Analysis Of Pedestrian-induced Vibration And Vibration Control Method Of Self-anchored Suspension Footbridge

Abstract:The vibration caused by walking on the footbridge will not lead to destruction of the bridge. The situation that the vibration will be so intense that the pedestrians will have uncomfortable physiological and psychological feelings is more likely to occur. The self-anchored suspension bridge forms a longitudinal self-balancing system with the main cable anchored on the stiffened girder, Hence, it is different in static and dynamic characteristics from the land-anchored suspension bridge. Based on the study of the Ningxiang Weijiang Xingheliizhou footbridge, this dissertation attempts to analyze the parameters of structural dynamic characteristics, pedestrian-induced vibration, comfort assessment and the method of vibration control. The main contents are as follows:(1) Finite element analysis software Midas Civil2012is used to establish finite element model of a self-anchored suspension footbridge, and the parameters which influences structural dynamic characteristic is analyzed, including the ratio of sag to span, the main girder vertical bending stiffness, lateral bending stiffness of the main girder and the axial stiffness of the main cable.(2) The gradient value of objective function is used to the design variables, the sensitive coefficient of structural parameters is introduced to analyze the sensitivity of dynamic characteristics of the self-anchored suspension footbridge. The results show that, vertical stiffness of the whole structure is more sensitive to the change of the ratio of sag to span, and lateral stiffness of the whole structure has the maximum sensitivity coefficient to the lateral bending stiffness of the main beam.(3) The dynamic response of the finite model is calculated under the load of national standards of comfort. Then, analyze the walking comfort by evaluating the dynamic response.(4) The limit of lateral peak accelerate is proposed by consolidating German norms and European norms, namely it meets the requirement of comfort and lateral stability of structure when the peak accelerate of lateral vibration below the limit. The critical wide span ratio is set to1/28after the comfort analysis of the self-anchored suspension footbridge with double main rib under the change of parameter.(5) The comfort of self-anchored suspension footbridge with wind resistant cable and Tuned Mass Damper is analyzed, and the influence of comfort by setting wind resistant cable and Tuned Mass Damper is evaluated.