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Home > Publications > International Concrete Abstracts Portal
The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.
Showing 1-5 of 23 Abstracts search results
Document:
SP120-16
Date:
June 1, 1990
Author(s):
Antoine E. Naaman
Publication:
Symposium Papers
Volume:
120
Abstract:
A simple methodology for the solution of beams prestressed or partially prestressed with external or unbonded tendons in the linear elastic cracked and uncracked range of behavior is described. It leads to equations allowing the computation of stresses in the concrete section, the tensile reinforcing steel, the compression reinforcing steel, and the prestressing steel. In particular, it is shown that the stress in unbonded tendons is a function of the applied loading, the steel profile, and the ratio of the crack width (or crack band width) to the span. These factors can all be accounted for through the use of a strain reduction coefficient ê for the uncracked range of behavior and a similar coefficient êc for the cracked range of behavior. It is shown that, when the strain reduction coefficients ê and êc are taken equal to unity, the solutions developed here revert to the solutions developed earlier for partially prestressed beams with bonded tendons.
DOI:
10.14359/2765
SP120-06
Pham Xuan Thao
The use of tendons placed outside the concrete for the longitudinal prestressing of bridge decks is particularly well suited to the triangulated trusses that have now proven effective. Experience acquired first on the Tehran Stadium roofing (internal tendons) and then on the externally prestressed Bubiyan Bridge in Kuwait has highlighted the numerous advantages to be derived from the latter system. The technology has, therefore, been used again, with external tendons, in the construction of the Sylans and Glacieres viaducts located along the Macon-Geneva-Mont Blanc highway in France, on behalf of the Societe des Autoroutes Paris Rhin-Rhone. The two viaducts have a total length of 1500 m. Each consists of two parallel decks, 10.75 m wide. Typical spans are 60 m long. The deck is precast in forms as a series of 4.66 m long elements and erected by sequential cantilevering using a launching girder.
10.14359/3424
SP120-07
Alan Matejowsky
The state of Texas is involved in two projects that use precast concrete segmental erection methods with external post-tensioning tendons. Design and construction features of these projects, along with construction problems related to external tendons, are described. The future of segmental construction and use of external tendons in Texas are discussed.
10.14359/3428
SP120-08
G. Causse
The bridge that links Re Island and the mainland was completed in April, 1988. It crosses a 3000 m wide sea channel that separates the island from the town of La Rochelle, on the west coast of France. The deck of the bridge is a concrete box girder built by the balanced cantilever method with precast segments. The prestressing tendons are partly inside the concrete and partly external.
10.14359/3433
SP120-04
C. J. Burgoyne
Paper describes the properties of parallel-lay ropes with a polyaramid (Kelvar 49) core, with particular reference to the long-term properties that are important to the designers of prestressing systems. The anchorage and prestressing systems are described, and results are given for stress-strain, relaxation, creep, stress-rupture, and fatigue behavior. Durability and thermal response are also considered, and it is inferred that the lack of corrosion, in addition to the high strength and high stiffness, makes these materials ideal for use as prestressing tendons where the concrete cannot be used to provide corrosion protection to steel. Descriptions are given of tests on beams prestressed with external tendons, showing that a ductile response can be achieved in a beam made from two brittle materials. It is concluded that these materials will extend the range of structures that can be built with prestressed concrete, and will at last allow the realization of the full potential of externally prestressed concrete.
10.14359/3234
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