Fixed Angle Shear Theories - Unified Theory of Concrete Structures - page 222

ν 12 and ν 21

Figure 6.5 Hsu/Zhu ratio

Based on the test data shown in Figure 6.5(a), the following equation is suggested for the
Hsu/Zhu ratio ν 12 :

ν 12 = 0 . 2 + 850 ε sf ε sf ≤ ε y (6.32)

ν 12 = 1 . 9 ε sf >ε y (6.33)

Figure 6.5(a) clearly shows that the Hsu/Zhu ratio ν 12 lies outside the valid range of 0-0.5

for the Poisson ratio of continuous materials.
The measured data for Hsu/Zhu ratio ν 21 are plotted in Figure 6.5(b). It can be seen that ν 21

is about 0.2-0.25 before cracking took place in the test panels. After cracking, however, ν 21

reduces rapidly to about 0.05 and then gradually approaches zero at yielding. Near the yielding
stage, negative

ν 21 begins to occur. It is interesting to note that the negative and positive values

of ν 21 occur alternatively in some specimens. For simplicity in an analytical model, ν 21 is