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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:
SP120-13
Date:
June 1, 1990
Author(s):
Christian Menn and Paul Gauvreau
Publication:
Symposium Papers
Volume:
120
Abstract:
A research project is currently underway at the Swiss Federal Institute of Technology, Zurich, to establish the feasibility of an alternative structural system for short-span highway bridges. Concerns over the long-term durability of structural systems currently used in the 25 to 40 m span range provided the primary motivation for the study. The proposed system consists of a solid concrete slab that is externally prestressed. The external tendons are deviated at the third points of each span using struts. A 1:3-scale model bridge has been constructed and is currently being tested to verify the behavior of the bridge under permanent, service, and ultimate static loads, as well as dynamic and fatigue loads. The favorable results obtained thus far have confirmed the feasibility of the proposed structural system, and will serve as a basis for extending the concept to spans greater than 40 m in length.
DOI:
10.14359/3266
SP120-15
Robert J. F. Macgregor, Michael E. Kreger, and John E. Breen
An experimental investigation was conducted to examine the service and ultimate load behavior of segmentally precast box girder bridges with external post-tensioning tendons. A primary interest of this study was to examine the effect of joint type (dry versus epoxied joints) on the stiffness, strength, and ductility of the structure. A three-span reduced scale segmental box girder model was constructed, then tested in three stages. Flexural behavior was examined first, then shear tests were conducted on the damaged structure. Test results and observations are presented.
10.14359/3277
SP120-17
J. Muller and Y. Gauthier
The concept of precast segmental construction with external tendons has been developed extensively since 1978, starting with the construction of the Long Key Bridge (Florida). Since this first experience, many other structures (more than 5,500,000 ftý of deck) have been designed and successfully built using the same method. The performance of all bridges now in operation has been excellent. However, some questions were raised in the minds of engineers, unfamiliar with the method, regarding the behavior of structures prestressed with external tendons beyond the range of design loads (serviceability limit state). Because continuous reinforcement is not usually provided across the match cast joints between segments, concern was expressed that adequate ultimate behavior and sufficient strength could not be obtained. To provide a satisfactory answer to these legitimate questions, a special computer program (DEFLECT) has been developed to analyze accurately the response of the structures prestressed by external tendons. Moreover, several tests are available to confirm the behavior of such structures while verifying the validity of the DEFLECT computer program. This design tool has been used to predict the structural behavior of simply supported and continuous structures beyond joint opening, up to ultimate capacity of the girders with and without thermal loads. Several different prestressing methods have been analyzed with different bonding conditions at the point of deviation of the external tendons. It was found systematically that structures prestressed with either internal or external tendons behave essentially the same way at all loading stages up to ultimate.
10.14359/3281
SP120-18
J. EiblI
Experience gained in the design of several externally prestressed bridges is reported. New cables especially developed by contractors are discussed. Also, the main experimental results gained at the author's institute for reinforced concrete are given.
10.14359/3286
SP120-16
Antoine E. Naaman
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.
10.14359/2765
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