Seismic Response Mitigation of a Long-Span Tower Bridge with Two Types of Constraint System

Table 2

Vibration frequencies and the corresponding modal shapes of the bridge.

Order	Frequency (Hz)		Mode description	Modal shape
	VD	ECD
1	0.1106	0.2110	Longitudinal drift of main girder
2	0.2269	0.2269	The 1^st-order symmetric transverse bending of the main girder
3	0.2754	0.2757	The 1^st-order symmetric longitudinal bending of the main girder
4	0.2925	0.2925	The reverse side bending of the two main towers
5	0.2978	0.2978	The same side bending of the two main towers
6	0.3625	0.3744	The 1^st-order antisymmetric vertical bending of the main girder
7	0.4555	0.4555	The longitudinal vibration of pier #7
8	0.4745	0.4748	The longitudinal vibration of pier #0
9	0.5141	0.5161	The 2^nd-order symmetric longitudinal bending of the main girder
10	0.5658	0.5658	The 1^st-order symmetric transverse bending of the main girder + transverse bending of piers #0, #1, and #2