Earthquake-Induced In-Building Motion Criteria

Two 10-member ensembles of digitally generated waveforms that simulate real earthquake accelerograms are used to excite mathematical models of two-story to 20-story buildings of widths ranging from 100 ft to 300 ft and founded on soils characterized by shear-wave velocities of up to 4,000 fps. Realistic equivalent structural damping is determined and used in this analysis based on the actual building response data recorded during the San Fernando earthquake of 1971. Calculated upper bound motion responses on floors throughout the buildings are presented in terms of peak values of accelaration, velocity, and displacement. Envelopes of damped response spectra derived from the in-building accelerograms are also presented, and the use of these spectra is demonstrated with an illustrative example.