Control Effect and Mechanism of Cantilever Horizontal Splitting Plates on Flutter Performance of a Box Deck

Abstract:

Various aerodynamic control measures,such as central stabilizing plate,central slotting and cantilever horizontal splitting plate (CHSP),are investigated via a serious wind tunnel tests of sectional model in order to improve the flutter stability of a steel box deck cablestayed bridge with a main span of 1 400 m.The results show that CHSP is the most effective among the measures investigated,and can significantly improve the bridge flutter performance,especially in the case of +3° wind attack angle.Using a 2dimensional and three degree of freedom (3DOF) coupled flutter analysis method,the flutterdriving mechanism and flutter pattern of both the original box deck and that with CHSP measures are then analyzed and compared with each other.It is found that for the decks with aerodynamic shapes between streamline body and bluff body,the control effect of CHSP on flutter depends on both the width and the wind attack angle.A reasonable width of CHSP should be determined with an integrated consideration of its flutter control effect at various wind attack angles.Moreover,the analysis result of flutter control mechanism of CHSP indicates that the measures of CHSP improves the flutter performance of box deck by changing the variation patterns of two aerodynamic damping items generated by the twistinvolved deck motions,in conjunction with changing the coupling effect among degrees of freedoms.

Key words:superlong span bridge; flutter control; cantilever horizontal splitting plate; control mechanism; flutter pattern