Structural Behaviour of Prestressed Concrete Hollow Beams
This thesis is concerned with the primary objective of studying the structural behaviour of prestressed concrete hollow beams. Ten simply supported rectangular hollow beams and one rectangular solid beam were tested on an effective span of 2.80m subjected to two third point loadings. The variabl...
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| 主要作者: | |
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| 格式: | Thesis |
| 语言: | English English |
| 出版: |
1993
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| 主题: | |
| 在线阅读: | http://psasir.upm.edu.my/id/eprint/9876/1/FK_1993_1_A.pdf |
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| 总结: | This thesis is concerned with the primary objective of
studying the structural behaviour of prestressed concrete
hollow beams. Ten simply supported rectangular hollow beams and
one rectangular solid beam were tested on an effective span of
2.80m subjected to two third point loadings. The variables in
the study were the percentage of self weight reduced and the
amount of prestressing wires. Eight beams were tested unbonded
while the other two beams were fully bonded.Ultimate loads, cracking loads, crack widths and
deflections were recorded at various loadings and crack
propagations were observed. The results obtained were compared
with theoretical values.
It was observed that due to the absence of material in
the hollow portion, compared to a solid beam with similar
outside dimensions, the ultimate moment carrying capacity of
prestressed hollow beam is reduced if neutral axis of the beam
at failure is located below the top flange. However, if the
neutral axis of the beams at failure is located within the top
flange, then the ultimate moment carrying capacity is at least
equivalent to that of a solid beam. It was also observed that
the theory on the ultimate moment carrying capacity presented
in this thesis gives a fairly good prediction. However, the
theory used to predict cracking load as well as deflection was
found not suitable for unbonded beams as it greatly
underestimates the deflection and overestimates the cracking
load. It was also observed that bonding has a great influence
on crack widths and deflections. Bonded beams show more uniform
crack distribution with reduced maximum crack width and
increased ultimate load capacity. From test results, it is
recommended that prestressed hollow beams should be made bonded
in order to achieve at least the predicted cracking load. |
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