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Home > Publications > International Concrete Abstracts Portal
Showing 1-5 of 23 Abstracts search results
Document:
SP120-06
Date:
June 1, 1990
Author(s):
Pham Xuan Thao
Publication:
Symposium Papers
Volume:
120
Abstract:
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.
DOI:
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
SP120-11
Andrew E. N. Osborn and H. Kent Preston
Over 600 bridges composed of adjacent prestressed concrete box beams were built in the early 1950s in Pennsylvania. The box beams were placed side by side and had an asphalt wearing course on top. Span lengths ranged form 30 to 60 ft. Their design was very conservative by today's standards. The concretes used in these bridges have high chloride contents; water leaks down through the joint between box units and the strands often have inadequate cover. Thus, it is not surprising that many of the box beams are deteriorating due to corrosion of their prestressing strands. This project was directed toward developing economical repair schemes for these bridges. The literature survey did not reveal any schemes specifically applicable to adjacent box beams. Two external reinforcement repair schemes were developed and trial installations were made on a bridge near York, Pa. Both schemes included the removal of deteriorated concrete, placement of external reinforcement beneath the beam, and application of shotcrete to the soffit of the beam. In Scheme 1, the external reinforcement consisted of epoxy-coated reinforcing bars. This repair method restored ultimate flexural capacity but did not restore lost prestress. It was the least costly of the two methods. In Scheme 2, post-tensioned, epoxy-coated strand was used. This restored the full ultimate flexural capacity and most of the lost prestress. Difficulties were encountered in installing anchors for the post-tensioned system, but its performance was good. The bridge was tested after repair. The external reinforcements were found to be fully composite with the original beams. The tests also revealed the lateral distribution of wheel loads. In spite of the poor condition of the bridge, the wheel loads were well distributed laterally, leading to a structure that was stronger and stiffer than expected.
10.14359/3437
SP120
Editors: Antoine Naaman and John Breen
SP120 External prestressing--that is, the use of unbonded prestressing tendons outside the concrete section of a structural concrete member--offers substantial economic savings and a dramatic increase in construction speed, making it an extremely attractive option for the construction of new concrete structures, particularly bridges. It is also a logical choice for the rehabilitation and strengthening of many existing structures. ACI's symposium volume, External prestressing in Bridges, provides the last word on this important technological development Based on experience in both the U.S. and Europe, the book addresses: *The state of the art, *Technologies for construction, *Applications in new construction and rehabilitation, *Testing and experimental observations, *Analysis and design considerations. Covering practical construction information as well as analysis and design, this is required reading for anyone involved in building bridges.
10.14359/14153
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