VULNERABILITY ASSESSMENT OF PRECAST CONCRETE CLADDING WALLS FOR POLICE STATIONS

Critical Infrastructures – 6C
Chair: Dörr / Gündisch

VULNERABILITY ASSESSMENT OF PRECAST CONCRETE CLADDING
WALLS FOR POLICE STATIONS
Sapienza University of Rome
Giannicola Giovino1, Pierluigi Olmati2, Franco Bontempi3
1

Ph.D. Student, P.E., Capt. of Carabinieri Corps, Email: giannicola.giovino@uniroma1.it

2

Ph.D. Candidate, P.E., Email: pierluigi.olmati@uniroma1.it

3

Full Professor, Ph.D., P.E., Email: franco.bontempi@uniroma1.it
Giovino G, Olmati P, Bontempi F

- September 18, 2013 -

giannicola.giovino@uniroma1.it
www.francobontempi.org

Presentation outline

2

1

Introduction

2

Test matrix

3

Experimental results

4

Numerical investigation

5

Conclusions




Introduction

3

1

This study presents both experimental and numerical investigations on the
assessment of precast concrete wall panels, for using as exterior cladding
system, subjected to explosive detonations

2
improving the performances of the Italian
police stations against external explosions.

3
4
5

collect data in order to verify and validate both analytical and
numerical model
The aim
of study

check with the experimental evidence the necessity of
properly design the cladding system of the Italian police
stations.



giannicola.giovino@uniroma1.it 3

Introduction

4

1
2

The Italian police stations have a widespread distribution on the national
territory

obviously an advantage for the
community

3

they do not have a structure with
adequate performance against manmade attacks

4
5

But often, these police stations are
no other than common civil
buildings adapted for police use

Is not economical sustainable to retrofit these buildings for police use, but it is
necessary to design and build new police stations providing the adequate
resistance performance against man-made attack


giannicola.giovino@uniroma1.it 4


5

1

Introduction

2

Test matrix

3


4


5

Conclusions





6

1
2
Domusnovas (CI)

3

Via Industriale 8/d
Ghedi (BS)
Tel: +39 030 9043 1

4

www.rwm-italia.com

5

The experimental test took place the July 22 and 23, 2013 at the facility of the
R.W.M. ITALIA s.p.a. at Domusnovas (Sardinia – Italy).



Test matrix

7

Three specimens are tested, and each is subjected to a single detonation

1
Specimen A

2
Designed with a minimum amount of required reinforcement (0.15 %)

3
Specimens B and C

4
5

Designed to achieve a specific maximum deflection if subjected to a
specific blast demand




Test matrix

8

Entry and exit ramp
3500

1

3100

Sandbags

Rupture discs

1500

Explosive charge

750

EAST

WEST

NORTH

SOUTH

Blast side

2

Planar view

Panel

800

500

Concrete support
4800
1080

1750

1370

3

Wall

4
Specimen

A
B
C

Length

Width

Thickness

Stand-off

[mm]

5

Test matrix
Not to scale

[mm]

[mm]

[mm]

3500
3500
3500

1500
1500
1500

150
200
200

1500
1500
1500



Explosive
weight

Reinforcement

[kg TNTeq] Longitudinal/Transversal
3.5
3.5
5.5

7 Φ8 / 10 Φ8
12 Φ10 / 10 Φ8
12 Φ10 / 10 Φ8


Test matrix

9

Explosive charge

PBXN-109

Comb device

1500

Wall

Longitudinal section

4800

EAST

1

WEST

1080

2

Coaxial tubes device

3500
3100

t

Panel

400

3

Concrete support
Ground

Not to scale

a
b
c

4
Panel

5

A
B
C

t

a

b

c

[mm]

[mm]

[mm]

[mm]

150
200
200

1550
1160
880

1550
1550

Two kinds of
displacement meter


comb device
2030


coaxial tube
device


Test matrix

10

1
2
3

specimen ready to be tested

4

displacement meter

explosive charge

explosive charge

5
rupture disc
large view with the explosive just armed



Test matrix

11
rupture disc
specimen

1
2
supports

charge supports

3
sand bags

operation for positioning

4
5
specimen



Test matrix

12

1
2
3
4
5


giannicola.giovino@uniroma1.it12


13

1

Introduction

2

Test matrix

3


4


5

Conclusions





14

Specimen A

1
2
maximum and residual
deflection = 108 mm.

3
4

The deflection of the
specimen A reached the
full scale value of the
coaxial tubes device.

5




15

Specimen B

1
2

The specimen B shows a ductile
failure with a diffuse crack
patterns on the central one third
of the panel span
(max 3 mm width)
maximum and the residual deflection
= 70 mm and 35 mm

3
4
5




16

Specimen C

1
2

Heavy crack patterns are
assessed. Along the mid-span of
the panel diffuse cracks are
present
(width until 10 mm)
maximum and the residual deflection
= 123 mm and 82 mm

3
4
5




17

1

Introduction

2

Test matrix

3


4


5

Conclusions





18

1
2
3
4
5




19

1

Entry and exit ramp
3500
3100

Sandbags

NORTH

Blast side

SOUTH

Rupture discs
Explosive charge

750

1500

3

500

EAST

WEST

2
Panel

800
Concrete support

1750

1370

4

4800
1080

Wall
Not to scale

5




20

1

Using the uncoupled approach the image charge provides acceptable results
without increasing the computational effort.

Reflecting surface

2
3

Image charge
side
West
North
South
East

C
A

Stand-off
[m]
6009
4705
4705
13505

α
[degrees]
27
35
35
13

B

4
Reflecting surface

5

Elementary scenario of
reverberating shock waves




21

Concrete and steel specimen testing

1
2
3
4

Specimen
N°

Concrete
Rc [MPa]

Rebar steel
fy [MPa]

Rebar steel
ft [MPa]

1
2
3
4
5
6
Average

37.46
35.87
35.60
35.19
29.89
31.01
34.17

536
540
541
547
549
547
543

616
625
626
670
676
672
647

5




22

Concrete model - the Continuous Surface Cap Model

1
Density

2.248 lbf/in4 s2
2.4*103 kg/m3

2

fcm

4060 psi
28 N/mm2

3

Cap
retraction
Rate
effect
Erosion

4
5

active
active
none

Steel model – the kinematic hardening plasticity model
•
•
•
•

yielding stress=543 MPa
Cowper and Symonds strain-rate model: D=500 s-1 q=6
steel Young’s modulus=200 GPa
Poisson coefficient=0.3





23

1
2
3
4
5




24

1
2
3
4
5




25

1

Experimental
Specime
n

2
3

A
B
C

Numerical

Experimental

δmax
[mm]

δres
[mm]

δmax
[mm]

δres
[mm]

θmax
[deg]

θres
[deg]

θmax
[deg]

θres
[deg]

108*
70
123

108*
35
82

244
58
114

240
50
106

4.0*
2.6
4.5

4.0*
1.3
3.0

8.9
2.1
4.2

8.8
1.8
3.9

* Full scale value

Component damage levels

4

Numerical

θ [degree]

µ [-]

Blowout
Hazardous Failure
Heavy Damage
Moderate Damage
Superficial Damage

>10°
≤10°
≤5°
≤2°
none

none
none
none
none
1

5
US Army Corps of Engineers (USACE). Methodology Manual for the Single-Degree-of-Freedom
Blast Effects Design Spreadsheets. The United States Army Corps of Engineers.




26

1

Introduction

2

Test matrix

3


4


5

Conclusions




Conclusions

27

1
2

- Three concrete cladding wall panels has been tested at the
testing site of the R.W.M. Italia.
- If designed for blast a concrete wall panel is able to withstand
the blast demand and it can be used as a protective cladding
wall.

3

- The carried out numerical simulations are able to predict
sufficiently the deflection of the wall panels.

4

- The image charge method can be used for taking account the
reverberating of the shock wave.

5

- The conducted test can be used as benchmark for the
Arbitrary Lagrangian Eulerian method.



Critical Infrastructures – 6C
Chair: Dörr / Gündisch




VULNERABILITY ASSESSMENT OF PRECAST CONCRETE CLADDING WALLS FOR POLICE STATIONS

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