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Various response functions in lattice domes reliability via analytical integration and finite element method

Pokusiński B., Kamiński M.

International Journal of Applied Mechanics and Engineering

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2018

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Vol. 23, no. 2

445--469

EN

The main aim of this work is to verify an influence of the response function type in direct symbolic derivation of the probabilistic moments and coefficients of the structural state variables of axisymmetric spherical steel dome structures. The second purpose is to compare four various types of domes (ribbed, Schwedler, geodesic as well as diamatic) in the context of time-independent reliability assessment in the presence of an uncertainty in the structural steel Young modulus. We have considered various analytical response functions to approximate fundamental eigenfrequencies, critical load multiplier, global extreme vertical and horizontal displacements as well as local deformations. Particular values of the reliability indices calculated here can be of further assistance in the reliability assessment by comparing the minimal one with its counterpart given in the Eurocode depending upon the durability class, reference period and the given limit state type.

2

The least squares stochastic finite element method in structural stability analysis of steel skeletal structures

Kamiński M., Szafran J.

International Journal of Applied Mechanics and Engineering

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2015

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Vol. 20, no. 2

299--318

EN

The main purpose of this work is to verify the influence of the weighting procedure in the Least Squares Method on the probabilistic moments resulting from the stability analysis of steel skeletal structures. We discuss this issue also in the context of the geometrical nonlinearity appearing in the Stochastic Finite Element Metod equations for the stability analysis and preservation of the Gaussian probability density function employed to model the Young modulus of a structural steel in this problem. The weighting procedure itself (with both triangular and Dirac-type) shows rather marginal influence on all probabilistic coefficients under consideration. This hybrid stochastic computational technique consisting of the FEM and computer algebra systems (ROBOT and MAPLE packages) may be used for analogous nonlinear analyses in structural reliability assessment.

3

Some reliability issues of the corrugated i-beam girder

Sokołowski D, Kamiński M.

Engineering Transactions

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2015

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Vol. 63, iss. 3

297--315

EN

The main aim of this paper is reliability analysis of the corrugated-web I-girder carried out to verify its susceptibility to the random corrosion of the web and to make a comparison of the results of the first and of the second order reliability analysis. The methodology implemented in the study is based on the stochastic finite element method related to the generalized stochastic perturbation technique, where a discretization of the entire structure is carried out with four-node quadrilateral shell finite elements. This is numerically implemented using the FEM engineering system ROBOT and computer algebra system MAPLE, where all probabilistic procedures are programmed. The perturbation-based results are compared with these coming from the Monte-Carlo simulation and with an analytical solution obtained via symbolic integration carried out in MAPLE also. The indices of reliability are determined for the maximum deflections of the beam as the function of an input coefficient of variation of the web’s thickness whose meaning is the extent of a corrosion process.

4

Navier–Stokes problems with random coefficients by the Weighted Least Squares Technique Stochastic Finite Volume Method

Kamiński M., Ossowski R. L.

Archives of Civil and Mechanical Engineering

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2014

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Vol. 14, no. 4

745--756

EN

The main aim of this article is numerical solution to the Navier–Stokes equations for incompressible, non-turbulent and subsonic fluid flows with Gaussian physical random parameters. It is done with the use of the specially adopted Finite Volume Method extended towards probabilistic analysis by the generalized stochastic perturbation technique. The key feature of this approach is the weighted version of the Least Squares Method implemented symbolically in the system MAPLE to recover nodal polynomial response functions of the velocities, pressures and temperatures versus chosen input random variable(s). Such an implementation of the Stochastic Finite Volume Method is applied to model 3D flow problem in the statistically homogeneous fluid with uncertainty in its viscosity and, separately, coefficient of the heat conduction. Probabilistic central moments of up to the fourth order and the additional characteristics are determined and visualized for the cavity lid driven flow owing to the specially adopted graphical environment FEPlot. Further numerical extension of this technique is seen in an application of the Taylor–Newton–Gauss approximation technique, where polynomial approximation may be replaced with the exponential or hyperbolic ones.