Nonlinear aerostatic stability analysis of new suspension bridges with multiple main spans
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TECHNICAL PAPER
Nonlinear aerostatic stability analysis of new suspension bridges with multiple main spans Wen-Ming Zhang • Yao-Jun Ge • Marc L. Levitan
Received: 22 March 2011 / Accepted: 11 August 2011 / Published online: 28 March 2013 Ó The Brazilian Society of Mechanical Sciences and Engineering 2013
Abstract In order to solve the aerostatic stability problem of long-span bridges more effectively, an upper limit of the external iteration number is set optimally to improve the incremental double iteration method, and an optimum iteration method is brought forward. For new suspension bridges with multiple main spans, the assumption of the spatial uniformity of wind speed is invalid due to their long decks and high towers. Taking into account the spatial nonuniformity of wind speed, a program corresponding to the optimum iteration method is developed and used to analyze the full-range aerostatic stability of the Maanshan Bridge, which is a long-span suspension bridge with double main spans in China, and the effect of wind speed spatial nonuniformity on the aerostatic stability of the bridge is investigated analytically. The result shows that the lowest critical wind speed of aerostatic instability is gained when the distribution of wind speed is non-uniform and the spatial non-uniformity of wind speed has a considerable effect on the aerostatic stability of suspension bridges with multiple main spans. The optimum iteration method is
Technical Editor: Marcelo Savi. W.-M. Zhang (&) School of Civil Engineering, Southeast University, Nanjing 210096, Jiangsu, China e-mail: [email protected] Y.-J. Ge State Key Laboratory for Disaster Reduction in Civil Engineering, Tongji University, Shanghai 200092, China e-mail: [email protected] M. L. Levitan Civil and Environmental Engineering Department, Louisiana State University, Baton Rouge, LA 70803, USA e-mail: [email protected]
compared with the method without improvement in analysis, and the result indicates that the accuracy and efficiency of the optimum iteration method are much better, so the validity and advancement of the optimum iteration method are proved. Keywords Suspension bridge Multiple main spans Aerostatic stability The spatial non-uniformity of wind speed Optimum iteration List of symbols b Deck width CH (a) Coefficient of drag force in wind axes CM (a) Coefficient of pitch moment in wind axes CV (a) Coefficient of lift force in wind axes e Coefficient of wind speed distributing non-symmetrically Em Modulus of elasticity h Vertical projected area of deck I Serial number of current iteration I2 Out-of-plane moments of inertia I3 In-plane moments of inertia Im Mass moment of inertia per unit length Jd Torsional moments of inertia [Ke] Structural elastic stiffness matrix [Kg] Geometrical stiffness matrix L Total length of bridge spans L1 Width of wind distribution M Mass per unit length Na Number of nodes subjected to the displacementdependent wind load PH Drag force of wind load per unit span PM Pitch moment of wind load per unit span PV Lif
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