PSI - Issue 11

R. Capozucca et al. / Procedia Structural Integrity 11 (2018) 402–409

408

7

R. Capozuc

ca, E. Magagnin

/ Structural Inte

grity Procedia 0

0 (2018) 000–000

i, M.V. Vecchietti

Table

4. Exp. results f

L P or strengthened R oad [kN] Defle midsp [mm]

C beam B2 at da ction at an

mage degrees D at ressive ete ε c

i .

Strain comp concr (10 3 0.10 )

Curvature χ [mm -1 ·10 -5 ]

Strain at steel (intrados) ε s

Damage degrees

(10 -6 ) -0.08 -0.94 -1.90 -7.37 -

D* 1 D* 2 D* 3 D* 4 D* 5

4

.00

0.61 2.83 8.65

0.33 1.51 3.31 10.00 -

8.00

0.31 0.72 1.4 -

16.00

2 3

8.00 7.35

17.00 62.25

T for t again conc

he beam was he different d observe the rete cracking

analysed und amage degre shift of the d damage.

er vibration a e, at each poi iagrams at va

t every damag nt of the acce rious steps D

e step in the lerometer, ar i with reducti

free-free edge e shown for B on of the freq

condition. Th 1 in Figure uency values

e FRF envel 9. It is possib due to incre

opes, le to asing

Fig.8. Crackin

g state of beam B

2 at steps of stat

ic damage D 4 *.

Table

5. Exp. average

frequency values Damage degree

for r = 1,2,3 mo f 1 [Hz] 121 121.17 112 106.33 93,5 ariation valu t the unloade * and D 4 *, c caused by th st load level ow load steps

des of damaged R Δf 1 /f Di* (%) f [

C beam B2.

/f Di*

Δf 3 /f D (%)

Δf 2 (%)

f 3 [Hz]

2 Hz]

i*

-

3 3 3 2 2

33.14 33.67 19.33 92.33

-

631.2 629.2 604. 566.2 524,2

5 5

-

D 0 * D 1 * D 2 * D 3 * D 4 *

0 8 5

0 4 8 4

0 4 6 7

88

5 5

12

80,5

In with at th vibra conc varia

Figure 10 th the initial va e high dama tion mode. T rete cracking tions are also

e frequency v lue recorded a ge levels, D 3 his result is at the lowe recorded at l

es in referenc d condition D ause the grea e presence o s. In the cas that trigger th

e to the differ 0* for B2. It test frequenc f the strength e of unreinf e concrete cr

ent damage d is possible to y’s variation, ening that a orced beams acking.

egree by bend notice how th up to 50%, llows to decr without FRP

ing are comp e load increm in the fist na ease the effe rod, the hi

ared ents tural ct of ghest

1

0,1

0,01

0,001

lg

0,0001

MODE II D 0 *

MO D 0 *

DE IV

200 MODE D 0 *

I

600 80 requency [Hz MODE D 0 *

III

0,00001

0

400

0 1000 ]

F

Fi

g.9. Envelope of

FRFs for differen

t damage degree

, D* I , for beam B 2.