Study Of Narrow Truss Suspension Bridge Flutter Stability

Suspension bridge can make full use of materials, and has the characteristics of light weight and provincial materials, therefore in various system of bridge, suspension bridge spanning capacity is the largest, span can achieve 1000 meters. The major disadvantage of suspension bridge is stiffness small, easy to produce larger deflection and vibration, should pay attention to take corresponding measures.With span increasing, structure of rigid smaller and smaller; The use of steel make the whole structure of self-respect mitigated, damping corresponding decrease,and then presents how to improve long-span bridges the wind resistance problems. In the design of large span bridge flutter, must ensure that its critical wind speed than exemplified place chatter of inspection wind speed, in order to avoid catastrophic flutter instability phenomena. In some cases, because other conditions,it is hardly to adjust the bridge's basic forms of large cross-section, and chatter critical wind speed can not reach the required, the vibration control measures will be the only feasible scheme. Usually consider from three aspects, namely, structural measures, pneumatic measures and mechanical measures.The mainly goal of structural measures is to improve the structure of torsional rigidity, increases the structure of torsional vibration frequency, change the structure dynamic characteristics, improve bridge double clamped, dynamic stability, so can improve structure of wind resistance stability.Pneumatic measures is by selecting the aerodynamic stability good cross-section or when such as the cross-section shape of beams, tower structure elements of bridge due to various requirements will be very complex, often cannot fully satisfy wind resistance requirements, to the structure of the cross section shape modified or additional some external devices, thus to improve structure around the flow around state, reduce aerodynamic, reduce the wind-induced vibration amplitude, improve the wind resistance stability.Mechanical control measures mainly is installed on the stiffening girder assistive devices to increase structure damping, or on the structure add a certain weight to improve the quality of structure of aerodynamic stability so as to reduce the wind-induced vibration. Goal is to reduce the bridge structure component of the overall or vibration output.Taking saiwudiegeer bridge and liujiaxia bridge for study, research based on structural measures and pneumatic measures to truss suspension bridge flutter critical wind speed impact. Xinjiang bridge in the original design scheme not through situations, against the wind cable, central fasteners and various bridge structure of wind resistance measures do experiments. In the original design scheme of liujiaxia bridge not through conditions, to fluctuation central stable board, guide plate, impact-proof column detail structure and impact-proof column height to the changes and experimental research, in various combination scheme, choose the most economical, beautiful, effectively plan.