TY - JOUR A1 - Harirchian, Ehsan A1 - Jadhav, Kirti A1 - Mohammad, Kifaytullah A1 - Aghakouchaki Hosseini, Seyed Ehsan A1 - Lahmer, Tom T1 - A Comparative Study of MCDM Methods Integrated with Rapid Visual Seismic Vulnerability Assessment of Existing RC Structures JF - Applied Sciences N2 - Recently, the demand for residence and usage of urban infrastructure has been increased, thereby resulting in the elevation of risk levels of human lives over natural calamities. The occupancy demand has rapidly increased the construction rate, whereas the inadequate design of structures prone to more vulnerability. Buildings constructed before the development of seismic codes have an additional susceptibility to earthquake vibrations. The structural collapse causes an economic loss as well as setbacks for human lives. An application of different theoretical methods to analyze the structural behavior is expensive and time-consuming. Therefore, introducing a rapid vulnerability assessment method to check structural performances is necessary for future developments. The process, as mentioned earlier, is known as Rapid Visual Screening (RVS). This technique has been generated to identify, inventory, and screen structures that are potentially hazardous. Sometimes, poor construction quality does not provide some of the required parameters; in this case, the RVS process turns into a tedious scenario. Hence, to tackle such a situation, multiple-criteria decision-making (MCDM) methods for the seismic vulnerability assessment opens a new gateway. The different parameters required by RVS can be taken in MCDM. MCDM evaluates multiple conflicting criteria in decision making in several fields. This paper has aimed to bridge the gap between RVS and MCDM. Furthermore, to define the correlation between these techniques, implementation of the methodologies from Indian, Turkish, and Federal Emergency Management Agency (FEMA) codes has been done. The effects of seismic vulnerability of structures have been observed and compared. KW - Erdbebensicherheit KW - damaged buildings KW - earthquake safety assessment KW - soft computing techniques KW - rapid visual screening KW - seismic risk estimation KW - Multi-criteria decision making KW - vulnerability assessment KW - OA-Publikationsfonds2020 Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20200918-42360 UR - https://www.mdpi.com/2076-3417/10/18/6411/htm VL - 2020 IS - Volume 10, issue 18, article 6411 PB - MDPI CY - Basel ER - TY - INPR A1 - Khosravi, Khabat A1 - Sheikh Khozani, Zohreh A1 - Mao, Luka T1 - A comparison between advanced hybrid machine learning algorithms and empirical equations applied to abutment scour depth prediction N2 - Complex vortex flow patterns around bridge piers, especially during floods, cause scour process that can result in the failure of foundations. Abutment scour is a complex three-dimensional phenomenon that is difficult to predict especially with traditional formulas obtained using empirical approaches such as regressions. This paper presents a test of a standalone Kstar model with five novel hybrid algorithm of bagging (BA-Kstar), dagging (DA-Kstar), random committee (RC-Kstar), random subspace (RS-Kstar), and weighted instance handler wrapper (WIHWKstar) to predict scour depth (ds) for clear water condition. The dataset consists of 99 scour depth data from flume experiments (Dey and Barbhuiya, 2005) using abutment shapes such as vertical, semicircular and 45◦ wing. Four dimensionless parameter of relative flow depth (h/l), excess abutment Froude number (Fe), relative sediment size (d50/l) and relative submergence (d50/h) were considered for the prediction of relative scour depth (ds/l). A portion of the dataset was used for the calibration (70%), and the remaining used for model validation. Pearson correlation coefficients helped deciding relevance of the input parameters combination and finally four different combinations of input parameters were used. The performance of the models was assessed visually and with quantitative metrics. Overall, the best input combination for vertical abutment shape is the combination of Fe, d50/l and h/l, while for semicircular and 45◦ wing the combination of the Fe and d50/l is the most effective input parameter combination. Our results show that incorporating Fe, d50/l and h/l lead to higher performance while involving d50/h reduced the models prediction power for vertical abutment shape and for semicircular and 45◦ wing involving h/l and d50/h lead to more error. The WIHW-Kstar provided the highest performance in scour depth prediction around vertical abutment shape while RC-Kstar model outperform of other models for scour depth prediction around semicircular and 45◦ wing. KW - maschinelles Lernen Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20210311-43889 N1 - This is the pre-peer reviewed version of the following article: https://www.sciencedirect.com/science/article/abs/pii/S0022169421001475?via%3Dihub ; https://doi.org/10.1016/j.jhydrol.2021.126100 ER - TY - JOUR A1 - Alalade, Muyiwa A1 - Reichert, Ina A1 - Köhn, Daniel A1 - Wuttke, Frank A1 - Lahmer, Tom ED - Qu, Chunxu ED - Gao, Chunxu ED - Zhang, Rui ED - Jia, Ziguang ED - Li, Jiaxiang T1 - A Cyclic Multi-Stage Implementation of the Full-Waveform Inversion for the Identification of Anomalies in Dams JF - Infrastructures N2 - For the safe and efficient operation of dams, frequent monitoring and maintenance are required. These are usually expensive, time consuming, and cumbersome. To alleviate these issues, we propose applying a wave-based scheme for the location and quantification of damages in dams. To obtain high-resolution “interpretable” images of the damaged regions, we drew inspiration from non-linear full-multigrid methods for inverse problems and applied a new cyclic multi-stage full-waveform inversion (FWI) scheme. Our approach is less susceptible to the stability issues faced by the standard FWI scheme when dealing with ill-posed problems. In this paper, we first selected an optimal acquisition setup and then applied synthetic data to demonstrate the capability of our approach in identifying a series of anomalies in dams by a mixture of reflection and transmission tomography. The results had sufficient robustness, showing the prospects of application in the field of non-destructive testing of dams. KW - Damm KW - Defekt KW - inverse analysis KW - damage identification KW - full-waveform inversion KW - dams KW - wave propagation KW - OA-Publikationsfonds2022 Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20221201-48396 UR - https://www.mdpi.com/2412-3811/7/12/161 VL - 2022 IS - Volume 7, issue 12, article 161 PB - MDPI CY - Basel ER - TY - THES A1 - Vogler, Verena T1 - A framework for artificial coral reef design: Integrating computational modelling and high precision monitoring strategies for artificial coral reefs – an Ecosystem-aware design approach in times of climate change N2 - Tropical coral reefs, one of the world’s oldest ecosystems which support some of the highest levels of biodiversity on the planet, are currently facing an unprecedented ecological crisis during this massive human-activity-induced period of extinction. Hence, tropical reefs symbolically stand for the destructive effects of human activities on nature [4], [5]. Artificial reefs are excellent examples of how architectural design can be combined with ecosystem regeneration [6], [7], [8]. However, to work at the interface between the artificial and the complex and temporal nature of natural systems presents a challenge, i.a. in respect to the B-rep modelling legacy of computational modelling. The presented doctorate investigates strategies on how to apply digital practice to realise what is an essential bulwark to retain reefs in impossibly challenging times. Beyond the main question of integrating computational modelling and high precision monitoring strategies in artificial coral reef design, this doctorate explores techniques, methods, and linking frameworks to support future research and practice in ecology led design contexts. Considering the many existing approaches for artificial coral reefs design, one finds they often fall short in precisely understanding the relationships between architectural and ecological aspects (e.g. how a surface design and material composition can foster coral larvae settlement, or structural three-dimensionality enhance biodiversity) and lack an integrated underwater (UW) monitoring process. Such a process is necessary in order to gather knowledge about the ecosystem and make it available for design, and to learn whether artificial structures contribute to reef regeneration or rather harm the coral reef ecosystem. For the research, empirical experimental methods were applied: Algorithmic coral reef design, high precision UW monitoring, computational modelling and simulation, and validated through parallel real-world physical experimentation – two Artificial Reef Prototypes (ARPs) in Gili Trawangan, Indonesia (2012–today). Multiple discrete methods and sub techniques were developed in seventeen computational experiments and applied in a way in which many are cross valid and integrated in an overall framework that is offered as a significant contribution to the field. Other main contributions include the Ecosystem-aware design approach, Key Performance Indicators (KPIs) for coral reef design, algorithmic design and fabrication of Biorock cathodes, new high precision UW monitoring strategies, long-term real-world constructed experiments, new digital analysis methods and two new front-end web-based tools for reef design and monitoring reefs. The methodological framework is a finding of the research that has many technical components that were tested and combined in this way for the very first time. In summary, the thesis responds to the urgency and relevance in preserving marine species in tropical reefs during this massive extinction period by offering a differentiated approach towards artificial coral reefs – demonstrating the feasibility of digitally designing such ‘living architecture’ according to multiple context and performance parameters. It also provides an in-depth critical discussion of computational design and architecture in the context of ecosystem regeneration and Planetary Thinking. In that respect, the thesis functions as both theoretical and practical background for computational design, ecology and marine conservation – not only to foster the design of artificial coral reefs technically but also to provide essential criteria and techniques for conceiving them. Keywords: Artificial coral reefs, computational modelling, high precision underwater monitoring, ecology in design. N2 - Charakteristisch für das Zeitalter des Klimawandels sind die durch den Menschen verursachte Meeresverschmutzung sowie ein massiver Rückgang der Artenvielfalt in den Weltmeeren. Tropische Korallenriffe sind als eines der ältesten und artenreichsten Ökosysteme der Erde besonders stark gefährdet und stehen somit symbolisch für die zerstörerischen Auswirkungen menschlicher Aktivitäten auf die Natur [4], [5]. Um dem massiven Rückgang der Korallenriffe entgegenzuwirken, wurden von Menschen künstliche Riffsysteme entwickelt [6], [7]. Sie sind Beispiele dafür, wie Architektur und die Regenerierung von Ökosystemen miteinander verbunden werden können [8]. Eine Verknüpfung von einerseits künstlichen und andererseits komplexen, sich verändernden natürlichen Systemen, stellt jedoch eine Herausforderung dar, u.a. in Bezug auf die Computermodellierung (B-Rep Modellierung). Zum Erhalt der Korallenriffe werden in der vorliegende Doktorarbeit Strategien aus der digitalen Praxis neuartig auf das Entwerfen von künstlichen Korallenriffen angewendet. Die Hauptfrage befasst sich damit, wie der Entwurfsprozess von künstlichen Korallenriffen unter Einbeziehung von Computermodellierung und hochpräzisen Überwachungsstrategien optimiert werden kann. In diesem Zusammenhang werden Techniken, Methoden sowie ein übergeordnetes Framework erforscht, welche zukünftige Forschung und Praxis in Bezug auf Ökologie-geleitete Entwurfsprozesse fördern soll. In Anbetracht der vielen vorhandenen künstlichen Riffsysteme, kann man feststellen, dass die Zusammenhänge zwischen Architektur- und Ökosystem-Anforderungen nicht genau untersucht und dadurch bei der Umsetzung nicht entsprechend berücksichtigt werden. Zum Beispiel wie Oberflächenbeschaffenheit und Materialität eine Ansiedlung von Korallenlarven begünstigt oder wie eine räumlich vielseitige Struktur die Artenvielfalt verbessern kann. Zudem fehlt ein integrierter Unterwasser-Überwachungsprozess, welcher Informationen über das Ökosystem liefert und diese dem Entwurf bereitstellt. Zusätzlich ist eine Unterwasser-Überwachung notwendig, um herauszufinden, ob die künstlichen Riffstrukturen zur Regenerierung beitragen oder dem Ökosystem gänzlich schaden. In dieser Forschungsarbeit werden empirische und experimentelle Methoden angewendet: Algorithmisches Entwerfen für Korallenriffe, hochpräzise Unterwasser-Überwachung, Computermodellierung und -simulation. Die Forschung wird seit 2012 bis heute durch zwei Riffprototypen (Artificial Reef Prototypes – ARPs) in Gili Trawangan, Indonesien validiert. Zusätzlich wurden weitere separate Methoden und Techniken in insgesamt siebzehn computergestützten Experimenten entwickelt und so angewendet, dass viele kreuzvalidiert und in ein Framework integriert sind, welches dann als bedeutender Beitrag dem Forschungsgebiet zur Verfügung steht. Weitere Hauptbeiträge sind der Ökosystem-bewusste Entwurfsansatz (Ecosystem-aware design approach), Key Performance Indicators (KPIs) für das Gestalten von Korallenriffen, algorithmisches Entwerfen und die Herstellung von Biorock-Kathoden, neue hochpräzise Unterwasser-Überwachungsstrategien, reale Langzeitexperimente, neue digitale Analysemethoden, sowie zwei webbasierte Softwareanwendungen für die Gestaltung und die Überwachung von künstlichen Korallenriffen. Das methodische Framework ist das Hauptergebnis der Forschung, da die vielen technischen Komponenten in dieser Weise zum ersten Mal getestet und kombiniert wurden. Zusammenfassend reagiert die vorliegende Doktorarbeit sowohl auf die Dringlichkeit als auch auf die Relevanz der Erhaltung von Artenvielfalt in tropischen Korallenriffen in Zeiten eines massiven Aussterbens, indem sie einen differenzierten Entwurfsansatz für künstliche Korallenriffe offeriert. Die Arbeit zeigt auf, dass ein digitales Entwerfen einer solchen „lebendigen Architektur“ unter Berücksichtigung vielfältiger Anforderungen und Leistungsparametern machbar ist. Zusätzlich bietet sie eine ausführliche kritische Diskussion über die Rolle von computergestützten Entwerfen und Architektur im Zusammenhang mit Regenerierung von Ökosystemen und “Planetary Thinking”. In dieser Hinsicht fungiert die Doktorarbeit als theoretischer und praktischer Hintergrund für computergestütztes Entwerfen, Ökologie und Meeresschutz. Eine Verbesserung des Entwerfens von künstlichen Korallenriffen wird nicht nur auf technischer Ebene aufgezeigt, sondern es werden auch die wesentlichen Kriterien und Techniken für deren Umsetzung benannt. Schlüsselwörter: Künstliche Korallenriffe, Computermodellierung, hochpräzise Unterwasser-Überwachung, Ökologie im Architekturentwurf. KW - Korallenriff KW - Algorithmus KW - Architektur KW - Meeresökologie KW - Software KW - Artificial coral reefs KW - Computational modelling KW - High precision underwater monitoring KW - Ecology in design KW - Künstliche Korallenriffe KW - Unterwasserarchitektur Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20220322-46115 UR - https://artificialreefdesign.com/ SN - 978-3-00-074495-2 N1 - Die URL führt zu 3D Modelle von echten Korallenriffen. ER - TY - JOUR A1 - Harirchian, Ehsan A1 - Kumari, Vandana A1 - Jadhav, Kirti A1 - Raj Das, Rohan A1 - Rasulzade, Shahla A1 - Lahmer, Tom T1 - A Machine Learning Framework for Assessing Seismic Hazard Safety of Reinforced Concrete Buildings JF - Applied Sciences N2 - Although averting a seismic disturbance and its physical, social, and economic disruption is practically impossible, using the advancements in computational science and numerical modeling shall equip humanity to predict its severity, understand the outcomes, and equip for post-disaster management. Many buildings exist amidst the developed metropolitan areas, which are senile and still in service. These buildings were also designed before establishing national seismic codes or without the introduction of construction regulations. In that case, risk reduction is significant for developing alternatives and designing suitable models to enhance the existing structure’s performance. Such models will be able to classify risks and casualties related to possible earthquakes through emergency preparation. Thus, it is crucial to recognize structures that are susceptible to earthquake vibrations and need to be prioritized for retrofitting. However, each building’s behavior under seismic actions cannot be studied through performing structural analysis, as it might be unrealistic because of the rigorous computations, long period, and substantial expenditure. Therefore, it calls for a simple, reliable, and accurate process known as Rapid Visual Screening (RVS), which serves as a primary screening platform, including an optimum number of seismic parameters and predetermined performance damage conditions for structures. In this study, the damage classification technique was studied, and the efficacy of the Machine Learning (ML) method in damage prediction via a Support Vector Machine (SVM) model was explored. The ML model is trained and tested separately on damage data from four different earthquakes, namely Ecuador, Haiti, Nepal, and South Korea. Each dataset consists of varying numbers of input data and eight performance modifiers. Based on the study and the results, the ML model using SVM classifies the given input data into the belonging classes and accomplishes the performance on hazard safety evaluation of buildings. KW - Erdbeben KW - Vulnerability KW - Earthquake KW - damaged buildings KW - earthquake safety assessment KW - soft computing techniques KW - rapid visual screening KW - Machine Learning KW - vulnerability assessment KW - OA-Publikationsfonds2020 Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20201022-42744 UR - https://www.mdpi.com/2076-3417/10/20/7153 VL - 2020 IS - Volume 10, issue 20, article 7153 PB - MDPI CY - Basel ER - TY - THES A1 - Mukherjee, Nilangshu T1 - A numerical comparison of the impact of different climatic conditions in different geographic locations on the construction of an office building N2 - The aim of my research is to observe the variance of energy efficiency of a typical multi-story office building under the exposure of different climatic conditions. Energy efficiency requirements in building codes or energy standards are among the most important single measures for buildings’ energy efficiency. Therefore, this study can be set up for a better understanding of how energy efficiency of a building changes under the effect of adverse to moderate climatic conditions which possess a mentionable effect on the operation of a building. This thesis is structured in three balanced and conceptual steps. Following the aim of the project, the virtual building model is to be analyzed under the effect of seven distinct climatic conditions namely work environment of New Delhi, Mumbai, Berlin, Lisbon, Copenhagen, Dubai and Montreal. Firstly, the task is to do a complete literature research based on the scope of similar researches and studying the problems in detail along with the theoritical background all the concepts which are implemented to get the numerical results. This chapter also comprises a detailed study of the climatic conditions of the above-mentioned cities. Different climatic traits like temperature variations, count of heating and cooling degree days, relative humidity, temperature range and comfort zonal charts for the specified cities are studied in detail. This study helps to understand the effect of these adverse to moderate climates on the operation of the building. On the second step, the virtual building model is prepared on a software platform named Revit Structures. This virtual building model is not necessarily a complete building, but it has the relevant functionalities of a real building. We perform the energy analysis and the heating and cooling analysis on this virtual building model to study the operational outcome of the building under different climatic conditions in detail. By the end of these above two tasks, two scenarios are observed. On one hand, we have a literature research and on the other hand we have the numerical results. Therefore, finally we present a comparative scenario based on the energy efficient performances of the building under such variant climatic conditions. This is followed by the prediction of thermal comfort level inside the building and it based on Fanger’s PMV Model. Understanding the literature and the numerical values in detail helps us to predict the index thermal comfort level inside the building. The conclusion of this master thesis focuses mainly on the scopes of improvement of energy efficiency requirements in energy codes if any, differentiated according to specific locations. The initial aim of my hypothesis which is to study the impacts of climatic variations on the energy efficient performances of a building is fulfilled but as such topics have very deep and broad roots, the scope of further improvements is always predominant. KW - Klima KW - Energieeffizienz KW - Climatic conditions KW - Building performance Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20170811-32700 ER - TY - THES A1 - Hollberg, Alexander T1 - A parametric method for building design optimization based on Life Cycle Assessment - Appendix T2 - A parametric method for building design optimization based on Life Cycle Assessment N2 - The building sector is responsible for a large share of human environmental impacts, over which architects and planners have a major influence. The main objective of this thesis is to develop a method for environmental building design optimization based on Life Cycle Assessment (LCA) that is applicable as part of the design process. The research approach includes a thorough analysis of LCA for buildings in relation to the architectural design stages and the establishment of a requirement catalogue. The key concept of the novel method called Parametric Life Cycle Assessment(PLCA) is to combine LCA with parametric design. The application of this method to three examples shows that building designs can be optimized time-efficiently and holistically from the beginning of the most influential early design stages, an achievement which has not been possible until now. KW - Ökobilanz Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20161101-26884 ER - TY - THES A1 - Mizrak Bilen, Burcin T1 - A Power-Centered Approach to the Capitalization of Climate Change in Property Sector and Strategic Limitation N2 - The capitalization of ‘certified’ sustainable building sector will be investigated over the power theory of value approach of Jonathan Nitzan and Shimshon Bichler. The study will be initiated by questioning why the environment problems are one of the first items on the agenda and by sharing the ideas of scholars who approaches the subject skeptically, because the predominant literature underlying the necessity and prominence of the topic is already well-known and adapted by the majority. Over the theory developed by Nitzan and Bichler, the concepts of capitalization, strategic sabotage, power, legitimacy, and obedience will be discussed. The hypothesis of “the absentee owners of the construction sector, holding the whip hand and capitalizing the ecology, control the growth and the creativity of green building production and make it carbon-dependent, in order to increase their profit margin” will be questioned. To strengthen the arguments in the hypothesis, the factors, the institutional arrangements, value measurement methods, which affect directly the net present value, will be investigated both in corporation and in building scale in detail, because net present value/ capitalization is asserted as the most important criteria by Nitzan and Bichler to make the investment decisions in the capitalist economic system. To trace the implications of power and the strategic sabotage that power caused, as the empirical dimension of this dissertation, an interface exploring the correlational ties between the climate responsive architecture and the ever changing political, economical, and social contexts and building economics praxis by decades will be developed and the expert interviews will be conducted with the design teams and the appraisers. N2 - Die Kapitalisierung des "zertifizierten" nachhaltigen Gebäudesektors wird im Rahmen des Ansatzes der Machttheorie des Wertes von Jonathan Nitzan und Shimshon Bichler untersucht. Die Studie wird mit der Frage beginnen, warum die Umweltprobleme zu den ersten Punkten auf der Tagesordnung gehören und mit der Teilung von Ideen von Gelehrten, die sich dem Thema skeptisch nähern. Denn die vorherrschende Literatur, die der Notwendigkeit und Bedeutung des Themas zugrunde liegt, ist bereits von der Mehrheit bekannt und angewandt. Über die von Nitzan und Bichler entwickelte Theorie werden die Begriffe Kapitalisierung, strategische Sabotage, Macht, Legitimität und Gehorsam diskutiert. Die Hypothese "Die abwesenden Eigentümer des Bausektors, die die Peitsche halten und die Ökologie kapitalisieren, kontrollieren das Wachstum und die Kreativität der grünen Gebäudeproduktion und machen sie CO2-abhängig, um ihre Gewinnspanne zu erhöhen" wird in Frage gestellt. Um die Argumente in der Hypothese zu stärken, werden die Faktoren, institutionellen Arrangements und Wertmessmethoden, die sich direkt auf den Kapitalwert auswirken, sowohl im Unternehmens- als auch im Gebäudebereich detailliert untersucht. Denn der Barwert/die Kapitalisierung wird von Nitzan und Bichler als wichtigstes Kriterium für die Investitionsentscheidungen im kapitalistischen Wirtschaftssystem herangezogen. Nach der Vorbereitung einer Schnittstelle, die die historische Entwicklung der nachhaltigen Architektur in Verbindung mit dem sich ständig verändernden politisch-ökonomischen System und mit den sich ständig ändernden Prioritäten der Bauökonomie, Architektur-, Umwelt- und Sozialwissenschaften darstellt, wurden die halbstrukturierten Tiefeninterviews mit Experten - Architekten, Immobiliengutachtern, einem Mitarbeiter einer Investmentbank und einem CEO, aus aller Welt, durchgeführt um die wahrscheinlichen restriktiven und begrenzenden Auswirkungen der institutionellen Macht, ihres Netzes von Machtverhältnissen, ihrer Kontrollmechanismen, die im Streben nach unterschiedlichem Gewinnwachstum eingesetzt werden, und ihrer Gründe hinter dieser institutionellen Kontrolle auf dem zertifizierten Markt für umweltfreundliches Bauen und den damit verbundenen Materialien und Energiemärkte zu erforschen. Die Interviews sind in vier Titel unterteilt: die Vorteile (warum), die Kontrollmechanismen (wie), die Machtverhältnisse (wer) und die strategische Sabotage (was). Dies dient dazu, um einen Beitrag zur Lesbarkeit von Macht im zertifizierten für umweltfreundliches Bauen zu leisten. KW - Klimaänderung KW - Machttheorie KW - Kapitalisierung KW - capitalization KW - power theory of value KW - climate change KW - property sector KW - strategic limitation Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20190107-38406 ER - TY - THES A1 - Fauth, Judith T1 - A process-oriented decision model for determining the permitability of construction projects N2 - In recent years, the discussion of digitalization has arrived in the media, at conferences, and in committees of the construction and real estate industry. While some areas are producing innovations and some contributors can be described as pioneers, other topics still show deficits with regard to digital transformation. The building permit process can also be counted in this category. Regardless of how architects and engineers in planning offices rely on innovative methods, building documents have so far remained in paper form in too many cases, or are printed out after electronic submission to the authority. Existing resources – for example in the form of a building information model, which could provide support in the building permit process – are not being taken advantage of. In order to use digital tools to support decision-making by the building permit authorities, it is necessary to understand the current situation and to question conditions before pursuing the overall automation of internal authority processes as the sole solution. With a substantive-organizational consideration of the relevant areas that influence building permit determination, an improvement of the building permit procedure within authorities is proposed. Complex areas – such as legal situations, the use of technology, as well as the subjective alternative action – are determined and structured. With the development of a model for the determination of building permitability, both an understanding of influencing factors is conveyed and an increase in transparency for all parties involved is created. In addition to an international literature review, an empirical study served as the research method. The empirical study was conducted in the form of qualitative expert interviews in order to determine the current state in the field of building permit procedures. The collected data material was processed and subsequently subjected to a software-supported content analysis. The results were processed, in combination with findings from the literature review, in various analyses to form the basis for a proposed model. The result of the study is a decision model that closes the gap between the current processes within the building authorities and an overall automation of the building permit review process. The model offers support to examiners and applicants in determining building permit eligibility, through its process-oriented structuring of decision-relevant facts. The theoretical model could be transferred into practice in the form of a web application. KW - Baugenehmigung KW - Entscheidungsmodell KW - Bauantrag KW - Prozessmanagement KW - Projektmanagement KW - Building permit KW - Building application KW - Decision-making KW - Process management KW - Project management Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20220309-46020 UR - https://e-pub.uni-weimar.de/opus4/frontdoor/index/index/docId/4509 N1 - This work is a translation of the original dissertation (German language) which is accessible at: https://doi.org/10.25643/bauhaus-universitaet.4509 and deposited here as URL link. ER - TY - THES A1 - Sowoidnich, Thomas T1 - A Study of Retarding Effects on Cement and Tricalcium Silicate Hydration induced by Superplasticizers N2 - Fließmittel werden in Betonen verwendet, um deren Fließeigenschaften während der Verarbeitung zu verbessern und Wasser einzusparen. Beide Faktoren beeinflussen nicht nur den Frischbeton, sondern auch signifikant die Festbetoneigenschaften. Nachteilig wirken sich Fließmittel auf die Festigkeitsentwicklung aus, die z.T. sehr stark verzögert wird. Dies ist vor allem bei Bauteilen, die im Rahmen eines Vorfertigungsprozesses hergestellt werden, ein ökonomischer Nachteil. Die vorliegende Arbeit widmet sich den Ursachen für die Verzögerung der Portlandzementhydratation bei Verwendung von Fließmitteln. Um die komplexen Reaktionen, die während der Portlandzementhydratation auftreten, zu vereinfachen, betrachtet ein überwiegender Teil der Arbeit die Wechselwirkung Fließmittel-Tricalciumsilikat (Abk. Ca3SiO5 oder C3S, Hauptbestandteil von Portlandzementklinker). Die Untersuchungen werden in drei Hauptteilen durchgeführt, wobei Methoden wie u.a. isotherme Wärmeflusskalorimetrie, Elektrische Leitfähigkeit, Elektronenmikroskopie, ICP-OES, TOC als auch Analytische Ultrazentrifugation Anwendung finden. Basierend auf der Wechselwirkung von Kationen mit anionischen Ladungsträgern von Polymeren wird die Interaktion von Calcium mit Fließmitteln im ersten Teil der Arbeit untersucht. Dabei kommt es überwiegend zur Komplexierung von Calciumionen durch die funktionellen Gruppen der Plymere (Carboxyl- bzw. Sulfonguppen), die in zementären Umgebungen sowohl gelöst in der wässrigen Phase als auch als Bestandteil von Partikelgrenzflächen vorhanden sind. Neben diesen Effekten kann auch gezeigt werden, dass Fließmittel die Bildung von nanoskaligen Partikeln hervorrufen, die infolge der sterischen Wirkung von Fließmitteln dispergiert in der wässrigen Phase vorliegen (Clusterbildung). Analog zu neuesten Erkenntnissen aus dem Bereich der Biomineralisation ist daher davon auszugehen, dass diese Nanopartikel durch Agglomeration das Kristallwachtsum beeinflussen. Ausgehend von der Annahme, dass die Auflösungs- und/ oder Fällungskinetik durch die Wirkung von Fließmitteln behindert und damit für den Verzögerungseffekt der Fließmittel während der komplexen Hydratationsreaktion verantwortlich seien können, werden die zugrundeliegenden Vorgänge im zweiten Abschnitt getrennt voneinander untersucht. Es wird anhand von Lösungsuntersuchungen an C-S-H Phasen und Portlandit herausgestellt, dass die Komplexierung von gelösten Calciumionen durch funktionelle Gruppen der Polymere die Löslichkeit von Portlandit erhöht. Im Gegensatz führt die Komplexierung von Calciumionen in der wässrigen Phase zu einer Verringerung der Calciumionenkonzentration in der wässrigen Phase. Diese Effekte werden auf die unterschiedlich starke Adsorptionsneigung der Polymere an C-S-H-Phasen und Portlandit zurückgeführt. Es wird davon ausgegangen, dass die Adsorption aufgrund der größeren spezifischen Oberfläche stärker an den C-S-H-Phasen als am Portlandit auftritt. Demnach stellt sich dar, dass die Polymere erst nachdem die funktionellen Gruppen Calciumionen aus der wässrigen Phase komplexiert haben an den C-S-H-Phasen adsorbieren. Weiterhin kann gezeigt werden, dass die freie C3S Auflösungsrate in Anwesenheit von Fließmitteln keinen direkten Zusammenhang zur Verzögerung erkennen lässt. Teilweise kommt es zu einer in Bezug zur Kontrollprobe ohne Fließmittel erhöhten sowie auch verringerten Auflösungsrate. Wird das Komplexierungsvemögen der Fließmittel berücksichtigt, so kann durchaus eine verlangsamte freie Auflösungsrate ermittelt werden. Doch auch Calcit zeigt einen verzögernden Einfluss auf die freie C3S Auflösung, obwohl es den Gesamtprozess der Hydratation signifikant beschleunigt. Somit kann die behinderte Auflösung als mögliche Ursache für die verzögernde Wirkung während der Zementhydratation weder bestätigt noch widerlegt werden. Dieser Punkt sollte in zukünftigen Arbeiten weiter untersucht werden. Im letzten Schritt dieses Untersuchungsabschnitts wird die reine Kristallisation von C-S-H-Phasen und Portlandit untersucht. Es stellt sich heraus, dass Fließmittel insbesondere durch die Wirkung der Komplexierung von Ionen in der wässrigen Phase sowohl die Induktionszeit verlängern als auch die Kristallwachstumsrate verändern. Dies allein kann aber nicht die komplette Verzögerungswirkung erklären. Ein wichtiger Verzögerungsfaktor ist die Adsorption der Polymere an Kristalloberflächen als auch eine fließmittelbedingte Dispergierung von nanoskaligen Einzelpartikeln, die deren Agglomeration zu Kristallen behindert. Im letzten Hauptuntersuchungsabschnitt werden die gewonnenen Erkenntnisse auf die während der Zement- und Tricalciumsilikathydratation parallel ablaufenden Reaktionen analysiert. Dabei wird insbesondere die ionische Zusammensetzung der wässrigen Phase von C3S Pasten und Suspensionen untersucht, um Hinweise für eine kinetische Hemmung der Hydratationsreaktion zu identifizieren. Zusammenfassend wird festgestellt, dass die Ursachen der verzögernden Wirkung von Fließmitteln auf die Hydratation von C3S auf die starke Verzögerung der Kristallisation von Hydratphasen zurückzuführen ist. Dabei kommt den zwei Faktoren Komplexierung von Calciumionen an Oberflächen und Stabilisierung von nanoskaligen Partikeln eine zentrale Bedeutung zu. Diese Effekte können durch die Wirkung als Templat als auch durch Erhöhung der Löslichkeit infolge Komplexierung freier/gelöster Ionen teilkompensiert werden. Dass die Auflösungsreaktion durch die Anwesenheit von Fließmitteln behindert wird, kann nur indirekt anhand der Entwicklung von Ionenkonzentrationen festgestellt werden. Ob dieser Vorgang die Ursache oder die Folge des Lösungs-Fällungs-Mechanismus der Hydratation ist und damit die verzögernde Wirkung durch behinderte Auflösung des Edukts hervorgerufen wird, bleibt Gegenstand weiterer Untersuchungen. Im Rahmen der Arbeit kann auch gezeigt werden, dass Fließmittel chemisch als Inhibitoren wirken indem sie den Frequenzfaktor verringern. Darüber hinaus wird erstmalig eine Methode entwickelt, die die Bestimmung der Ionenkonzentration in Pasten in-situ erlaubt. Mit deren Hilfe wird dargestellt, dass die Entwicklung der Ionenkonzentration als auch die allgemein verwendete Wärmefreisetzungsrate (Kalorimetrie) miteinander korrespondiert. Darüber hinaus erlaubt die entwickelte Methode die weitere Differenzierung der Accelerationsperiode in drei Stadien. Die Kristallisation von C-S-H-Phasen und Portlandit ist für den Beginn der Haupthydratationsperiode entscheidend. N2 - Superplasticizers are utilized both to improve the fluidity during the placement and to reduce the water content of concretes. Both effects have also an impact on the properties of the hardened concrete. As a side effect the presence of superplasticizers affects the strength development of concretes that is strongly retarded. This may lead to an ecomomical drawback of the concrete manufacturing. The present work is aimed at gaining insights on the causes of the retarding effect of superplasticizers on the hydration of Portland cement. In order to simplify the complex interactions occurring during the hydration of Portland cement the majority of the work focuses on the interaction of superplasticizer and tricalcium silicate (Ca3SiO5 or C3S, the main compound of Portland cement clinker). The tests are performed in three main parts accompanied by methods as for example isothermal conduction calorimetry, electrical conductivity, Electron Microscopy, ICP-OES, TOC, as well as Analytical Ultracentrifugation. In the first main part and based on the interaction of cations and anionic charges of polymers, the interactions between calcium ions and superplasticizers are investigated. As a main effect calcium ions are complexed by the functional groups of the polymers (carboxy, sulfonic). Calcium ions may be both dissolved in the aqueous phase and a constitute of particle interfaces. Besides these effects it is furthermore shown that superplasticizers induce the formation of nanoscaled particles which are dispersed in the aqueous phase (cluster formation). Analogous to recent findings in the field of biomineralization, it is reasonable to assume that these nanoparticles influence the crystal growth by their assembly process. Based on the assumption that superplasticizers hinder either or both dissolution and precipitation and by that retard the cement hydration, the impact on separate reactions is investigated. On experiments that address the solubility of C-S-H phases and portlandite, it is shown that complexation of calcium ions in the aqueous phase by functional groups of polymers increases the solubility of portlandite. Contrary, in case of C-S-H solubility the complexation of calcium ions in solution leads to decrease of the calcium ion concentration in the aqueous phase. These effects are explained by differences in adsorption of polymers on C-S-H phases and portlandite. It is proposed that adsorption is stronger on C-S-H phases compared to portlandite due to the increased specific surface area of C-S-H phases. Following that, it is claimed that before polymers are able to adsorb on C-S-H phases the functional groups must be screened by calcium ions in the aqueous phase. It is further shown that data regarding the impact of superplasticizers on the unconstrained dissolution rate of C3S does not provide a clear relation to the overall retarding effect occurring during the hydration of C3S. Both increased and decreased dissolution rate with respect to the reference sample are detected. If the complexation capability of the superplasticizers is considered then also a reduced dissolution rate of C3S is determined. Despite the fact that the global hydration process is accelerated, the addition of calcite leads to a slower dissolution rate. Thus, a hindered unconstrained dissolution of C3S as possibly cause for the retarding effect still remains open for discussion. In the last section of this part, the pure crystallization of hydrate phases (C-S-H phases, portlandite) is fathomed. Results clearly show that superplasticizers prolong the induction time and modify the rate of crystal growth during pure crystallization in particular due to the complexation of ions in solution. But this effect is insufficient to account for the overall retarding effect. Further important factors are the blocking of crystal growth faces by adsorbed polymers and the dispersion of nanoscaled particles which hinders their agglomeration in order to build up crystals. In the last main part of the work, the previously gathered results are utilized in order to investigate hydration kinetics. During hydration, dissolution and precipitation occur in parallel. Thereby, special attention is laid on the ion composition of the aqueous phase of C3S pastes and suspensions in order to determine the rate limiting step. All in all it is concluded that the retarding effect of superplasticizers on the hydration of tricalcium silicate is based on the retardation of crystallization of hydrate phases (C-S-H phases and portlandite). Thereby, the two effects complexation of calcium ions on surfaces and stabilization of nanoscaled particles are of major importance. These mechanisms may partly be compensated by template performance and increase in solubility by complexation of ions in solution. The decreased dissolution rate of C3S by the presence of superplasticizers during the in parallel occuring hydration process can only be assessed indirectly by means of the development of the ion concentrations in the aqueous phase (reaction path). Whether this observation is the cause or the consequence within the dissolution-precipitation process and therefore accounts for the retarding effect remains a topic for further investigations. Besides these results it is shown that superplasticizers can be associated chemically with inhibitors because they reduce the frequency factor to end the induction period. Because the activation energy is widely unaffected it is shown that the basic reaction mechanism sustain. Furthermore, a method was developed which permits for the first time the determination of ion concentrations in the aqueous phase of C3S pastes in-situ. It is shown that during the C3S hydration the ion concentration in the aqueous phase is developed correspondingly to the heat release rate (calorimetry). The method permits the differentiation of the acceleration period in three stages. It is emphasized that crystallization of the product phases of C3S hydration, namely C-S-H phases and portlandite, are responsible for the end of the induction period. KW - Cement KW - Tricalcium silicate KW - Superplasticizer KW - Complexation KW - Retardation Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20160224-25444 SN - 978-3-00-052204-8 ER -