Once the displacement time-history record is obtained from an acceleration record, ground motion may be applied to specific support restraints through manual multi-support excitation, described as follows:

1. At joints of interest, define a load pattern. This load pattern should apply unit values of joint displacement in the direction of applied acceleration.
2. Restrain these joints only in the direction of loading.
3. Create a time-history function which will describe variation of the joint displacements in time.
4. Define a time-history load case which specifies both the displacement and the time function, as shown in Figure 1:

Figure 1: Definition of load case for multi-support excitation

See Also

• Displacement-record conversion – Displacement time-history record

• Support settlement – Joint displacement and restraint