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Die interdisziplinäre Dissertationsschrift lässt sich im Horizont internationaler Forschungen zu Denkmalwerten, neuer Ansätze in der Kultur- und Wissensvermittlung rund um Baudenkmale sowie künstlerisch- ethnographischem Forschen an und mit Denkmalen verorten.
Der erste Teil der Arbeit widmet sich Denkmalen und der Denkmalpflege im Kontext künstlerischer und sozialwissenschaftlicher Allianzen. Ausgangspunkt ist die Feststellung, dass die Denkmalpflege zwar sehr vieles über Denkmale weiß, aber kaum etwas über deren Rezeption beim breiten Publikum. Im Mittelpunkt steht die Frage, wie hier Praktiken der bildenden Kunst und Arbeitsweisen der Kulturanthropologie die Disziplin der Denkmalpflege bereichern können, oder sogar müssen.
Den zweiten Teil bildet eine empirische Studie, in der die populäre Wahrnehmung von Denkmalen qualitativ erforscht wird. Das Schloss und Rittergut Bedheim im südlichen ländlichen Thüringen dient dabei als konkreter Untersuchungsort. Reaktionen von Besucherinnen und Besuchern werden mit Hilfe von drei künstlerischen Eingriffen angeregt und diese dann ethnographisch-offen dokumentiert und ausgewertet.
Auf dieser Basis werden Zugänge zum Denkmal ermittelt. Während die meisten BesucherInnen das Denkmal als „Arbeit“ wahrnehmen, geraten einige ins „Träumen“ oder „Erinnern“, man „genießt“ das Ensemble als authentische und ästhetische Ressource, oder findet Zugang über das spontane „Erklären“ baukonstruktiver oder baulicher Situationen. Für andere bedeutet der Besuch die „Teilhabe“ an einem Prozess. Schloss Bedheim wird als Ort stetiger Veränderung geschätzt. In der Wahrnehmung der BesucherInnen verquicken sich Aspekte des Bewunderns mit solchen des Abgrenzens. Die eigene Alltagswelt und das eigene Zuhause bilden hierbei Bezugspunkte. Schloss Bedheim wird auf diese Weise zum Imaginationsraum, zur Energietankstelle und zur gern besuchten Problemwelt.
Die Ergebnisse der Arbeit liegen in zwei Erkenntnisfeldern: Auf einer methodischen Ebene zeigt sie, wie in der Denkmalpflege vertiefte Fachlichkeit mit einer tatsächlichen Kontaktaufnahme mit dem Publikum verbunden werden kann und damit soziale Gefüge an Baudenkmalen qualitativ ermittelt werden können. Ebenso wird deutlich, dass künstlerische Eingriffe Auslöser von Gesprächen sind, als Kontaktflächen zur Alltagswelt dienen und so zu einer vielfältigen Auseinandersetzung mit Denkmalen führen.
Auf einer inhaltlichen Ebene liefert die Arbeit Erkenntnisse zu Wahrnehmungsweisen von Denkmalen. Neben den erwähnten Zugängen, wird die Existenz und Bedeutung einer regional vernetzten Wahrnehmung von Denkmalen aufgedeckt. Des Weiteren zeigen die Ergebnisse, dass das Öffnen von Baudenkmalen als und im Prozess ungenutzte Potentiale birgt und es wird angeregt, dies in zukünftigen denkmalpflegerischen Konzepten eine größere Rolle spielen zu lassen. Die Vision eines „Kompendiums der Zugänge“ wird entwickelt, mit dessen Hilfe sich ein enormes Wissen über Rollen und Bedeutungen die Baudenkmale in unserer Gesellschaft spielen, sammeln ließe.
This thesis examines urban partition in Nicosia, the capital of Cyprus, and how its changing roles and shifting perceptions in a post-conflict setting reflect power relations, and their constant renegotiation. Nicosia, the capital of Cyprus, was officially divided in 1974 in the aftermath of an eighteen-year-long conflict between the island’s Turkish- and Greek-Cypriot communities. As a result, a heavily militarized Buffer Zone, established as an emergency measure against perpetuation of intercommunal violence, has been cutting through its historic centre ever since.
This thesis departs from a genuine interest in the material and ideational dimensions of urban partition. How is it constructed, not merely in physical terms but in the minds of the societies affected by conflict? How is it established in official and everyday discourses? What kinds of mechanisms have been developed to maintain it, and make an inseparable part of the urban experience? Moreover, taking into account the consensus in relevant literature pertaining to the imperative for its removal, this thesis is inquiring into the relevance of peace agreements to overcoming urban partition. For this purpose, it also looks at narratives and practices that have attempted to contest it.
The examples examined in this thesis offer pregnant analytical moments to understand Nicosia’s Buffer Zone as a dynamic social construct, accommodating multiple visions of and for the city. Its space ‘in-between’ facilitates encounters between various actors, accommodates new meanings, socio-spatial practices and diverse imaginaries. In this sense, urban partition is explored in this thesis as a phenomenon that transcends scales as well as temporalities, entwining past, present, and future.
This work presents a robust status monitoring approach for detecting damage in cantilever structures based on logistic functions. Also, a stochastic damage identification approach based on changes of eigenfrequencies is proposed. The proposed algorithms are verified using catenary poles of electrified railways track. The proposed damage features overcome the limitation of frequency-based damage identification methods available in the literature, which are valid to detect damage in structures to Level 1 only. Changes in eigenfrequencies of cantilever structures are enough to identify possible local damage at Level 3, i.e., to cover damage detection, localization, and quantification. The proposed algorithms identified the damage with relatively small errors, even at a high noise level.
This thesis presents the advances and applications of phase field modeling in fracture analysis. In this approach, the sharp crack surface topology in a solid is approximated by a diffusive crack zone governed by a scalar auxiliary variable. The uniqueness of phase field modeling is that the crack paths are automatically determined as part of the solution and no interface tracking is required. The damage parameter varies continuously over the domain. But this flexibility comes with associated difficulties: (1) a very fine spatial discretization is required to represent sharp local gradients correctly; (2) fine discretization results in high computational cost; (3) computation of higher-order derivatives for improved convergence rates and (4) curse of dimensionality in conventional numerical integration techniques. As a consequence, the practical applicability of phase field models is severely limited.
The research presented in this thesis addresses the difficulties of the conventional numerical integration techniques for phase field modeling in quasi-static brittle fracture analysis. The first method relies on polynomial splines over hierarchical T-meshes (PHT-splines) in the framework of isogeometric analysis (IGA). An adaptive h-refinement scheme is developed based on the variational energy formulation of phase field modeling. The fourth-order phase field model provides increased regularity in the exact solution of the phase field equation and improved convergence rates for numerical solutions on a coarser discretization, compared to the second-order model. However, second-order derivatives of the phase field are required in the fourth-order model. Hence, at least a minimum of C1 continuous basis functions are essential, which is achieved using hierarchical cubic B-splines in IGA. PHT-splines enable the refinement to remain local at singularities and high gradients, consequently reducing the computational cost greatly. Unfortunately, when modeling complex geometries, multiple parameter spaces (patches) are joined together to describe the physical domain and there is typically a loss of continuity at the patch boundaries. This decrease of smoothness is dictated by the geometry description, where C0 parameterizations are normally used to deal with kinks and corners in the domain. Hence, the application of the fourth-order model is severely restricted. To overcome the high computational cost for the second-order model, we develop a dual-mesh adaptive h-refinement approach. This approach uses a coarser discretization for the elastic field and a finer discretization for the phase field. Independent refinement strategies have been used for each field.
The next contribution is based on physics informed deep neural networks. The network is trained based on the minimization of the variational energy of the system described by general non-linear partial differential equations while respecting any given law of physics, hence the name physics informed neural network (PINN). The developed approach needs only a set of points to define the geometry, contrary to the conventional mesh-based discretization techniques. The concept of `transfer learning' is integrated with the developed PINN approach to improve the computational efficiency of the network at each displacement step. This approach allows a numerically stable crack growth even with larger displacement steps. An adaptive h-refinement scheme based on the generation of more quadrature points in the damage zone is developed in this framework. For all the developed methods, displacement-controlled loading is considered. The accuracy and the efficiency of both methods are studied numerically showing that the developed methods are powerful and computationally efficient tools for accurately predicting fractures.
In the last decades, Finite Element Method has become the main method in statics and dynamics analysis in engineering practice. For current problems, this method provides a faster, more flexible solution than the analytic approach. Prognoses of complex engineer problems that used to be almost impossible to solve are now feasible.
Although the finite element method is a robust tool, it leads to new questions about engineering solutions. Among these new problems, it is possible to divide into two major groups: the first group is regarding computer performance; the second one is related to understanding the digital solution.
Simultaneously with the development of the finite element method for numerical solutions, a theory between beam theory and shell theory was developed: Generalized Beam Theory, GBT. This theory has not only a systematic and analytical clear presentation of complicated structural problems, but also a compact and elegant calculation approach that can improve computer performance.
Regrettably, GBT was not internationally known since the most publications of this theory were written in German, especially in the first years. Only in recent years, GBT has gradually become a fertile research topic, with developments from linear to non-linear analysis.
Another reason for the misuse of GBT is the isolated application of the theory. Although recently researches apply finite element method to solve the GBT's problems numerically, the coupling between finite elements of GBT and other theories (shell, solid, etc) is not the subject of previous research. Thus, the main goal of this dissertation is the coupling between GBT and shell/membrane elements. Consequently, one achieves the benefits of both sides: the versatility of shell elements with the high performance of GBT elements.
Based on the assumptions of GBT, this dissertation presents how the separation of variables leads to two calculation's domains of a beam structure: a cross-section modal analysis and the longitudinal amplification axis. Therefore, there is the possibility of applying the finite element method not only in the cross-section analysis, but also the development for an exact GBT's finite element in the longitudinal direction.
For the cross-section analysis, this dissertation presents the solution of the quadratic eigenvalue problem with an original separation between plate and membrane mechanism. Subsequently, one obtains a clearer representation of the deformation mode, as well as a reduced quadratic eigenvalue problem.
Concerning the longitudinal direction, this dissertation develops the novel exact elements, based on hyperbolic and trigonometric shape functions. Although these functions do not have trivial expressions, they provide a recursive procedure that allows periodic derivatives to systematise the development of stiffness matrices. Also, these shape functions enable a single-element discretisation of the beam structure and ensure a smooth stress field.
From these developments, this dissertation achieves the formulation of its primary objective: the connection of GBT and shell elements in a mixed model. Based on the displacement field, it is possible to define the coupling equations applied in the master-slave method. Therefore, one can model the structural connections and joints with finite shell elements and the structural beams and columns with GBT finite element.
As a side effect, the coupling equations limit the displacement field of the shell elements under the assumptions of GBT, in particular in the neighbourhood of the coupling cross-section.
Although these side effects are almost unnoticeable in linear analysis, they lead to cumulative errors in non-linear analysis. Therefore, this thesis finishes with the evaluation of the mixed GBT-shell models in non-linear analysis.
Natural Urban Resilience: Understanding general urban resilience through Addis Ababa’s inner city
(2021)
This dissertation describes the urban actors and spatial practices that contribute to natural urban resilience in Addis Ababa’s inner city. Natural urban resilience is a non-strategical and bottom-up, everyday form of general urban resilience – an urban system’s ability to maintain its essential characteristics under any change. This study gains significance by exposing conceptual gaps in the current un-derstanding of general urban resilience and highlighting its unconvincing applicability to African cities. This study attains further relevance by highlighting the danger of the ongoing large-scale redevelopment of the inner city. The inner city has naturally formed, and its urban memory, spaces, and social cohesion contribute to its primarily low-income population’s resilience. This thesis argues that the inner city’s demolition poses an incalculable risk of maladaptation to future stresses and shocks for Addis Ababa. The city needs a balanced urban discourse that highlights the inner city’s qualities and suggests feasible urban transformation measures. “Natural Urban Resilience” contributes an empirical study to the debate by identifying those aspects of the inner city that contribute to general resilience and identifies feasible action areas. This study develops a qualitative research design for a single case study in Addis Ababa. The data is obtained through expert interviews, interviews with resi-dents, and the analysis of street scene photos, which are abstracted using Grounded Theory. That way, this thesis provides first-time knowledge about who and what generates urban resilience in the inner city of Addis Ababa and how. Furthermore, the study complements existing theories on general urban resilience. It provides a detailed understanding of the change mechanisms in resilience, of which it identifies four: adaptation, upgrading, mitigation, and resistance. It also adapts the adaptive cycle, a widely used concept in resilience thinking, conceptually for urban environments. The study concludes that the inner city’s continued redevelopment poses an incalculable threat to the entire city. Therefore, “Natural urban resilience” recommends carefully weighing any intervention in the inner city to promote Addis Ababa’s overall resilience. This dissertation proposes a pattern language for natural urban resilience to support these efforts and to translate the model of natural urban resilience into practice.
Housing estates were fundamentally conceived upon state socialist utopia ideas to provide standard housing for citizens. While former state socialist housing estates have been extensively researched in the field of architecture, urban and sociology studies, there is still a gap in identifying how production processes affect morphological changes during the post-socialist era. This thesis compares the processes in the production of the largest housing estates of Marzahn in GDR and Petržalka in Czechoslovakia from 1970 to 1989 through contextual analysis of primary and secondary sources, which include visual maps, diagrams from professional architecture and planning journals, government documents and textbooks, as well as academic journals, books and newspaper articles. Then it discusses how these processes inadvertently created conducive conditions affecting their development in the market economy after 1989. It then interprets the results through application of Actor-Network Theory and Historical Institutionalism, while conceptualising them through David Harvey’s dialectical utopianism theory. Harvey (2000) delineates two types of utopia, one of spatial form and one of process. The former refers to materialised ideals in physical forms whereas the latter refers to the ongoing process of spatializing. The thesis aims to show how the production of Marzahn in GDR was more path dependent on policies established in 1950s and 1960s whereas Petržalka was a product of new Czechoslovakian policies in 1970s, changing aspects of the urban planning process, a manifestation of a more emphatic technocratic thinking on a wider scale. This ultimately influences the trajectories of development after 1989, showing more effects in Petržalka.
Transformation of the Environment: Influence of “Urban Reagents.” German and Russian Case Studies
(2021)
An urban regeneration manifests itself through urban objects operating as change agents. The en-tailed diverse effects on the surroundings demonstrate experimental origin - an experiment as a preplanned but unpredictable method. An understanding of influences and features of urban ob-jects requires scrutiny due to a high potential of the elements to force an alteration and reactions. This dissertation explores the transformation of the milieu and mechanisms of this transformation.
This dissertation investigates the interactions between urban form, allocation of activities, and pedestrian movement in the context of urban planning. The ability to assess the long-term impact of urban planning decisions on what people do and how they get there is of central importance, with various disciplines addressing this topic. This study focuses on approaches proposed by urban morphologists, urban economists, and transportation planners, each aiming the attention at a different part of the form-activity-movement interaction. Even though there is no doubt about the advantages of these highly focused approaches, it remains unclear what is the cost of ignoring the effect of some interactions while considering others. The general aim of this dissertation is to empirically test the validity of the individual models and quantify the impact of this isolationist approach on their precision and bias.
For this purpose, we propose a joined form-activity-movement interaction model and conduct an empirical study in Weimar, Germany. We estimate how the urban form and activities affect movement as well as how movement and urban form affect activities. By estimating these effects in isolation and simultaneously, we assess the bias of the individual models.
On the one hand, the empirical study results confirm the significance of all interactions suggested by the individual models. On the other hand, we were able to show that when these interactions are estimated in isolation, the resulting predictions are biased. To conclude, we do not question the knowledge brought by transportation planners, urban morphologists, and urban economists. However, we argue that it might be of little use on its own.
We see the relevance of this study as being twofold. On the one hand, we proposed a novel methodological framework for the simultaneous estimation of the form-activity-movement interactions. On the other hand, we provide empirical evidence about the strengths and limitations of current approaches.
Die Arbeit leistet einen wissenschaftlichen Beitrag zur Erforschung der Einsatzmöglichkeiten eines Immobilienportfoliomanagements für öffentliche museale Schlösserverwaltungen in Deutschland. Insbesondere wird ein für deren Organisation spezifisches Modell zur Investitionssteuerung herausgearbeitet und dessen Anwendbarkeit in der Praxis mit Experten diskutiert.