Wind Tunnel Measurements for Flutter of a Long-Afterbody Bridge Deck

Abstract

Bridges are an important component of transportation. Flutter is a self-excited, large amplitude vibration, which may lead to collapse of bridges. It must be understood and avoided. This paper takes the Jianghai Channel Bridge, which is a significant part of the Hong Kong-Zhuhai-Macao Bridge, as an example to investigate the flutter of the bridge deck. Firstly, aerodynamic force models for flutter of bridges were introduced. Then, wind tunnel tests of the bridge deck during the construction and the operation stages, under different wind attack angles and wind velocities, were carried out using a high frequency base balance (HFBB) system and laser displacement sensors. From the tests, the static aerodynamic forces and flutter derivatives of the bridge deck were observed. Correspondingly, the critical flutter wind speeds of the bridge deck were determined based on the derivatives, and they are compared with the directly measured flutter speeds. Results show that the observed derivatives are reasonable and applicable. Furthermore, the critical wind speeds in the operation stage is smaller than those in the construction stage. Besides, the flutter instabilities of the bridge in the construction and the operation stages are good. This study helps guarantee the design and the construction of the Jianghai Channel Bridge, and advances the understanding of flutter of long afterbody bridge decks.

Keywords: aerodynamic force; critical flutter wind speed; flutter derivatives; long-afterbody bridge deck.

Figure 1

The Jianghai Channel Bridge: (a) overview; and (b) dimensions of the bridge deck (cm).

Figure 1

The Jianghai Channel Bridge: (a) overview; and (b) dimensions of the bridge deck (cm).

Figure 2

The test models for force measurements: (a) the test model in the operation stage; and (b) the test model in the construction stage.

Figure 3

Definitions of aerodynamic force coefficients: drag, lift and moment force.

Figure 4

The test models for response measurements: (a) the test model in the operation stage; and (b) the test model in the construction stage.

Figure 5

The drag force coefficients of the test models under different wind attack angles: (a) in local coordinate system; and (b) in global coordinate system.

Figure 6

The lift force coefficients of the test models under different wind attack angles: (a) in local coordinate system; and (b) in global coordinate system.

Figure 7

The moment force coefficients of the test models under different wind attack angles.

Figure 8

The flutter derivatives of the test model under different wind attack angles in the operation stage: (a) flutter derivatives $A_1^{*},A_2^{*},A_3^{*},A_4^{*}$; (b) flutter derivatives $H_1^{*},H_2^{*},H_3^{*},H_4^{*}$.

Figure 9

The flutter derivatives of the test model under different wind attack angles in the construction stage: (a) flutter derivatives $A_1^{*},A_2^{*},A_3^{*},A_4^{*}$; (b) flutter derivatives $H_1^{*},H_2^{*},H_3^{*},H_4^{*}$.

Figure 10

Comparisons of the flutter derivatives of the test model in the operation stage ($\alpha {=5}^{\circ }$): (a) flutter derivatives $A_1^{*},A_2^{*},A_3^{*},A_4^{*}$; (b) flutter derivatives $H_1^{*},H_2^{*},H_3^{*},H_4^{*}$.

Figure 11

Comparisons of the flutter derivatives of the test model in the construction stage ($\alpha {=5}^{\circ }$): (a) flutter derivatives $A_1^{*},A_2^{*},A_3^{*},A_4^{*}$; (b) flutter derivatives $H_1^{*},H_2^{*},H_3^{*},H_4^{*}$.