Environmental Engineering Reference
In-Depth Information
Fig. 3.2 Stress-strain curve for steel reinforcement for use in deformation calculations, including
tension stiffening (see [35] 8.5.1)
the use of the mean values of the material properties divided by the partial safety factor
( g C ¼ 1.50 or g CA ¼ 1.30) (Table 3.1):
f cm
g C ¼
f ck þ 8 MPa
½
E c0m
g C
E cm
g C
f c ¼
and E c0 ¼
or E c ¼
g C
In the latter case, however, the design values of the material strengths (e.g.
g C )
have to be used for determining the ultimate load-carrying capacity at the critical cross-
section.
a f ck /
3.2.2 Non-linear stress-strain curve for reinforcing steel
Figure 3.2 applies to reinforcement in tension. The bilinear stress-strain curve of DIN
1045-1 [33] 9.2 applies to reinforcement in compression.
According to Figure 3.2, the unfavourable tension stiffening effect can be taken into
account for the redistribution of the internal forces in statically indeterminate
structures. However, when calculating the internal forces according to second-order
Table 3.1 Comparison of both approaches for normal-strength concretes (see also Figure 3.1)
DIN 1045-1
Concrete
C 12/15 C 16/20 C 20/25 C 25/30 C 30/37 C 35/45 C 40/50 C 45/55 C 50/60
8.5.1 (4)
f cR [MPa] ¼
8.67
11.56
14.45
18.06
21.68
25.29
28.90
32.51
36.13
E cR [MPa] ¼
25 787
27 403
28 848
30 472
31 939
33 282
34 525
35 685
36 773
k ¼
5.354
4.504
4.192
3.711
3.389
3.159
2.987
2.799
2.647
8.6.1 (7)
f c [MPa] ¼
13.33
16.00
18.67
22.00
25.33
28.67
32.00
35.33
38.67
E c0 [MPa] ¼
17 191
18 268
19 232
20 314
21 293
22 188
23 017
23 790
24 516
k ¼
2.321
2.169
2.164
2.031
1.933
1.858
1.798
1.717
1.648
 
Search WWH ::




Custom Search