Vertical Vibration Analysis And Control For The Structure Under Working Loads

As the use of light-weight and high strength building materials, the advancementsof structural analysis and design techniques, the needs of the building function andthe development of construction technology, many long-span structures are widelyused in huge public buildings. Large-span structures including the large-span floorand large-span footbridge are characterized by large span, light weight, low damping.Despite large span structures are able to meet the requirement of bearing capacity anddeformation through structural design, with a large number of pedestrians walking onthem they are likely to generate significant dynamic response, which to some extentmakes occupants or users feel uncomfortable or even panic and reduces theapplicability of the structure. Therefore, vibration control based on the human bodycomfort for large span structure under pedestrian load is necessary.On the engineering background of a indoor pedestrian bridge, this dissertationsystematically studied the problems of comfort and vibration control under humanactivities. It mainly analyzed the dynamic response of pedestrian bridge with boxsection under the action of pedestrian loads, and evaluated comfort of thesepedestrian bridge. In addition, tuned mass dampers (TMD) are arranged in order toreduce the vertical vibration response and to ensure the use safety and personalcomfort, the main research contents are as follows:(1) The features of common pedestrian load and mathematic modes are explained,domestic and foreign research of floor structure and codes of floor vibration arecomprehensively analyzed. Combining with the actual situation of the project,evaluation and analysis methods of vibration comfort for large span structures underthe pedestrian load excitation are summarized;(2) The theories and parameter design method of vertical vibration damping device(TMD) are introduced. Mainly the criteria of the equivalent linearization method isused in order to replace approximataly the original damped structure by anenquivalent undamped one. Then the approximate analytical solution of the TMD’sparameters is deduced by using known results for the undamped structure obtained;(3) On account of the pedestrian bridge structure, boundary conditions are cinfirmed in order to establish the finite element model of the structure and dynamiccharacteristics were analyzed. On the basis of natural frequency of vibration andvibration mode the most unfavorable area of vertical vibration was preliminarilyestimated;(4) The location and quantity of the tuned mass damper were arranged optimallyand damping effect was calculated. The acceleration response after damping controlmeets the requirement of existing specification.Finally, the full text of work was summarized, the corresponding conclusions weredrawn and the next work was put forward.