| Budget Amount *help |
¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1988: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1987: ¥1,200,000 (Direct Cost: ¥1,200,000)
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| Research Abstract |
Partially prestressed concrete beams, in which flexural cracking is permitted under full working loads, were tested under reversed cyclic loading as experienced at earthquake, and their inelastic behavior and deterioration process were compared with those of reinforced and fully prestressed concrete beams. Some tests were also done to study the effect of repair applied to the damaged beams after loading.
Each beam of bxhx1=10x20x160cm was hinged at two ends with a span length of 140cm, and the reversed cyclic flexure was applied at a shear span - effective depth ratio of approximately 4.0.
The main test variables were i) mechanical degree of prestress ( =Apfpy/(Apfpy+Asfsy), in which Ap,fpy: area and yield strength of prestressing bar, As,fsy: area and yield strength of nontensioned deformed bar) : =0-1.0, ii) design strength of concrete : fc'=400, 800kg/cm2, iii) volume ratio of lateral confinement : s=0-2.8%, and iv) yield strength of lateral confinement : fsyh=3200, 14400kg/cm2.
The test results showed that i) load-deflection hysteresis, ductility and energy dissipation as well as beam deterioration were significantly affected by values of , s and fsyh, ii) attainable maximum tensile stress of lateral confinement increased with increasing s/fc' in case of fsyh=14400kg/cm2 , while lateral steel reached its yield strength irrespective of s/fc'-value in case of fsyh=3200kg/cm2, iii) partially prestressing was very effective for preventing degradation of concrete shear resistance under reversed cyclic loading and iv) appropriate repair method was to be selected taking into account inelastic deformation properties in addition to load carrying capacity.
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