The seismic design forces have greatly increased with the advent of the current code in my area. In addition, there is a lot more information that I need to have to determine what force is appropriate. Why is this?
During the 1989 and 1994 earthquakes that occurred in California, considerable information was gathered that had not previously been available. When experts reviewed this data, it was found that factors such as soil type, proximity to a known fault, and equipment elevation in a building had a significant impact in the actual forces. The force equations were modified to take this into account.