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Polymer modification of mortar and concrete is a widely used technique in order to improve their durability properties. Hitherto, the main application fields of such materials are repair and restoration of buildings. However, due to the constant increment of service life requirements and the cost efficiency, polymer modified concrete (PCC) is also used for construction purposes. Therefore, there is a demand for studying the mechanical properties of PCC and entitative differences compared to conventional concrete (CC). It is significant to investigate whether all the assumed hypotheses and existing analytical formulations about CC are also valid for PCC. In the present study, analytical models available in the literature are evaluated. These models are used for estimating mechanical properties of concrete. The investigated property in this study is the modulus of elasticity, which is estimated with respect to the value of compressive strength. One existing database was extended and adapted for polymer-modified concrete mixtures along with their experimentally measured mechanical properties. Based on the indexed data a comparison between model predictions and experiments was conducted by calculation of forecast errors.
Im Rahmen der Forschung an Bauteil- und Fügestellendämpfung wurden die Schwingungen der Bauteile bisher mit 1D-Laser-Vibrometern gemessen. Nun steht ein 3D-Laser-Scanner zur Verfügung. Diese Arbeit beschäftigt sich mit der Frage, ob mit dem 3D-Laser-Scanner bessere und weitere relevante Daten bei der Schwingungsmessung gewonnen werden können.
This article presents the Rigid Finite Element Method in the calculation of reinforced concrete beam deflection with cracks. Initially, this method was used in the shipbuilding industry. Later, it was adapted in the homogeneous calculations of the bar structures. In this method, rigid mass discs serve as an element model. In the flat layout, three generalized coordinates (two translational and one rotational) correspond to each disc. These discs are connected by elastic ties. The genuine idea is to take into account a discrete crack in the Rigid Finite Element Method. It consists in the suitable reduction of the rigidity in rotational ties located in the spots, where cracks occurred. The susceptibility of this tie results from the flexural deformability of the element and the occurrence of the crack. As part of the numerical analyses, the influence of cracks on the total deflection of beams was determined. Furthermore, the results of the calculations were compared to the results of the experiment. Overestimations of the calculated deflections against the measured deflections were found. The article specifies the size of the overestimation and describes its causes.
The conservation of living heritage sites is a highly complex process. Two factors need careful consideration in order to achieve a balance in the management of such sites: the conservation demands of conservation experts for built heritage and the needs of local people for development of their heritage living space. The complexity of factors involved make for an interesting study of living heritage, taken up by this research in its main case study of the town of Nan in Thailand.
Research into the historical background of Nan and its cultural heritage reveals a living heritage site, which is both unique and diverse. Present day Nan was examined using a variety of analysis tools, which were applied to data from interviews, empirical data, field surveys, and documents, in order to better understand the nature of the living heritage site and changing trends over time. Luang Prabang in Lao PDR, a World Heritage site since 1995, was also selected as a further case study with which to compare Nan’s potential World Heritage status from a point of view of changes to living heritage attributes.
The outcomes of the research indicate the importance of the management of the sites, which can be at risk of losing balance by focusing on one aspect of heritage to the detriment of the other. The conservation perspective, if allowed to dominate, as in Luang Prabang, can cause irreparable damage to the social fabric, where the development needs of the town are not met. This research concludes that a balance of power amongst stakeholders in the collaborative networks managing such sites is vital to sustaining a balance of living heritage attributes.
The stress state of a piecewise-homogeneous elastic body, which has a semi-infinite crack along the interface, under in-plane and antiplane loads is considered. One of the crack edges is reinforced by a rigid patch plate on a finite interval adjacent to the crack tip. The crack edges are loaded with specified stresses. The body is stretched at infinity by specified stresses. External forces with a given principal vector and moment act on the patch plate. The problem reduces to a Riemann-Hilbert boundary-value matrix problem with a piecewise-constant coefficient for two complex potentials in the plane case and for one in the antiplane case. The complex potentials are found explicitly using a Gaussian hypergeometric function. The stress state of the body close to the ends of the patch plate, one of which is also simultaneously the crack tip, is investigated. Stress intensity factors near the singular points are determined.
It is well-known that the solution of the fundamental equations of linear elasticity for a homogeneous isotropic material in plane stress and strain state cases can be equivalently reduced to the solution of a biharmonic equation. The discrete version of the Theorem of Goursat is used to describe the solution of the discrete biharmonic equation by the help of two discrete holomorphic functions. In order to obtain a Taylor expansion of discrete holomorphic functions we introduce a basis of discrete polynomials which fulfill the so-called Appell property with respect to the discrete adjoint Cauchy-Riemann operator. All these steps are very important in the field of fracture mechanics, where stress and displacement fields in the neighborhood of singularities caused by cracks and notches have to be calculated with high accuracy. Using the sum representation of holomorphic functions it seems possible to reproduce the order of singularity and to determine important mechanical characteristics.
This is a work concerned with the increasing processes of social exclusion in cities nowadays. In approaching this phenomenon, the research highlights how people interact with their institutional environments. This is also, perhaps centrally, an investigation into the possibility to engage an individual perspective to understand the transformation in urban experience, which is orienting society to new uses and forms of exclusion. Following the perspective deployed by the so-called “sociology of individuals” in French sociology or “reengagement of agency” in the Anglo-Saxon world; I claim that individuals as well as collectives are gaining increasing power to question and re-organize institutions. This re-organization, in the case of socio-urban institutions, is no guarantee for major levels in integration, cohesion, and equality. Unfortunately, social institutions are becoming hard in its exclusionary capabilities under people intervention during the last four decades.
I believe that urban sociology is a field of struggle between different perspectives competing to “make sense” of social phenomena in cities. The orientation supported in this research is just one on many and it follows the roots of people and their life experiences within cities and how they influence the processes that shape the city. The last formulation is possibly not the clearest, because as we all know, references to “inhabitants” are presented in every variant of urban sociology. Nevertheless, there are not many variants focusing on peoples’ capability to influence institutional environments and by this way affecting the urban condition in which they find themselves. The particular institution selected for this study is the “School”.
This thesis is organized around two parts: part one includes the conceptual framework, methodological approach, and historical contextualization; part two describes three case studies produced to analyse the forms of and the relations between individuals and school institution. Part one starts from a premise: within the context of declining welfare State in the case of industrialized countries, an important part of urban studies focuses on economic and spatial restructuration. Confronted with the same situation, a part of social sciences shifts to the individuals’ agency and social uncertainty. This research is embedded in the last theoretical description presented above, thus, because it tries to observe urban processes from the perspective of the individual and outside of developed economies. In this sense, Latin America represents a fundamental reference because urban conditions are historically marked by weak institutional arrangements to integrating people and large levels of marginality and exclusion among population. In this scenario individuals’ practices around inclusion-exclusion have an essential meaning in everyday life.
Part two offers three study cases in which the relation between individuals and school institutions has been analyzed for the Metropolitan area of Santiago de Chile (MAS). Using different methodological resources an exhaustive account on three levels is presented: i) geo-referencing State intervention in public policies connected with neighborhood and schools to understand the form and extent of socio-urban exclusion in MAS, ii) narrative biographies applied to parents with children attending primary school, in order to reconstruct the familiar process of school selection and describing its impacts on the stabilization of school as an exclusionary device, and iii) autoethnography to describe in detail the temporal dimension involved in stabilizing actions which reinforces social mechanisms of urban integration-exclusion during the last three decades in Chile.
A key argument advanced by this research proposes that: the way in which the idea of integration is enacted by people in their biographical careers imprints changes on the institutional orientation and by this way, contributes to the reorganization urban life. The high level of social exclusion in Santiago de Chile is not accountable without considering transformation in all socio-urban institutions, especially the school. No family considers social integration with people from a low social, economical or cultural background as relevant orientation for school selection. This particularity of the Chilean social reality is not derivable from any big capitalistic or modernization processes impacting our cities.
Within the light of the thesis findings, I conclude that socio-urban institutions logics must be reassessment under the influences of people actions and representations. I also propose a consideration to major complementarities between urban studies and urban-institutions analysis. The school institutions is not just a sectorial field reserved to the researcher in education, on the contrary, it represent a key entrance to address people’s experience in their institutional urban environments. The re-emergence of social and urban movements in 2010, under the “Arab Spring” or the “Chilean Student Movements”, is not only a demonstration in the public space as result of major global trends. These situations are in essence, for this research, individuals gathering together and calling for recognition and autonomy inside institutional environment that tends to reject them. Similar situation was the focus of the Latin American urban sociology research, within the focus on grassroots and urban social movements at the end of the 1960s and beginning of the 1970s.
In both cases, socio-urban institutions, unaware of recognition requirements claimed by inhabitants, are not beyond individual or collective reach. My main concern is to show that socio-urban institutions are constantly re-shaped as a result of individual action, what makes the difference, is the spirit that we all, socially, imprint on the logics of our socio-urban institutions, moving them to inclusion or exclusion.