Überprüfung des Tragverhaltens der Talbrücke Altwipfergrund

Validation of the structural behaviour of the Altwipfergrund Bridge. At the middle of the eighties in France composite bridges with corrugated steel webs have been built for the first time. Just a few years later this principle was adopted in Japan and many bridges of this kind have been built. At the same time in Germany also, the first considerations about these bridges have been taken place, but unfortunately to this date only one construction has been built, i.e. the Altwipfergrund Bridge. A comprehensive research project is presently carried out for research on general behaviour and the detailing of bridges with corrugated steel webs. The results are accompanied by measurements at the Altwipfergrund Bridge. Thus it was possible to validate the results of numerical calculations and laboratory tests by the results of measurements. Based on this information, the potential of these structures regarding web thickness, amount and style of prestressing and reduction of composite joints can be identified.     

Teil 1: Aufstellung der Bedingungsgleichungen mit Überprüfung der Lösbarkeit

An Extension of the technical bending Theory Because of the non‐linearity of reinforced concrete, the technique of superposition cannot be used. For the usual combination of internal forces (N_x, V_y, V_z, M_z, M_y and T_x) no method of calculating the corresponding strains has yet been established. The classical bending theory which is applied in the current design codes provides for only three of the six internal forces N_x, M_y und M_z) a corresponding state of strain. Here, the technical bending theory is extended in such a way that the deformation can also be calculated for all the internal forces in the general case. This results in a state of strain that is curved because of the shearing strain which must be taken into consideration. The extension of the classical technical bending theory furthermore fulfills the necessary equilibrium and geometrical compatibility conditions and takes into account a realistic material behavior.     

Analytische Lösungen von Rechenmodellen als Voraussetzung zur Überprüfung der Güte der in Rechenprogrammen angewendeten Strahlungsmodelle

Analytical solutions of computational modells as a requirement for verifiing the quality of radiation models applied in computa‐tional programs. The computational capabilities of investigations of the coupled energy transfer due to conduction, convection and radiation are undergoing far‐reaching innovations in last decades. Increasing computational speed and capacity were requirements for numerical modelling heat transfer. New possibilities in solving complex applications – e.g. radiative heat transfer – are available in CFD programs. Questions in surface temperature, temperature and velocity field, gas phase temper‐ature, heat flux due to radiation within absorbing, emitting and scattering media – e.g. in combustions chambers or at glass melting processes – have increased the development of radiation models in CFD. Radiation models are developed for several fields of applications. They were permanently extended and improved. The accuracy of radiation models and the possibility in modelling simple as well as complex radiation processes make them to useful and reliable tools in CFD. However, each of the models has its advantages and limits. The engineer has to choose for a radiation model which is practical and appropriate for the application.     

Überprüfung und Bewertung der seismischen Bemessungsgrößen nach DIN 19700 am Beispiel der Thüringer Talsperren

Examination and evaluation of seismic design criteria according to DIN 4149 by the example of the Thuringia dams. According to the new DIN 19700 dams and other water retaining structures are classified with respect to their storage capacity and height leading to differentiated demands on design and safety verification. Since the dams are located in quite different seismic regions, these demands have to reflect the level of seismic hazard (in terms of zones expressing different intensity intervals). The paper investigates the requirements connected with the introduction of DIN 19700 and the problems arising when implementing the code in a nation‐wide scale acknowledging the federal system in Germany. In this context and due to some normative elements, deviating from DIN 19700, the Thuringian Technical Guide is considered more in detail. Basic contours of a unified strategy for the state of Thuringia and the required steps of action are presented. The procedure allows for effects of synergy by maintaining the transformability of the guidelines to other German States.     

Messverfahren zur Überprüfung randschichtnaher Veränderungen des Werkstoffzustandes als Folge mechanischer Oberflächenbehandlungen

Zur Charakterisierung der ermüdungsrelevanten Werkstoffveränderungen infolge hochfrequenter Schweißnahtnachbehandlung hat sich der Einsatz von mikromagnetischen Werkstoff‐ und Spannungsanalysen vorteilhaft gezeigt. Für Standardbauteile hat sich gezeigt, dass die Qualitätssicherung der Nachbehandlung mit höherfrequenten Hämmerverfahren bei Einhaltung der Behandlungsparameter durch eine Sichtkontrolle möglich ist. Das Mikromagnetische Verfahren ermöglicht bei neuen Anwendungsfällen eine Gütekontrolle der Nachbehandlung an Arbeitsproben ·und am Realbauteil. A measurement technique for inspection of material subsurface changes after mechanical surface treatment. The micro‐magnetic stress and material analysis has shown to be advantageous for characterizing the fatigue related material properties after high frequency post weld treatment. The quality control of standard parts treated by high frequency hammer peeing with the same peening parameters is possible by means of visual inspection. For new applications, the micro‐magnetic analysis provides a quality control of post weld treated work samples and real components.