Method of Analysis

Application Criteria

Single Mode

1) Soil profile type A, B, C or D.

2) Bridge without significant curvature, defined as having a subtended angle in plan not more than 30˚.

3) Effective period.

4) Effective damping. Method may be used when but less than 0.50 provided that is used.

5) Distance from active fault is more than 10 km.

6) The isolation system does not limit maximum displacement to less than the calculated demand.

7) The isolation system meets the re-centering capability criteria of Section 3.4 (Constantinou, et al., 2007) [7] .

Multimode

1) Soil profile type A, B, C or D.

2) Bridge of any configuration.

3) Effective period.

4) Effective damping. Method may be used when but less than 0.50 provided that is used.

5) Distance from active fault >10 km.

6) The isolation system does not limit maximum displacement to less than the calculated demand.

7) The isolation system meets the re-centering capability criteria of Section 3.4 (Constantinou, et al., 2007) [7] .

Response History

1) Applicable in all cases.

2) Required when distance to active fault is less than 10 km.

3) Required when soil profile type is E or F.

4) Required when or.

5) Required when the isolation system does not meet there-centering capability criteria of Section 3.4 (Constantinou, et al., 2007) [6] , but it meets the criterion that the period calculated using the tangent stiffness of the isolation system at the design displacement is less than 6.0 sec.