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

Table 4

Values of annual exceedance probability for 3-story frame.

(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
Prob(IO)	100%	35%	40%	45%
Prob(LS)	68%	35%	32%	26%

(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	2.11	1.5	1.37
Prob(IO)	100%	24%	26%	28%
Prob(LS)	68%	23%	22%	17%

(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	2.11	1.5	1.37
Prob(IO)	100%	10%	18%	24%
Prob(LS)	68%	22%	21%	13%