Late Holocene aeolian activity and landscape development in anorthern German inland dune system. An approach to spatially reconstruct past landscape dynamics usinggeoarchaeological records and scientific visualization techniques

The purpose of this thesis is to investigate and spatially reconstruct long-term aeolian landscape dynamics using a small inland dune system in Northern Germany as a case study. Against the background of the dune formation of the Kuhharder Hill dune (KHD), this thesis investigated the timing, causes, effects and magnitude of phases of aeolian activity since the beginning of the Holocene. In order to reconstruct past landscape changes and palaeo-environmental conditions, a multidisciplinary approach was chosen that combined pedological and geomorphologic analysis of aeolian sediments and past dune surfaces, chronology (14C and OSL dating), detailed stratigraphy, as well as palaeo-botanical records of charcoal and pollen. [...] On the basis of palaeo-environmental results, and the creation of digital elevation models of buried dune surfaces, 3D visualisation techniques were used in order to visually reconstruct the past environmental conditions and local dune development. A visualization model was developed which to account of the varying quality concerning temporal and spatial resolution of the geoarchaeological data.Die Arbeit rekonstruiert und quantifiziert die langfristige äolische Dynamik und ehemalige Mensch-Umwelt-Interaktionen am Beispiel der Entwicklung einer Binnendünenlandschaft in Norddeutschland. Im Mittelpunkt steht die Erörterung der Ursachen sowie die Untersuchung der Auswirkungen und Intensität von Phasen äolischer Aktivität und Winderosionsereignissen seit dem Holozän im Raum Joldelund. Zur Rekonstruktion vergangener Umweltzustände und Landschaftsveränderungen wurde ein multidisziplinärer Ansatz gewählt, der bodenkundliche sowie geomorphologische Analysen der äolischen Sedimente und begrabenen Dünenoberflächen, Datierungsmethoden (14C und OSL Datierung), detaillierte Stratigraphie sowie paläobotanische Methoden (Holzkohle- und Pollenanalyse) verbindet. [...] Basierend auf den geoarchäologischen Befunden und digitalen Geländemodellen der ehemaligen Dünenoberflächen wurde ein Visualisierungsmodell entwickelt, mit dem Ziel, einerseits wissenschaftlich belastbare 3D-Landschaftsvisualisierungen zu erstellen und andererseits, geoarchäologische Befunde der breiten Öffentlichkeit verständlich zu präsentieren

Mechanical model to predict the resistance of the shear connection in composite beams with deep steel decking

The resistance of a typical shear connection with headed shear studs in a composite beam is analysed for the normal case in accordance with EN 1994-1-1. The reducing effect of a trapezoidal metal decking to the ultimate loadbearing capacity is considered with empirically derived reduction factors and equations that were developed between the late 1970s and early 1980s. The RFCS research project ”DISCCO“ investigated the shear stud resistance with novel types of steel decking. In many cases, the shear resistance predicted by EN 1994-1-1 was not reached in tests. In the respective experiments with composite beams and deep decking, a concrete cone failure mode was identified and not a pure shear failure of the stud. This failure mode acted in combination with the loadbearing capacity of the shear stud, which formed one or two plastic hinges in the shaft depending on the actual geometry. Based on these observations, new equations have been developed to predict the shear connection's resistance with more accuracy. The yield hinge mechanism of the shear stud, which was developed by Lungershausen, was extended by the aforementioned loadbearing component ”concrete cone“. The formulae consider the geometry of the stud and the steel decking and the material strength of the stud and the concrete. The statistical evaluation of the equations developed demonstrates good agreement with test results