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Home > Publications > International Concrete Abstracts Portal
Showing 1-5 of 15 Abstracts search results
Document:
SP272-07
Date:
October 1, 2010
Author(s):
D. Joo Kim, S. El-Tawil, and A.E. Naaman
Publication:
Symposium Papers
Volume:
272
Abstract:
The effect of matrix strength (or composition) on the pullout behavior of high strength deformed steel fibers is investigated. High-strength steel hooked (H-) and twisted (T-) fiber are used in three different matrices with three different compositions generating a low (4.1 ksi [28 MPa]), medium (8.1 ksi [56 MPa]) and high (12.2 ksi [84 MPa]) compressive strength. Although both fibers produce a higher pullout load with a higher compressive strength matrix, T- fiber shows a more sensitive behavior to the matrix strength or composition than H- fiber. Moreover, T- fiber leads to significant enhancements in both pullout load and pullout energy in higher strength matrix than in lower strength matrix. It is observed that T- fiber is generally more efficient in a higher-strength matrix than in a lower-strength matrix.
DOI:
10.14359/51664089
SP272-03
K.H. Tan and D. Kong
This paper presents a simple direct method to determine the external tendon configuration required for a desired increase in load-carrying capacity of continuous beams. The tendon layout is selected based on the concept of equivalent loads, but need not be concordant. By considering the collapse mechanism of the beam, the increase in load-carrying capacity can be related directly to the tendon force. It is shown that the increase in load-carrying capacity is partly due to an increase in the force in the compression zone arising from the horizontal component of the prestressing force, and partly due to the upward components of the prestressing force. The method was verified with a test program on six two-span continuous beams, in which the tendon profile and loading pattern were varied. Comparison of the test results and those available in the literature showed that the proposed method gives a reasonably conservative design. A simplified method based on the direct balancing of increased loads is also proposed.
10.14359/51664085
SP272-04
C.J. Burgoyne and H.Y. Leung
This paper describes an experimental study of a new form of prestressed concrete beam. Aramid Fiber Reinforced Polymers (AFRPs) are used to provide compression confinement in the form of interlocking circular spirals, while external tendons are made from parallel-lay aramid ropes. The response shows that the confinement of the compression flange significantly increases the ductility of the beam, allowing much better utilization of the fiber strength. The failure of the beam is characterized by rupture of spiral confinement reinforcement.
10.14359/51664086
SP272-05
J. Giancaspro, P. Balaguru, and C.G. Papakonstantinou
There are a limited number of experimental results available on the retrofit of prestressed concrete structural elements. In addition, there is a lack of analytical models dealing with the flexural performance of such elements. This study addresses the latter problem by presenting a methodology for analysis and design of prestressed concrete flexural elements strengthened with externally bonded, fiber reinforced composites. The method provides systematic suggestions on the analysis and design of strengthened prestressed concrete beams with both bonded and unbonded tendons. The method can be used to determine the flexural capacity and to compute stresses and strains in concrete, tendons, and externally bonded fiber reinforcement. Compared to existing experimental data on carbon strengthened beams, the model provides very good prediction of the flexural performance of strengthened prestressed beams. The equations are also applicable to other fiber types including glass, steel, and aramid.
10.14359/51664087
SP272-02
H. Mutsuyoshi and H. Minh
Prestressed (PS)concrete technology is being used all over the world in the construction of a wide range of structures, particularly bridges. However, many PS bridges have been deteriorating even before the end of their design service-life due to corrosion and other environmental effects. In view of this, a number of innovative technologies have been developed in Japan to increase not only the structural performance of PS bridges, but also their long-term durability. These include the development of novel structural systems and the advancement in construction materials. This paper presents an overview of such innovative technologies on PS bridges including a brief discussion of their development and applications in actual construction projects. Some noteworthy structures, which represent the state-of-the-art technologies in the construction of PS bridges in Japan, are also presented.
10.14359/51664084
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