Static And Dynamic Research Of Silos On Structure-Foundation Interaction

The theoretical analysis and experiment research on silos have been carried out for many years. Some scholars have put forward many kinds of computing models in the static and dynamic calculating of silos structure, according to experiment results and shell theories. All these models suppose that silo structure is on the rigid foundation exclusive of the interaction of base-foundation-structure and the attenuation of silo's vibration made by bulk solid, and therefore little research of the dynamic interaction of bulk solid and silos has been made. No research reference has yet been found as to the response of the silos on different foundation to the vibration of the foundation in the concerned experimental research. The essay makes series research on the experimental and theoretical calculation of the static and dynamic interaction of base-foundation-silo and makes static and dynamic experimental research on silo models on different foundations. After comparing the static and dynamic calculating analysis of finite element method on silo models and material subjects with experiment results, the essay provides dynamic calculating models of silo structure under the dynamic force when the effect of the force of silo wall received from bulk solid is considered. The essay also makes research on attenuation of silo's vibration by the action of bulk solid. This paper makes the following research work:1. Make first systematic experiment research on silos in the field. Design and make tubular-support and columns-support lucite silo models as well as rubber cushion imitating elastic foundation. Make static and dynamic experiments on elastic and rigid foundations under several kinds of working condition and correct the experiment condition according to FEM calculating result and re-experiment.2. Firstly provide mathematic models on the effect of the force of silo wall relieved from bulk solid and attenuation of silo's vibration. Use finite element method to make static and dynamic calculating analysis on silo models on different foundation. Make research on the reaction of bulk solid to silo wall and to attenuation of silo structure while the dynamic response of silo models to foundation's simple harmonic motion is calculated. After repetitive calculating and comparing with experiment results, the conclusion is reached: for tubular-support or columns-support silo structure when foundation is moving in the horizontal direction, the relative motion between 70-80% of the bulk solid in the lower part of the stock bin and silo wall can be neglected and the relative motion between 20-30% of the bulk solid in the upper part of the stock bin and silo wall must be considered. Compared with in the rigid foundation, relative motion between bulk solid and silo wall and the bending deformation of silo wall are both reduced when silo structure is put in the elastic foundation. This conclusion is in harmony with the phenomenon observed in sample experiment and the amounts of bulk solid which have relative inter-motion reduces when the rigidity of the foundation increases.3. Use finite element method to make systematic analysis on the interaction among elastic base-silo-bulk solid and draw effective conclusions. When making finite element calculation on model silo, single silo and group silos, consider the exact change of the rigid of each section of the structure. Divide the silo body and the foundation into element of plate and shells, of truss, of beam and of brick and then make calculation so that the model can reflect the real condition of the structure and the foundation.4. Based on a lot of calculating analyses on various working condition, the thesis give the approximate calculating formula of multi-order natural frequency of vibration of round silo.5. Take consideration of the interaction of bulk solid and silo and obtain the calculating formula of the character of natural frequency of vibration of round silo, and revise the norm of the calculating for model of silo's seismic resistance.Since th...