Bipedal Pedestrians Induced Structural Vibration Based On Self-driven Mechanism

It is a key-point with structural serviceability and security that locomotive crowd can cause unpredictable vibration of slender structures. The walking pedestrian would inevitably induce structural vibration. When the excited rate from motion pedestrian is close to natural frequency of structure, the stepping frequency with pedestrian tends to consistent with structural natural frequency for keeping physical balance. Under this situation, the dynamic resonant interaction between pedestrians and structure is occurred. Dynamic measurements have shown that human can alter natural frequency and damping of structures. In order to explore this mechnism, a bipedal model with lump mass, spring-damping legs has been used to study the effect of motion pedestrians on structural properties. However, the energy feedback mechanism for keeping gait movement stability of bipedal model inheres in a non-ignorable defect. The feedback mechanism is too sensitive for a slight change of human energy to make it difficult to deal with more complex walking behaviors or dynamic crowd problems. Facing the above difficulties,this thesis makes a further research from theory and numerical simulation. The studying contents can be summarized as follows:(1) Based on a self-driven mechanism with walking kinetic energy, a bipedal pedestrian-structure interaction theory about vertical vibration is proposed and it can be applied to the more complicated walking behavior or multi-pedestrian environment. The pedestrian-structure system considers the contribution from human mass,leg spring stiffness and damping. Calculation results including structural dynamic responses and properties are compared with existing research results. In addition, the effect of pedestrian parameters including human mass, leg stiffness and damping ratio on the structural responses and properties are.researched.(2) Based on social force mechanism, structural vertical dynamic responses and properties induced by pedestrians are studied under a motion crowd environment. In addition, the effect of crowd density on the structural dynamic responses and properties are explored. And based on the hypothesis with a uniform distribution and synchronous motion behavior of walking crowd on the top of structure, the analytical solution between crowd size and structural dynamic properties is deduced. The influence of crowd density on structural vertical dynamic responses and properties are also been studied.(3) Based on the self-driven mechanism, a structural lateral vibration theory under bipedal pedestrian excitation is proposed. A pedestrian-structure system equation is established by the biomechanical bipedal locomotive model. The effect of pedestrian on structural lateral dynamic responses and properties is studied. In addition, the influence of pedestrian parameters including body mass, legs stiffness and damping on structural responses and properties are analyzed.(4) Based on asocial force mechanism, the effect of motion crowd on structural lateral dynamic response and characteristics is studied. The influence of crowd size is also been studied. And based on the hypothesis with a uniform distribution and synchronous motion behavior of crowd on the top of structure, a analytical solution between crowd size and structural lateral dynamic properties is deduced. The influence of crowd size on structural lateral dynamic responses and properties are also been studied.(5) Based on the self- driven mechanism, a three-dimensional pedestrian-structure dynamic interaction theory is proposed. The structural dynamic responses and properties under walking pedestrian excitation are studied. In addition, the three-dimensional vibrations of bipedal pedestrian under structural impact are studied.