Study Of Vibration Response And Control For Large-Span Floors Based On Human-Structure Interaction

With the continuous development of structure and the wide use of high strength lightweight materials, the large-span, lightweight, flexible, low damping structure has been the trend of development gradually. Problem of vibration induced by human activities becomes increasingly serious and widespread concerned, and study on dynamic response and vibration control of large-span structure is less based on the theory of human-structure interaction. The crowd which stay or walk on structure not only enlarge the mass of the structure and apply dynamic load,but also interact with the structure as system with mass, stiffness and damper. It is of great significance to study the human-structure interaction in the field comprehending the dynamic property, response and the vibration control influenced by human.Based on domestic and foreign research achievements of the human-structure interaction theory, four aspects of body vibration model, influence on dynamic property, influence on response and vibration control using MTMD and two projects of no baggage promenade of nanjing lukou airport and observation platform of Beijing Olympic watchtowers is studied in this paper. The main research contents and conclusions in this paper are as follows:1. A low frequency experiment slab is designed and installed. The slab is size of 5 m × 8 m,in the form of steel and concrete composite floor slab.It is designed to have low-frequency,as to simulate large-span structure, then human- structure interaction experiment is carried out. The test slab satisfies the requirement of load capacity and normal use through the theoretical calculation and finite element calculation on the software of Sap2000. Series of methods are took to increase the quality of concrete pavement and reduce the its rigidity, quality block and TMD is installed to make the slab have low frequency; Finite element simulation and modal test was carried out, which fits well and the base modal frequency is 4.6HZ,damping ratio 0.7%.2. Identification test of parameter of the human body dynamic model is carried out with 40 individuals. Human stay on the structure is simulated as one degree of freedom dynamic model, human-structure two degrees of freedom dynamic model is established and the free vibration equation is solved. Natural frequency and damping ratio of the test slab are obtained by modal test before and after a individual stay on it, then generate them into the equation to get the body vibration fundamental frequency and damping ratio,4.6HZ and 36.81% for human stand,4.91 HZ and 44.06% for human sit. Error analysis is carried out in allusion to part of variables, which confirmed the accuracy of the parameters.3. Analysis of the influence of human-structure interaction on structure dynamic characteristics is carried out. Human-structure two degrees of freedom system, human-beam modal coupling system, human-slab infinite degree of freedom system theory model and the human-structure finite element model is respectively established and dynamic characteristics of the structure is analyzed in the field of human-structure mass ratio, structural frequency, influence of parameters is analyzed based on the parameters this paper obtained. Modal mass participation is presented creatively in this paper to study the vibration characteristics of each modal and how structure and people participate in the vibration intuitively. Modal test of different numbers of people stay on the slab which is of low frequency and high frequency is carried out to verify theoretical results. The requency of low frequency-slab decrease, high frequency-slab increase and damping increase with number of human increase.4. Analysis of the vibration response and MTMD vibration control under the action of crowd based on the human-structure interaction is carried out. Human-structure-TMD three degrees of freedom system and human-beam-TMD system are stablished, response under the pedestrian loads is calculated, influence on the structural vibration response and the of TMD control effect of the human is anlysised. Fitting formula of resonance frequency under human activities and the parameters of the optimization of TMD are obtained. In most cases,human reduce the dynamic response and improve the effect and robustness of TMD.Based on the test slab, vibration response and vibration energy of structure before and after human stay is anlysised, which confirmed energy dissipation effect of human. Impact test of pedestrian is carried out to compare the foot force difference on the rigid ground and test slab, force on flexible structure is bigger. The finite element calculation is carried out to check the test cases.5. The dynamic characteristics test and vibration response test and calculation under human activity load before and after the damping device installed is carried out in actual long-span bridge and floor. Comparion of the results with or without consideration of the human-structure interaction is carried out, which shows that it is more appropriate to consider thehuman-structure interaction and the human-structure result is closer to the calculationresults and the test result.