Efficient Analytical Model for Calculation of the Influence Zone inside the Subsoil below Foundations Slabs

This paper presents analytical approaches for evaluating the depth of the influence zone. The model focuses on variations in the ground water table. Referring to [6], the term influence zone is assigned to the region where the load has a substantial influence on the deformation of the soil skeleton. The first approach relies on an analytical solution based on an analysis of the Westergard subspace, assuming an elastic material response. This idea is accompanied by the effect of water pressure on the effective (skeleton) stress state. The approach provides any extremely efficient estimate of the depth of the influence zone. The proposed analytical solution is verified against the finite element analysis, assuming that the material response is driven by the modified Cam clay model. The predicted analytical result is found to be in a good agreement with the numerical solution derived with the help of the ADINA 8.1 general-purpose finite element code. The presented results further suggest that this analytical procedure can be applied to solve the interaction problem of the slab and the subsoil and its progress in the structural process, namely by varying the ground water table.

Variable Local Moduli of Elasticity as Inputs to FEM-based Models of Beams made from Glued Laminated Timber

The present paper is concerned with the formulation of advanced FEM based models of beams made from glued timber segments. These models account for variable elastic moduli in individual segments and their analysis is based on the application of LHS method. All results from probabilistic calculations are compared with experimental measurements conducted on twenty beams as well as with the FEM results derived for the same beams assuming deterministic analysis with piecewise constant moduli in individual segments. The main contribution of enhanced probabilistic models is seen primarily in the ability to provide cost effective designs of long-span glued timber structures

Nondestructive Strength Grading of Structural Timber

The paper is concerned with the investigation of the use of non-destructive testing methods for the grading of structural timber and for the determination of the performance of structural timber elements. The investigations dealt with the ultrasonic method and the methods of longitudinal and transverse vibrations. The usability of these methods was verified at samples with the structural dimensions. The principle of the work lies in the search for statistic relationships between parameters characterising the timber quality (e.g. bending strength, modulus of elasticity) and magnitudes measured by the above mentioned non-destructive testing methods (e.g. natural frequency, dynamic modulus of elasticity)