NDT Test Results
situ vertical displacement gages (VDs) are used to measure the vertical
deflections of the slab.
Gage VD2 is located at the
center of north edge of the slab.
four gages (VD1, VD3, VD4, and VD5) are positioned at the corners of the slab
Figure 4). The FAA profiling device was used to measure
the profile along the north edge of the slab from the west to east.
The locations of VD1, VD2, and VD3 are very
close to the path of the profiling device.
comparing the profiling device measurements with the in situ Vertical
Displacement Transducers, we define an index
Rc = The reading at the center of profile
with zero at the profile ends, as shown in
Figure 9. Idealized
View of a Curled Slab.
Rc is compared with the
difference between the average of the corner deflections and the center
deflection on the north edges of the slab 0.5 *(V3+V1)-V2.
Note that sensor VD3 did not work past 6/16/03,
therefore, 0.5*(V3+V1) is replaced by the average of the corner deflections of
the slab, (V1+V4+V5)/3 or V3=V1 is assumed.
Figure 10 shows the time histories of the Rc and
VD measurements with initial values = 0.
Figure 11 gives the relationship between the readings of VD2 and the
corner deflections of the slab.
They show a
strong linear relation.
is therefore, a good indication of curling of the slab corners with, in this
case, a proportionality factor of slightly more than two.