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

Table 5

The amounts of annual exceedance probability; 9-story structure.

(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)	2	3	2.65	2.52
Prob(IO)	100%	65%	92%	98%
Prob(LS)	78%	40%	32%	22%

(b) Period = 4 s

Structure	Fixed base	Base isolated 1 (4 s)	Base isolated 2 (4 s)	Base isolated 3; (4 s)
Period(s)	2	3.17	2.72	2.62
Prob(IO)	100%	55%	69%	83%
Prob(LS)	78%	38%	23%	14%

(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)	2	3.3	2.87	2.72
Prob(IO)	100%	33%	53%	79%
Prob(LS)	78%	36%	19%	12%