Research On Vibration Servicebility Of Large Span Floor System

With the widely utility of light and high-strength materials and the rapid improvement of design methods together with the better construction skill, large span floor systems has been extensively applied in the public and residential buildings. As results, the span of slab structures in modern buildings is increasing, while the stiffness becomes smaller. The bigger span and less structural members make large span floor decreased damping and smaller fundamental frequency. Some public places with all kind of activities, such as pedestrian bridge, larger dance hall, exhibitions and gyms, are easy to be suffered from vibration serviceability problems to cause public panic when the vertical vibrations caused by crowd-induced load and rhythmic movement exceed the limitation.In this thesis, following studies have been investigated to figure out the vibration serviceability of large span floor structures on the basis of three projects.(1) Regarding the research of vibration serviceability of large span slab structures, an introduction to compare advantages and disadvantages of different evaluation criteria has been made to find out the reasonable criteria and thus has provided the theoretical background for the evaluation of the comfort.(2) Based on the Fourier series method, first 15 orders floor structural vertical vibration peak acceleration formula under pedestrian frequency impact load has been derived. Taking the pedestrian bridge located in the intersection as an example, two different methods, including the resultant force from first 15 orders pedestrian load and the method provided from the current code, was compared. The more acceptable acceleration method will laid foundation on the calculation of vibration comfort(3) Vibration calculation of large span floor unde r rhythmic movement has been made based on the comfort analysis of gym floor. As for the unsatisfied floor, reasons have been investigated and three possible reinforcement solutions have also been provided. After the comparison of three methods, the best p lan has been accepted to be the reference for the design and reinforcement of the structure.(4) The vibration serviceability analysis has been also applied to a corridor between the main building and the podium in a five-star hotel. ANSYS has been used to do the modal and dynamic analysis under different loading circumstances including slow walking, normal walking, fast working, slow running, fast running and jumping. Installing TMD and six structural reinforcement methods of enhancing beam cross section have been proposed to meet the requirement for the unsatisfied floors. With the comparison of different methods, the best solution has been chosen to provide suggestions to the vibration serviceability design and reinforcement design.