Nonlinear Finite Element Analysis of Concrete Structures

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80 mm
Fig. 5.1-1: Configuration of panel tested by Peter (1964)
finite element modelling uses two triangular plane stress elements
only. The reinforcement is simulated by means of two bars
in each direction. The thickness of these bars is determined so
that the employed bar volume corresponds to the given one.
The same concrete mix and storing was applied for all panels.
Even so, testing of concrete specimens indicated some scatter
from panel to panel; nowever, to facilitate comparison the mean
parameter values are applied in the analysis. Of the measured
parameters only the uniaxial tensile strength a. = 1.74 MPa
assumed to be equal to the measured Brazilian splitting strength
4
and the initial Young's modulus E. = 2.45*10 MPa are of interest.
Poisson's ratio was assumed to be v. = 0.2. The experimentally
determined stress-strain curve for the reinforcement
bars was simulated by a trilinear curve as shown in fig. 2. The
full strength of the bars occurs when the strain is ground
80 0/00f due to inhomogenities, etc., in the panels this stress
value is not expected to be reached for all bars in one direction
even at failure load. The approximation employed can be
considered as a reasonable approach to reality.
For a fixed force F = 350 kN let us first consider the horizontal
displacement 6 and vertical displacement 6 as functions
of the angle a. This is shown in figs. 3 and 4 both for the ex-