Seismic Fragility Estimates of LRB Base Isolated Frames Using Performance-Based Design

Table 3

Periods and spectral accelerations of 3-story frame at IO and LS states.

(a) Period = 2.5 s

Structure	Fixed base	Base isolated 1 (2.5 s)	Base isolated 2 (2.5 s)	Base isolated 3; (2.5 s)
Period(s)	1	2.11	1.5	1.37
Sa(IO (g))	0.59	0.30	0.39	0.43
Sa(LS (g))	0.89	0.44	0.59	0.65

(b) Period = 4 s

Structure	Fixed base	Base isolated 1 (4 s)	Base isolated 2 (4 s)	Base isolated 3; (4 s)
Period(s)	1	2.35	1.72	1.54
Sa(IO (g))	0.59	0.25	0.34	0.38
Sa(LS (g))	0.89	0.38	0.52	0.58

(c) Period = 5.5 s

Structure	Fixed base	Base isolated 1 (5.5 s)	Base isolated 2 (5.5 s)	Base isolated 3; (5.5 s)
Period(s)	1	2.52	1.93	1.71
Sa(IO (g))	0.59	0.23	0.31	0.35
Sa(LS (g))	0.89	0.35	0.46	0.52