examined section matches the particular photogrammetric measurement,
therefore also being within the constant moment
section.
Fig. 20a and b shows the sections of the FE-model‘s longitudinal
side and of the reference slab test, respectively, and Fig. 21a and b
shows those of the slabs that were strengthened double-ply. To be
able to compare both procedures, dot pitch measurements were
conducted, of which one measurement was taken within the compression
zone at a distance of 15 mm to the upper slab edge, and
the other measurement was taken at the level of the steel reinforcement.
In addition, the strengthened slab strain on the textile
reinforcement level was taken in consideration (Fig. 21a and b).
The distances between both points were chosen according to the
observed and calculated crack distances and amounted to
230 mm, 120 mm, and 70 mm. It was assumed that the two different
reference lengths of 120 mm and 230 mm between the finite
element and the photogrammetric analysis (see Fig. 20a and b)
do not influence the strain determination since the chosen lengths
are more than seven times bigger than the maximal concrete grain
diameter (16 mm) [21]. This way, local strain peaks measurable
with the photogrammetric setup are smeared well for the mean
strain calculations.
The measurement results of the compression zone are shown in
Figs. 20c and 21c, and those of the reinforcement level in Figs. 20d
and 21d. As the force was kept constant for a short period every
10 kN to document crack progressions, the course of the photogrammetric
measurement in Fig. 21d is serrated.
It can be observed that the characteristic lines of the test show a
course comparable to each particular simulation. Marginal deviations
as with the Young’s modulus within the compression zone
(Fig. 20c) as well as the onset of the steel reinforcement yielding
(Fig. 20d) can mainly be attributed to differing material characteristics
as those vary within a distinct range.
Thus, the simulations appear to give a good illustration of the
tests, which particularly matters in respect to the load distribution
at the cross section.