Working a problem where there are two one-story buildings of different heights next to each other. Earthquake imparts a base motion z(t) that is a cosine function. I'm given a shape function for a column of height L when deriving the EOM for each building. I'm supposed to estimate the distance I need to keep the two buildings apart, so they avoid hitting (pounding) each other. Any tips or similar problems I can review to get me started?