Civil Engineering Reference
In-Depth Information
ε
ε
t
, as a function of cracking strain
ε
r
and angle
α
r
Figure 5.6
Steel strains,
and
α
r
=
45
◦
provides the best design. Substituting
α
r
=
45
◦
into Equations (5.56)
point of view,
and (5.57) gives the principle of first invariance of strains:
1
2
(
ε
=
ε
t
=
ε
r
+
ε
d
)
(5.58)
For
ε
r
=
1
.
5
ε
y
and
ε
d
=
0, both Equation (5.58) and Figure 5.6(a) give the steel strains
ε
=
ε
t
=
0
.
75
ε
y
.
