Abstract
Evaluation of earthquake-resisting capacity of existing reinforced concrete buildings revealed that a considerable number of existing building needed strengthening of certain extent, and the review of structural design for such strengthening showed that the most favored strengthening method was to increase stiffness and strength by adding cast-in-place shear wall panels to frames. Currently used design recommendation for postcast shear wall was develeloped on the basis of the available test data utilizing single story and single span wall specimens. But confining effects of the adjacent frame of such specimens are smaller than those of the actual buildings and the ultimate strength of the specimens may be dictated by the flexural yielding. For the reevaluation of current design recommendations, nine wal specimens of about one third scale were tested. Wall panels were cast monolithically with frames in three specimens, and wall panels added to existing open frames in the other six specimes. The main variables were the strength and stiffness of columns on both sides of walls and construction method. Major findings from tests include the following : (1) Increased confining effect around the wall increased the shear strength of both monolithic and postcast walls. (2) Shear strength of postcast walls was lower than that corresponding to monolithic walls, but deformation capacity of postcast walls was superior. (3) The improvement of construction method could reduce the slippage along the construction joints of postcast wall specimens, resulting in the deformation characteristics similar to those of monolithic wall specimens.
