Giovanna Concu. The issue of assessing the structural adequacy of existing buildings involves several problems when a unique and reliable strategy of modelling and analyzing is looked for. This is mainly related to the peculiarity of each construction in a context of broad variety. In this light the structural model and consequently the judgment on structural adequacy should be derived from a process of knowledge of the construction carried through steps of different reliability. This paper focuses on a fundamental step of the knowledge acquisition process, which is the surveying campaign aimed at assessing some of the parameter to be implemented into the structural model (geometry, detailing and properties of the materials). The main aspects of a proper and effective planning of the diagnostic campaign are issued and discussed also with reference to some case studies. Special emphasis is given to the usefulness of non-destructive testing methods, the criteria underlying their selection and the relevance of their calibration.

1. Knowledge acquisition of existing buildings by means of diagnostic surveying.
Case studies.
Giovanna Concu, Nicoletta Trulli, Monica Valdès
Department of Civil and Environmental Engineering and Architecture
University of Cagliari - Italy

2. G. Concu, N. Trulli, M. Valdès – Knowledge acquisition of existing buildings by means of diagnostic surveying. Case studies.
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KNOWLEDGE ACQUISITION PROCESS
STEPS
Øresearch and collection of existing data and information
Øgeometric an structural survey
Øassessment of materials properties
LEVEL OF KNOWLEDGE CONFIDENCE FACTOR
PARAMETERS FOR THE
STRUCTURAL MODEL
Øgeometry
Østructural details
Øproperties of the material

3. G. Concu, N. Trulli, M. Valdès – Knowledge acquisition of existing buildings by means of diagnostic surveying. Case studies.
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KNOWLEDGE ACQUISITION PROCESS
Geometry
Structural details
Tests
Inspections
Properties of the material
Diagnostic campaign PLANNING

4. G. Concu, N. Trulli, M. Valdès – Knowledge acquisition of existing buildings by means of diagnostic surveying. Case studies.
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PLANNING THE DIAGNOSTIC CAMPAIGN
to achieve the highest possible level of knowledgeGOAL
CONSTRAINS
REQUIREMENTS
o statistical representativeness (single element – entire structure)
o reliability
o accuracy required
o accessibility
o admissible damage – invasiveness
o costs (time – money)

5. G. Concu, N. Trulli, M. Valdès – Knowledge acquisition of existing buildings by means of diagnostic surveying. Case studies.
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CASE STUDIES
CONCRETE STRUCTURES
Hotel Council Housing Building
Examples of some points concerning tests planning and implementation

6. G. Concu, N. Trulli, M. Valdès – Knowledge acquisition of existing buildings by means of diagnostic surveying. Case studies.
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Ground floor
Basement
CASE STUDY: HOTEL
Typical floor

7. G. Concu, N. Trulli, M. Valdès – Knowledge acquisition of existing buildings by means of diagnostic surveying. Case studies.
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CASE STUDY: HOTEL
Floor Concrete
samples
expected
Cores
extracted
UT
(V)
R
(Ir)
PO
(F)
Basement 3 3 4 15 4
Ground 12 6 5 18 8
Second 6 2 2 13 1
Third 6 2 2 8 1
Fourth 6 2 2 6 1
Total 32 15 15 60 15
LEVEL OF KNOWLEDGE = LC2 The number of concrete specimens depends on the floor area
Recurring geometric and structural layouts + Homogeneous areas + Non Destructive Testing (NDT)
Decrease of the number of specimens
Ultrasonic Testing (UT)
Rebound Hammer Test (R)
Pull-out Test (PO)

8. G. Concu, N. Trulli, M. Valdès – Knowledge acquisition of existing buildings by means of diagnostic surveying. Case studies.
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CASE STUDY: HOTEL
RESULTS
parameter mean standard deviation coeff. of variation
fc (N/mm2) 22.68 5.16 0.23
V (m/s) 3654.89 276.01 0.07
Ir 38.06 4.27 0.11
F (kN) 31.06 5.36 0.17

9. G. Concu, N. Trulli, M. Valdès – Knowledge acquisition of existing buildings by means of diagnostic surveying. Case studies.
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CASE STUDY: HOTEL
NDT parameter Correlation Formula
suggested by Italian Standards
r2
V fest = a + ebV 0.60
Ir fest = a + Irb 0.57
F fest = a + bF 0.44
V, Ir fest = a + bIr + cV 0.60
V, F fest = a + bV + cF 0.67
Ir, F fest = a + bIr + cF 0.59
V, Ir, F fest = a + bV + cIr + dF 0.68
NDT CALIBRATION
NDT parameters have been correlated to cores compressive strength

10. G. Concu, N. Trulli, M. Valdès – Knowledge acquisition of existing buildings by means of diagnostic surveying. Case studies.
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CASE STUDY: HOTEL
Compressive strength estimated by correlation formulas
Element fc
(N/mm2)
fest,V
(N/mm2)
fest,Ir
(N/mm2)
fest,PO
(N/mm2)
fest,Comb
(N/mm2)
Basement
Pillar 1 22.9 23.8 22.9
Pillar 2 19.8 19.9 21.7 21.1 19.0
Pillar 3 19.4 19.4
Pillar 4 22.1 22.1
Pillar 5 21.2 20.9 22.0 18.7 20.7
Pillar 6 24.4 24.4
Pillar 7 21.8 21.8
Pillar 8 20.9 20.9
Pillar 9 21.0 21.0
Pillar 10 23.5 23.5
Pillar 11 22.7 22.7
Pillar 12 20.5 20.5
Pillar 13 20.9 19.7 18.7

11. G. Concu, N. Trulli, M. Valdès – Knowledge acquisition of existing buildings by means of diagnostic surveying. Case studies.
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CASE STUDY: COUNCIL HOUSING BUILDING
typical floor

12. G. Concu, N. Trulli, M. Valdès – Knowledge acquisition of existing buildings by means of diagnostic surveying. Case studies.
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CASE STUDY: COUNCIL HOUSING BUILDING
Floor Concrete
samples
expected
Cores
extracted
UT
(V)
R
(Ir)
PO
(F)
Ground 2 7 7 9 8
First 3 8 8 15 10
Second 3 6 11 19 15
Third 3 5 9 18 16
Total 11 26 35 61 49
LEVEL OF KNOWLEDGE = LC2 The number of concrete specimens depends on the floor area
Visual inspection
High number of samples + NDT
Ultrasonic Testing (UT)
Rebound Hammer Test (R)
Pull-out Test (PO)
High level of damage

13. G. Concu, N. Trulli, M. Valdès – Knowledge acquisition of existing buildings by means of diagnostic surveying. Case studies.
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CASE STUDY: HOTEL BUILDING
RESULTS
parameter mean standard deviation coeff. of variation
fc (N/mm2) 24.92 6.85 0.27
V (m/s) 3170.72 439.83 0.14
Ir 32.21 4.74 0.15
F (kN) 31.70 7.29 0.23

14. G. Concu, N. Trulli, M. Valdès – Knowledge acquisition of existing buildings by means of diagnostic surveying. Case studies.
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CASE STUDY: COUNCIL HOUSING BUILDING
NDT parameter Correlation Formula
suggested by Italian Standards
r2
V fest = a + ebV 0.66
Ir fest = a + Irb 0.12
F fest = a + bF 0.43
V, Ir fest = a + bIr + cV 0.77
V, F fest = a + bV + cF 0.76
Ir, F fest = a + bIr + cF 0.41
V, Ir, F fest = a + bV + cIr + dF 0.72
NDT CALIBRATION
NDT parameters have been correlated to cores compressive strength

15. G. Concu, N. Trulli, M. Valdès – Knowledge acquisition of existing buildings by means of diagnostic surveying. Case studies.
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CASE STUDY: COUNCIL HOUSING BUILDING
Compressive strength estimated by correlation formulas
Element fc
(N/mm2)
fest,V
(N/mm2)
fest,Ir
(N/mm2)
fest,PO
(N/mm2)
fest,Comb
(N/mm2)
Ground
floor
Pillar 1 33.4 25.1 26.6 28.4 28.5
Pillar 9 25.6 27.1 32.6 31.3
Pillar 11 28.5 25.1 23.4 23.1
Pillar 13 26.1 26.6 30.0 29.5
Pillar 15 26.1 25.0 24.9 23.2
Pillar 23 19.7 25.6 25.7 25.1
Pillar 30 27.3 29.4 25.9 23.5 28.5
Pillar 31 26.6 26.6 26.3 29.4
Pillar 33 26.5 27.2 31.3

16. G. Concu, N. Trulli, M. Valdès – Knowledge acquisition of existing buildings by means of diagnostic surveying. Case studies.
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CONCLUDING REMARKS
The planning of the diagnostic surveying should follow the acquisition of some preliminary data
Ø General and specificinformation already available
Ø Geometric survey
Ø Visual inspection
Ø Identification of homogeneous areas
The selection of the diagnostic testing method should followthe analysis of some aspects
Ø Information available
Ø Required accuracy
Ø Admissible level of invasiveness
Ø Costs
NDT methods are powerful tools
Ø QUALITATIVE purpose (comparison, preliminary testsfor identifying homogeneousareas)
Ø QUANTITATIVE purpose (mechanical properties of the material) CALIBRATION is mandatory
NDT calibration is an essential step necessary for extending testing results to broader samples and estimating
mechanical and physical properties

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CONCLUDING REMARKS
The diagnostic campaign is an essential part of the knowledge acquisition process concerning existing buildings
Ø it has to be accurately planned
Ø it has to be considered, in effect, a design process
Ø it claims experienced specialists and sometimes multidisciplinary staff (historical buildings, protected buildings,..)
Ø it needs a budget proportional to the type and the amount of work

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THANK YOU FOR YOUR KIND ATTENTION
FURHER INFO: gconcu@unica.it