Nonlinear Finite Element Analysis of Concrete Structures

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loading = 26 %
loading = 63 %
loading = 96 %
Fig. 5.3-9: Development in the A-2 beam of contour lines for
the nonlinearity index in per cent. Loadings expressed
as per cent of predicted failure load.
Let us now consider the predicted crack development of the A-2
beam. This is shown in fig. 10. The reinforcement is also shown
or this figure by the dotted lines whereas regions where yielding
occurs in the bars are indicated by full lines. Note that
identical loadings in per cent for the OA-2 and the A-2 beams
correspond to a 12% larger absolute load for the A-2 beam. With
this in mind figs. 10a) and 10b) correspond quite closely to
figs. 6a) and 6b), respectively. However, some changes in the
behaviour exist. Secondary cracks initiate now at 51% loading
compared to 63% loading for the OA-2 beam. Strain softening
adjacent to the load point develops now at 63% loading compared
to 82% loading for the OA-2 beam. Yielding of the stirrups follows
the location of the inclined cracks. A quite pronounced development
of inclined cracks occurs at 81% loading. The crack
pattern just before failure, fig. 10c), indicates a somewhat
further development of inclined cracks compared to fig. 6c).
Yielding at the load point of the compressive steel initiates