Stability of steel dome structures

Abstract

Basically, the geometric nonlinearity of space structures has been discussed in this Thesis. There are totally three types of nonlinearities, which are a) the geometric nonlinearity which arises from the large nodal deflections and finite changes in the geometry of deformed structure, b) the material nonlinearity, and c) the combination of both the geometric and material nonlinearities. Linear and nonlinear parts of the tangent stiffness matrices are derived for bar elements in 2-Dimension, and also for truss bar elements in space structures in order to see the effect of the nonlinearity on materials. Furthermore a number of numerical computational techniques have been described, including a) Regular, b) Halved, and c) Mid – Point Incremental Load Procedures, as well as the Newton – Raphson iteration schemes, with modifications of the stiffness matrices at each loading step. Moreover, in order to investigate the effects of geometric nonlinearity on space structures, a typical steel dome structure is selected, which is analyzed by utilizing the LUSAS package program. Firstly, some pilot test examples are investigated by using the LUSAS program and the solutions are compared with the exact solutions. Secondly, a complete steel lattice dome, with a diameter of 72 meter, has been fully analyzed using the nonlinear Newton – Raphson iteration scheme and the steel structural elements have been designed in accordance with TS 648-Turkish Standard.