| Budget Amount *help |
¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 1997: ¥100,000 (Direct Cost: ¥100,000)
Fiscal Year 1996: ¥300,000 (Direct Cost: ¥300,000)
Fiscal Year 1995: ¥1,100,000 (Direct Cost: ¥1,100,000)
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| Research Abstract |
In the present study, following four studies were carried out to examined the size effect on the compressive behavior of concrete prism under uniaxial compression..
1)In the present study, the effects of the specimen size and aggregate size on the inelastic stress-strain behavior of plain and confined concrete were examined. The following statement can be drawn from the study.
a)For air cured plain microconcrete in which the size of aggregate is reduced inproportion to the size of a specimen, the compressive strength increased and the descending portion of stress-strain curve showed more brittle behavior with increasing size of specimen or aggregate.
b)The compressive strength of confined concrete increased with increasing size of specimen when cured in air. On the other hand, the size effect was almost negligible in water cured specimens. The stress-strain curve of confined concrete showed more brittle behavior with increasing size of specimen and degree of such size effectdepended on th
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e spacing of hoops.
2)A series of uniaxial compression tests of confined concretes were carried out to examine the size effects on their compressive behavior. The strength of concrete has been varied from about 300-700 kgf/cm^2 to the ultra-high level of about 1000 kgf/cm^2. Based on the test results, discussion was carried out concerning the effect of specimen size on compressive strength, strain at the peak stress, and stress-strain curves of confined concrete.
3)The effects of specimen size on stress-strain behavior of confined concrete and confined micro-concrete prism are examined. Experimental factors include the section size of specimen (bxb, b=9.7,15,20 and 25cm), the pitch of hoops (proportional pitch and fixed pitch), and the type of hoops (rectangular hoop and rectangular hoop with cross type subtie). The maximum sizes of aggregate are 15mm for normal concrete, and 12,9 and 6mm for microconcrete. Following statements can be drawn from the test results.
a)For the same lateral reinforcement ratio, size effect on the strength of confined concrete with fixed pitch of hoop (S=1.6cm, rectangular hoop) is smaller than thoseof large specimen with proportional pitch of hoop (S=b/6, S=1.6cm for b=9.7cm), but the size effect on the stress-strain behavior is still rather remarkable.
b)The Size effect of stress-strain curves of confined microconcrete are observed, as well as that of normal concrete.
4)The comprete formulas of stress-strain curves of the confined concrete considering specimen sizes are proposed. These formulas considerthe experimental factors including the section size of specimen, the pitch of hoops (proportional pitch), concrete strength and yield strength of hoops. The results from the formulas agree well with the test results. Less
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