Study On Free Vibration Features And Vibration Reduction Technology Of Cable Supported Concrete Floor Structure

At present, the demand for large-span spatial structure grows gradually, and how to develop a new structure provided with the advantages of reasonable force and efficient performance is a significant research direction of large span space structure study. On this background, a new cable-supported structure, cable-supported ribbed beam composite slab structure(CBS) based on the concept of tensegrity, is proposed in this paper. The new pre-stressed spatial structure is combined with traditional concrete floor slab and cable tension system. The study on static characteristics and construction technology of CBS has carried on, and some meaningful results are acquired already, while the dynamics characteristics of CBS have not been studied yet. Depending on National Science Foundation of China《Study on Cable Supported Concrete Roof Structure Based on Concept of Tensegrity》(51208317) and Hebei higher outstanding young scientific and technological research fund project《Study on Dynamic Characteristics and Vibration Reduction Technology of Cable Supported Concrete Roof Structure》(Z2013037), this paper deals with a testing and analytical method for studying CBS self-vibration features. Then, on the basis of clear natural vibration characteristics of floor, the analysis on human comfort has been carried on, besides the suitable and effective measure of vibration reduction for this kind of structure is pointed out. The main contents of research are as follows:(1) After the experimental model of CBS is designed and produced, the CBS of vibration modes and natural frequencies are obtained by hammering method and by using data collection and processing software DASP V10.(2) In order to utilize numerical simulation method to study CBS free vibration features, the numerical model of CBS is established by the finite element software MIDAS/GEN firstly, the natural vibration characteristics are studied by using numerical simulation method and the results are compared with the test data analysis. On this basis, the influence of structure parameters on the structural natural vibration characteristics is studied.(3) The structure vibration comfort under pedestrian loads is studied and evaluated. According to CBS characteristics, the vibration reduction method is put forward, and the effect of this method is analyzed and evaluated.Through the above research, the main results are as follows. The CBS is provided with low rigidity and complex dynamic performance; besides, its low order modes are mainly vertical vibration. Furthermore, four important parameters affecting the free vibration features of the CBS are discussed. The results indicate that the sag-span ratio, depth of the ribbed beam, cable diameter and the thickness of plate have little impact on the low modes, whereas for the high modes, only the depth of the ribbed beam has a great influence on it, but the other parameters can be ignored. The floor can produce strong vibration response under human-induced loads, which can’t meet the demand of human comfort. In order to improve CBS applying functions, the measure of vibration reduction by installing vertical tuned mass dampers(TMD) with their parameters seasonably designed is put forward, and the results of numerical simulation shows the scheme of the structure has good vibration control effect.