arangio sapienza-may2015
TRANSCRIPT
StructuralStructural design design ofof newnew panelspanels forfor the the
mosaicsmosaics ofof Villa Villa SilinSilin, Leptis Magna , Leptis Magna
S. Arangio. F. Bontempi, M.L. Santarelli, M. Zuena, G. Quattrociocchi.
B. Davidde Petriaggi, A. El-Turki, F. Olini
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Structural design of new panels for the mosaics of Villa Silin, Leptis Magna
Prof. Maria Laura Santarelli: Scientific Coordinator
Prof. Franco Bontempi
Stefania Arangio, Ph.D., P.E.
Martina Zuena, Ph.D. student
Gaia Quattrociocchi, Ph.D. student
Adel El-Turki - Department of Antiquities of Libya, Tripoli
Barbara Davidde Petriaggi
Fabrizio Olini
People involved in the project
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Structural design of new panels for the mosaics of Villa Silin, Leptis Magna
1. Design of the new support panels for the mosaic
2. Choice of the materials
3. Numerical analyses
4. Experimental tests for the identification of the mechanical
properties of the mixes
Outline
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Structural design of new panels for the mosaics of Villa Silin, Leptis Magna
1. Design of the new support panels for the mosaic
2. Choice of the materials
3. Numerical analyses
4. Experimental tests for the identification of the mechanical
properties of the mixes
Outline
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Structural design of new panels for the mosaics of Villa Silin, Leptis Magna
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Structural design of new panels for the mosaics of Villa Silin, Leptis Magna
Case study
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Structural design of new panels for the mosaics of Villa Silin, Leptis Magna
Case study
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Structural design of new panels for the mosaics of Villa Silin, Leptis Magna
View of the mosaic
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Structural design of new panels for the mosaics of Villa Silin, Leptis Magna
Damage
Deformation of the pavement
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Structural design of new panels for the mosaics of Villa Silin, Leptis Magna
Damage
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Structural design of new panels for the mosaics of Villa Silin, Leptis Magna
Damage
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Structural design of new panels for the mosaics of Villa Silin, Leptis Magna
Analysis of the damage
It is possible to observe a significant degradation of the mosaic.
The existing screed was inserted in a restoration done in the ’70s. It is made by concrete with embedded reinforcing bars.
Over time the steel of the bars oxidized and caused damage to the structure of
the floor, making also some mosaic tiles fall off.
The observed damage and degradation may depend on various factors :
•Concrete and steel are not suitable in case of aggressive environmental
conditions;
•the non-adequate thickness of the support can have led to the occurrence of
cracks;
•wrong (or no existent) isolation joints and dilatation joints
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Structural design of new panels for the mosaics of Villa Silin, Leptis Magna
Detachment of the panels
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Structural design of new panels for the mosaics of Villa Silin, Leptis Magna
Detachment of the panels
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Structural design of new panels for the mosaics of Villa Silin, Leptis Magna
Design of the new supports for the panels
Design Requirements:
-Non - invasive and reversible intervention;
-Use of natural sustainable materials;
-Compatibility of the material with the residual concrete.
-Adequate structural performance.
Design strategy:
Considering the natural environment of the villa, which is characterized by large changes in temperature and humidity, the strategy of the project has been
oriented toward techniques that can avoid the development of cracks as
-inclusion of fibers with a good tensile behaviour in the mortar mix
-use of natural fiber grids to avoid the use of metallic reinforcements;
-use of mortars/conglomerates with near-zero shrinkage.
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Structural design of new panels for the mosaics of Villa Silin, Leptis Magna
Final design
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Structural design of new panels for the mosaics of Villa Silin, Leptis Magna
Final design
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Structural design of new panels for the mosaics of Villa Silin, Leptis Magna
1. Design of the new support panels for the mosaic
2. Choice of the materials
3. Numerical analyses
4. Experimental tests for the identification of the mechanical
properties of the mixes
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Structural design of new panels for the mosaics of Villa Silin, Leptis Magna
Materials
1. Mortar
• with natural hydraulic limes (NHL) as St. Astier
2. Chopped and milled fibers for crack control
3. Basalt grid as reinforcement
3. Basalt Minibars
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Structural design of new panels for the mosaics of Villa Silin, Leptis Magna
Properties
•Fast and effective mixing
•Fibers do not float or sink
•The grids allow thinner pavements.
•Easy to install.
•Minibars can be added to the mixes instead of the metallic bars.
Advantages
•Non corrosive•High tensile strenght
•Low weight (density 1/3 of steel)
•Moderate cost•Increases chemical resistance for a significant reduction of shrinkage cracks
Properties of basalt
Fibers
Grids
Minibars
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Structural design of new panels for the mosaics of Villa Silin, Leptis Magna
1. Design of the new support panels for the mosaic
2. Choice of the materials
3. Numerical analyses
4. Experimental tests for the identification of the mechanical
properties of the mixes
Outline
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Structural design of new panels for the mosaics of Villa Silin, Leptis Magna
Consideration for the numerical analyses
• It is necessary to consider that the mosaic could be used so it should have
an adequate strenght
• Load in service conditions: 2,5 kN/m2
• Specific attention to the transitory phase.
• The ultimate limit state is never reached because a significant defirmation
woul detach the tiles of the mosaic
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Structural design of new panels for the mosaics of Villa Silin, Leptis Magna
Plate n.1: non linear analysis
Square plate1m x1m with unilateral supports
Non linear material
Principal stress �22 Principal stress �11
Load:
1kN on 0.25m x 0.25m
4 restraints
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Structural design of new panels for the mosaics of Villa Silin, Leptis Magna
Plate n.1: non linear analysis
In the considered range the behavior is linear
2,5 kN on
0,25m x0,25m
Square plate1m x1m with unilateral restraints
Non linear material
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Structural design of new panels for the mosaics of Villa Silin, Leptis Magna
Plate n.2: non linear analysis – transitory phase
Plate 2m x1m with with 4 compression- only edges supports
Non linear material – transitory phase
Due carichi da 2,5 kN su impronta 0,25m x 0,25m
Deformed shape (1,5xservice load)
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Structural design of new panels for the mosaics of Villa Silin, Leptis Magna
Dead Load
Piastra n.2: analisi non lineare – fase transitoria
Plate 2m x1m with with 4 compression- only edges supports
Non linear material – transitory phase
In the considered range the behavior is linear
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Structural design of new panels for the mosaics of Villa Silin, Leptis Magna
Outline
1. Design of the new support panels for the mosaic
2. Choice of the materials
3. Numerical analyses
4. Experimental tests for the identification of the mechanical
properties of the mixes
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Structural design of new panels for the mosaics of Villa Silin, Leptis Magna
Setup of the flexural test
8 plates (dimensions 1m x 0,5 m) with different mixes
Simply supported
Increasing load applied at the mid span
Maximum expected load:150 kgMaximum expected vertical displacements: < 40 mm
P
50 cm
90 cm
5 cm
10 cm
30 cm
sensors
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Structural design of new panels for the mosaics of Villa Silin, Leptis Magna
Flexural test
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Structural design of new panels for the mosaics of Villa Silin, Leptis Magna
Mixes of the plates
n. NHL 5 Chopped fibers Basalt grid
(H=2,5cm)
Minibars
B1 X NO X NO
B2 X X (1/2”) 6%W X NO
B3 X X (1/2” ) 3%W X NO
B4 X X (2%W) NO X
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Structural design of new panels for the mosaics of Villa Silin, Leptis Magna
NHL 5 + sand (1:2) + H2O + basalt grid
Results: mix B1
0
50
100
150
200
0 10 20 30 40 50
Lo
ad
(k
g)
Vertical displacements (mm)
Load - Vertical displacements
mixture B1
mixture B1_2Brittle fracture
Cracking
Mortar + grid
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Structural design of new panels for the mosaics of Villa Silin, Leptis Magna
Results: mix B1
crack1
crack 2
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Structural design of new panels for the mosaics of Villa Silin, Leptis Magna
Mix 2: NHL 5 + sand (1:2) + H2O + chopped fibers 6% + basalt grid
Mix 3: NHL 5 + sand (1:2) + H2O + chopped fibers 3% + basalt grid
Results: mix B2 - mix B3
0
50
100
150
200
0 10 20 30 40 50
Lo
ad
(k
g)
Vertical displacements (mm)
Load - Vertical displacements
mixture B2
mixture B3
6% fibers
3% fibers
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Structural design of new panels for the mosaics of Villa Silin, Leptis Magna
Mix 4: NHL 5 + sand (1:2) + H2O + chopped fibers + minibars
Results: mix B4
0
50
100
150
200
0 10 20 30 40 50
Lo
ad
(k
g)
Vertical displacements (mm)
Load - vertical displacements
mixture B4_1
mixture B4_2
mixture B4_3
Good behavior in case of load/unload cycles
Uso di materiali innovativi per il risanamento del supporto di un mosaico
Mix B4: deformazione
Uso di materiali innovativi per il risanamento del supporto di un mosaico
Minibars in the fracture zone
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Structural design of new panels for the mosaics of Villa Silin, Leptis Magna
Comparison of the behavior
0
50
100
150
200
0 10 20 30 40 50
Ca
ric
o (
kg
)
Spostamenti verticali (mm)
DIAGRAMMA CARICHI-SPOSTAMENTI VERTICALI
mix1
mix1_2
mix2
mix3
mix4_1
mix4_2
mix4_3
Only grid
grid +
chopped
chopped +
minibars
LOAD – DISPLACEMENTS
Vertical displacements
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Structural design of new panels for the mosaics of Villa Silin, Leptis Magna
Comparison of the behavior for displacements < 1,5mm
0
50
100
150
200
0,00 0,50 1,00 1,50
Cari
co
(k
g)
Spostamenti verticali (mm)
DIAGRAMMA CARICHI-SPOSTAMENTI VERTICALI
mix1
mix2
mix3
mix4
solo rete
grid + chopped
chopped + minibars
Range for the considered case study
LOAD – DISPLACEMENTS
Vertical displacements
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Structural design of new panels for the mosaics of Villa Silin, Leptis Magna
Additional load tests…
around 300 kg…
Test with an increasing load
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Structural design of new panels for the mosaics of Villa Silin, Leptis Magna
40 cm
400 kg
About 400 kg on a span of 40 cm
Additional load tests…
Uso di materiali innovativi per il risanamento del supporto di un mosaico
“Impact” test
40 cmH = 50 cm
50 kg
Uso di materiali innovativi per il risanamento del supporto di un mosaico
70 kg
“Impact” test with increasing load
Uso di materiali innovativi per il risanamento del supporto di un mosaico
85 kg
“Impact” test with increasing load
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Structural design of new panels for the mosaics of Villa Silin, Leptis Magna
Conclusions
Features of the intervention:
•Natural materials with a good behavior in aggressive environmental
conditions
•The intervention is reversible
The project has been carried out with the deep interaction between
technicians and researchers with different expertise
The results of the experimental tests have shown that the chosen solution
meets the requirements from both the philological and the structural
points of view
