Modal Identification Of Large-span Stucture Floor Based On The Serviceability Evaluation

In recent years, the continuous development of new materials, structural systems and high-strength, lightweight materials wide used in large-span space structures such as shopping malls, stadiums, railway stations, pedestrian bridges in public places, the floor of modern building are becoming lighter, more flexible and larger span, resulting in a significant reduction in the vibration frequency. These structures are easy to produce significant dynamic response with some external dynamic motivation interference, although these dynamic response can not bring safety problems to the structure, but it will bring discomfort feelings to the people on the floor. Typically, the vibration of the floor structure caused by human activities is mainly vertical vibration, people are also most sensitive to vertical vibration response fo the structure. With the improvement of people’s living standards and quality of life, the requirements of building comfort caused people’s more and more attention. In vibration environment, evaluate the effect of vibration sense of comfort of the occupants, is called comfort evaluation. Currently, the widely used evaluation index are mainly vibration frequency and acceleration internationally.How to identify the vertical bending natural frequency of the computing modal of large-span structure slab, as usual, people often observe the modal shape figures to get the natural frequency; but when the modal numbers of structure are intensive, the results are sometimes not very convincing. By taking the Zhengzhou East Railway Station as the engineering background of large-span,heigh flexibility structure, propose two methods to identify the1st vertical bending natural frequency of floor-MAC value method and pulse excitation method, and the results are compared to field measurement results. The results demonstrated that the analysis model and approach proposed is reliable and accurate for identifying the natural frequency of floor effectively, which can guide vibration comfort evaluation that is followed. Finally, recommendations and prospect are proposed on the basis of summary of the research work by this paper.