Seismic evaluation and retrofit of welded moment connection of early high-rise buildings subjected to long-period ground motions

Two models representing early highrise buildings, height of 75 m and 150 m, are prepared for dynamic response analysis as shown in Fig. 1. These models are designed according to the seismic regulations in the 1970s, namely, for Level-1 ground motion (PGA 0.2∼0.25 m/s2), the frame should remain elastic and story drift should be less than 1/200, and for Level-2 (PGA 0.3∼0.4 m/s2), story drift and its ductility factor should be less than 1/100 and 2.0, respectively. The PGAs of input ground motion for the design was smaller than the value in current regulation.