New Materials for the Rehabilitation of Cultural Heritage - Czech ...

New Materials for the Rehabilitation of Cultural Heritage 21
The values of coefficient �may be assumed equal to 1.5 for stonework, and equal to 1.3 for
brickworks. After crack formation it is necessary to check that the reinforced coating be able
to support a tensile force at least equal to 60% of the peak value, so as to avoid significant
softening branches after the crack formation.
Figure 14 –Deformation of mesh wires due to the diagonal deformation of the coating mortar
in correspondence of the tensile strength in the coating mortar [15]
Figure 15 –Simplified strut-and-tie scheme that simulates the stresses in one grid of the
GFRP mesh embedded in the coating.
In the scheme of Fig. 15, it was assumed an equivalent strut with a width equal to 0.25 the
diagonal length ( 2 �p
) to represent the mortar effect. By imposing that the force F that
causes the compression collapse of the strut or the tension collapse of the GFRP wire be equal
to the 60% of the maximum one that caused the cracking it was possible to determine the
minimum thickness of the coating to be used in order that the mortar strut would not fail for
an equivalent tensile stress lower than 60% of the maximum one, as