@article{NagelSimonKuemmeletal., author = {Nagel, Falk and Simon, Flaviu and K{\"u}mmel, Benjamin and Bergmann, Jean Pierre and Hildebrand, J{\"o}rg}, title = {Optimization Strategies for Laser Welding High Alloy Steel Sheets}, series = {Physics Procedia}, journal = {Physics Procedia}, doi = {10.1016/j.phpro.2014.08.040}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20170425-31554}, pages = {1242 -- 1251}, abstract = {A known phenomenon during laser welding of thin sheets is the deformation caused by thermally induced stresses. This deformation can result in a change of the gap width between the welded parts, which leads to an unstable welding process. Inducing displacements by using a second heat source will compensate for the change in gap width, hence optimizing the welding process. The base material is 1 mm thick austenitic stainless steel 1.4301, which is welded by a CO2 laser. The second heat source is a diode laser. The gap between the welded parts was set between 0.05 mm and 0.1 mm. The influence of the second heat source on the welding process and the welding result is described. The usage of a second heat source allows a higher gap width to be set prior to the welding process. The results of the numerical simulation were found to be corresponding to those of the experiments.}, subject = {Edelstahl}, language = {en} } @article{MeyerKohlstockHauptHeldtetal., author = {Meyer-Kohlstock, Daniel and Haupt, Thomas and Heldt, Erik and Heldt, Nils and Kraft, Eckhard}, title = {Biochar as Additive in Biogas-Production from Bio-Waste}, series = {ENERGIES}, journal = {ENERGIES}, doi = {10.3390/en9040247}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20170406-31119}, abstract = {Previous publications about biochar in anaerobic digestion show encouraging results with regard to increased biogas yields. This work investigates such effects in a solid-state fermentation of bio-waste. Unlike in previous trials, the influence of biochar is tested with a setup that simulates an industrial-scale biogas plant. Both the biogas and the methane yield increased around 5\% with a biochar addition of 5\%-based on organic dry matter biochar to bio-waste. An addition of 10\% increased the yield by around 3\%. While scaling effects prohibit a simple transfer of the results to industrial-scale plants, and although the certainty of the results is reduced by the heterogeneity of the bio-waste, further research in this direction seems promising.}, subject = {Festphasen-Fermentation}, language = {en} } @article{MeelSatirasetthaveeKanitpongetal., author = {Meel, Inder P. and Satirasetthavee, Dussadee and Kanitpong, Kunnawee and Taneerananon, Pichai}, title = {Using Czech TCT to Assess Safety Impact of Deceleration Lane at Thai U-turns}, series = {ENGINEERING JOURNAL-THAILAND}, journal = {ENGINEERING JOURNAL-THAILAND}, doi = {10.4186/ej.2016.20.1.121}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20170406-31097}, pages = {121 -- 135}, abstract = {Purpose of this study is to evaluate safety impact of the deceleration lane at the Upstream Zone of at-grade U-turns on 4-lane divided Thai highways. A substantial speed reduction is required by vehicles for diverging and making U-turn, and the deceleration lanes are provided for this purpose. These lanes are also providing a storage space for the U-turning vehicles to avoid unnecessary blockage of through lanes and reduce the potential of rear-end collisions. The safety at the U-turn is greatly influenced by the proper or improper use of the deceleration lanes. Subject to their length, full or partial speed adjustment can occur within the deceleration lane also the road users' behavior is influenced. To assess the safety impact, the four groups of U-turns with the varying length of deceleration lanes were identified. Owing to limitation of availability and reliability of road crash data in Thailand, widely accepted Traffic Conflict Technique (TCT) was used as an alternative and proactive methodology. The U-turns' geometric data, traffic conflicts and volume data were recorded in the field at 8 locations, 8 hours per location. Severity Conflict Rate (SCR) was assessed by applying a weighing factor (based on the severity grades according to the Czech TCT) to the observed conflicts related to the conflicting traffic volumes. A comparative higher value of SCR represents a lower level of safety. According to the results, increase in the functional length of the deceleration lane yields a lower value of SCR and a higher level of the road safety.}, subject = {Verkehrssicherheit}, language = {en} } @article{MorgenthalYamasaki, author = {Morgenthal, Guido and Yamasaki, Y.}, title = {Aerodynamic Behaviour of Very Long Cable-Stayed Bridges during Construction}, series = {Procedia Engineering}, journal = {Procedia Engineering}, doi = {10.1016/j.proeng.2011.07.184}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20170425-31525}, pages = {1463 -- 1471}, abstract = {Stonecutters and Sutong Bridge have pushed the world record for main span length of cable-stayed bridges to over 1000m. The design of these bridges, both located in typhoon prone regions, is strongly influenced by wind effects during their erection. Rigorous wind tunnel test programmes have been devised and executed to determine the aerodynamic behaviour of the structures in the most critical erection conditions. Testing was augmented by analytical and numerical analyses to verify the safety of the structures throughout construction and to ensure that no serviceability problems would affect the erection process. This paper outlines the wind properties assumed for the bridge sites, the experimental test programme with some of its results, the dynamic properties of the bridges during free cantilevering erection and the assessment of their aerodynamic performance. Along the way, it discusses the similarities and some revealing differences between the two bridges in terms of their dynamic response to wind action.}, subject = {Kabelbr{\"u}cke}, language = {en} } @article{ChubukovKapitanovMoninaetal., author = {Chubukov, A. and Kapitanov, Valeriy and Monina, Olga and Silyanov, Valentin and Brannolte, Ulrich}, title = {Calculation of Traffic Capacity of Signaled Intersections}, series = {Transportation Research Procedia 20}, journal = {Transportation Research Procedia 20}, doi = {10.1016/j.trpro.2017.01.032}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20170401-30964}, pages = {125 -- 131}, abstract = {In order to calculate traffic capacity of signaled intersections, it was suggested to apply an approach based on the concept of congestions. The paper states examples of traffic capacity calculation.}, subject = {Verkehr}, language = {en} } @article{MeelBrannolteSatirasetthaveeetal., author = {Meel, Inder P. and Brannolte, Ulrich and Satirasetthavee, Dussadee and Kanitpong, Kunnawee}, title = {Safety impact of application of auxiliary lanes at downstream locations of Thai U-turns}, series = {IATSS Research}, journal = {IATSS Research}, doi = {10.1016/j.iatssr.2016.06.002}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20170401-31016}, abstract = {To assess the safety impact of auxiliary lanes at downstream locations of U-turns, the Traffic Conflict Technique was used. On the basis of the installed components at those locations, four types of U-turns were identified: those without any auxiliary lane, those with an acceleration lane, those with outer widening, and those with both an acceleration lane and outer widening. The available crash data is unreliable, therefore to assess the level of road safety, Conflict Indexes were formulated to put more emphasis on severe crashes than on slight ones by using two types of weighting coefficients. The first coefficient was based on the subjective assessment of the seriousness of the conflict situation and the second was based on the relative speed and angle between conflicting streams. A comparatively higher Conflict Index value represents a lower level of road safety. According to the results, a lower level of road safety occurs if two components apply or if a location is without any auxiliary lane. The highest level of road safety occurs if the layout includes only a single component, either an acceleration lane or outer widening.}, subject = {Verkehrssicherheit}, language = {en} } @article{WangArash, author = {Wang, Quan and Arash, Behrouz}, title = {Announcement of a virtual special issue on computational carbon nanoscience}, series = {Carbon}, journal = {Carbon}, doi = {10.1016/j.carbon.2015.05.082}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20170428-31695}, pages = {370 -- 372}, abstract = {The Carbon journal is pleased to introduce a themed collection of recent articles in the area of computational carbon nanoscience. This virtual special issue was assembled from previously published Carbon articles by Guest Editors Quan Wang and Behrouz Arash, and can be accessed as a set in the special issue section of the journal website homepage: www.journals.elsevier.com/carbon. The article below by our guest editors serves as an introduction to this virtual special issue, and also a commentary on the growing role of computation as a tool to understand the synthesis and properties of carbon nanoforms and their behavior in composite materials.}, subject = {Kohlenstoff}, language = {en} } @article{BremerWollweberWeigandetal., author = {Bremer, K. and Wollweber, M. and Weigand, F. and Rahlves, M. and Kuhne, Michael and Helbig, R. and Roth, B.}, title = {Fibre Optic Sensors for the Structural Health Monitoring of Building Structures}, series = {Procedia Technology 26}, journal = {Procedia Technology 26}, doi = {10.1016/j.protcy.2016.08.065}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20170331-30912}, pages = {524 -- 529}, abstract = {In this work different fibre optic sensors for the structural health monitoring of civil engineering structures are reported. A fibre optic crack sensor and two different fibre optic moisture sensors have been designed to detect the moisture ingress in concrete based building structures. Moreover, the degeneration of the mechanical properties of optical glass fibre sensors and hence their long-term stability and reliability due to the mechanical and chemical impact of the concrete environment is discussed as well as the advantage of applying a fibre optic sensor system for the structural health monitoring of sewerage tunnels is demonstrated.}, subject = {Structural Health Monitoring}, language = {en} } @article{MasoodKharalNasir, author = {Masood, R. and Kharal, M. K. N. and Nasir, A.R.}, title = {Is BIM Adoption Advantageous for Construction Industry of Pakistan?}, series = {Procedia Engineering}, journal = {Procedia Engineering}, doi = {10.1016/j.proeng.2014.07.021}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20170425-31509}, pages = {229 -- 238}, abstract = {Lack of Information technology applications on construction projects lead to complex flow of data during project life cycle. Building Information Modeling (BIM) has gained attention in the Architectural, Engineering and Construction (AEC) industry, envisage the use of virtual n-dimensional (n-D) models to identify potential conflicts in design, construction or operational of any facility. A questionnaire has been designed to investigate perceptions regarding BIM advantages. Around 102 valid responses received from diversified stakeholders. Results showed very low BIM adoption with low level of 'Buzz'. BIM is a faster and more effective method for designing and construction management, it improves quality of the design and construction and reduces rework during construction; which came out as the top thee advantages according to the perception of AEC professionals of Pakistan.BIM has least impact on reduction of cost, time and human resources. This research is a bench mark study to understand adoption and advantageous of BIM in Pakistan Construction Industry.}, subject = {Building Information Modeling}, language = {en} } @article{MeunierWaltherWorsleyetal., author = {Meunier, David and Walther, Christoph and Worsley, Tom and Dahl, Alexander and Le Ma{\^i}tre, H{\´e}l{\`e}ne}, title = {Evolutions of the Reference Values Used in Transport CBA National Guidelines of 3 Countries and What they Reveal}, series = {Transportation Research Procedia 13}, journal = {Transportation Research Procedia 13}, doi = {10.1016/j.trpro.2016.05.011}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20170406-31106}, pages = {100 -- 113}, abstract = {The paper presents, analyses and compares the evolution of reference values used in national guidelines issued for cost-benefit analysis of transport infrastructure projects, over the last fifty years, in France, UK and Germany.}, subject = {Verkehrsinfrastruktur}, language = {en} } @phdthesis{Froebel, author = {Fr{\"o}bel, Toni}, title = {Data coupled civil engineering applications: Modeling and quality assessment methods}, publisher = {Verlag der Bauhaus-Universit{\"a}t Weimar 2013}, address = {Weimar}, isbn = {978-3-86068-486-3}, doi = {10.25643/bauhaus-universitaet.1836}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20130128-18366}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {153}, abstract = {The planning process in civil engineering is highly complex and not manageable in its entirety. The state of the art decomposes complex tasks into smaller, manageable sub-tasks. Due to the close interrelatedness of the sub-tasks, it is essential to couple them. However, from a software engineering point of view, this is quite challenging to do because of the numerous incompatible software applications on the market. This study is concerned with two main objectives: The first is the generic formulation of coupling strategies in order to support engineers in the implementation and selection of adequate coupling strategies. This has been achieved by the use of a coupling pattern language combined with a four-layered, metamodel architecture, whose applicability has been performed on a real coupling scenario. The second one is the quality assessment of coupled software. This has been developed based on the evaluated schema mapping. This approach has been described using mathematical expressions derived from the set theory and graph theory by taking the various mapping patterns into account. Moreover, the coupling quality has been evaluated within the formalization process by considering the uncertainties that arise during mapping and has resulted in global quality values, which can be used by the user to assess the exchange. Finally, the applicability of the proposed approach has been shown using an engineering case study.}, subject = {Data exchange, Schema mapping, Quality assessment, Uncertainty, Coupling, BIM, Design patterns, Metamodel architecture}, language = {en} } @phdthesis{SalehiSadaghiani, author = {Salehi Sadaghiani, Mohamad Reza}, title = {Suffusion Phenomenon in Widely Graded Soils - Influence of Homogeneity}, publisher = {Blueprint}, address = {Weimar}, doi = {10.25643/bauhaus-universitaet.2681}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20161020-26819}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {160}, abstract = {Problemstellung und Zielsetzung der Arbeit D{\"a}mme und Deiche f{\"u}r z.B. Fluß-, Kanal- oder Speicherbauten sind Erdbauwerke mit großer Kubatur, die meistens großen Platzbedarf und enormen Materialverbrauch erfordern. Aus der Vielfalt von Materialien die uns zur Herstellung der D{\"a}mme zur Verf{\"u}gung stehen, muss immer die wirtschaftlichste L{\"o}sung gefunden werden. Aus diesem Grund werden im Dammbau, die im Umfeld nat{\"u}rlich anstehenden B{\"o}den verwendet. Meist handelt es sich um weitgestufte B{\"o}den, so dass bei der Herstellung der Erdbauwerke eine potenzielle Gefahr der Entmischung besteht. Bei einer hydraulischen Beanspruchung solcher B{\"o}den k{\"o}nnen verschiedene Prozesse der inneren Erosion auftreten, deren Ph{\"a}nomene in Filtration, Suffosion, Kolmation und r{\"u}ckschreitende Erosion unterschieden werden. In der Geotechnik beschreibt man den Transport von Feinteilen aus einem Erdstoff mit dem Begriff "Suffosion". Kommt es zum Materialtransport innerhalb des Bodens, verursacht dies eine Erh{\"o}hung der Wasserdurchl{\"a}ssigkeit und des Porenanteils. Gleichzeitig nehmen die Raumdichte des Bodengef{\"u}ges und die Tragf{\"a}higkeit des Bodens ab. Suffosion ist geometrisch m{\"o}glich, wenn die Porenengstellen der groben, skelettbildenden Fraktionen gr{\"o}ßer als die Korngr{\"o}ßen der mobilen feinen Fraktionen des Bodens sind. Sobald ein kritischer hydraulischer Gradient erreicht wird, werden die mobilen feinen Partikel transportiert. Wegen des starken Einfl usses der Struktur spielt die Homogenit{\"a}t des Korngef{\"u}ges bei allen Prozessen der inneren Erosion eine große Rolle. Die Effekte der Suffosion k{\"o}nnen bei verschiedenen Erdbauwerken unterschiedliche Wirkung haben und zur Beeintr{\"a}chtigung der Funktion oder zu Sch{\"a}den f{\"u}hren. Zu den Aufgaben der Ingenieure z{\"a}hlt die Absch{\"a}tzung, inwiefern die hydrodynamischen Einwirkungen einen standsicherheitrelevanten Einfl uss haben. Die Rolle der Partikelzusammensetzung zur Initialisierung und Fortsetzung des Materialtransportes (Suffosion) wurde noch nicht vollst{\"a}ndig untersucht. Alle g{\"a}ngigen Kriterien gehen von einer Homogenit{\"a}t des Gef{\"u}ges aus. Daher ist das Hauptziel dieser Arbeit, ein analytisches Suffosionskriterium unter Ber{\"u}cksichtigung der Homogenit{\"a}t abzuleiten. Das Kriterium soll in der Lage sein, die mobilen, lokal beweglichen, sowie die suffosiven, global beweglichen Fraktionen eines weitgestuften Bodens einzusch{\"a}tzen. Stand der Wissenschaft Geometrische Suffosionskriterien basieren auf Untersuchungen, die zur Dimensionierung von Erdstofffi ltern im Dammbau entwickelt wurden. Als Eingangsparameter werden die Korngr{\"o}ßenverteilungen der B{\"o}den herangezogen. Fundamentale geometrische Suffosionskriterien wurden u. a. von Ziems (1969), Burenkova (1993), Kenney \& Lau (1986), Wan und Fell (2008) und Witt (2013) entwickelt. Mit den verf{\"u}gbaren Kriterien zur Beurteilung der inneren Suffosionsbest{\"a}ndigkeit kann die Wahrscheinlichkeit eines Materialtransportes nicht quantitativ beurteilt werden. Die zahlreichen Kriterien basieren im Wesentlichen auf empirischen Ans{\"a}tzen und sind nur f{\"u}r spezifische Bodenarten und Randbedingungen anwendbar. Die Anwendungsgrenzen der Suffosionskriterien werden hinsichtlich der Bodenart und des Ungleichf{\"o}rmigkeitsgrades meist {\"u}berschritten. Dar{\"u}ber hinaus ist das Ph{\"a}nomen "Suffosion" in erster Linie ein Problem, das auf der Partikelebene untersucht werden muss. Die Homogenit{\"a}t der Kornzusammensetzung der Erdstoffe fi ndet explizit keine Rolle in den verf{\"u}gbaren Kriterien und die aktuellen internationalen Forschungsaktivit{\"a}ten zeigen, dass haupts{\"a}chlich weitere empirische Ans{\"a}tze entwickelt werden. Eingesetzte Methoden F{\"u}r die analytische Beschreibung von suffosiven Materialtransportprozessen in weitgestuften Erdstoffen unter Ber{\"u}cksichtigung der Homogenit{\"a}tseffekte, muss das Ph{\"a}nomen auf der Partikelebene beschrieben werden. Dies setzt drei Arbeitsschritte und Teilziele voraus: i) Die Kenntnis und Beschreibung der Gef{\"u}gestruktur ii) Beschreibung und Dimensionierung eines repr{\"a}sentativen Volumens iii) Konstruktion einer homogenen Packung f{\"u}r beliebige Korngr{\"o}ßßenverteilungslinien und Quantifizierung des vorhandenen Homogenit{\"a}tsgrads. Die granularen Packungen wurden sowohl experimentell als auch numerisch anhand sequentieller Mischversuche (SFT) untersucht. In einer stochastisch homogenen Packung werden der Anteil der skelettbildenden und der mobilen Fraktionen identifi ziert und ein Bereich als Trenndurchmesser, der Skelett und mobile Feinteile abgrenzt, bestimmt. Dadurch kann die Gef{\"u}gestruktur in suffosiv und nicht suffosive Gruppen klassifi ziert werden. Der experimentelle Ansatz wurde numerisch mittels Diskreter Element Methode (DEM) simuliert, um die Kontaktkr{\"a}fte und Anzahl der Nachbarn f{\"u}r verschiedene Bodenfraktionen (Skelett und bis zu gewissen Bereichen auch die F{\"u}llung) zu finden. Das kleinste repr{\"a}sentative Volumen (REV) f{\"u}r solch eine Bodenpackung wird numerisch bestimmt. Eine Methode zur Festlegung der relevanten Skala zur Quantifi zierung der Homogenit{\"a}t wurde vorgeschlagen. Als Bindeglied wurden 2D-Aufnahmen der experimentell oder numerisch erzeugten Packungen angefertigt, um mit Methoden der digitalen Bildverarbeitung die relevanten Kennwerte der Packung und die Anzahl der skelettbildenden Partikel zu ermitteln. Die erfassten Oberfl{\"a}chen dienen der statistischen Analyse der r{\"a}umlichen Streuung skeletviitbildender Partikel. Anhand der Berechnung der Varianz k{\"o}nnen die unterschiedlichen Parameter miteinander verglichen werden. Eine Varianz von Null bedeutet totale Homogenit{\"a}t. Ein Programm wurde in MATLAB geschrieben, um die Bildanalyse und die Varianzkalkulationen anhand unterschiedlicher Eingangsparameter durchzuf{\"u}hren. Ein analytisch beschreibbares Packungsmodell wird vorgeschlagen, um Homogenit{\"a}t und REV mit Suffosion in Verbindung zu bringen. Basierend auf diesem Modell wird ein Suffosionskriterium entwerfen, das in der Lage ist die Masse des ausgesp{\"u}lten Materials aus einem weitgestuften Boden zu prognostizieren. Wesentliche Ergebnisse Suffosion ist ein Ph{\"a}nomen der Partikelskala und der Partikeltransport ist abh{\"a}ngig von der Partikelanordnung. Die Zusammensetzung der skelettbildenden Partikel bestimmt die Eigenschaft des Porenraums. Die charakteristischen Parameter der Bodenstruktur eines weitgestuften Bodens wurden anhand sequentieller Mischversuche (SFT) festgestellt. Dadurch kann ein weitgestufter Boden in suffosiv oder nicht-suffosiv eingestuft werden. Das granulare Material formt ein Skelett, wenn die ben{\"o}tigte Mindestmasse oder das repr{\"a}{\"a}sentative Volumen erreicht wird. Dies ist eine notwendige Bedingung f{\"u}r die weiteren Untersuchungen. Diese Mindestmasse bzw. das repr{\"a}sentatives Volumen wurde numerisch mittels DEM Simulationen ermittelt. Eine statistische Methode f{\"u}r die Quantifi zierung der Homogenit{\"a}t f{\"u}r 2D-Aufnahmen in Abh{\"a}ngigkeit der Gr{\"o}ße des repr{\"a}sentativen Volumens wurde vorgeschlagen. Diese Methode wurde f{\"u}r komplexe stochastisch homogene, segregierte sowie f{\"u}r homogene Gitter-Packungen getestet. Die Ergebnisse sind vergleichbar mit dem bekannten Verfahren des Voronoi-Diagramms. Der Vorteil dieser Methode ist, dass viele Parameter ber{\"u}cksichtigt und in den Code integriert werden k{\"o}nnen. Eine in-situ Versuchsmethode f{\"u}r die Quantifi zierung der Homogenit{\"a}t wurde vorgeschlagen. Dar{\"u}ber hinaus wurde gezeigt, dass der lockerste und der dichteste Zustand eines weitgestuften Bodens, welcher gem{\"a}ß den Standardrichtlinien ermittelt werden kann, nicht die ultimativen Zust{\"a}nde sind. Die ultimativen Zust{\"a}nde k{\"o}nnen durch die vorgeschlagene Probenvorbereitung ermittelt werden. Ein homogenes Packungsmodell f{\"u}r weitgestufte B{\"o}den mit dominanter Grobmatrix wurde vorgestellt. Die Idee dieses Packungsmodells basiert auf der immer wiederkehrenden Natur der Homogenit{\"a}t und des Segregationsprozesses. Dieses Modell wurde durch Suffosionsversuche getestet und validiert. Basierend auf dem vorgeschlagenen Packungsmodell wurde eine neue experimentelle Methode zur qualitativen Beurteilung der Suffosionsanf{\"a}lligkeit vorgestellt. Ein neues analytisches Suffosionskriterium, basierend auf dem vorgeschlagenen Packungsmodel unter Ber{\"u}cksichtigung der Homogenit{\"a}t im REV wurde entworfen. Damit k{\"o}nnen die mobilen sowie suffosiven Fraktionen eines weitgestuften Bodens ermittelt werden.}, subject = {Homogenit{\"a}t}, language = {en} } @misc{Jahn, type = {Master Thesis}, author = {Jahn, Rosa}, title = {Evaluation von Nutzerbed{\"u}rfnissen in Wohngeb{\"a}uden unter Ber{\"u}cksichtigung hygrothermischer Messdaten}, doi = {10.25643/bauhaus-universitaet.1875}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20130320-18758}, school = {Bauhaus-Universit{\"a}t Weimar}, abstract = {Evaluation von Nutzerbed{\"u}rfnissen in Wohngeb{\"a}uden unter Ber{\"u}cksichtigung hygrothermischer Messdaten}, subject = {Raumklima}, language = {de} } @article{Aguinaga, author = {Aguinaga, Jos{\´e} Guillermo De}, title = {Error in prediction due to data type availability in a coupled hydro-mechanical model}, series = {Electronic Journal of Geotechnical Engineering}, journal = {Electronic Journal of Geotechnical Engineering}, doi = {10.25643/bauhaus-universitaet.3117}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20170413-31170}, pages = {2459 -- 2471}, abstract = {Different types of data provide different type of information. The present research analyzes the error on prediction obtained under different data type availability for calibration. The contribution of different measurement types to model calibration and prognosis are evaluated. A coupled 2D hydro-mechanical model of a water retaining dam is taken as an example. Here, the mean effective stress in the porous skeleton is reduced due to an increase in pore water pressure under drawdown conditions. Relevant model parameters are identified by scaled sensitivities. Then, Particle Swarm Optimization is applied to determine the optimal parameter values and finally, the error in prognosis is determined. We compare the predictions of the optimized models with results from a forward run of the reference model to obtain the actual prediction errors. The analyses presented here were performed calibrating the hydro-mechanical model to 31 data sets of 100 observations of varying data types. The prognosis results improve when using diversified information for calibration. However, when using several types of information, the number of observations has to be increased to be able to cover a representative part of the model domain. For an analysis with constant number of observations, a compromise between data type availability and domain coverage proves to be the best solution. Which type of calibration information contributes to the best prognoses could not be determined in advance. The error in model prognosis does not depend on the error in calibration, but on the parameter error, which unfortunately cannot be determined in inverse problems since we do not know its real value. The best prognoses were obtained independent of calibration fit. However, excellent calibration fits led to an increase in prognosis error variation. In the case of excellent fits; parameters' values came near the limits of reasonable physical values more often. To improve the prognoses reliability, the expected value of the parameters should be considered as prior information on the optimization algorithm.}, subject = {Sensitivit{\"a}tsanalyse}, language = {en} } @phdthesis{Alexander, author = {Alexander, Anne}, title = {Quantitative Erfassung von Risiken und Simulation ihrer Auswirkungen auf den Verlauf eines Bauprojektes}, doi = {10.25643/bauhaus-universitaet.2051}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20130927-20514}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {171}, abstract = {Das Bauwesen hat sich in den letzten Jahren durch die Globalisierung des Marktes verbunden mit einer verst{\"a}rkten Nutzung moderner Technologien stark gewandelt. Die Planung und die Durchf{\"u}hrung von Bauvorhaben werden zunehmend komplexer und sind mit erh{\"o}hten Risiken verbunden. Geld- und Zeitressourcen werden bei einem immer h{\"a}rter werdenden Konkurrenzkampf knapper. Das Projektmanagement stellt L{\"o}sungsans{\"a}tze bereit, um Bauvorhaben auch unter erschwerten Bedingungen und erh{\"o}hten Risiken erfolgreich zum Abschluss zu bringen. Dabei hat ein systematisches Risikomanagement beginnend bei der Projektentwicklung bis zum Projektabschluss eine f{\"u}r den Projekterfolg entscheidende Bedeutung. Ziel der Arbeit ist es, eine quantitative Risikoerfassung f{\"u}r Projektmanager als professionelle Bauherrenvertretung und die Simulation der Risikoauswirkungen auf den Verlauf eines Projektes w{\"a}hrend der Planungs- und Bauphase zu erm{\"o}glichen. Mit Hilfe eines abstrakten Modells soll eine differenzierte, praxisnahe Simulation durchf{\"u}hrbar sein, die die verschiedenen Arten der Leistungs- und Kostenentstehung widerspiegelt. Parallel dazu soll die Beschreibung von Risiken so abstrahiert werden, dass beliebige Risiken quantitativ erfassbar und anschließend ihre Auswirkungen inklusive m{\"o}gliche Gegenmaßnahmen in das Modell integrierbar sind. Anhand zweier Beispiele werden die unterschiedlichen Einsatzm{\"o}glichkeiten der quantitativen Erfassung von Projektrisiken und der anschließenden Simulation ihrer Auswirkungen aufgezeigt. Bei dem ersten Beispiel, einem realen, bereits abgeschlossenen Schieneninfrastrukturprojekt, wird die Wirksamkeit einer vorbeugenden Maßnahme gegen ein Projektrisiko untersucht. Im zweiten Beispiel wird ein Planspielansatz zur praxisnahen Aus- und Weiterbildung von Projektmanagern entwickelt. Inhalt des Planspiels ist die Planung und Errichtung eines privatfinanzierten, {\"o}ffentlichen Repr{\"a}sentationsbaus mit teilweiser Fremdnutzung.}, subject = {Risiko}, language = {de} } @article{Bargstaedt, author = {Bargst{\"a}dt, Hans-Joachim}, title = {Challenges of BIM for Construction Site Operations}, series = {Procedia Engineering}, journal = {Procedia Engineering}, doi = {10.1016/j.proeng.2015.08.123}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20170413-31218}, pages = {52 -- 59}, abstract = {Building Information Modeling is a powerful tool for the design and for a consistent set of data in a virtual storage. For the application in the phases of realization and on site it needs further development. The paper describes main challenges and main features, which will help the development of software to better service the needs of construction site managers}, subject = {Building Information Modeling}, language = {en} } @inproceedings{KieselEngelsVoelker, author = {Kiesel, Gerd and Engels, Merit and V{\"o}lker, Conrad}, title = {Energetische Transformation im l{\"a}ndlichen Raum - Aufbau eines prozessorientierten Entwicklungs- und Moderationsmodells}, series = {Schriftenreihe des Fachgebiets Bauphysik/Energetische Geb{\"a}udeoptimierung}, booktitle = {Schriftenreihe des Fachgebiets Bauphysik/Energetische Geb{\"a}udeoptimierung}, editor = {Kornadt, Oliver and Carrigan, Svenja and Hofmann, Markus and V{\"o}lker, Conrad}, publisher = {Eigenverlag Technische Universit{\"a}t Kaiserslautern}, address = {Kaiserslautern}, isbn = {978-3-95974-176-7}, issn = {2363-8206}, doi = {10.25643/bauhaus-universitaet.4656}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20220617-46566}, pages = {3}, abstract = {Kleine Kommunen im l{\"a}ndlichen Raum sind aufgrund ihrer oft eingeschr{\"a}nkten personellen und finanziellen Kapazit{\"a}ten bisher eher sporadisch in den Themenfeldern Energieeffizienz und Erneuerbare Energien aktiv. Immer wieder stellt sich daher Frage, wie die Klimaschutzstrategien des Bundes und der L{\"a}nder dort mit dem verf{\"u}gbaren Personal kosteng{\"u}nstig realisierbar sind. Vor diesem Hintergrund wird ein Werkzeug entwickelt, mit dessen Hilfe der aktive Einstieg in diese Thematik mit geringen Aufwand und {\"u}berwiegend barrierefrei m{\"o}glich ist. Der Aufbau eines prozessorientierten Entwicklungs- und Moderationsmodells zur Erprobung und Umsetzung bezahlbarer Handlungsoptionen f{\"u}r Energieeinsparungen und effizienten Energieeinsatz im {\"u}berwiegend l{\"a}ndlichen gepr{\"a}gten Raum ist der Schwerpunkt der Softwarel{\"o}sung. Kommunen werden mit deren Hilfe in die Lage versetzt, in die notwendigen Prozesse der Energie- und W{\"a}rmewende einzusteigen. Dabei soll der modulare Aufbau die regul{\"a}ren Schritte notwendiger (integrierter) Planungsprozesse nicht vollst{\"a}ndig ersetzen. Vielmehr k{\"o}nnen innerhalb der Online-Anwendung - {\"u}berwiegend automatisiert - konkrete Maßnahmenvorschl{\"a}ge erstellt werden, die ein solides Fundament der k{\"u}nftigen energetischen Entwicklung der Kommunen darstellen. F{\"u}r eine gezielte Validierung der Ergebnisse und der Ableitung potentieller Maßnahmen werden f{\"u}r die Erprobung Modellkommunen in Th{\"u}ringen, Bayern und Hessen als Reallabore einbezogen. Das Tool steht bisher zun{\"a}chst nur den beteiligten Modellkommunen zur Verf{\"u}gung. Die entwickelte Softwarel{\"o}sung soll k{\"u}nftig Schritt f{\"u}r Schritt allen interessierten Kommunen mit diversen Hilfsmitteln und einer Vielzahl anderer praktischer Bestandteile zur Verf{\"u}gung gestellt werden.}, subject = {Modellierung}, language = {de} } @article{VoelkerBeckmannKoehlmannetal., author = {V{\"o}lker, Conrad and Beckmann, Julia and Koehlmann, Sandra and Kornadt, Oliver}, title = {Occupant requirements in residential buildings - an empirical study and a theoretical model}, series = {Advances in Building Energy Research}, journal = {Advances in Building Energy Research}, number = {7 (1)}, doi = {10.25643/bauhaus-universitaet.3813}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20181015-38137}, pages = {35 -- 50}, abstract = {Occupant needs with regard to residential buildings are not well known due to a lack of representative scientific studies. To improve the lack of data, a large scale study was carried out using a Post Occupancy Evaluation of 1,416 building occupants. Several criteria describing the needs of occupants were evaluated with regard to their subjective level of relevance. Additionally, we investigated the degree to which deficiencies subjectively exist, and the degree to which occupants were able to accept them. From the data obtained, a hierarchy of criteria was created. It was found that building occupants ranked the physiological needs of air quality and thermal comfort the highest. Health hazards such as mould and contaminated building materials were unacceptable for occupants, while other deficiencies were more likely to be tolerated. Occupant satisfaction was also investigated. We found that most occupants can be classified as satisfied, although some differences do exist between different populations. To explain the relationship between the constructs of what we call relevance, acceptance, deficiency and satisfaction, we then created an explanatory model. Using correlation and regression analysis, the validity of the model was then confirmed by applying the collected data. The results of the study are both relevant in shaping further research and in providing guidance on how to maximize tenant satisfaction in real estate management.}, subject = {Post Occupancy Evaluation}, language = {en} } @article{MotraHildebrandDimmigOsburg, author = {Motra, Hem Bahadur and Hildebrand, J{\"o}rg and Dimmig-Osburg, Andrea}, title = {Assessment of strain measurement techniques to characterise mechanical properties of structural steel}, series = {Engineering Science and Technology, an International Journal}, journal = {Engineering Science and Technology, an International Journal}, doi = {10.1016/j.jestch.2014.07.006}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20170425-31540}, pages = {260 -- 269}, abstract = {Strain measurement is important in mechanical testing. A wide variety of techniques exists for measuring strain in the tensile test; namely the strain gauge, extensometer, stress and strain determined by machine crosshead motion, Geometric Moire technique, optical strain measurement techniques and others. Each technique has its own advantages and disadvantages. The purpose of this study is to quantitatively compare the strain measurement techniques. To carry out the tensile test experiments for S 235, sixty samples were cut from the web of the I-profile in longitudinal and transverse directions in four different dimensions. The geometry of samples are analysed by 3D scanner and vernier caliper. In addition, the strain values were determined by using strain gauge, extensometer and machine crosshead motion. Three techniques of strain measurement are compared in quantitative manner based on the calculation of mechanical properties (modulus of elasticity, yield strength, tensile strength, percentage elongation at maximum force) of structural steel. A statistical information was used for evaluating the results. It is seen that the extensometer and strain gauge provided reliable data, however the extensometer offers several advantages over the strain gauge and crosshead motion for testing structural steel in tension. Furthermore, estimation of measurement uncertainty is presented for the basic material parameters extracted through strain measurement.}, subject = {Baustahl}, language = {en} } @phdthesis{Link, author = {Link, Tim}, title = {Entwicklung und Untersuchung von alternativen Dicalciumsilicat-Bindern auf der Basis von alpha-C2SH}, doi = {10.25643/bauhaus-universitaet.3722}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20180205-37228}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {292}, abstract = {Um den Klimawandel zu begrenzen, m{\"u}ssen die CO2-Emissionen drastisch gesenkt werden [100]. Bis 2050 soll bei der Herstellung von Zement eine Einsparung um 51-60 \% auf 0,425-0,350 tCO2/tZement erfolgen [7]. Um dieses Ziel zu erreichen, sind alternative Bindemittelkonzepte notwendig [70]. Diese Arbeit widmet sich alternativen, hochreaktiven Dicalciumsilicat-Bindemitteln, die durch die thermische Aktivierung von α-Dicalcium-Silicat-Hydrat (α-C2SH) erzeugt werden. Das α-C2SH ist eine kristalline C S H-Phase, die im hydrothermalen Prozess, beispielsweise aus Branntkalk und Quarz, herstellbar ist. Die thermische Aktivierung kann bei sehr niedrigen Temperaturen erfolgen (>420 °C) und f{\"u}hrt zu einem Multiphasen-C2S-Binder. Als besonders reaktive Bestandteile k{\"o}nnen x-C2S und r{\"o}ntgenamorphe Anteile enthalten sein. Weiterhin k{\"o}nnen β C2S, γ C2S und Dellait (Ca6(SiO4)(Si2O7)(OH)2) entstehen. Im Rahmen der Arbeit wird zun{\"a}chst der Stand des Wissens zur Polymorphie und Hydratation von C2S zusammengefasst. Es werden bekannte C2S-basierte Bindemittelkonzepte vorgestellt und bewertet. Die Herstellung von C2S-Bindern wird experimentell im Labormaßstab untersucht. Dabei kommen unterschiedliche Autoklaven und ein Muffelofen zum Einsatz. Die Herstellungsparameter werden hinsichtlich Phasenbestand und Reaktivit{\"a}t optimiert. Die Bindemittel werden durch quantitative R{\"o}ntgen-Phasenanalyse (QXRD), Rasterelektronenmikroskopie (REM), N2-Adsorption (BET-Methode), Heliumpycnometer, Thermoanalyse (TGA/DSC) und 29Si-MAS- sowie 29Si-1H-CP/MAS-NMR-Spektroskopie charakterisiert. Das Hydratationsverhalten der Bindemittel wird vorrangig mithilfe von W{\"a}rmeflusskalorimetrie untersucht. Weiterhin werden in situ und ex situ XRD-, TGA/DSC- und REM-Untersuchungen durchgef{\"u}hrt. Anhand von zwei Bindemitteln wird die F{\"a}higkeit zur Erzielung hoher Festigkeiten demonstriert. Abschließend erfolgt eine Absch{\"a}tzung zu Energiebedarf und CO2-Emissionen f{\"u}r die Herstellung der untersuchten C2S-Binder. Die Ergebnisse zeigen, dass f{\"u}r eine hohe Reaktivit{\"a}t der Binder eine niedrige Brenntemperatur und ein geringer Wasserdampfpartialdruck w{\"a}hrend der thermischen Aktivierung entscheidend sind. Weiterhin muss das hydrothermal hergestellte α-C2SH eine m{\"o}glichst hohe spezifische Oberfl{\"a}che aufweisen. Diese Parameter beeinflussen den Phasenbestand und die phasenspezifische Reaktivit{\"a}t. Brenntemperaturen von ca. 420-500 °C f{\"u}hren zu hochreaktiven Bindern, die im Rahmen dieser Arbeit als Niedertemperatur-C2S-Binder bezeichnet werden. Temperaturen von ca. 600-800 °C f{\"u}hren zu Bindern mit geringerer Reaktivit{\"a}t, die im Rahmen dieser Arbeit als Hochtemperatur-C2S bezeichnet werden. H{\"o}here Brenntemperaturen (1000 °C) f{\"u}hren zu Bindemitteln, die innerhalb der ersten drei Tage keine hydraulische Aktivit{\"a}t zeigen. Die untersuchten Bindemittel k{\"o}nnen sehr hohe Reaktionsgeschwindigkeiten erreichen. Die W{\"a}rmeflusskalorimetrie deutet bei einigen Bindemitteln einen nahezu vollst{\"a}ndigen Umsatz innerhalb von drei Tagen an. Durch XRD wurde f{\"u}r einen Binder der vollst{\"a}ndige Verbrauch von x-C2S innerhalb von drei Tagen nachgewiesen. F{\"u}r einen mittels in-situ-XRD und W{\"a}rmeflusskalorimetrie untersuchten Binder wurde gezeigt, dass die Phasen vorrangig in der Reihenfolge r{\"o}ntgenamorph > x-C2S > β-C2S > γ-C2S hydratisieren. Hydratationsprodukte sind nadelige C S H-Phasen und Portlandit. Die Herstellung durch thermische Aktivierung von α-C2SH f{\"u}hrt zu tafeligen Bindemittelpartikeln, die teilweise Zwickelr{\"a}ume und Poren zwischen den einzelnen Partikeln einschließen. Um eine verarbeitbare Bindemittelpaste zu erzeugen, sind daher sehr hohe Wasser/Bindemittel-Werte (z. B. 1,4) erforderlich. Der Wasseranspruch kann durch Mahlung etwa auf das Niveau von Zement gesenkt werden. Die Druckfestigkeitsentwicklung wurde an zwei Niedertemperatur-C2S-Kompositbindern mit 40 \% Kalksteinmehl bzw. 40 \% H{\"u}ttensand untersucht. Aufgrund von theoretischen Betrachtungen zur Porosit{\"a}t in Abh{\"a}ngigkeit des w/b-Wertes wurde dieser auf 0,3 festgelegt. Durch Zugabe von PCE-Fließmittel wurde ein verarbeitbarer M{\"o}rtel erhalten. Die Festigkeitsentwicklung ist sehr schnell. Der Kalksteinmehl-Binder erreichte nach zwei Tagen 46 N/mm². Bis Tag 28 trat keine weitere Festigkeitssteigerung ein. Der H{\"u}ttensand-Binder erreichte nach zwei Tagen 62 N/mm². Durch die H{\"u}ttensandreaktion stieg die Festigkeit bis auf 85 N/mm² nach 28 Tagen an. F{\"u}r den Herstellungsprozess von Niedertemperatur-C2S-Binder wurden Energieverbr{\"a}uche und CO2-Emissionen abgesch{\"a}tzt. Es deutet sich an, dass, bezogen auf die Bindemittelmenge, keine wesentlichen Einsparungen im Vergleich zur Portlandzementherstellung m{\"o}glich sind. F{\"u}r die tats{\"a}chlichen Emissionen muss jedoch zus{\"a}tzlich die Leistungsf{\"a}higkeit der Bindemittel ber{\"u}cksichtigt werden. Die Leistungsf{\"a}higkeit kann als erforderliche Bindemittelmenge betrachtet werden, die je m³ Beton eingesetzt werden muss, um bestimmte Festigkeits-, Dauerhaftigkeits- und Verarbeitungseigenschaften zu erreichen. Aus verschiedenen Ver{\"o}ffentlichungen [94, 201, 206] wurde die These abgeleitet, dass die Leistungsf{\"a}higkeit eines Bindemittels maßgeblich von der C-S-H-Menge bestimmt wird, die w{\"a}hrend der Hydratation gebildet wird. Daher wird f{\"u}r NT-C2S-Binder eine außergew{\"o}hnlich hohe Leistungsf{\"a}higkeit erwartet. Auf Basis der Leistungsf{\"a}higkeitsthese verringern sich die abgesch{\"a}tzten CO2-Emissionen von NT-C2S-Bindern, sodass gegen{\"u}ber Portlandzement ein m{\"o}gliches Einsparpotenzial von 42 \% ermittelt wurde.}, subject = {Belit}, language = {de} } @article{FaridmehrTahirLahmer, author = {Faridmehr, Iman and Tahir, Mamood Md. and Lahmer, Tom}, title = {Classification System for Semi-Rigid Beam-to-Column Connections}, series = {LATIN AMERICAN JOURNAL OF SOLIDS AND STRUCTURES 11}, journal = {LATIN AMERICAN JOURNAL OF SOLIDS AND STRUCTURES 11}, doi = {10.1590/1679-78252595}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20170401-30988}, pages = {2152 -- 2175}, abstract = {The current study attempts to recognise an adequate classification for a semi-rigid beam-to-column connection by investigating strength, stiffness and ductility. For this purpose, an experimental test was carried out to investigate the moment-rotation (M-theta) features of flush end-plate (FEP) connections including variable parameters like size and number of bolts, thickness of end-plate, and finally, size of beams and columns. The initial elastic stiffness and ultimate moment capacity of connections were determined by an extensive analytical procedure from the proposed method prescribed by ANSI/AISC 360-10, and Eurocode 3 Part 1-8 specifications. The behaviour of beams with partially restrained or semi-rigid connections were also studied by incorporating classical analysis methods. The results confirmed that thickness of the column flange and end-plate substantially govern over the initial rotational stiffness of of flush end-plate connections. The results also clearly showed that EC3 provided a more reliable classification index for flush end-plate (FEP) connections. The findings from this study make significant contributions to the current literature as the actual response characteristics of such connections are non-linear. Therefore, such semirigid behaviour should be used to for an analysis and design method.}, subject = {Tragf{\"a}higkeit}, language = {en} } @phdthesis{Giebson, author = {Giebson, Colin}, title = {Die Alkali-Kiesels{\"a}ure-Reaktion in Beton f{\"u}r Fahrbahndecken und Flugbetriebsfl{\"a}chen unter Einwirkung alkalihaltiger Enteisungsmittel}, isbn = {978-3-00-044366-4 (Druckversion)}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20131217-20916}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {208}, abstract = {Das Hauptziel der Arbeit war es zu kl{\"a}ren, ob alkalihaltige Enteisungsmittel eine Alkali-Kiesels{\"a}ure-Reaktion (AKR) ausl{\"o}sen und/oder beschleunigen k{\"o}nnen und was die dabei ggf. zugrunde liegenden Mechanismen sind. Die Untersuchungen dazu ergaben, dass die auf Verkehrsfl{\"a}chen eingesetzten alkalihaltigen Enteisungsmittel auf Basis von Natriumchlorid (Fahrbahndecken) bzw. auf Basis der Alkaliacetate und -formiate (Flugbetriebsfl{\"a}chen) den Ablauf einer AKR in Betonen mit alkalireaktiven Gesteinsk{\"o}rnungen ausl{\"o}sen und mitunter stark beschleunigen k{\"o}nnen. Dabei nimmt die AKR-f{\"o}rdernde Wirkung der Enteisungsmittel in der Reihenfolge Natriumchlorid - Alkaliacetate - Alkaliformiate erheblich zu. Es zeigte sich, dass im Fall der Alkaliacetate und -formiate nicht allein die Zufuhr von Alkalien von Bedeutung ist, sondern dass es außerdem zu einer Freisetzung von OH-Ionen aus dem Portlandit und folglich zu einem Anstieg des pH-Wertes in der Porenl{\"o}sung kommt. Dadurch wird der Angriff auf alkalireaktives SiO2 in Gesteinsk{\"o}rnungen verst{\"a}rkt und der Ablauf einer AKR beschleunigt. Unter {\"a}ußerer NaCl-Zufuhr kommt es hingegen nicht zu einem Anstieg des pH-Wertes, was der Grund f{\"u}r die weniger stark AKR-f{\"o}rdernde Wirkung von NaCl ist. Von Bedeutung sind hier die zugef{\"u}hrten Na-Ionen und offenbar ein sich andeutender, direkter Einfluss von NaCl auf das SiO2-L{\"o}severhalten. Sind pH-Wert und Na-Konzentration in der Porenl{\"o}sung ausreichend hoch, wird sich thermodynamisch bedingt AKR-Gel bilden. Die Bildung von FRIEDEL'schem Salz ist dabei nur eine Begleiterscheinung, aber keine Voraussetzung f{\"u}r den Ablauf einer AKR unter {\"a}ußerer NaCl-Zufuhr. Es zeigte sich weiter, dass sich mit der FIB-Klimawechsellagerung als Performance-Pr{\"u}fung das AKR-Sch{\"a}digungspotential von Betonen f{\"u}r Fahrbahndecken und Flugbetriebsfl{\"a}chen zuverl{\"a}ssig beurteilen l{\"a}sst. Die Vorteile der FIB-Klimawechsellagerung liegen in der Pr{\"u}fung kompletter, projektspezifischer Betonzusammensetzungen unter Beachtung aller praxisrelevanten klimatischen Einwirkungen und vor allem in der Ber{\"u}cksichtigung einer {\"a}ußeren Alkalizufuhr. Innerhalb von 36 Wochen kann das AKR-Sch{\"a}digungspotential einer Betonzusammensetzung f{\"u}r eine Nutzungsdauer von 20-30 Jahren in der Praxis sicher beurteilt werden.}, subject = {Beton}, language = {de} } @article{ZhangRen, author = {Zhang, Yongzheng and Ren, Huilong}, title = {Implicit implementation of the nonlocal operator method: an open source code}, series = {Engineering with computers}, volume = {2022}, journal = {Engineering with computers}, publisher = {Springer}, address = {London}, doi = {10.1007/s00366-021-01537-x}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20220216-45930}, pages = {1 -- 35}, abstract = {In this paper, we present an open-source code for the first-order and higher-order nonlocal operator method (NOM) including a detailed description of the implementation. The NOM is based on so-called support, dual-support, nonlocal operators, and an operate energy functional ensuring stability. The nonlocal operator is a generalization of the conventional differential operators. Combined with the method of weighed residuals and variational principles, NOM establishes the residual and tangent stiffness matrix of operate energy functional through some simple matrix without the need of shape functions as in other classical computational methods such as FEM. NOM only requires the definition of the energy drastically simplifying its implementation. The implementation in this paper is focused on linear elastic solids for sake of conciseness through the NOM can handle more complex nonlinear problems. The NOM can be very flexible and efficient to solve partial differential equations (PDEs), it's also quite easy for readers to use the NOM and extend it to solve other complicated physical phenomena described by one or a set of PDEs. Finally, we present some classical benchmark problems including the classical cantilever beam and plate-with-a-hole problem, and we also make an extension of this method to solve complicated problems including phase-field fracture modeling and gradient elasticity material.}, subject = {Strukturmechanik}, language = {en} } @phdthesis{Vu, author = {Vu, Bac Nam}, title = {Stochastic uncertainty quantification for multiscale modeling of polymeric nanocomposites}, doi = {10.25643/bauhaus-universitaet.2555}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20160322-25551}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {265}, abstract = {Nanostructured materials are extensively applied in many fields of material science for new industrial applications, particularly in the automotive, aerospace industry due to their exceptional physical and mechanical properties. Experimental testing of nanomaterials is expensive, timeconsuming,challenging and sometimes unfeasible. Therefore,computational simulations have been employed as alternative method to predict macroscopic material properties. The behavior of polymeric nanocomposites (PNCs) are highly complex. The origins of macroscopic material properties reside in the properties and interactions taking place on finer scales. It is therefore essential to use multiscale modeling strategy to properly account for all large length and time scales associated with these material systems, which across many orders of magnitude. Numerous multiscale models of PNCs have been established, however, most of them connect only two scales. There are a few multiscale models for PNCs bridging four length scales (nano-, micro-, meso- and macro-scales). In addition, nanomaterials are stochastic in nature and the prediction of macroscopic mechanical properties are influenced by many factors such as fine-scale features. The predicted mechanical properties obtained by traditional approaches significantly deviate from the measured values in experiments due to neglecting uncertainty of material features. This discrepancy is indicated that the effective macroscopic properties of materials are highly sensitive to various sources of uncertainty, such as loading and boundary conditions and material characteristics, etc., while very few stochastic multiscale models for PNCs have been developed. Therefore, it is essential to construct PNC models within the framework of stochastic modeling and quantify the stochastic effect of the input parameters on the macroscopic mechanical properties of those materials. This study aims to develop computational models at four length scales (nano-, micro-, meso- and macro-scales) and hierarchical upscaling approaches bridging length scales from nano- to macro-scales. A framework for uncertainty quantification (UQ) applied to predict the mechanical properties of the PNCs in dependence of material features at different scales is studied. Sensitivity and uncertainty analysis are of great helps in quantifying the effect of input parameters, considering both main and interaction effects, on the mechanical properties of the PNCs. To achieve this major goal, the following tasks are carried out: At nano-scale, molecular dynamics (MD) were used to investigate deformation mechanism of glassy amorphous polyethylene (PE) in dependence of temperature and strain rate. Steered molecular dynamics (SMD)were also employed to investigate interfacial characteristic of the PNCs. At mico-scale, we developed an atomistic-based continuum model represented by a representative volume element (RVE) in which the SWNT's properties and the SWNT/polymer interphase are modeled at nano-scale, the surrounding polymer matrix is modeled by solid elements. Then, a two-parameter model was employed at meso-scale. A hierarchical multiscale approach has been developed to obtain the structure-property relations at one length scale and transfer the effect to the higher length scales. In particular, we homogenized the RVE into an equivalent fiber. The equivalent fiber was then employed in a micromechanical analysis (i.e. Mori-Tanaka model) to predict the effective macroscopic properties of the PNC. Furthermore, an averaging homogenization process was also used to obtain the effective stiffness of the PCN at meso-scale. Stochastic modeling and uncertainty quantification consist of the following ingredients: - Simple random sampling, Latin hypercube sampling, Sobol' quasirandom sequences, Iman and Conover's method (inducing correlation in Latin hypercube sampling) are employed to generate independent and dependent sample data, respectively. - Surrogate models, such as polynomial regression, moving least squares (MLS), hybrid method combining polynomial regression and MLS, Kriging regression, and penalized spline regression, are employed as an approximation of a mechanical model. The advantage of the surrogate models is the high computational efficiency and robust as they can be constructed from a limited amount of available data. - Global sensitivity analysis (SA) methods, such as variance-based methods for models with independent and dependent input parameters, Fourier-based techniques for performing variance-based methods and partial derivatives, elementary effects in the context of local SA, are used to quantify the effects of input parameters and their interactions on the mechanical properties of the PNCs. A bootstrap technique is used to assess the robustness of the global SA methods with respect to their performance. In addition, the probability distribution of mechanical properties are determined by using the probability plot method. The upper and lower bounds of the predicted Young's modulus according to 95 \% prediction intervals were provided. The above-mentioned methods study on the behaviour of intact materials. Novel numerical methods such as a node-based smoothed extended finite element method (NS-XFEM) and an edge-based smoothed phantom node method (ES-Phantom node) were developed for fracture problems. These methods can be used to account for crack at macro-scale for future works. The predicted mechanical properties were validated and verified. They show good agreement with previous experimental and simulations results.}, subject = {Polymere}, language = {en} } @article{AchenbachLahmerMorgenthal, author = {Achenbach, Marcus and Lahmer, Tom and Morgenthal, Guido}, title = {Identification of the thermal properties of concrete for the temperature calculation of concrete slabs and columns subjected to a standard fire—Methodology and proposal for simplified formulations}, series = {Fire Safety Journal 87}, journal = {Fire Safety Journal 87}, doi = {10.1016/j.firesaf.2016.12.003}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20170331-30929}, pages = {80 -- 86}, abstract = {The fire resistance of concrete members is controlled by the temperature distribution of the considered cross section. The thermal analysis can be performed with the advanced temperature dependent physical properties provided by 5EN6 1992-1-2. But the recalculation of laboratory tests on columns from 5TU6 Braunschweig shows, that there are deviations between the calculated and measured temperatures. Therefore it can be assumed, that the mathematical formulation of these thermal properties could be improved. A sensitivity analysis is performed to identify the governing parameters of the temperature calculation and a nonlinear optimization method is used to enhance the formulation of the thermal properties. The proposed simplified properties are partly validated by the recalculation of measured temperatures of concrete columns. These first results show, that the scatter of the differences from the calculated to the measured temperatures can be reduced by the proposed simple model for the thermal analysis of concrete.}, subject = {Sensitivit{\"a}tsanalyse}, language = {en} } @phdthesis{Nowak, author = {Nowak, Saskia}, title = {Alterung von Calciumsulfatphasen : Physiko-chemisch bedingte Feuchteaufnahmen und Einfluss auf die Reaktivit{\"a}t}, isbn = {978-3-00-041328-5}, doi = {10.25643/bauhaus-universitaet.1873}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20130320-18731}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {155}, abstract = {Die Arbeit zeigt die wesentlichen Gr{\"u}nde auf, warum betahalbhydratreiche Niederbranntgipsbinder (industriell als Stuckgips bezeichnet) oft sehr unterschiedliche Eigenschaften aufweisen. Der Anteil an Halbhydrat, welches aus dem stark hygroskopischen Anhydrit III (A III) durch die Reaktion mit Luftfeuchtigkeit entsteht, stellt einen erheblichen, bislang vollkommen unbeachteten Einfluss dar. Dieses Halbhydrat aus A III zeigt andere Oberfl{\"a}cheneigenschaften und ein Reaktionsverhalten, das von frisch gebranntem Betahalbhydrat abweicht. Es zeigt sich, wie weitreichend der Einfluss physiko-chemischer Oberfl{\"a}chenprozesse wie Adsorption und Kondensation ist. Hierdurch wird nicht nur die Oberfl{\"a}chenenergie der Partikel abgebaut, sondern auch eine Verminderung der Hydratationsw{\"a}rme verursacht. Somit wirken sich physikalische Vorg{\"a}nge thermodynamisch aus. Einwirkende und resultierende Parameter einer Alterung wirken wie folgt {\"a}ußerst komplex zusammen: Die dominierenden Bindemitteleigenschaften Abbindeverhalten und Wasseranspruch ver{\"a}ndern sich durch eine Alterung sowohl aufgrund der Phasenumwandlungen als auch infolge der Ver{\"a}nderungen der Kristallite. Ebenso einflussreich ist die Ver{\"a}nderung der Oberfl{\"a}chencharakteristik. Die Auswirkung der Alterung auf die Reaktivit{\"a}t geht deutlich {\"u}ber den Abbau von Anhydrit III, die Dezimierung von abbindef{\"a}higem Material und die beschleunigende Wirkung von Alterungsdihydrat hinaus. Das Wachstum der Kristallite von Halbhydrat und die Verringerung der inneren Energie sowie die energetisch g{\"u}nstige spontane Beladung der Kristallgitterkan{\"a}le kleinster Anhydrit III-Kristallite mit dampff{\"o}rmigem Wasser m{\"u}ssen als maßgebliche Ursachen f{\"u}r die Abnahme der Reaktivit{\"a}t infolge der Alterung herausgestellt werden. Die Abnahme der spezifischen Oberfl{\"a}che und der Oberfl{\"a}chenenergie wirken sich außerdem auf den L{\"o}sungs- und den Hydratationsprozess aus. Der auf der Oberfl{\"a}che von Anhydrit III kristallisierte Anhydrit II wirkt sich auch nach der Umwandlung von A III in Halbhydrat l{\"o}sungshemmend aus. Infolge der alterungsbedingten Dihydratbildung, die bei anhaltender Feuchteeinwirkung einsetzt, wird diese Wirkung aufgehoben bzw. vermindert. Obgleich Dihydrat f{\"u}r seinen Beschleunigungseffekt bekannt ist, entfaltet Alterungsdihydrat infolge seiner besonderen Ausbildung innerhalb der wenige Molek{\"u}llagen umfassenden Kondenswasserschicht nur eine geringe keimbildende Wirkung. Eine wesentliche Erkenntnis betrifft den Bindungscharakter des {\"U}berst{\"o}chiometrischen Wassers. Diesbez{\"u}glich ist eine rein physikalische Bindung nachweisbar. Das in der Arbeit als st{\"a}rker adsorptiv gebunden bezeichnete Wasser kommt neben der Freien Feuchte ausschließlich bei Anwesenheit von Halbhydrat vor. Dieser Zusammenhang wird erstmalig hergestellt und mit Hilfe der kristallchemisch bedingten h{\"o}heren Oberfl{\"a}chenenergie von Halbhydrat erkl{\"a}rt.}, subject = {Alterung}, language = {de} } @phdthesis{Hanna, author = {Hanna, John}, title = {Computational Fracture Modeling and Design of Encapsulation-Based Self-Healing Concrete Using XFEM and Cohesive Surface Technique}, doi = {10.25643/bauhaus-universitaet.4746}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20221124-47467}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {125}, abstract = {Encapsulation-based self-healing concrete (SHC) is the most promising technique for providing a self-healing mechanism to concrete. This is due to its capacity to heal fractures effectively without human interventions, extending the operational life and lowering maintenance costs. The healing mechanism is created by embedding capsules containing the healing agent inside the concrete. The healing agent will be released once the capsules are fractured and the healing occurs in the vicinity of the damaged part. The healing efficiency of the SHC is still not clear and depends on several factors; in the case of microcapsules SHC the fracture of microcapsules is the most important aspect to release the healing agents and hence heal the cracks. This study contributes to verifying the healing efficiency of SHC and the fracture mechanism of the microcapsules. Extended finite element method (XFEM) is a flexible, and powerful discrete crack method that allows crack propagation without the requirement for re-meshing and has been shown high accuracy for modeling fracture in concrete. In this thesis, a computational fracture modeling approach of Encapsulation-based SHC is proposed based on the XFEM and cohesive surface technique (CS) to study the healing efficiency and the potential of fracture and debonding of the microcapsules or the solidified healing agents from the concrete matrix as well. The concrete matrix and a microcapsule shell both are modeled by the XFEM and combined together by CS. The effects of the healed-crack length, the interfacial fracture properties, and microcapsule size on the load carrying capability and fracture pattern of the SHC have been studied. The obtained results are compared to those obtained from the zero thickness cohesive element approach to demonstrate the significant accuracy and the validity of the proposed simulation. The present fracture simulation is developed to study the influence of the capsular clustering on the fracture mechanism by varying the contact surface area of the CS between the microcapsule shell and the concrete matrix. The proposed fracture simulation is expanded to 3D simulations to validate the 2D computational simulations and to estimate the accuracy difference ratio between 2D and 3D simulations. In addition, a proposed design method is developed to design the size of the microcapsules consideration of a sufficient volume of healing agent to heal the expected crack width. This method is based on the configuration of the unit cell (UC), Representative Volume Element (RVE), Periodic Boundary Conditions (PBC), and associated them to the volume fraction (Vf) and the crack width as variables. The proposed microcapsule design is verified through computational fracture simulations.}, subject = {Beton}, language = {en} } @article{IlyaniAkmarKramerRabczuk, author = {Ilyani Akmar, A.B. and Kramer, O. and Rabczuk, Timon}, title = {Multi-objective evolutionary optimization of sandwich structures: An evaluation by elitist non-dominated sorting evolution strategy}, series = {American Journal of Engineering and Applied Sciences}, journal = {American Journal of Engineering and Applied Sciences}, doi = {10.3844/ajeassp.2015.185.201}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20170418-31402}, pages = {185 -- 201}, abstract = {In this study, an application of evolutionary multi-objective optimization algorithms on the optimization of sandwich structures is presented. The solution strategy is known as Elitist Non-Dominated Sorting Evolution Strategy (ENSES) wherein Evolution Strategies (ES) as Evolutionary Algorithm (EA) in the elitist Non-dominated Sorting Genetic algorithm (NSGA-II) procedure. Evolutionary algorithm seems a compatible approach to resolve multi-objective optimization problems because it is inspired by natural evolution, which closely linked to Artificial Intelligence (AI) techniques and elitism has shown an important factor for improving evolutionary multi-objective search. In order to evaluate the notion of performance by ENSES, the well-known study case of sandwich structures are reconsidered. For Case 1, the goals of the multi-objective optimization are minimization of the deflection and the weight of the sandwich structures. The length, the core and skin thicknesses are the design variables of Case 1. For Case 2, the objective functions are the fabrication cost, the beam weight and the end deflection of the sandwich structures. There are four design variables i.e., the weld height, the weld length, the beam depth and the beam width in Case 2. Numerical results are presented in terms of Paretooptimal solutions for both evaluated cases.}, subject = {Optimierung}, language = {en} } @article{LeNguyenLudwig, author = {Le, Ha Thanh and Nguyen, Sang Thanh and Ludwig, Horst-Michael}, title = {A Study on High Performance Fine-Grained Concrete Containing Rice Husk Ash}, series = {International Journal of Concrete Structures and Materials}, journal = {International Journal of Concrete Structures and Materials}, doi = {10.1007/s40069-014-0078-z}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20170425-31477}, pages = {301 -- 307}, abstract = {Rice husk ash (RHA) is classified as a highly reactive pozzolan. It has a very high silica content similar to that of silica fume (SF). Using less-expensive and locally available RHA as a mineral admixture in concrete brings ample benefits to the costs, the technical properties of concrete as well as to the environment. An experimental study of the effect of RHA blending on workability, strength and durability of high performance fine-grained concrete (HPFGC) is presented. The results show that the addition of RHA to HPFGC improved significantly compressive strength, splitting tensile strength and chloride penetration resistance. Interestingly, the ratio of compressive strength to splitting tensile strength of HPFGC was lower than that of ordinary concrete, especially for the concrete made with 20 \% RHA. Compressive strength and splitting tensile strength of HPFGC containing RHA was similar and slightly higher, respectively, than for HPFGC containing SF. Chloride penetration resistance of HPFGC containing 10-15 \% RHA was comparable with that of HPFGC containing 10 \% SF.}, subject = {Hochfester Beton}, language = {en} } @article{ZhuangHuangLiangetal., author = {Zhuang, Xiaoying and Huang, Runqiu and Liang, Chao and Rabczuk, Timon}, title = {A coupled thermo-hydro-mechanical model of jointed hard rock for compressed air energy storage}, series = {Mathematical Problems in Engineering}, journal = {Mathematical Problems in Engineering}, doi = {10.1155/2014/179169}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20170428-31726}, abstract = {Renewable energy resources such as wind and solar are intermittent, which causes instability when being connected to utility grid of electricity. Compressed air energy storage (CAES) provides an economic and technical viable solution to this problem by utilizing subsurface rock cavern to store the electricity generated by renewable energy in the form of compressed air. Though CAES has been used for over three decades, it is only restricted to salt rock or aquifers for air tightness reason. In this paper, the technical feasibility of utilizing hard rock for CAES is investigated by using a coupled thermo-hydro-mechanical (THM) modelling of nonisothermal gas flow. Governing equations are derived from the rules of energy balance, mass balance, and static equilibrium. Cyclic volumetric mass source and heat source models are applied to simulate the gas injection and production. Evaluation is carried out for intact rock and rock with discrete crack, respectively. In both cases, the heat and pressure losses using air mass control and supplementary air injection are compared.}, subject = {Energiespeicherung}, language = {en} } @article{AmaniSaboorBagherzadehRabczuk, author = {Amani, Jafar and Saboor Bagherzadeh, Amir and Rabczuk, Timon}, title = {Error estimate and adaptive refinement in mixed discrete least squares meshless method}, series = {Mathematical Problems in Engineering}, journal = {Mathematical Problems in Engineering}, doi = {10.1155/2014/721240}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20170413-31181}, abstract = {The node moving and multistage node enrichment adaptive refinement procedures are extended in mixed discrete least squares meshless (MDLSM) method for efficient analysis of elasticity problems. In the formulation of MDLSM method, mixed formulation is accepted to avoid second-order differentiation of shape functions and to obtain displacements and stresses simultaneously. In the refinement procedures, a robust error estimator based on the value of the least square residuals functional of the governing differential equations and its boundaries at nodal points is used which is inherently available from the MDLSM formulation and can efficiently identify the zones with higher numerical errors. The results are compared with the refinement procedures in the irreducible formulation of discrete least squares meshless (DLSM) method and show the accuracy and efficiency of the proposed procedures. Also, the comparison of the error norms and convergence rate show the fidelity of the proposed adaptive refinement procedures in the MDLSM method.}, subject = {Elastizit{\"a}t}, language = {en} } @phdthesis{Budarapu, author = {Budarapu, Pattabhi Ramaiah}, title = {Adaptive multiscale methods for fracture}, doi = {10.25643/bauhaus-universitaet.2391}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20150507-23918}, school = {Bauhaus-Universit{\"a}t Weimar}, abstract = {One major research focus in the Material Science and Engineering Community in the past decade has been to obtain a more fundamental understanding on the phenomenon 'material failure'. Such an understanding is critical for engineers and scientists developing new materials with higher strength and toughness, developing robust designs against failure, or for those concerned with an accurate estimate of a component's design life. Defects like cracks and dislocations evolve at nano scales and influence the macroscopic properties such as strength, toughness and ductility of a material. In engineering applications, the global response of the system is often governed by the behaviour at the smaller length scales. Hence, the sub-scale behaviour must be computed accurately for good predictions of the full scale behaviour. Molecular Dynamics (MD) simulations promise to reveal the fundamental mechanics of material failure by modeling the atom to atom interactions. Since the atomistic dimensions are of the order of Angstroms ( A), approximately 85 billion atoms are required to model a 1 micro- m^3 volume of Copper. Therefore, pure atomistic models are prohibitively expensive with everyday engineering computations involving macroscopic cracks and shear bands, which are much larger than the atomistic length and time scales. To reduce the computational effort, multiscale methods are required, which are able to couple a continuum description of the structure with an atomistic description. In such paradigms, cracks and dislocations are explicitly modeled at the atomistic scale, whilst a self-consistent continuum model elsewhere. Many multiscale methods for fracture are developed for "fictitious" materials based on "simple" potentials such as the Lennard-Jones potential. Moreover, multiscale methods for evolving cracks are rare. Efficient methods to coarse grain the fine scale defects are missing. However, the existing multiscale methods for fracture do not adaptively adjust the fine scale domain as the crack propagates. Most methods, therefore only "enlarge" the fine scale domain and therefore drastically increase computational cost. Adaptive adjustment requires the fine scale domain to be refined and coarsened. One of the major difficulties in multiscale methods for fracture is to up-scale fracture related material information from the fine scale to the coarse scale, in particular for complex crack problems. Most of the existing approaches therefore were applied to examples with comparatively few macroscopic cracks. Key contributions The bridging scale method is enhanced using the phantom node method so that cracks can be modeled at the coarse scale. To ensure self-consistency in the bulk, a virtual atom cluster is devised providing the response of the intact material at the coarse scale. A molecular statics model is employed in the fine scale where crack propagation is modeled by naturally breaking the bonds. The fine scale and coarse scale models are coupled by enforcing the displacement boundary conditions on the ghost atoms. An energy criterion is used to detect the crack tip location. Adaptive refinement and coarsening schemes are developed and implemented during the crack propagation. The results were observed to be in excellent agreement with the pure atomistic simulations. The developed multiscale method is one of the first adaptive multiscale method for fracture. A robust and simple three dimensional coarse graining technique to convert a given atomistic region into an equivalent coarse region, in the context of multiscale fracture has been developed. The developed method is the first of its kind. The developed coarse graining technique can be applied to identify and upscale the defects like: cracks, dislocations and shear bands. The current method has been applied to estimate the equivalent coarse scale models of several complex fracture patterns arrived from the pure atomistic simulations. The upscaled fracture pattern agree well with the actual fracture pattern. The error in the potential energy of the pure atomistic and the coarse grained model was observed to be acceptable. A first novel meshless adaptive multiscale method for fracture has been developed. The phantom node method is replaced by a meshless differential reproducing kernel particle method. The differential reproducing kernel particle method is comparatively more expensive but allows for a more "natural" coupling between the two scales due to the meshless interpolation functions. The higher order continuity is also beneficial. The centro symmetry parameter is used to detect the crack tip location. The developed multiscale method is employed to study the complex crack propagation. Results based on the meshless adaptive multiscale method were observed to be in excellent agreement with the pure atomistic simulations. The developed multiscale methods are applied to study the fracture in practical materials like Graphene and Graphene on Silicon surface. The bond stretching and the bond reorientation were observed to be the net mechanisms of the crack growth in Graphene. The influence of time step on the crack propagation was studied using two different time steps. Pure atomistic simulations of fracture in Graphene on Silicon surface are presented. Details of the three dimensional multiscale method to study the fracture in Graphene on Silicon surface are discussed.}, subject = {Material}, language = {en} } @phdthesis{Le, author = {Le, Ha Thanh}, title = {Behaviour of Rice Husk Ash in Self-Compacting High Performance Concrete}, publisher = {Bauhaus-Universit{\"a}t Weimar, F.A. Finger- Institut f{\"u}r Baustoffkunde, Professur Werkstoffe des Bauens}, address = {Weimar}, isbn = {978-3-00-048928-0}, doi = {10.25643/bauhaus-universitaet.2373}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20150310-23730}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {181}, abstract = {The main objective of this thesis is to investigate the characteristics of rice husk ash RHA) and then its behaviour in self-compacting high performance concrete (SCHPC) with respects to rheological properties, hydration and microstructure development and alkali silica reaction, in comparison with silica fume (SF). The main results show that the RHA is a macro-mesoporous amorphous siliceous material with a very high silica content comparable with SF. The pore size distribution is the most important parameter of RHA besides amorphous silica content. This parameter affects pore volume, specific surface area, and thus the water demand and the pozzolanic reactivity of RHA and its behaviour in SCHPC. The incorporation of RHA decreases filling and passing abilities, but significantly increases plastic viscosity and segregation resistance of SCHPC. Therefore, RHA can be used as a viscosity modifying admixture for SCHPC. The incorporation of RHA increases the superplasticizer adsorption, the superplasticizer saturation dosage, yield stress and plastic viscosity of mortar. Fresh mortar formulated from SCHPC is a shear-thickening material. The incorporation of RHA/SF ecreases the shearthickening degree. The incorporation of RHA/SF increases the degree of cement hydration. SF appears more effective at 3 days possibly due to the better nucleation site effect, whereas RHA dominates at the later ages possibly due to the internal water curing effect. The incorporation of RHA/SF increases the degree of C3S hydration, particularly the C3S hydration rate from 3 to 14 days. The pozzolanic reaction takes place outside and inside RHA particles. The internal pozzolanic eaction products consolidate the pores inside RHA particles rather than contribute to the pore refinement in the cement matrix. In the presence of the high alkali concentration, RHA particles act as microreactive aggregates and react with alkali hydroxide to generate the expansive alkali silica reaction products. Increasing the particle size and temperature increases the alkali silica reactivity of RHA. The mechanism for the successive pozzolanic and alkali silica reactions of RHA is theorized. Additionally, a new simple mix design method is proposed for SCHPC containing various supplementary cementitious materials, i.e. RHA, SF, fly ash and limestone powder.}, subject = {Werkstoffkunde}, language = {en} } @phdthesis{Buchwald, author = {Buchwald, Anja}, title = {Der Einfluss des Kalziums auf die Kondensation von (Alumo-)Silikaten in alkali-aktivierten Bindern}, doi = {10.25643/bauhaus-universitaet.2104}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20140124-21046}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {35}, abstract = {Es werden geopolymere und alkali-aktivierte Bindemittel definiert und ihre prinzipiellen technischen und {\"o}kologischen Eigenschaften diskutiert.}, subject = {Bindemittel}, language = {de} } @phdthesis{Vollmering, author = {Vollmering, Max}, title = {Damage Localization of Mechanical Structures by Subspace Identification and Krein Space Based H-infinity Estimation}, doi = {10.25643/bauhaus-universitaet.3772}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20180730-37728}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {205}, abstract = {This dissertation is devoted to the theoretical development and experimental laboratory verification of a new damage localization method: The state projection estimation error (SP2E). This method is based on the subspace identification of mechanical structures, Krein space based H-infinity estimation and oblique projections. To explain method SP2E, several theories are discussed and laboratory experiments have been conducted and analysed. A fundamental approach of structural dynamics is outlined first by explaining mechanical systems based on first principles. Following that, a fundamentally different approach, subspace identification, is comprehensively explained. While both theories, first principle and subspace identification based mechanical systems, may be seen as widespread methods, barely known and new techniques follow up. Therefore, the indefinite quadratic estimation theory is explained. Based on a Popov function approach, this leads to the Krein space based H-infinity theory. Subsequently, a new method for damage identification, namely SP2E, is proposed. Here, the introduction of a difference process, the analysis by its average process power and the application of oblique projections is discussed in depth. Finally, the new method is verified in laboratory experiments. Therefore, the identification of a laboratory structure at Leipzig University of Applied Sciences is elaborated. Then structural alterations are experimentally applied, which were localized by SP2E afterwards. In the end four experimental sensitivity studies are shown and discussed. For each measurement series the structural alteration was increased, which was successfully tracked by SP2E. The experimental results are plausible and in accordance with the developed theories. By repeating these experiments, the applicability of SP2E for damage localization is experimentally proven.}, subject = {Strukturmechanik}, language = {en} } @article{VuBacNguyenXuanChenetal., author = {Vu-Bac, N. and Nguyen-Xuan, Hung and Chen, Lei and Lee, C.K. and Zi, Goangseup and Zhuang, Xiaoying and Liu, G.R. and Rabczuk, Timon}, title = {A phantom-node method with edge-based strain smoothing for linear elastic fracture mechanics}, series = {Journal of Applied Mathematics}, journal = {Journal of Applied Mathematics}, doi = {10.1155/2013/978026}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20170426-31676}, abstract = {This paper presents a novel numerical procedure based on the combination of an edge-based smoothed finite element (ES-FEM) with a phantom-node method for 2D linear elastic fracture mechanics. In the standard phantom-node method, the cracks are formulated by adding phantom nodes, and the cracked element is replaced by two new superimposed elements. This approach is quite simple to implement into existing explicit finite element programs. The shape functions associated with discontinuous elements are similar to those of the standard finite elements, which leads to certain simplification with implementing in the existing codes. The phantom-node method allows modeling discontinuities at an arbitrary location in the mesh. The ES-FEM model owns a close-to-exact stiffness that is much softer than lower-order finite element methods (FEM). Taking advantage of both the ES-FEM and the phantom-node method, we introduce an edge-based strain smoothing technique for the phantom-node method. Numerical results show that the proposed method achieves high accuracy compared with the extended finite element method (XFEM) and other reference solutions.}, subject = {Finite-Elemente-Methode}, language = {en} } @phdthesis{Flohr, author = {Flohr, Alexander}, title = {Der Einfluss von Polymermodifikationen, unterschiedlichen Gesteinsk{\"o}rnungen und Gesteinsk{\"o}rnungssubstitutionsmaterial auf das Verformungs- und Bruchverhalten von Beton}, doi = {10.25643/bauhaus-universitaet.2003}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20130806-20035}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {148}, abstract = {In dieser Arbeit werden die Ergebnisse von experimentellen Untersuchungen an unbewehrten und bewehrten modifizierten Betonen unter monoton steigender Belastung bis zum Bruch, einfacher Kurzzeitbelastung im Grenzbereich der Tragf{\"a}higkeit und mehrfach wiederholter Belastung mit kontinuierlicher Be- und Entlastungsgeschwindigkeit vorgestellt und ausgewertet. F{\"u}r die Modifizierung der Betone wurden zwei grunds{\"a}tzliche Vorgehens¬weisen angewendet: die Variation der Gesteinsk{\"o}rnung und die Modifizierung der Bindemittelphase mit thermoplastischen Polymeren. Die Auswirkungen der Modifikationen auf die Festigkeitseigenschaften und das Form{\"a}nderungsverhalten des Betons bei Kurzzeitbelastung waren dabei von besonderem Interesse. Die beobachteten Ver{\"a}nderungen der Festbetoneigenschaften sowie der nichtlineare Zu-sammenhang zwischen den elastischen und nichtelastischen Verformungsanteilen signali-sieren, dass derartige Modifizierungen das Verformungs- und Bruchverhalten von Beton sig-nifikant beeinflussen und somit beim Nachweis der Tragf{\"a}higkeit und Gebrauchstauglichkeit ber{\"u}cksichtigt werden m{\"u}ssen. Neben der Evaluierung des beanspruchungsabh{\"a}ngigen Form{\"a}nderungsverhaltens werden die etablierten Ans{\"a}tze zur Beschreibung der Gef{\"u}gezu-standsbereiche bei Druckbelastung weiter entwickelt, so dass die {\"U}berg{\"a}nge zwischen den Bereichen exakt ermittelt und die Auspr{\"a}gung der Bereiche quantifiziert werden k{\"o}nnen. Damit ist ein genauerer Vergleich der durch die Modifizierungen hervorgerufenen Ver{\"a}nde-rungen m{\"o}glich.}, subject = {Beton}, language = {de} } @inproceedings{GeskeBenzVoelker, author = {Geske, Mara and Benz, Alexander and V{\"o}lker, Conrad}, title = {Anwendung georeferenzierter Bilddaten bei energetischen Quartiersanalysen}, series = {Tagungsband Bauphysiktage Kaiserslautern 2022}, booktitle = {Tagungsband Bauphysiktage Kaiserslautern 2022}, editor = {Kornadt, Oliver and Carrigan, Svenja and Hofmann, Markus and V{\"o}lker, Conrad}, publisher = {Eigenverlag der Technischen Universit{\"a}t Kaiserslautern}, address = {Kaiserslautern}, isbn = {987-3-95974-176-7}, issn = {2363-8206}, doi = {10.25643/bauhaus-universitaet.4654}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20220617-46544}, pages = {127-129}, abstract = {Bei Analysen des Geb{\"a}udebestands im Quartierskontext werden zu Dokumentationszwecken viele Bilddaten erzeugt. Diese Daten sind im Nachhinein h{\"a}ufig keinen eindeutig genauen Standorten und Blickwinkeln auf das Bauwerk zuzuordnen. Insbesondere gilt dies f{\"u}r Ortsunkundige oder f{\"u}r Detailaufnahmen. Eine zus{\"a}tzliche Herausforderung stellt die Aufnahme von W{\"a}rmebr{\"u}cken- oder andersartigen Geb{\"a}udedetails durch Thermogramme dar. In der Praxis kommen hier oftmals analoge, fehleranf{\"a}llige L{\"o}sungen zum Einsatz. Durch die Nutzung von Georeferenzierung kann diese L{\"u}cke geschlossen und eine eindeutige Kommunikation und Auswertung gew{\"a}hrleistet werden. Im Gegensatz zu den {\"u}blichen Kameras sind Smartphones nach Stand der Technik ausreichend ausgestattet, um neben Daten zu Standort auch die Orientierungswinkel einer Bildaufnahme zu dokumentieren. Die georefenzierten Bilder k{\"o}nnen auf Grundlage der in den sogenannten Exif-Daten mitgeschriebenen Informationen h{\"a}ndisch in ein bestehendes Quartiersmodell integriert werden. Anhand eines universit{\"a}ren Musterquartiers wird die nutzerfreundliche Realisierung beispielhaft erprobt und auf ihre Potentiale zur Automatisierung in Python untersucht. Hierf{\"u}r wurde ein bestehendes Quartiersmodell als geometrische Grundlage genutzt und um RGB-Bilder sowie Thermogramme erweitert. Das beschriebene Vorgehen wird im Rahmen der Anwendung auf seinen m{\"o}glichen Einsatz im Rahmen einer energetischen Quartierserfassung sowie einer Bauschadensdokumentation untersucht. Mit dem vorliegenden Beitrag wird dem Nutzenden ein Werkzeug bereitgestellt, das die hochwertige Dokumentation einer Bestandserfassung, auch im Quartierskontext, erm{\"o}glicht.}, subject = {Quartiersanalyse}, language = {de} } @phdthesis{Hamdia, author = {Hamdia, Khader}, title = {On the fracture toughness of polymeric nanocomposites: Comprehensive stochastic and numerical studies}, doi = {10.25643/bauhaus-universitaet.3765}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20180712-37652}, school = {Bauhaus-Universit{\"a}t Weimar}, abstract = {Polymeric nanocomposites (PNCs) are considered for numerous nanotechnology such as: nano-biotechnology, nano-systems, nanoelectronics, and nano-structured materials. Commonly , they are formed by polymer (epoxy) matrix reinforced with a nanosized filler. The addition of rigid nanofillers to the epoxy matrix has offered great improvements in the fracture toughness without sacrificing other important thermo-mechanical properties. The physics of the fracture in PNCs is rather complicated and is influenced by different parameters. The presence of uncertainty in the predicted output is expected as a result of stochastic variance in the factors affecting the fracture mechanism. Consequently, evaluating the improved fracture toughness in PNCs is a challenging problem. Artificial neural network (ANN) and adaptive neuro-fuzzy inference system (ANFIS) have been employed to predict the fracture energy of polymer/particle nanocomposites. The ANN and ANFIS models were constructed, trained, and tested based on a collection of 115 experimental datasets gathered from the literature. The performance evaluation indices of the developed ANN and ANFIS showed relatively small error, with high coefficients of determination (R2), and low root mean square error and mean absolute percentage error. In the framework for uncertainty quantification of PNCs, a sensitivity analysis (SA) has been conducted to examine the influence of uncertain input parameters on the fracture toughness of polymer/clay nanocomposites (PNCs). The phase-field approach is employed to predict the macroscopic properties of the composite considering six uncertain input parameters. The efficiency, robustness, and repeatability are compared and evaluated comprehensively for five different SA methods. The Bayesian method is applied to develop a methodology in order to evaluate the performance of different analytical models used in predicting the fracture toughness of polymeric particles nanocomposites. The developed method have considered the model and parameters uncertainties based on different reference data (experimental measurements) gained from the literature. Three analytical models differing in theory and assumptions were examined. The coefficients of variation of the model predictions to the measurements are calculated using the approximated optimal parameter sets. Then, the model selection probability is obtained with respect to the different reference data. Stochastic finite element modeling is implemented to predict the fracture toughness of polymer/particle nanocomposites. For this purpose, 2D finite element model containing an epoxy matrix and rigid nanoparticles surrounded by an interphase zone is generated. The crack propagation is simulated by the cohesive segments method and phantom nodes. Considering the uncertainties in the input parameters, a polynomial chaos expansion (PCE) surrogate model is construed followed by a sensitivity analysis.}, subject = {Bruch}, language = {en} } @phdthesis{Vesper, author = {Vesper, Andreas}, title = {Entwicklung eines Berechnungsverfahrens zur Ermittlung der Kapazit{\"a}t in lichtsignalgeregelten Zufahrten mit zus{\"a}tzlichen Aufstellstreifen bei gleichzeitiger Freigabezeit}, doi = {10.25643/bauhaus-universitaet.3789}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20180925-37895}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {338}, abstract = {Im Rahmen der Dissertation ist ein analytisches Berechnungsverfahren zur Ermittlung der Kapazit{\"a}t in lichtsignalgeregelten Zufahrten mit zus{\"a}tzlichen Aufstellstreifen bei gleichzeitiger Freigabezeit entwickelt worden, dass sich durch folgende Eigenschaften auszeichnet: a) einfaches Berechnungsverfahren - Ansatz eines einfachen linearen Berechnungsansatzes, der auf den Grundzusammenh{\"a}ngen des Verkehrsablaufs in lichtsignalgeregelten Zufahrten aufbaut, b) breites Anwendungsgebiet - Berechnungsverfahren kann in Zufahrten mit bis zu zwei zus{\"a}tzlichen Aufstellstreifen angewendet werden, c) hohe Genauigkeit - Im Rahmen eines direkten Vergleichs konnte u. a. gezeigt werden, dass mit dem hergeleiteten analytischen Berechnungsverfahren genauere Kapazit{\"a}tswerte ermittelt werden k{\"o}nnen, als mit dem Berechnungsverfahren nach HBS 2015.}, subject = {Verkehrssignalanlage}, language = {de} } @article{ZhangHaoWangetal., author = {Zhang, Chao and Hao, Xiao-Li and Wang, Cuixia and Wei, Ning and Rabczuk, Timon}, title = {Thermal conductivity of graphene nanoribbons under shear deformation: A molecular dynamics simulation}, series = {Scientific Reports}, journal = {Scientific Reports}, doi = {10.1038/srep41398}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20170428-31718}, abstract = {Tensile strain and compress strain can greatly affect the thermal conductivity of graphene nanoribbons (GNRs). However, the effect of GNRs under shear strain, which is also one of the main strain effect, has not been studied systematically yet. In this work, we employ reverse nonequilibrium molecular dynamics (RNEMD) to the systematical study of the thermal conductivity of GNRs (with model size of 4 nm × 15 nm) under the shear strain. Our studies show that the thermal conductivity of GNRs is not sensitive to the shear strain, and the thermal conductivity decreases only 12-16\% before the pristine structure is broken. Furthermore, the phonon frequency and the change of the micro-structure of GNRs, such as band angel and bond length, are analyzed to explore the tendency of thermal conductivity. The results show that the main influence of shear strain is on the in-plane phonon density of states (PDOS), whose G band (higher frequency peaks) moved to the low frequency, thus the thermal conductivity is decreased. The unique thermal properties of GNRs under shear strains suggest their great potentials for graphene nanodevices and great potentials in the thermal managements and thermoelectric applications.}, subject = {W{\"a}rmeleitf{\"a}higkeit}, 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{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} } @techreport{VogelVoelkerArnoldetal., author = {Vogel, Albert and V{\"o}lker, Conrad and Arnold, J{\"o}rg and Schmidt, Jens and Thurow, Torsten and Braunes, J{\"o}rg and Tonn, Christian and Bode, Kay-Andr{\´e} and Baldy, Franziska and Erfurt, Wolfgang and Tatarin, Ren{\´e}}, title = {Methoden und Baustoffe zur nutzerorientierten Bausanierung. Schlussbericht zum InnoProfile Forschungsvorhaben}, organization = {Bauhaus-Universit{\"a}t Weimar}, isbn = {978-3-86068-501-3 (Printausg.)}, doi = {10.25643/bauhaus-universitaet.2022}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20130830-20229}, pages = {106}, abstract = {Nutzerorientierte Bausanierung bedeutet eine gegen{\"u}ber dem konventionellen Vorgehen deutlich verst{\"a}rkte Ausrichtung des Planungs- und Sanierungsprozesses auf die Anforderungen und Bed{\"u}rfnisse des zuk{\"u}nftigen Nutzers eines Geb{\"a}udes. Dies hat einerseits ein hochwertigeres Produkt zum Ergebnis, erfordert andererseits aber auch den Einsatz neuer Methoden und Baustoffe sowie ein vernetztes Zusammenarbeiten aller am Bauprozess Beteiligten. Der Fokus der Publikation liegt dabei auf den Bereichen, die eine hohe Relevanz f{\"u}r die nutzerorientierte Bausanierung aufweisen. Dabei handelt es sich insbesondere um: Computergest{\"u}tztes Bauaufmaß und digitale Bauwerksmodellierung (BIM), bauphysikalische Methoden zur Optimierung von Energieeffizienz und Behaglichkeit bei der Sanierung von Bestandsgeb{\"a}uden, zerst{\"o}rungsfreie Untersuchungsmethoden im Rahmen einer substanzschonenden Bauzustandsanalyse und Entwicklung von Erg{\"a}nzungsbaustoffen. Das Projekt nuBau ist eine Kooperation zwischen den Fakult{\"a}ten Bauingenieurwesen und Architektur der Bauhaus-Universit{\"a}t Weimar. Die beteiligten Professuren sind: Bauphysik, Informatik in der Architektur, Polymere Werkstoffe und Werkstoffe des Bauens.}, subject = {Nutzerorientierte Bausanierung}, language = {de} } @article{HarirchianKumariJadhavetal., author = {Harirchian, Ehsan and Kumari, Vandana and Jadhav, Kirti and Rasulzade, Shahla and Lahmer, Tom and Raj Das, Rohan}, title = {A Synthesized Study Based on Machine Learning Approaches for Rapid Classifying Earthquake Damage Grades to RC Buildings}, series = {Applied Sciences}, volume = {2021}, journal = {Applied Sciences}, number = {Volume 11, issue 16, article 7540}, publisher = {MDPI}, address = {Basel}, doi = {10.3390/app11167540}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20210818-44853}, pages = {1 -- 33}, abstract = {A vast number of existing buildings were constructed before the development and enforcement of seismic design codes, which run into the risk of being severely damaged under the action of seismic excitations. This poses not only a threat to the life of people but also affects the socio-economic stability in the affected area. Therefore, it is necessary to assess such buildings' present vulnerability to make an educated decision regarding risk mitigation by seismic strengthening techniques such as retrofitting. However, it is economically and timely manner not feasible to inspect, repair, and augment every old building on an urban scale. As a result, a reliable rapid screening methods, namely Rapid Visual Screening (RVS), have garnered increasing interest among researchers and decision-makers alike. In this study, the effectiveness of five different Machine Learning (ML) techniques in vulnerability prediction applications have been investigated. The damage data of four different earthquakes from Ecuador, Haiti, Nepal, and South Korea, have been utilized to train and test the developed models. Eight performance modifiers have been implemented as variables with a supervised ML. The investigations on this paper illustrate that the assessed vulnerability classes by ML techniques were very close to the actual damage levels observed in the buildings.}, subject = {Maschinelles Lernen}, language = {en} } @article{GuerlebeckLegatiukWebber, author = {G{\"u}rlebeck, Klaus and Legatiuk, Dmitrii and Webber, Kemmar}, title = {Operator Calculus Approach to Comparison of Elasticity Models for Modelling of Masonry Structures}, series = {Mathematics}, volume = {2022}, journal = {Mathematics}, number = {Volume 10, issue 10, article 1670}, publisher = {MDPI}, address = {Basel}, doi = {10.3390/math10101670}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20220721-46726}, pages = {1 -- 22}, abstract = {The solution of any engineering problem starts with a modelling process aimed at formulating a mathematical model, which must describe the problem under consideration with sufficient precision. Because of heterogeneity of modern engineering applications, mathematical modelling scatters nowadays from incredibly precise micro- and even nano-modelling of materials to macro-modelling, which is more appropriate for practical engineering computations. In the field of masonry structures, a macro-model of the material can be constructed based on various elasticity theories, such as classical elasticity, micropolar elasticity and Cosserat elasticity. Evidently, a different macro-behaviour is expected depending on the specific theory used in the background. Although there have been several theoretical studies of different elasticity theories in recent years, there is still a lack of understanding of how modelling assumptions of different elasticity theories influence the modelling results of masonry structures. Therefore, a rigorous approach to comparison of different three-dimensional elasticity models based on quaternionic operator calculus is proposed in this paper. In this way, three elasticity models are described and spatial boundary value problems for these models are discussed. In particular, explicit representation formulae for their solutions are constructed. After that, by using these representation formulae, explicit estimates for the solutions obtained by different elasticity theories are obtained. Finally, several numerical examples are presented, which indicate a practical difference in the solutions.}, subject = {Mauerwerk}, language = {en} } @article{TarabenMorgenthal, author = {Taraben, Jakob and Morgenthal, Guido}, title = {Integration and Comparison Methods for Multitemporal Image-Based 2D Annotations in Linked 3D Building Documentation}, series = {Remote Sensing}, volume = {2022}, journal = {Remote Sensing}, number = {Volume 14, issue 9, article 2286}, publisher = {MDPI}, address = {Basel}, doi = {10.3390/rs14092286}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20220513-46488}, pages = {1 -- 20}, abstract = {Data acquisition systems and methods to capture high-resolution images or reconstruct 3D point clouds of existing structures are an effective way to document their as-is condition. These methods enable a detailed analysis of building surfaces, providing precise 3D representations. However, for the condition assessment and documentation, damages are mainly annotated in 2D representations, such as images, orthophotos, or technical drawings, which do not allow for the application of a 3D workflow or automated comparisons of multitemporal datasets. In the available software for building heritage data management and analysis, a wide range of annotation and evaluation functions are available, but they also lack integrated post-processing methods and systematic workflows. The article presents novel methods developed to facilitate such automated 3D workflows and validates them on a small historic church building in Thuringia, Germany. Post-processing steps using photogrammetric 3D reconstruction data along with imagery were implemented, which show the possibilities of integrating 2D annotations into 3D documentations. Further, the application of voxel-based methods on the dataset enables the evaluation of geometrical changes of multitemporal annotations in different states and the assignment to elements of scans or building models. The proposed workflow also highlights the potential of these methods for condition assessment and planning of restoration work, as well as the possibility to represent the analysis results in standardised building model formats.}, subject = {Bauwesen}, language = {en} } @article{Hanna, author = {Hanna, John}, title = {Computational Modelling for the Effects of Capsular Clustering on Fracture of Encapsulation-Based Self-Healing Concrete Using XFEM and Cohesive Surface Technique}, series = {Applied Sciences}, volume = {2022}, journal = {Applied Sciences}, number = {Volume 12, issue 10, article 5112}, publisher = {MDPI}, address = {Basel}, doi = {10.3390/app12105112}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20220721-46717}, pages = {1 -- 17}, abstract = {The fracture of microcapsules is an important issue to release the healing agent for healing the cracks in encapsulation-based self-healing concrete. The capsular clustering generated from the concrete mixing process is considered one of the critical factors in the fracture mechanism. Since there is a lack of studies in the literature regarding this issue, the design of self-healing concrete cannot be made without an appropriate modelling strategy. In this paper, the effects of microcapsule size and clustering on the fractured microcapsules are studied computationally. A simple 2D computational modelling approach is developed based on the eXtended Finite Element Method (XFEM) and cohesive surface technique. The proposed model shows that the microcapsule size and clustering have significant roles in governing the load-carrying capacity and the crack propagation pattern and determines whether the microcapsule will be fractured or debonded from the concrete matrix. The higher the microcapsule circumferential contact length, the higher the load-carrying capacity. When it is lower than 25\% of the microcapsule circumference, it will result in a greater possibility for the debonding of the microcapsule from the concrete. The greater the core/shell ratio (smaller shell thickness), the greater the likelihood of microcapsules being fractured.}, subject = {Beton}, language = {en} } @article{RabczukZhuangOterkus, author = {Rabczuk, Timon and Zhuang, Xiaoying and Oterkus, Erkan}, title = {Editorial: Computational modeling based on nonlocal theory}, series = {Engineering with Computers}, volume = {2023}, journal = {Engineering with Computers}, number = {Volume 39, issue 3}, publisher = {Springer}, address = {London}, doi = {https://doi.org/10.1007/s00366-022-01775-7}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20230517-63658}, pages = {1}, abstract = {Nonlocal theories concern the interaction of objects, which are separated in space. Classical examples are Coulomb's law or Newton's law of universal gravitation. They had signficiant impact in physics and engineering. One classical application in mechanics is the failure of quasi-brittle materials. While local models lead to an ill-posed boundary value problem and associated mesh dependent results, nonlocal models guarantee the well-posedness and are furthermore relatively easy to implement into commercial computational software.}, subject = {Computersimulation}, language = {en} } @article{RenZhuangOterkusetal., author = {Ren, Huilong and Zhuang, Xiaoying and Oterkus, Erkan and Zhu, Hehua and Rabczuk, Timon}, title = {Nonlocal strong forms of thin plate, gradient elasticity, magneto-electro-elasticity and phase-field fracture by nonlocal operator method}, series = {Engineering with Computers}, volume = {2021}, journal = {Engineering with Computers}, doi = {10.1007/s00366-021-01502-8}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20211207-45388}, pages = {1 -- 22}, abstract = {The derivation of nonlocal strong forms for many physical problems remains cumbersome in traditional methods. In this paper, we apply the variational principle/weighted residual method based on nonlocal operator method for the derivation of nonlocal forms for elasticity, thin plate, gradient elasticity, electro-magneto-elasticity and phase-field fracture method. The nonlocal governing equations are expressed as an integral form on support and dual-support. The first example shows that the nonlocal elasticity has the same form as dual-horizon non-ordinary state-based peridynamics. The derivation is simple and general and it can convert efficiently many local physical models into their corresponding nonlocal forms. In addition, a criterion based on the instability of the nonlocal gradient is proposed for the fracture modelling in linear elasticity. Several numerical examples are presented to validate nonlocal elasticity and the nonlocal thin plate.}, subject = {Bruchmechanik}, language = {en} }