| Budget Amount *help |
¥3,400,000 (Direct Cost: ¥3,400,000)
Fiscal Year 2003: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 2002: ¥2,800,000 (Direct Cost: ¥2,800,000)
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| Research Abstract |
The bridge piers of reinforced concrete lack the deformation capacity against an earthquake load. Namely, the compression rupture of reinforced concrete causes the buckling of a compression reinforcing-bar and consequently weakens the bending strength of RC structures sharply. Therefore, in order to improve the deformation capacity of RC structures it is effective to prevent reinforcing-bars from losing strength due to buckling. The concrete columns reinforced with CFTs or with reinforcing bars have been tested under an axially constant load and a transversely cyclic load. The reinforcement types, the diameter-thickness ratio of steel-tubes and the bond method of a tubular steel to concrete have been investigated in relation to the load carrying capacity and deformation capacity of the columns.
The following have been found.
(1)The cyclic load seriously reduces the deformation capacity, i.e. the ductility index, especially that of the concrete column with reinforcing bars.
(2)Both yield load and maximum load are high in the concrete columns under the axial load ratio of N/f_c0=0.1 as compared with N/f_c=0.05, when the other conditions are same. Conversely, the ductility index, δ_U/δ_y, is high in the specimens under the axial load ratio of N/f_c=0.05.
(3)The concrete column with CFT is excellent in load-carrying capacity, deformation capacity, and energy absorption capacity as compared with the concrete column with reinforcing bars.
(4)The diameter-thickness ratio of tubular steel does not influence the load-carrying capacity, and deformation capacity. The surface treatment on a steel-tube has a good effect on those capacities. It is important for us to improve the bond method in order to employ CFT.
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