage in Germany. The aim of the project Innovative Vulnerability and Risk Assessment of Urban Areas against Flood Events (INNOVARU) involved the development of a practicable flood damage model that enables realistic damage statements for the residential building stock. In addition to the determination of local flood risks, it also takes into account the vulnerability of individual buildings and allows for the prognosis of structural damage. In this paper, we discuss an improved method for the prognosis of structural damage due to flood impact. Detailed correlations between inundation level and flow velocities depending on the vulnerability of the building types, as well as the number of storeys, are considered. Because reliable damage data from events with high flow velocities were not available, an innovative approach was adopted to cover a wide range of flow velocities. The proposed approach combines comprehensive damage data collected after the 2002 flood in Germany with damage data of the 2011 Tohoku earthquake tsunami in Japan. The application of the developed methods enables a reliable reinterpretation of the structural damage caused by the August flood of 2002 in six study areas in the Free State of Saxony.}, subject = {Bauschaden}, language = {en} } @article{MehlingSchnabelLondong, author = {Mehling, Simon and Schnabel, Tobias and Londong, J{\"o}rg}, title = {Investigation on Energetic Efficiency of Reactor Systems for Oxidation of Micro-Pollutants by Immobilized Active Titanium Dioxide Photocatalysis}, series = {Water}, volume = {2022}, journal = {Water}, number = {Volume 14, issue 7, article 2681}, publisher = {MDPI}, address = {Basel}, doi = {10.3390/w14172681}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20220912-47130}, pages = {1 -- 15}, abstract = {In this work, the degradation performance for the photocatalytic oxidation of eight micropollutants (amisulpride, benzotriazole, candesartan, carbamazepine, diclofenac, gabapentin, methlybenzotriazole, and metoprolol) within real secondary effluent was investigated using three different reactor designs. For all reactor types, the influence of irradiation power on its reaction rate and energetic efficiency was investigated. Flat cell and batch reactor showed almost similar substance specific degradation behavior. Within the immersion rotary body reactor, benzotriazole and methylbenzotriazole showed a significantly lower degradation affinity. The flat cell reactor achieved the highest mean degradation rate, with half time values ranging from 5 to 64 min with a mean of 18 min, due to its high catalysts surface to hydraulic volume ratio. The EE/O values were calculated for all micro-pollutants as well as the mean degradation rate constant of each experimental step. The lowest substance specific energy per order (EE/O) values of 5 kWh/m3 were measured for benzotriazole within the batch reactor. The batch reactor also reached the lowest mean values (11.8-15.9 kWh/m3) followed by the flat cell reactor (21.0-37.0 kWh/m3) and immersion rotary body reactor (23.9-41.0 kWh/m3). Catalyst arrangement and irradiation power were identified as major influences on the energetic performance of the reactors. Low radiation intensities as well as the use of submerged catalyst arrangement allowed a reduction in energy demand by a factor of 3-4. A treatment according to existing treatment goals of wastewater treatment plants (80\% total degradation) was achieved using the batch reactor with a calculated energy demand of 7000 Wh/m3.}, subject = {Fotokatalyse}, language = {en} } @article{AlYasiriMutasharGuerlebecketal., author = {Al-Yasiri, Zainab Riyadh Shaker and Mutashar, Hayder Majid and G{\"u}rlebeck, Klaus and Lahmer, Tom}, title = {Damage Sensitive Signals for the Assessment of the Conditions of Wind Turbine Rotor Blades Using Electromagnetic Waves}, series = {Infrastructures}, volume = {2022}, journal = {Infrastructures}, number = {Volume 7, Issue 8 (August 2022), article 104}, editor = {Shafiullah, GM}, publisher = {MDPI}, address = {Basel}, doi = {10.3390/infrastructures7080104}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20220831-47093}, pages = {18}, abstract = {One of the most important renewable energy technologies used nowadays are wind power turbines. In this paper, we are interested in identifying the operating status of wind turbines, especially rotor blades, by means of multiphysical models. It is a state-of-the-art technology to test mechanical structures with ultrasonic-based methods. However, due to the density and the required high resolution, the testing is performed with high-frequency waves, which cannot penetrate the structure in depth. Therefore, there is a need to adopt techniques in the fields of multiphysical model-based inversion schemes or data-driven structural health monitoring. Before investing effort in the development of such approaches, further insights and approaches are necessary to make the techniques applicable to structures such as wind power plants (blades). Among the expected developments, further accelerations of the so-called "forward codes" for a more efficient implementation of the wave equation could be envisaged. Here, we employ electromagnetic waves for the early detection of cracks. Because in many practical situations, it is not possible to apply techniques from tomography (characterized by multiple sources and sensor pairs), we focus here on the question of whether the existence of cracks can be determined by using only one source for the sent waves.}, subject = {Windkraftwerk}, language = {en} } @article{ArtusKoch, author = {Artus, Mathias and Koch, Christian}, title = {Object-Oriented Damage Information Modeling Concepts and Implementation for Bridge Inspection}, series = {Journal of Computing in Civil Engineering}, volume = {2022}, journal = {Journal of Computing in Civil Engineering}, number = {Volume 36, issue 6}, doi = {10.1061/(ASCE)CP.1943-5487.0001030}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20220826-47087}, pages = {1 -- 21}, abstract = {Bridges are designed to last for more than 50 years and consume up to 50\% of their life-cycle costs during their operation phase. Several inspections and assessment actions are executed during this period. Bridge and damage information must be gathered, digitized, and exchanged between different stakeholders. Currently, the inspection and assessment practices rely on paper-based data collection and exchange, which is time-consuming and error-prone, and leads to loss of information. Storing and exchanging damage and building information in a digital format may lower costs and errors during inspection and assessment and support future needs, for example, immediate simulations regarding performance assessment, automated maintenance planning, and mixed reality inspections. This study focused on the concept for modeling damage information to support bridge reviews and structural analysis. Starting from the definition of multiple use cases and related requirements, the data model for damage information is defined independently from the subsequent implementation. In the next step, the implementation via an established standard is explained. Functional tests aim to identify problems in the concept and implementation. To show the capability of the final model, two example use cases are illustrated: the inspection review of the entire bridge and a finite-element analysis of a single component. Main results are the definition of necessary damage data, an object-oriented damage model, which supports multiple use cases, and the implementation of the model in a standard. Furthermore, the tests have shown that the standard is suitable to deliver damage information; however, several software programs lack proper implementation of the standard.}, subject = {Building Information Modeling}, language = {en} } @article{PatzeltErfurtLudwig, author = {Patzelt, Max and Erfurt, Doreen and Ludwig, Horst-Michael}, title = {Quantification of cracks in concrete thin sections considering current methods of image analysis}, series = {Journal of Microscopy}, volume = {2022}, journal = {Journal of Microscopy}, number = {Volume 286, Issue 2}, doi = {10.1111/jmi.13091}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20220811-46754}, pages = {154 -- 159}, abstract = {Image analysis is used in this work to quantify cracks in concrete thin sections via modern image processing. Thin sections were impregnated with a yellow epoxy resin, to increase the contrast between voids and other phases of the concrete. By the means of different steps of pre-processing, machine learning and python scripts, cracks can be quantified in an area of up to 40 cm2. As a result, the crack area, lengths and widths were estimated automatically within a single workflow. Crack patterns caused by freeze-thaw damages were investigated. To compare the inner degradation of the investigated thin sections, the crack density was used. Cracks in the thin sections were measured manually in two different ways for validation of the automatic determined results. On the one hand, the presented work shows that the width of cracks can be determined pixelwise, thus providing the plot of a width distribution. On the other hand, the automatically measured crack length differs in comparison to the manually measured ones.}, subject = {Beton}, language = {en} } @article{GuoZhuangChenetal., author = {Guo, Hongwei and Zhuang, Xiaoying and Chen, Pengwan and Alajlan, Naif and Rabczuk, Timon}, title = {Analysis of three-dimensional potential problems in non-homogeneous media with physics-informed deep collocation method using material transfer learning and sensitivity analysis}, series = {Engineering with Computers}, volume = {2022}, journal = {Engineering with Computers}, doi = {10.1007/s00366-022-01633-6}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20220811-46764}, pages = {1 -- 22}, abstract = {In this work, we present a deep collocation method (DCM) for three-dimensional potential problems in non-homogeneous media. This approach utilizes a physics-informed neural network with material transfer learning reducing the solution of the non-homogeneous partial differential equations to an optimization problem. We tested different configurations of the physics-informed neural network including smooth activation functions, sampling methods for collocation points generation and combined optimizers. A material transfer learning technique is utilized for non-homogeneous media with different material gradations and parameters, which enhance the generality and robustness of the proposed method. In order to identify the most influential parameters of the network configuration, we carried out a global sensitivity analysis. Finally, we provide a convergence proof of our DCM. The approach is validated through several benchmark problems, also testing different material variations.}, subject = {Deep learning}, language = {en} } @article{ChakrabortyAnitescuZhuangetal., author = {Chakraborty, Ayan and Anitescu, Cosmin and Zhuang, Xiaoying and Rabczuk, Timon}, title = {Domain adaptation based transfer learning approach for solving PDEs on complex geometries}, series = {Engineering with Computers}, volume = {2022}, journal = {Engineering with Computers}, doi = {10.1007/s00366-022-01661-2}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20220811-46776}, pages = {1 -- 20}, abstract = {In machine learning, if the training data is independently and identically distributed as the test data then a trained model can make an accurate predictions for new samples of data. Conventional machine learning has a strong dependence on massive amounts of training data which are domain specific to understand their latent patterns. In contrast, Domain adaptation and Transfer learning methods are sub-fields within machine learning that are concerned with solving the inescapable problem of insufficient training data by relaxing the domain dependence hypothesis. In this contribution, this issue has been addressed and by making a novel combination of both the methods we develop a computationally efficient and practical algorithm to solve boundary value problems based on nonlinear partial differential equations. We adopt a meshfree analysis framework to integrate the prevailing geometric modelling techniques based on NURBS and present an enhanced deep collocation approach that also plays an important role in the accuracy of solutions. We start with a brief introduction on how these methods expand upon this framework. We observe an excellent agreement between these methods and have shown that how fine-tuning a pre-trained network to a specialized domain may lead to an outstanding performance compare to the existing ones. As proof of concept, we illustrate the performance of our proposed model on several benchmark problems.}, subject = {Maschinelles Lernen}, language = {en} } @article{RoskammVollmer, author = {Roskamm, Nikolai and Vollmer, Lisa}, title = {Was ist Stadt? Was ist Kritik? Einf{\"u}hrung in die Debatte zum Jubil{\"a}umsheft von sub\urban}, series = {sub\urban. zeitschrift f{\"u}r kritische stadtforschung}, journal = {sub\urban. zeitschrift f{\"u}r kritische stadtforschung}, number = {Band 10, Nr. 1,}, publisher = {Sub\urban e.V.}, address = {Leipzig}, doi = {10.36900/suburban.v10i1.798}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20220811-46847}, pages = {127 -- 130}, abstract = {Im Heft zum zehnj{\"a}hrigen Jubil{\"a}um von sub\urban mit dem Themenschwerpunkt „sub\x: Verortungen, Entortungen" ver{\"o}ffentlichen wir eine Debatte, die von den bisherigen in unserer Zeitschrift in dieser Rubrik gef{\"u}hrten textlichen Diskussionen abweicht. Im Vorfeld der Planungen f{\"u}r unsere Jubil{\"a}umsausgabe haben wir die aktuellen Mitglieder unseres wissenschaftlichen Beirats darum gebeten, zwei grundlegende Fragen von kritischer Stadtforschung in kurzen Beitr{\"a}gen zu diskutieren: Was ist Stadt? Was ist Kritik?}, subject = {Stadt}, language = {de} }