what is seismic restraint loading?

Answer 1

"Seismic restraint loading" references a local load that has to be added to the design analysis of a structural member or members which is due to loads caused by a seismic event or an earthquake. These loads are usually due to piping system seismic anchor loads, or mechanical equipment seismic anchor loads.

The allowable stresses of structural members when seismic loads are considered are different than the allowable stresses due to dead loads or wind loads, so the members must be evaluated for all load conditions separately, the same as is done for the generalized building design loads.

Answer 2

I believe they are restraints from tension or compression loads due to seismic activity. They try to keep things still by transferring the forces to the restraints so there may not be damage. Think of it as reinforcement.