FORMATION OF SEISMIC JOINTS IN BUILDINGS AND DISPLACEMENT ON SOFT SOIL SITES AT STRONG EARTHQUAKES

Abstract

Peak ground acceleration, velocity, and displacement values calculated from strong motion records obtained from our seismic instruments on soft soil sites are evaluated.  Data from microseismic activities, as well as the motions from the 1988 Spitak earthquake were evaluated and the displacements for each site class defined by the Building Seismic Safety Council (BSSC) were computed.  It is observed that while the design accelerations increase for Site Class B rock to Site Class E soft soils at some rate, the displacements increase by a much larger rate.  While current building design according to seismic codes are based on acceleration values for different site class, it is recommended that for long-period structures, design parameters include peak ground displacements. The implications using ground displacements on foundation design and foundation ties are also discussed.