Seismc Retrofitting Metrhods for Reinforced Concrete Structures

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(1)A program to analyze the region where retrofitting is needed to prevent buckling of longitudinal reinforcement was coded in concrete jacketing method and steel jacketing method.(2)When RC beams with vertical construction joint is strengthened with steel jacketing, diagonal cracking load is increased and shear force carried by the stirrups at the joint is increased. The same retrofitting effect is expected when prestressing force is introduced perpendicularly to the vertical joint.(3)In retrofitting of RC columns with FRP sheet wrapping method, four models to estimate strain of the wrapped sheet were constructed, and it was made possible to estimate ultimate displacement for the failure mode of sheet breakage.(4)In wrapping of poly-acethal fiber sheet, whose breakage strain is extremely high, the followings were made clear : the sheet does not rupture at a normal ultimate state; ultimate deformability is improved; shear capacity is also increased. A model to predict ultimate deformation was constructed for the failure modes without rupture of the sheet.(5)Local buckling behavior of reinforcement within buckling length calculated using elastic buckling theory was spatially averaged and combined with the static lattice model. Analysis on wall-type piers showed that this model can accurately trace the post-peak behavior.(6)In seismic retrofitting of wall-type piers, it was shown that the method in which intermediate confirming reinforcement is anchored with expanding agent is very effective.(7)The experimental results on durability of RC members repaired with electrostatic method showed that permeability coefficient is little lowered and carbonation rate coefficient is even decreased under