| The widespread use of lightweight and high-strength materials makes the structure lighter,softer and less frequent,and people pay more and more attention to the comfort and safety caused by human-induced structural vibration.the analysis of human-structure coupling system is not only the basis for the study of human-induced structural vibration,but also the focus of scholars at home and abroad.The dynamic characteristics of the system composed of human and structure are related to the dynamic parameters of human and structure.Biomechanical studies show that different human posture has different damping and stiffness,which will inevitably affect the vertical dynamic characteristics of human-structure coupling system.Therefore,it is necessary to study the influence of different human posture on the dynamic characteristics of human-structure coupling system.In order to solve the above problems,this paper studies the influence of different human posture on the characteristics of human-structure dynamic system with the combination of experiment,theoretical analysis and numerical simulation.combined with the back analysis of human-structure two-degree-of-freedom dynamic model,the dynamic characteristics of human body under different posture are calculated.The main contents and results are as follows:A steel footbridge model is designed and made as the test platform,and the basic dynamic characteristics of the footbridge model are tested by free attenuation method and environmental vibration method.Furthermore,the basic dynamic characteristics of the structure are analyzed with the ANSYS finite element method,and the finite element model is modified based on the measured results.An experimental study on the influence of different posture of standing human body on the dynamic characteristics of footbridge model was carried out for six testers,the existence of human-bridge interaction was proved,and the effects of different posture of human body on structural frequency and damping were analyzed.The results show that the influence of different posture on the first-order vertical vibration frequency of the structure is the most significant in the middle of the span.Standing and sitting posture will significantly reduce the first-order vertical vibration frequency of the structure,while squatting position will increase the first-order vertical vibration frequency of the structure.The resident human body under three kinds of postureincreases the first-order modal damping ratio of the structure,but the standing posture has the greatest influence on the structural damping,and the sitting posture has the greatest influence on the structural damping.There are diametrically opposite results among different subjects,which may be related to different body parameters among the subjects.On the basis of the measured results,the dynamic equation of free vibration is further solved based on the theoretical model of two-degree-of-freedom coupling system of human structure.The natural frequency and damping ratio of components before and after single stay are obtained by modal test,and the fundamental frequency and damping ratio of human body vibration are calculated.The results show that the additional damping of human body under three kinds of posture is positive damping effect,in which the dispersion of additional damping of standing posture is larger than that of sitting and squatting posture.It is found that the human body residence in the standing and sitting posture will reduce the structural fundamental frequency and the negative stiffness contribution of the human body,while the squatting human body residence will increase the structural frequency.The additional stiffness of squatting position is positive,which enhances the overall stiffness of the structure. |
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