Structural Response to Truncated Earthquake Accelerograms

The discontinuity in the ground motion arising from the truncation of earthquake accelerograms may produce inaccuracies in the response of long period structures with low damping. The termination of the ground motion at a point where the acceleration is low and the use of a small time step during free vibration following the truncation of the record generally improve the results. However, these conditions are insufficient to guarantee acceptable results in all cases. An acceleration pulse is described which, when added to the end of the truncated record, eliminates the abrupt termination of the ground motion. The use of this suffixed pulse removes the uncertainty in the selection of the time of truncation and permits the use of a reasonable time step during free vibration.