Infilled Walls for Earthquake Strengthening

Five one-half scale reinforced concrete frames were constructed and tested under static reversed cycle loads to determine experimentally the effectiveness of infilled walls in strengthening and stiffening existing framed structures against earthquake loads. An unstrengthened portal frame and a frame with a monolithically cast infilled wall provided references for the three strengthening techniques. The first wall was cast-in-place within the existing frame; the second was a single precast panel that was bolted to top and bottom beams; and the third was made of six individual precast panels that were connected to the top and bottom beam and to each other. Tests showed that the cast-in-place wall strengthened the frame so that its capacity was similar to the monolithically cast specimen but that the cast-in-place system dissipated only one-half the energy. The multiple precast panel wall demonstrated greater ductility than the other infilled structures; although its maximum load capacity was about one-half that of the monolithically cast specimen.