Accession Number : ADA322930

Title :   Approximation and Derivatives of Survival in Structural Analysis and Design,

Corporate Author : UNIVERSITAET DER BUNDESWEHR MUENCHEN NEUBIBERG (GERMANY F R)

Personal Author(s) : Marti, K.

PDF Url : ADA322930

Report Date : MAR 1996

Pagination or Media Count : 34

Abstract : Yield stresses, allowable stresses, moment capacities (plastic moments), external loadings, manufacturing errors,... are not given fixed quantities in practice, but have to be modelled as random variables with a certain joint probability distribution. Hence, problems from limit (collapse) load analysis or plastic analysis and from plastic and elastic design of structures are treated in the framework of stochastic optimization. Using especially reliability-oriented optimization methods, the behavioral constraints are quantified by means of the corresponding probability ps of survival. Lower bounds for ps are obtained by selecting certain redundants in the vector of internal forces/bending-moments; moreover, upper bounds for ps are constructed by considering a pair of dual linear programs for the optimizational representation of the yield or safety constraints. Whereas the probability ps can be computed e.g. by sampling methods or by asymptotic expansion techniques based on Laplace integral representations of certain multiple integrals, efficient techniques for the computation of the sensitivities (of various orders) of ps with respect to input or design variables X and load factors lambda have yet to be developed. Hence, several new techniques (e.g. Transformation Method, Stochastic Completion Technique) are suggested for the numerical computation of derivatives of ps with respect to (X,lambda).

Descriptors :   *STRESS ANALYSIS, *STRUCTURAL ANALYSIS, MATHEMATICAL MODELS, OPTIMIZATION, STOCHASTIC PROCESSES, PROBABILITY DISTRIBUTION FUNCTIONS, RANDOM VARIABLES, LOADS(FORCES), LINEAR PROGRAMMING, ELASTIC PROPERTIES, GERMANY, PLASTIC PROPERTIES, TRUSSES, YIELD STRENGTH, FORCE(MECHANICS), BENDING MOMENTS, LAPLACE TRANSFORMATION.

Subject Categories : Mechanics
      Operations Research

Distribution Statement : APPROVED FOR PUBLIC RELEASE