Leonhardt, Andrä and Partners The consulting firm of Leonhardt, Andrä and Partners GmbH was established in 1938 by Professor Dr.-Ing. F. Leonhardt in his own name. In 1946, Dr.-Ing W. Andrä joined this office and became a full partner in 1953. Dipl.-Ing. W. Zellner joined the partnership in 1970 and Dipl.-Ing. W. Kunzl, Dr.-Ing. J. Falkner and Dipl.-Ing. B. Göhler in 1979 after having been with the firm for more than 15 years. The firm is presently comprised of 42 engineers (7 Dr.-Ing., 35 Dipl.-Ing.) and 43 technical staff members as graduate engineers, draftsmen, etc. The total staff is approximately 100 permanent employees. Leonhardt, Andrä and Partners, an independent consulting firm registered with the World Bank in the field of bridges and complex structures, has operated in many parts of the world. Even in those cases where it joined turnkey proposals on behalf of contractors for competitive bidding, its responsibility and interest has been limited to the design and construction supervision phases of the projects. The firm has never had any business or commercial interests as contractors in the actual construction of projects. The firm has designed more than two thousand structures, among them outstanding examples of long-span prestressed concrete and steel brides, including suspension and cable-stayed bridges with steel or concrete decks, television towers up to 1,086 feet in height, and many other types of structures. During more than four decades of professional practice, Leonhardt, Andrä and Partners has been in the forefront of the design profession through creativity and innovation, having conceived many new design theories and techniques, new structural elements and details, and construction methods. Illustrative of these accomplishments are:
- The main creative contribution to the development of the orthotropic steel deck came from Prof. Leonhardt in the 1930’s.
- A simplified analysis of girder grids was published in 1936.
- The prestressing system “Leoba” has been developed using single tendons with prestressing forces up to 155 tons.
- The prestressing system “Baur-Leonhardt” has been developed, comprised of concentrated cables with prestressing forces up to 3000 tons.
- Scientific work on prestressed concrete led to the book “Prestressed Concrete, Design and Construction” by Prof. Leonhardt, an internationally recognized standard text on the subject.
- A very successful development was the so-called “Taktschiebeverfahren”, an incremental launching method for the construction of long prestressed concrete bridges. Due to the successful application of the incremental launching method to approximately 100 bridges, including a swing bridge, this method is now under development for underwater tunnels. This investigation is supported by the German Ministry of Transportation.
- The main contributions to the development of neoprene pot bearings and teflon sliding bearings came from Prof. Leonhardt and Dr. Andrä.
- The development of aerodynamically safe suspension bridges with wind-shaped flat decks and inclined hangers of modern cable-stayed bridges.
- A new type of parallel-wire cable with a corrosion protection made of PE pipe, grouted with cement mortar, was developed especially for cable-stayed bridges in the 1960’s. Its anchorage uses a cold casting material of epoxy and steel balls to avoid the loss of fatigue strength which is caused by hot metal fillings.
- Design of the extremely complex tent roof structure (74,800 square meters in plan) for the Olympic Games in Munich, 1972. Developments derived from this tent roof structure are economical large cable-net cooling towers, solar chimneys, and large cable-stayed wind energy converters.
- Over the last decade the firm has also become active in the field of bridge maintenance, reconstruction and repair, including the reroping of two large cable-stayed bridges originally designed by others.
All of this experience and development has been shared with the civil engineering community via several books and more than 300 scientific papers. Consequently, several partners and key members of the firm have been named members of DIN-code committees and international working groups. |
