Zum Tragverhalten im Grundriss gekrümmter Verbundträger

In der vorliegenden Arbeit wird das Tragverhalten im Grundriss gekrümmter Träger untersucht. Offene und geschlossene Querschnitte mit oben liegender Betonplatte aus dem Verbundbrückenbau stehen dabei im Vordergrund. Maßgebende Parameter, die den Einfluss der Krümmung auf den Verlauf von Schnittgrößen und Verformungen in Ein- und Zweifeldträgern beschreiben, werden festgelegt. Die Auswirkungen des zeitabhängigen Betonverhaltens werden untersucht. Ersatzsysteme für stark gekrümmte Ein- und Zweifeldträger, bei denen die Krümmung mit Hilfe von Ersatzlasten am geraden Ersatzstab berücksichtigt wird, werden entwickelt. Außerdem wird ein mäßig gekrümmtes Stabelement für FE-Berechnungen hergeleitet. Ein Vorschlag zur Bemessung der Queraussteifungen in gekrümmten Trägern wird gemacht. Darüber hinaus wird die Modellierung querweicher Systeme unter Verwendung von Trägerrosten behandelt

Natural Regeneration of Scots Pine Requires the Application of Silvicultural Treatments such as Overstorey Density Regulation and Soil Preparation

Current management strategies for European Scots pine (Pinus sylvestris L.) forests are oriented towards the use of natural regeneration processes. They aim to maintain continuity of stand structure by preserving seed-producing and shelter trees at varying densities. Soil scarification techniques may be employed to support the natural regeneration of pine. Our study is based on data from seven study sites in the German lowlands, where the basal areas of the overstorey pine trees varied between 4 and 21 m2/ha. The soil scarification methods ranged from full surface ploughing by tractor or horse through small-scale scarification by cultivators to sites without soil scarification. Differences in the densities, spatial distributions, age structures, and above-ground development of pine seedlings were evaluated. We analysed the spatial interactions between overstorey pine trees and the densities of naturally regenerated pine seedlings as a function of the microsite types using the multitype Strauss hard-core process (MSH) method. The results show a significant decrease in height growth with increasing stand density after a period of 5 years, with seedling density and spatial patterns strongly influenced by soil scarification. The MSH pairwise interaction analyses revealed significant negative effects on seedling densities based on combinations of microsites and overstorey trees

Natural Regeneration of Scots Pine Requires the Application of Silvicultural Treatments such as Overstorey Density Regulation and Soil Preparation

Current management strategies for European Scots pine (Pinus sylvestris L.) forests are oriented towards the use of natural regeneration processes. They aim to maintain continuity of stand structure by preserving seed-producing and shelter trees at varying densities. Soil scarification techniques may be employed to support the natural regeneration of pine. Our study is based on data from seven study sites in the German lowlands, where the basal areas of the overstorey pine trees varied between 4 and 21 m2/ha. The soil scarification methods ranged from full surface ploughing by tractor or horse through small-scale scarification by cultivators to sites without soil scarification. Differences in the densities, spatial distributions, age structures, and above-ground development of pine seedlings were evaluated. We analysed the spatial interactions between overstorey pine trees and the densities of naturally regenerated pine seedlings as a function of the microsite types using the multitype Strauss hard-core process (MSH) method. The results show a significant decrease in height growth with increasing stand density after a period of 5 years, with seedling density and spatial patterns strongly influenced by soil scarification. The MSH pairwise interaction analyses revealed significant negative effects on seedling densities based on combinations of microsites and overstorey trees