Optimization Of Large Structural Systems Research Articles

An integrated framework including distinct algorithms for optimization of offshore towers under uncertainties

A reliability analysis is usually required to carry out design optimization of large structural systems to incorporate the uncertainties on the parameters such as material properties, external loads, manufacturing condition, etc. This procedure is called Reliability Based Design Optimization (RBDO), and requires a structural analysis program, a reliability analysis and optimization tools to couple effectively. In this paper, an integrated framework is proposed to implement the RBDO of the offshore towers. It has two distinct approaches to evaluate the probabilistic constraints; namely Reliability-Index based Approach (RIA) and Performance Measure Approach (PMA). The proposed framework also suggests Sequential Quadratic Programming (SQP) and Differential Evolution (DE) as optimization methods. Examples of monopod, tripod, and jacket towers under the reliability constraints based on limit states of the critical stress, buckling, and the natural frequency are presented to demonstrate the applicability of the implemented algorithm to realistic structural systems.

Design optimization of large structural systems with substructuring in a parallel computational environment

Design optimization of large structural systems can be attempted through a substructure strategy when difficulties are encountered with convergence of such problems. In this strategy the large structure is divided into several smaller substructures, and a subproblem is defined for each substructure. Solution of the large problem can be obtained iteratively through repeated solutions of the modest subproblems. Substructure strategies, in sequential as well as in parallel computational modes on a CRAY YMP multiprocessor computer, have been incorporated into the code CometBoards, which is an acronym for Comparative Evaluation Test Bed of Optimization and Analysis Routines for Design of Structures. Three issues, intensive computation, convergence of the iterative process, and analytically superior optimum, encountered during the implementation of substructure optimization into CometBoards have been solved. Coupling between subproblems as well as local and global constraints grouping are essential for convergence of the iterative process. The substructure strategy can produce an analytically superior optimum different from what can be obtained by regular optimization. For the problems solved, substructure optimization in a parallel computational mode made effective use of all assigned processors.

DCOC: An optimality criteria method for large systems Part I: theory

A highly efficient new method for the sizing optimization of large structural systems is introduced in this paper. The proposed technique uses new rigorous optimality criteria derived on the basis of the general methodology of the analytical school of structural optimization. The results represent a breakthrough in structural optimization in so far as the capability of OC and dual methods is increased by several orders of magnitude. This is because the Lagrange multipliers associated with the stress constraints are evaluated explicitly at the element level, and therefore, the size of the dual-type problem is determined only by the number of active displacement constraints which is usually small. The new optimaliy criteria method, termed DCOC, will be discussed in two parts. Part I gives the derivation of the relevant optimality criteria, the validity and efficiency of which are verified by simple test examples. A detailed description of the computational algorithm for structures subject to multiple displacement and stress constraints as well as several loading conditions is presented in Part II.

NATO/DFG advanced study institute optimization of large structural systems

NATO/DFG advanced study institute optimization of large structural systems

Optimization of large structural systems : Berchtesgaden, Germany, 23 September–4 October 1991 NATO/DFG Advanced Study Institute

Optimization of large structural systems : Berchtesgaden, Germany, 23 September–4 October 1991 NATO/DFG Advanced Study Institute

NATO/DFG advanced study institute optimization of large structural systems

NATO/DFG advanced study institute optimization of large structural systems

A note on truss design for stress and displacement constraints by optimality criteria methods

One of the difficulties with the optimization of large structural systems by optimality criteria (OC) methods, in which stress constraints are stated in terms of relative displacements, is the need to evaluate a large number of Lagrangians. An improved OC method, which does not require Lagrangians for stress constraints, is outlined in this note in the context of problems with stress constraints and a single displacement constraint. Whilst general formulae giving continuum-type optimality criteria for elastic systems are available (e.g. Rozvany 1989), the criteria for trusses are confirmed here by a simple derivation and verified on a ten-bar truss, for which the proposed technique and a dual programming method are shown to give a twelve-digit agreement.

Optimization of large structural systems

Optimization of large structural systems

Optimization of large structural systems NATO/DFG advanced study institute, Berchtesgaden, Germany 23 September–4 October 1991

Optimization of large structural systems NATO/DFG advanced study institute, Berchtesgaden, Germany 23 September–4 October 1991

Optimization of large structural systems

optimization of large structural systems

NATO advanced study institute optimization of large structural systems

NATO advanced study institute optimization of large structural systems