Simplify the following text for a Grade 9 native English-speaking person.
Original: Engineers need to know the quantified level of an actual or anticipated seismic performance associated with the direct damage to an individual building subject to a specified ground shaking . This is typically done by placing a model of the structure structure on a shake-table that simulates the earth shaking and observing its behavior .
Simplified: To test seismic performance of a building structure with experiments , it is may be put on a shake-table that behaves like the earth shaking .