Performance-Based Multiobjective Optimal Seismic Retrofit Method for a Steel Moment-Resisting Frame Considering the Life-Cycle Cost

Table 3

Optimal retrofit scheme of the three-story SMRF for performance objective 𝑃.

	Before	Scheme  1	Scheme  2	Scheme  3	Scheme  4	Scheme  5	Scheme  6
Number of retrofit connections	0	4	6	7	8	10	12
Retrofit location	—	X9-10; X14; X17	X6; X9-10; X15; X17-18	X7; X9–11; X15-16; X18	X2,; X7-8; X11–14; X16	X4–7. X9-10; X12-13; X15-16	X1; X7–14; X16–18
Initial retrofit cost; (thousand dollars)	0	80	120	140	160	200	240
Lifetime seismic damage cost; (thousand dollars)	475	343	326	300	295	290	284
Maximum interstory drift ratio (%)	5.27	4.95	4.91	4.51	4.50	4.46	4.20
Dissipated energy; (kN·m)	1,157.22	1,422.50	1,496.26	1,493.70	1,613.64	1,566.38	1,561.35