Form-active structures : study of representative examples

The present thesis is devoted to study representative examples of "form-active" structures and to present computational approaches and procedures which can be adopted to determine their initial configuration and their response to the applied loads. An introduction to the "form-active" structures and their applications are presented in Chapter 1. Chapter 2 is devoted to the derivation and the discussion of the tangent stiffness matrix, composed of the elastic stiffness matrix and the geometric stiffness matrix, in the convert of 3D trusses or cable systems, under the assumption of small strains and linear elasticity but large displacements. A combination between Finite Element method and Newton-Raphson’s iteration is generated in the MATLAB® R2017a environment. The important role of geometric stiffness matrix in the nonlinear analysis is introduced. The results are compared to commercial software (Midas GEN 2017) and are found to be in excellent agreement. The effects for the accuracy of this method are discussed. Cable structures are mainly discussed in Chapter 3 and Chapter 4, where the Force Density Method and Dynamic Relaxation Iteration are explained respectively. Examples show the advantages of these methods and further improvements are elaborated. Chapter 5 presents an original study of form-finding procedure for inflatable dams. In this chapter, it is illustrated that an alternative tool with computational advantage for the form-finding and analysis of inflatable dams through the discretized finite element method. This method has various applications in the area of inflatable dams such as single-anchor and double-anchor dams, as well as the application of updated internal air pressure scheme for large external loads. It is also flexible to deal with different initial configurations such as flat or circular configuration. This flexibility gives a possibility to analyze different inflatable dams with short or no anchorage separation (single anchorage systems).

The thesis does not contain Italian abstract.