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Structural Engineering and Mechanics
  Volume 4, Number 1, January 1996 , pages 25-35
DOI: https://doi.org/10.12989/sem.1996.4.1.025
 


Optimal cross-section and configuration design of cyclic loaded elastic-plastic structures
Valido AJ

 
Abstract
    This paper describes a continuum variational formulation for design optimization of nonlinear structures in the elastic-plastic domain, where unloading and reloading of the structures are allowed to occur. The Total Lagrangian procedure is used for the description of the structural deformation. The direct differentiation approach is used to derive the sensitivities of the various structural response measures with respect to the design parameters. Since the material goes into the inelastic range and unloading and reloading of the structure are allowed to occur, the structural response is path dependent and an additional step is needed to integrate the constitutive equations. It can be shown, consequently, that design sensitivity analysis is also path-dependent. The theory has been discretized by the finite element technique and implemented in a structural analysis code. Mathematical programming approach is used for the optimization process. Numerical applications on trusses are performed, where cross-sectional areas and nodal point coordinates are treated as design variables. Optimal designs have been obtained and compared by using two different strategies: a two level strategy where the levels are defined accordingly the type of design variables, cross sectional areas or node coordinates, and optimizing simultaneously with respect to both types of design variables.
 
Key Words
    optimal design, non-linear, structures
 
Address
Valido AJ, ESCOLA SUPER TECNOL,INST POLITECN SETUBAL RUA VALE CHAVES,P-2910 SETUBAL,PORTUGAL
 

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