Statische und kinetische Instabilitäten bei Bauwerken

In der Bautechnik treten oft, z. B. bei windbelasteten oder meerestechnischen Konstruktionen, statische oder dynamische Instabilitäten auf – manchmal auch ein Zusammenwirken (Interaktion) beider Mechanismen, wobei die Knick‐ oder Beuleigenformen durchaus verschieden von den entsprechenden Schwingungseigenformen sein können. Es soll dargestellt werden, wann die Stabilitätsuntersuchungen der Strukturen statisch durchgeführt werden dürfen und in welcher Form sich die Ergebnisse bei einer zusätzlichen dynamischen Belastung verändern. Static and dynamic instabilities of structures. In structural design e. g. under wind loads or offshore structures we often have static or dynamic instabilities sometimes also an interaction of both mechanisms, where the buckling modes may be different from the vibration modes. We want to recognize, whether the investigations may be static and how the results may alter by dynamic loads.     

Der Stabbogen bei stählernen Straßenbrücken – Entwicklungstendenzen der letzten 50 Jahre – Teil I

The strut arch in using of steel road bridges mainly in Germany – trends of developments into the last 50 years. By the presentation is given a survey about the development of the designing the arch construction for steel road bridges inclusive the constructive details. In the detail are considerd the suspensions with their connections, the cross‐sections of the arch, springing arch, arch model and the roadway‐constructions into different phases. At last of the investigation are presented some typical erection‐examples.     

SPS – ein neues Verfahren zur Instandsetzung und Ertüchtigung von stählernen orthotropen Fahrbahnplatten

SPS – an innovative method for the repair and refurbishment of orthotropic deck‐plates of steel‐bridges. This contribution describes how the new SPS‐Overlay technology has been applied in a pilot project for the refurbishment of orthotropic deckplates of road bridges in Germany. The main reason for such a refurbishment of orthotropic deckplates that have been designed and executed according to modern design rules as in EN 1993‐2 and that after 40 years of use have not yet exhibited any considerable fatigue damage is to make provisions for the current enhancement of traffic loads and traffic volume that could cause fatigue in the near future. The stepwise procedure to study the experience made with the SPS‐technology in the ship‐building area first, then to apply it to the retrofitting of damaged deckplates of a temporary bridge system (D‐Bridge) to gain experiences before it is used for retrofitting the deck of an old metro‐bridge in Berlin and to enter into the refurbishment of a bridge in the highway (Schönwasserparkbrücke near Krefeld) is explained in detail. Particular challenges for the use of the SPS‐technology for a highway bridge were: –·applicability on site under climate conditions –·fast execution to reduce restraints to traffic –·applicability of the guss asphalt layer with 75–80 mm thickness with a temperature of 225 °C without damaging the PUR sandwich core. The paper presents the technical developements including details of the scientific support, to justify the solution chosen toward the regulatory authorities. In conclusion the SPS‐technology has proved to be an efficient refurbishment method that meets all requirements.     

Tragfähigkeit von Winkelprofilen bei Druckbeanspruchung und realen Lagerungsbedingungen

Load bearing capacity of angle profiles under compression with realistic boundary conditions. In this paper the compression capacities of tests in literature are compared with results of a numerical study considering realistic boundary conditions. The main focus is on compression members with bolted connections on both ends. The presented compression capacities are also compared with design rules of different codes for transmission towers and steel structures (buildings). At the end of the article, an example shows the suggested design procedure in practice.     

Verbesserte Tragfähigkeit von dünnwandigen Tragwerken durch Hybridbauweise und Flächenstrukturierung

Improved load‐carrying capacity of thin‐walled structures via hybrid and non‐smooth wall constructions. This contribution deals with modified wall constructions of thin‐walled structures which aim to improve their load‐carrying capacity and imperfection‐sensitivity without a corresponding increase in total weight.