Ultimate Seismic Resistance Capacity for Long Span Lattice Structures under Vertical Ground Motions

Table 3

Natural vibration property.

(a) Xa

Mode  no.	Natural period (sec)			Effective mass ratio  (%)		Order
	𝜈=2	𝜈=3	𝜈=4	𝑋 direction	𝑍 direction	𝑋	𝑍
1	0.367	0.300	0.260	6.06	77.74	—	1
2	0.133	0.108	0.094	71.82	2.10	1	—
3	0.095	0.077	0.067	12.68	0.04	2	—
4	0.054	0.044	0.038	0.03	4.46	—	3
5	0.045	0.037	0.032	7.47	7.75	3	2

(b) Xb

Mode; no.	Natural period (sec)			Effective mass ratio  (%)		Order
	𝜈=2	𝜈=3	𝜈=4	𝑋 direction	𝑍 direction	𝑋	𝑍
1	0.356	0.290	0.252	6.86	77.42	3	1
2	0.131	0.107	0.092	70.50	2.70	1	—
3	0.093	0.076	0.066	14.09	0.13	2	—
4	0.054	0.044	0.038	0.11	3.97	—	3
5	0.044	0.036	0.031	6.63	7.98	—	2

(c) Wa

Mode; no.	Natural period (sec)			Effective mass ratio  (%)		Order
	𝜈=2	𝜈=3	𝜈=4	𝑋 direction	𝑍 direction	𝑋	𝑍
1	0.361	0.295	0.256	4.55	88.91	—	1
2	0.128	0.104	0.090	72.98	1.60	1	—
3	0.100	0.082	0.071	15.59	0.27	2	—
4	0.057	0.047	0.041	0.41	5.73	—	2
5	0.045	0.036	0.032	5.05	2.13	3	3

(d) Wb

Mode; no.	Natural period (sec)			Effective mass ratio  (%)		Order
	𝜈=2	𝜈=3	𝜈=4	𝑋 direction	𝑍 direction	𝑋	𝑍
1	0.350	0.286	0.248	5.29	88.68	3	1
2	0.126	0.103	0.089	71.34	2.13	1	3
3	0.099	0.081	0.070	17.76	0.48	2	—
4	0.057	0.047	0.040	0.21	5.24	—	2