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An analysis is described that models the behavior of planar prestressed concrete cablestayed bridges up to failure taking into account geometric and material nonlinearities. The geometric nonlinearities arise from cable sag, large deformations of the system, and from the shift of the centroid of the deck section caused by the material or by cracking of the concrete. The effect of the axial forces on the stiffness of the members is also considered. Material nonlinearities are encountered when one or more of the structure components, namely the stay cables, prestressing tendons, the reinforcement, or the concrete, exceed their elastic limits. Parametric studies are made on cablestayed bridges with the following cable arrangements: fan, semifan and harptype cable arrangement. To demonstrate the influence of the different types of nonlinearity on the internal forces and reactions three analyses were performed—namely elastic, geometric nonlinear, and geometric and material nonlinear analyses—and the results are compared.

A computer method is presented for the analysis of cablestayed prestressed concrete bridges for timedependent effects of creep and shrinkage of concrete and relaxation of prestressing steel. Nonlinear behavior due to change of geometry and change of stiffness arising from bending by axial forces is included.

Doppelkopfstäbe, mit Köpfen ähnlich wie bei Dübelleisten, können als Hauptbewehrung in Stahlbeton‐Konsolen verwendet werden. Das zeigen Versuche an sechs Doppelkonsolen unter vertikaler und horizontaler Belastung. In diesen Versuchen konnten keine Unterschiede zwischen kaltverformten und glatten Stäben als Gurtbewehrung festgestellt werden. Die Ankerköpfe ermöglichen eine einwandfreie Verankerung der Gurtstäbe auf kürzester Länge. Dadurch können Baustellenschweißungen und Bewehrungskonzentrationen mit Schlaufen oder Haken im Verankerungsbereich vermieden werden. Das hat wirtschaftliche Vorteile und ermöglicht auch höhere Tragfähigkeiten der Konsolen. Mit Stabwerkmodellen kann die Tragfähigkeit zuverlässig ermittelt werden.

The connection graph proof method for the propositional and the first order predicate calculus is described and a special type of an associative processor is introduced which is well-suited for a hardware implementation of this proof method for the propositional calculus. The problems with the extension to first order logic are sketched.

Es wird erstmals die Verstärkung von Flachdecken im Durchstanzbereich der Stützen mit Dübelleisten vorgestellt. Die Grundüberlegungen, die zu einem Versuchsprogramm führten werden erläutert und auch ein Vorschlag zur Bemessung der Dübelleisten und des Durchstanzkegels wird unterbreitet.

Mit Hilfe der Methode der finiten Elemente werden die Schnittkräfte und Spannungen von Querscheiben über den Stützen von Torsionshohlkastenträgern ermittelt. Die Ergebnisse werden zur Verallgemeinerung und Übertragbarkeit in Diagrammen dargestellt.

A computer method is presented for the analysis of cable‐stayed prestressed concrete bridges for time‐dependent effects of creep and shrinkage of concrete and relaxation of prestressing steel. Nonlinear behavior due to change of geometry and change of stiffness arising from bending by axial forces is included.

An analytical method for predicting shrinkage deformations in both cracked and uncracked states is discussed. The validity of this method was verified by conducting an experimental investigation in which deformations due to shrinkage were measured for more than 300 days in the laboratory. The curvatures due to shrinkage were found to be different in cracked and uncracked states. The introduction of compression reinforcement was found to reduce the shrinkage curvatures, whereas increase in tension reinforcement was found to increase shrinkage curvatures. Equations presented here for computing these deformations compare fairly well with experimental data and are recommended to be used in the serviceability analysis of concrete members.

A new method of construction for multispan cable‐stayed bridges is described. This method is one of several options developed for construction of the 13‐km‐long fixed link across the Northumberland Strait connecting Prince Edward Island with New Brunswick in eastern Canada. A 250‐m‐long cable‐stayed span is constructed by launching a 525‐m‐long steel truss underneath the bridge deck. The special feature of the method is the casting of the concrete deck slab of the 250‐m span in one operation in an elevated position (approximately 0.5 m above the final position). While the reinforcing and prestressing steel for the deck is placed, the stay cables are installed and temporarily anchored to the top chords of the steel truss. Because of the elevated deck position, the cables near the pylon are slack, and those further away are stressed much lower than the final level. By lowering the truss supporting the hardened deck by about 1 m, all the stay cables are stressed fully and the deck is suspended at the desired level. The truss is then launched to the next casting position. To support the truss during launching, flotation tanks are submerged from the ends of the truss into the water, exerting a constant uplift force of approximately 3 MN.