Das “Blaue Wunder” – Entwicklung neuer Methoden in der Tragwerksbeurteilung

The Elbe bridge “Blaues Wunder” in Dresden – development of new methods in the structure assessment. The Elbe bridge “Blaues Wunder” was built in 1893 and represents for many years a symbol of Dresden. After an introduction about the bridge system the following publication especially deals with the questions of static calculation, assessment of remaining fatigue life and further safe use of the construction.     

Die Innovation – Kleben – Aktuelles aus der “Arbeitsgruppe Kleben” des Fachverbandes Konstruktiver Glasbau – FKG

The Innovation – Bonding. Essential motivation for establishing the workgroup “Bonding” was that silicone bondings – in the structural engineering well known – received a great importance in the past years regarding application for structural glazing. Long times the application of silicones was only the usage in weather sealings and for sealings of insulated glass units. Due to the special properties of silicone this material has certainly the potential, in addition to the weather seal purpose, to take over also load bearing functions. The European Technical Guideline ETAG002 regulates actually the constructive requirements of line shaped silicone bondings. Nevertheless the knowledge of the real parameters of the pure material and its mechanical properties is very limited. This is the reason, that for using a silicone bonding, planned by engineering principles, experiments are necessary in wide areas. Reliable parameters and material properties are widely unknown, thus the sizing of a general bonding geometry with using Finite Element Analysis is unsatisfactory. The ETAG test specimen for tension is moreover unsuitable for retrieving direct material properties, due to edge effects leading to stress concentrations within the specimen. Therefore getting real parameters of the silicone material out of this kind of tests is nearly impossible. In the working group focus has been given on the development of theoretical models for the material silicone by a combined approach of experiment (material tests) and theory (analysis by FEM). Main objective is the establishment of design criteria for complex bonding geometries by application of engineering principles in the area of structural glazing. Based on the gained experience it will be possible in future: – to design arbitrary bonding geometries – to optimise them with respect to the most possible failure mechanism – to use simple formula and criteria for the design of arbitrary kinds of bondings – to limit extensive testing for each application. Extending the existing work program, it is envisaged in the short term to analyse bonding systems by duromer adhesives (e.g. acrylate, polyurethane).     

Zum Thema “Nachhaltigkeit” in der Stahlbauindustrie

Assessment of sustainability in the steel construction industry. The requirement for sustainability in construction results from deficits that currently exist in buildings in view of climate protection and energy efficiency. Systems for the assessment of sustainability will have a great impact on the competitiveness of construction and engineering services and on the real estate market. The new German assessment system gives clear quantitative reproducible sustainability criteria and is competitive in relation to other existing assessment systems. As energy efficiency is the dominant sustainability criterion for buildings, the paper demonstrates with examples from steel structures, how new innovative solutions for products and prefabricated components develop from integrating different aspects as structural resistance, serviceability and energy efficiency in the design. This leads to the concept of integrated design. Sustainable construction opens new fields for technology, markets, research and development in the steel construction field.     

“Die Raupe” – eine bewegliche Brückenkonstruktion

Für einen Brückenwettbewerb in Wien wurde ein Konzept einer beweglichen Brücke in Form eines Fischbauchträgers entwickelt, das neben seiner strengen Funktionalität und der materiellen Effizienz über einen innovativen Hebemechanismus verfügt. Die Idee des Hebevorgangs basiert auf einer Verkürzung des Trägeruntergurts durch Seile und zwei zwischengeschalteten hydraulischen Zylindern. Die Anhebung der Brücke zur Freihaltung des geforderten Lichtraumprofils erfolgt asymmetrisch, was ein raupenähnliches Verkrümmen zur Folge hat. Des Weiteren wurde die Deckplatte dahingehend optimiert, dass unter Verwendung hochfester Stähle die große Verformung über das elastische Werkstoffverhalten aufgenommen und so auf wartungsintensive Gelenke verzichtet werden kann. Durch das gewählte statische System mit dem applizierten Hebemechanismus kann die Einleitung großer Horizontalkräfte in den Boden vermieden und dadurch die Kosten deutlich gesenkt werden. Das Konzept wurde für eine Spannweite von ca. 60 m entwickelt, kann jedoch auch für andere Spannweiten adaptiert und so vielerorts eingesetzt werden. “The Caterpillar” – A moving bridge structure. For a design competition for a bridge in Vienna, a concept for a moving bridge in the form of a lenticular girder was developed which, in addition to its strict functionality and material efficiency, features an innovative lifting mechanism. The lifting principle is based on shortening the lower chord of the girder with the help of cables and two intermediate hydraulic cylinders. In order to create the required clearance profile, the bridge is lifted asymmetrically, which results in a deformation of the shape which is reminiscent of a caterpillar. In addition, the upper deck was designed using hightensile steel so that the considerable deformation could be absorbed by the elasticity of the material, which means that maintenance‐intensive hinges could be omitted. This structural system with its lifting mechanism makes it possible to significantly lower costs as there are no large horizontal forces to be transferred to the ground. The concept was developed for a span of approx. 60 m but can also be adapted to spans of different sizes and is therefore suitable for many situations.     

“Produktionsverfahren im Stahlbau” – online – Lehrveranstaltung via Internet – ein Versuch

“Production processes in steel construction” – online. Teaching via internet – an attempt. At TU Darmstadt the course “Production Processes in Steel Construction” is offered for resident students and via internet since two years. This enables external students to participate without being personally in Darmstadt. This was possible without a great burden on the existing course and the lecturer. In this we see an enhancement of the traditional curriculum. In times of reduced budgets this allows to offer courses which might not be presented with a reduced staff. This might be the basis for an inter‐university network of lectures and courses that can be created and offered for the benefit of the students. This paper describes the specific features that had to be regarded for the development of the project in the World Wide Web. Results of the evaluation and of the examinations are also given.     

Zur Neufassung der DIN 4178 “Glockentürme”

To the introduction of the revised German Code DIN 4178 “Bell towers“. The new German Code DIN 4178 replaces the version validated since 1978 for calculation and design of bell towers under bell ringing forces. It contains further aspects of maintenance and restoration especially of historical buildings and gives indications to measurement of oscillation.     

The Houston Growth Coalition In “Boom” and “Bust”

ABSTRACT: Although growth machine theory emphasizes the coalition's tactics and organization, it neglects adjustment to changing economic conditions. This article explores the changes in the strategy and organization of Houston's growth coalition during the peak growth of the 1970s and the decline of the 1980s. During the boom, the coalition focused not on additional growth but on easing the city's infrastructure problems. The coalition underwent several major changes during decline as it struggled to compete aggressively with other cities for various enterprises and to devise strategies for diversifying the economy. A growth coalition has the opportunity to establish the economic basis for future growth when the city's dominant industries reach maturity and decline.