Dynamic Analysis On The Space Reticulated Shells With Semi-rigid Connections

In traditional space shell analysis, the behavior of bars connections is treated as either pinned or rigid joints entity. While lots of constructions and theory experiments proved that the bars connections is between pinned and rigid, namely semi-rigid. But in practical construction, to a certain extent, so-called pinned joints possess rigidity, and so-called rigid joints possess flexibility. Though this idealistic hypothesis can simplify the design and analysis process largely, it causes the large difference between theory and practice, the structure's insecurity or conservation, and is waste of money. This paper analysed the dynamic performance on the double layer spherical reticulated shells and double layer cylindrical reticulated shells with semi-rigid connections under the present situation.Firstly, this paper reviewed the simulating the semi-rigid connections as rotatable springs at both ends, the element stiffness matrix of the space bar with semi-rigid connections is derived on the basis of the definition of the element stiffness. With the same method the formula which convert the load acting on the span of the bar into the load acting on the nodes is derived. The models is validated by using finite elements program. Using the established models, the subroutine UEL has been made.The major works in this thesis are: The finite element method is used to analyze the dynamic characteristics of the reticulated shell structures by a semi-rigid node model. The element stiffness matrix is established for the semi-rigid structures. The natural vibration characteristic is obtained by solving the eigen-value equations. The displacement results of semi-rigid structures are compared with that of the perfect hinged and complete rigid structures. The vibration-model superposition method is utilized to get the vertical seismic response for these three structures, i.e. semi-rigid, perfect hinged and complete rigid structures. The simulation results show the rationality of semi-rigid model for practical structure analysis. The conclusion of this paper can benefit the engineering design ofreticulated shell structures.