Final answer:
Seismic joints between buildings must be at least the sum of the calculated displacement values to prevent pounding during an earthquake. The separation accounts for the independent movement caused by seismic activities.
Step-by-step explanation:
When two buildings or portions of buildings are isolated by a seismic joint, they must be separated by at least the sum of the calculated displacement values of each building.
This is essential to avoid pounding during an earthquake. Seismic joints are crucial in buildings especially in earthquake-prone areas because they allow buildings to move independently without causing structural damage during the seismic activities. Earthquake effects on buildings can vary with resonance, standing waves, and constructive and destructive interference impacting differently depending on building height, the span of the roof, and distance from the epicenter.