| Interaction between the structures | Ground motions | Impact forces for elastic structures in kN | Impact forces for inelastic structures in kN |
| Left-middle | Northridge | 38.36 (174) | 4.08 (10) |
| Cope Mendocino | 12.57 (63) | 7.42 (16) | |
| Loma Prieta | 24 (64) | 1.46 (13) | |
| Superstition Hills | 24 (64) | 6.65 (11) | |
| Middle-right | Northridge | 16.16 (55) | 0.04 (2) |
| Cope Mendocino | 4.96 (22) | 0 | |
| Loma Prieta | 8.21 (12) | 0 | |
| Superstition Hills | 8.21 (11) | 0 |