Issue 45

F. Qui et alii, Frattura ed Integrità Strutturale, 45 (2018) 1-13; DOI: 10.3221/IGF-ESIS.45.01





   , p f r e  



p

3

0

f        

tt





  , p f r e  

3 + 3 3 / f f f   

 

Y

p f

0

/ 3

(7)



tt

cc

tt

cc

cc





N

  

  , 

'

'

'





p f 

/ Bf p f

f

f

r e

/ 3

/ 3

cc

c

c

cc

c

cc





where f cc and f t are respectively the static compressive strength and static tensile strength; are respectively the dynamic compressive and tensile enhancement factors resulted from the strain rate and  t are respectively the functions of shear damage and tensile softening of concrete [32-34]; B and N are empirical constants; r (  , e ) is the Lode corner effect [35], with  and e being the ratio between the Lode angle and the tensile meridian and the ratio between the Lode angle and the compressive meridian, respectively. As shown in Fig. 3, the strength surface of concrete can be classified into three segments : the tensile section ( p  0), the transition section (0  p  f cc /3) and the compressive section ( p  f cc /3). DIF m_t and DIF t effect;  c = f ' c DIF m_t  c and f tt = f t DIF t  t ; f ' c

Figure 3: Strength surface of concrete

Parameters

Mortar

ITZ

Aggregate

2100 2630

1800 2630

2600 2630

 0

(kg/m 3 )

 s0

(kg/m 3 )

p crush p lock

(MPa) (GPa)

10.7

6.4

23.3

3 3

3 3

3 3

n

K 1 K 2

(GPa) (GPa)

14.2

6.9 30 10 3.2 0.17 19.2

17.4

30

-3.0E3

0.20

0.30



K 3 (GPa) G (GPa)

10

1.5E5

10.7 32.0

14.7 70.0

f ' c

(MPa) (MPa)

f t

3.1

2.4

4.5

B N

1.54

1.54

1.95 0.76

0.8

0.8

Table 1 : Parameter values of the 3D meso-mechanical model.

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