Prüfung des Frost-Tausalz-Widerstandes von Beton für die Expositionsklasse XF2

In cold and moderate climates concrete can be subjected to a combined salt frost attack, which can cause scaling damage. Consequently, numerous test procedures were developed to determine the resistance of concrete compositions against this kind of attack. These tests typically mimic a severe attack with high levels of saturation, e.g. as for concrete pavements. Very few approaches exist for testing the salt frost scaling resistance of concretes, which are subjected only to medium levels of saturation, as such concrete elements typically don’t show notable scaling damage. However, the increasing use of low carbon cements with high clinker substitution rates might affect the salt frost scaling resistance of such concrete elements to some extent. To ensure adequate durability of such concretes it is thus desirable to determine their performance in an actual test procedure instead of relying on past experience. Thus, less severe test methods was developed, which are based on the Slab test and the CDF test, repectively.In kalten und gemäßigten Klimazonen kann Beton einem kombinierten Frost-Tausalz-Angriff ausgesetzt sein, der zu Schäden in Form von Abwitterungen führen kann. Daher wurden zahlreiche Prüfverfahren entwickelt, um die Widerstandsfähigkeit von Betonzusammensetzungen gegen diese Art des Angriffs zu bestimmen. Diese Tests simulieren in der Regel einen starken Angriff mit hohen Sättigungsgraden, wie z. B. bei Betonfahrbahnen. Es gibt nur sehr wenige Ansätze für die Prüfung des Widerstands von Betonen, die nur einem mittleren Sättigungsgrad ausgesetzt sind, da solche Betonelemente in der Regel keine nennenswerten Abwitterungen aufweisen. Die zunehmende Verwendung von klinkereffizienten Zementen könnte sich jedoch in gewissem Maße auf den Frost-Tausalz-Widerstand solcher Betonelemente auswirken. Um eine angemessene Dauerhaftigkeit zu gewährleisten ist es daher wünschenswert, ihre Leistungsfähigkeit in einem tatsächlichen Prüfverfahren zu ermitteln, anstatt sich auf Erfahrungswerte zu verlassen. Daher wurden Ansätze für abgeschwächte Prüfverfahren entwickelt, die auf dem Slab-Test bzw. dem CDF-Test beruhen

Verbindungen mit Nägeln im Holzbau – Die Erforschung und Entwicklung von Konstruktionsregeln

Der Nagel als tragendes Holzverbindungsmittel ist heute gut bekannt. Doch noch vor 100 Jahren war das anders: sein statisch konstruktiver Gebrauch war verboten. Das änderte sich mit Beginn dessen Erforschung Ende der 1920er Jahre. Seit 1933 ist der Nagel Bestandteil der deutschen Regelwerke und findet seitdem breite Verwendung. Über weite Teile des 20. Jahrhunderts diente er in Not- und Sparkonstruktionen wie Brett- und Bohlenbindern als hocheffizientes Verbindungsmittel der Wahl. Diese materialsparenden Tragwerke waren bei der periodisch im-mer wiederkehrenden Ressourcenknappheit sehr gefragt und sind ein wichtiger Bestandteil der Konstruktionsgeschichte des Holzbaus. In dem folgenden Beitrag wird die Erforschung des Na-geltragverhaltens und die einhergehende fortlaufende Normierung behandelt. Die Errungen-schaften einzelner Forschungsvorhaben werden vorgestellt. Anhand eines Zeitstrahls werden Zusammenhänge zwischen Forschung und Normung gezeigt. Tabellen und Grafiken verdeutli-chen die Änderungen innerhalb der Normen von der ersten DIN 1052 im Jahr 1933 über die erste eigenständige Holzbaunorm in der DDR, der TGL 112-0730, aus 1963 bis zur DIN 1052- 1988. Dabei wird immer Bezug zum derzeitigen Entwurf des Eurocode 5 genommen. Allgemein zeigt sich, dass ein Großteil der heutigen Kenntnisse immer noch auf die Grundlagenforschung der 1930er Jahre zurückgeht.The nail as a load-bearing timber fastener is well known today. But 100 years ago, it was different: its structural use was not allowed. This changed with the beginning of systematical research at the end of the 1920s. Since 1933, the nail has been part of the German regulations and has been widely used ever since. For much of the 20th century, it served as the highly efficient fastener of choice especially in roof structures such as board and plank trusses. These material-saving load-bearing structural elements were always in demand due to the periodically recurring scarcity of material resources and are an important part in con-struction history. The following article deals with the research of the load-bearing behaviour of nails and the standardisation that has constantly accompanied it. The achievements of individual research projects are presented. A timeline shows the connections between research and standardisation. Tables and graphics illustrate the changes within the standards from the first DIN 1052 in 1933 to the first independent timber construction standard in the DDR, TGL 112-0730, from 1963 to DIN 1052-1988. Reference is al-ways made to the Eurocode 5 valid today. In general, it can be seen that a large part of today's knowledge still goes back to the basic research of the 1930s

Data for sound pressure level prediction in lightweight constructions caused by structure-borne sound sources and their uncertainties

When predicting sound pressure levels induced by structure-borne sound sources and describing the sound propagation path through the building structure as exactly as possible, it is necessary to characterize the vibration behavior of the structure-borne sound sources. In this investigation, the characterization of structure-borne sound sources was performed using the two-stage method (TSM) described in EN 15657. Four different structure-borne sound sources were characterized and subsequently installed in a lightweight test stand. The resulting sound pressure levels in an adjacent receiving room were measured. In the second step, sound pressure levels were predicted according to EN 12354-5 based on the parameters of the structure-borne sound sources. Subsequently, the predicted and the measured sound pressure levels were compared to obtain reliable statements on the achievable accuracy when using source quantities determined by TSM with this prediction method

Teilhabe an Gesundheitsversorgung von aufenthaltsrechtlich illegalisierten Menschen in Deutschland

Die Gesundheitsversorgung in Deutschland ist seit den Bismarckschen Sozialreformen ein zunehmend institutionalisierter Teil der staatlichen Daseinsvorsorge im wohlfahrtsstaatlichen Gefüge. Institutionalisiert ist die Gesundheitsversorgung in korporatistischer Logik, das heißt in kooperativen Beziehungen zum privatwirtschaftlichen und zivilgesellschaftlichen Sektor und mit Befugnissen der Selbstverwaltung. Zudem fußt das Gesundheitssystem auf einem Versicherungssystem mit lohnabhängigen Abgaben. Institutionalisiert ist die staatliche Daseinsvorsorge jedoch auch in seinen Ausschlüssen. So werden Menschen ohne Bürgerrechte von vielen sozialen Rechten, wie von der Gesundheitsversorgung, ausgeschlossen, obwohl dieser Ausschluss im Widerspruch zu anderen konstitutiven Elementen des Nationalstaats steht. In diesem Working Paper werden die grundlegende Strukturen des deutschen Gesundheitssystems und darin innewohnende Funktionslogiken der Produktion von Teilhabe dargestellt. Abschließend werden in Anlehnung an Kronauer die verschiedenen Dimensionen von Teilhabe an Gesundheitsversorgung in ihrer Produktions- und Ausschlusslogik im Wohlfahrtsregime dargelegt dabei auf die Gruppe der aufenthaltsrechtlich Illegalisierten fokussiert, denen gesellschaftliche Teilhabe in vielen Lebensbereichen, wie auch stark im Gesundheitsbereich, untersagt wird. Gleichzeitig soll dargestellt werden, wie zivilgesellschaftliche Akteur*innen auch gegen staatliche Vorgaben oder Anreize, Teilhabe (wieder-)herstellen

On the use of climate models for estimating the non-stationary characteristic values of climatic actions in civil engineering practice

The characteristic values of climatic actions in current structural design codes are based on a specified probability of exceedance during the design working life of a structure. These values are traditionally determined from the past observation data under a stationary climate assumption. However, this assumption becomes invalid in the context of climate change, where the frequency and intensity of climatic extremes varies with respect to time. This paper presents a methodology to calculate the non-stationary characteristic values using state of the art climate model projections. The non-stationary characteristic values are calculated in compliance with the requirements of structural design codes by forming quasi-stationary windows of the entire bias-corrected climate model data. Three approaches for the calculation of non-stationary characteristic values considering the design working life of a structure are compared and their consequences on exceedance probability are discussed

Interactive Surface Environments: Design and Implementation

This dissertation presents three studies on the design and implementation of interactive surface environments. It puts forward approaches to engineering interactive surface prototypes using prevailing methodologies and technologies. The scholarly findings from each study have been condensed into academic manuscripts, which are conferred herewith. The first study identifies a communication gap between engineers of interactive surface systems (i.e., originators of concepts) and future developers. To bridge the gap, it explores a UML-based framework to establish a formal syntax for modeling hardware, middleware, and software of interactive surface prototypes. The proposed framework targets models-as-end-products, towards enabling a shared view of research prototypes thereby facilitating dialogue between concept originators and future developers. The second study positions itself to support developers with an open-source solution for exploiting 3D point clouds for interactive tabletop applications using CPU architectures. Given dense 3D point-cloud representations of tabletop environments, the study aims toward mitigating high computational effort by segmenting candidate interaction regions as a preprocessing step. The study contributes a robust open-source solution for reducing computational costs when leveraging 3D point clouds for interactive tabletop applications. The solution itself is flexible and adaptable to variable interactive surface applications. The third study contributes an archetypal concept for integrating mobile devices as active components in augmented tabletop surfaces. With emphasis on transparent development trails, the study demonstrates the utility of the open-source tool developed in the second study. In addition to leveraging 3D point clouds for real-time interaction, the research considers recent advances in computer vision and wireless communication to realize a modern, interactive tabletop application. A robust strategy that combines spatial augmented reality, point-cloud-based depth perception, CNN-based object detection, and Bluetooth communication is put forward. In addition to seamless communication between adhoc mobile devices and interactive tabletop systems, the archetypal concept demonstrates the benefits of preprocessing point clouds by segmenting candidate interaction regions, as suggested in the second study. Collectively, the studies presented in this dissertation contribute; 1—bridging the gap between originators of interactive surface concepts and future developers, 2— promoting the exploration of 3D point clouds for interactive surface applications using CPU-based architectures, and 3—leveraging 3D point clouds together with emerging CNN-based object detection, and Bluetooth communication technologies to advance existing surface interaction concepts

Addressing Controversial Topics in Search Engines

Search engines are very good at answering queries that look for facts. Still, information needs that concern forming opinions on a controversial topic or making a decision remain a challenge for search engines. Since they are optimized to retrieve satisfying answers, search engines might emphasize a specific stance on a controversial topic in their ranking, amplifying bias in society in an undesired way. Argument retrieval systems support users in forming opinions about controversial topics by retrieving arguments for a given query. In this thesis, we address challenges in argument retrieval systems that concern integrating them in search engines, developing generalizable argument mining approaches, and enabling frame-guided delivery of arguments. Adapting argument retrieval systems to search engines should start by identifying and analyzing information needs that look for arguments. To identify questions that look for arguments we develop a two-step annotation scheme that first identifies whether the context of a question is controversial, and if so, assigns it one of several question types: factual, method, and argumentative. Using this annotation scheme, we create a question dataset from the logs of a major search engine and use it to analyze the characteristics of argumentative questions. The analysis shows that the proportion of argumentative questions on controversial topics is substantial and that they mainly ask for reasons and predictions. The dataset is further used to develop a classifier to uniquely map questions to the question types, reaching a convincing F1-score of 0.78. While the web offers an invaluable source of argumentative content to respond to argumentative questions, it is characterized by multiple genres (e.g., news articles and social fora). Exploiting the web as a source of arguments relies on developing argument mining approaches that generalize over genre. To this end, we approach the problem of how to extract argument units in a genre-robust way. Our experiments on argument unit segmentation show that transfer across genres is rather hard to achieve using existing sequence-to-sequence models. Another property of text which argument mining approaches should generalize over is topic. Since new topics appear daily on which argument mining approaches are not trained, argument mining approaches should be developed in a topic-generalizable way. Towards this goal, we analyze the coverage of 31 argument corpora across topics using three topic ontologies. The analysis shows that the topics covered by existing argument corpora are biased toward a small subset of easily accessible controversial topics, hinting at the inability of existing approaches to generalize across topics. In addition to corpus construction standards, fostering topic generalizability requires a careful formulation of argument mining tasks. Same side stance classification is a reformulation of stance classification that makes it less dependent on the topic. First experiments on this task show promising results in generalizing across topics. To be effective at persuading their audience, users of an argument retrieval system should select arguments from the retrieved results based on what frame they emphasize of a controversial topic. An open challenge is to develop an approach to identify the frames of an argument. To this end, we define a frame as a subset of arguments that share an aspect. We operationalize this model via an approach that identifies and removes the topic of arguments before clustering them into frames. We evaluate the approach on a dataset that covers 12,326 frames and show that identifying the topic of an argument and removing it helps to identify its frames

Soil-structure interaction: A state-of-the-art review of modeling techniques and studies on seismic response of building structures

The present article aims to provide an overview of the consequences of dynamic soil-structure interaction (SSI) on building structures and the available modelling techniques to resolve SSI problems. The role of SSI has been traditionally considered beneficial to the response of structures. However, contemporary studies and evidence from past earthquakes showed detrimental effects of SSI in certain conditions. An overview of the related investigations and findings is presented and discussed in this article. Additionally, the main approaches to evaluate seismic soil-structure interaction problems with the commonly used modelling techniques and computational methods are highlighted. The strength, limitations, and application cases of each model are also discussed and compared. Moreover, the role of SSI in various design codes and global guidelines is summarized. Finally, the advancements and recent findings on the SSI effects on the seismic response of buildings with different structural systems and foundation types are presented. In addition, with the aim of helping new researchers to improve previous findings, the research gaps and future research tendencies in the SSI field are pointed out

Coopetition is King. Ökonomische Potentiale und medienpolitische Implikationen kooperativer Journalismusplattformen

Die vorliegende Studie geht der Fragestellung nach, wie sich eine anbieterübergreifende, abonnementbasierte Plattform für den digitalen Journalismus, also eine Art Spotify im Journalismus, auf die Umsätze der Anbieter journalistischer Inhalte und die Abonnements im Digitaljournalismus in Deutschland auswirken würde. Auf Basis drei sich ergänzender Schätzmethoden für Zahlungsbereitschaft, die in zwei Repräsentativbefragungen der deutschen Online-Bevölkerung mit insgesamt 8.000 Teilnehmenden angewandt wurden, gelangt das Whitepaper zu den folgenden Schlüsselbefunden

SE/ NPO Ecosystems and urban Governance in Johannesburg

This paper presents initial findings from the empirical analysis of community based social enterprise (SE) and non-profit organisation (NPO) ecosystems in Johannesburg. SEs and NPOs are widely recognised as contributors to the resilience of marginalised urban communities. However, the connection between these organisations , urban governance, and community resilience has not yet been sufficiently understood , particularly in African urban contexts. The 'Resilient Urban Communities' project focuses on Johannesburg as a case study to shed light on this under-researched topic. The key to exploring it is understanding SEs and NPOs as providers of public services, job creators, and promoters of good governance, all of which contribute to community resilience. Using this premise as a starting point, this paper investigates ecosystem conditions with a particular focus on state-civil society partnerships. Empirical data was generated through semi-struc-tured interviews and analysed with a grounded theory approach. Preliminary results of this ongoing research reveal that urban geography is a relevant ecosystem factor for SEs and NPOs from marginalised communities. We also suggest that co-production could be an opportunity for growth within the investigated state-civil society partnership