retrofitting techniques employing rc infilling of frame ... earthquake/stathis bousias... ·...
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University of Patras Structures Lab
Retrofitting Techniques employing RC infilling of
frame structures
Stathis BOUSIAS Dept of Civil Engineering, Univ. of Patras
Structures Laboratory
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b Retrofitting sub-standard structures
• Scope – Structural problem : “light” strengthening via RC walls – PsD testing problem : testing of stiff systems is prone to
control errors
• Scale ¾
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b Mode shapes
mode Period (sec) Part. Factor Model mass (%) 2η 0.6114 16.08 74.53 6η 0.1783 6.85 13.54 7η 0.0865 4.73 6.45
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b Design of the connection to frame
• Design shear forces : elastic shear forces magnified by
• New fib Model Code used for dimensioning
• Two approaches for the connection: – A : Wall reinforcement spliced with equal diameter anchors.
Additionally, one row of dowels is placed to resist shear
– B : One row of bars (dowels + anchors) along mid-width at centers of ¼ of the wall reinforcement spacing
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b Scheme A
• Dowels (16mm,130+130mm) • Anchors (10/8 mm, 130+590mm)
A
A
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b
16mm bars acting both as dowels & anchors Embedment length 130+590mm
B
B
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b Acquisition - visualization
• 96 acquisition channels • 13 network cameras • Photogrammetry at ground floor
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b Tele-presence
Telepresence Client
Data Collector
Telepresence Server
Internet
Lab.. Network
Test Structure
Controller
Network Camera
Virtual Network
Data Acquisition
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b Cyclic test - Repair
-80 -60 -40 -20 0 20 40 60 80
-250-200-150-100
-500
50100150200250
Μετακίνηση Κορυφής (mm)
Τέμν
ουσα
Βάσ
ης (k
N)
-0.89 -0.67 -0.44 -0.22 0 0.22 0.44 0.67 0.89Σχετική Μετακίνηση (%)
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b Hybrid test at 0.25g
0 2 4 6 8 10 12 14 16 18-400-350-300-250-200-150-100
-500
50100150200250300350400
Χρόνος (sec)
Τέμ
νουσ
α Β
άσης
(kN
)
Τέμνουσα Βάσης 1ης ΙδιομορφήςΤέμνουσα Βάσης
0 2 4 6 8 10 12 14 16 18-100
-75
-50
-25
0
25
50
75
100100
Χρόνος (sec)
Μετ
ακίν
ηση
(mm
)
4ος Όροφος3ος Όροφος2ος Όροφος1ος Όροφος
Floor Displacement history Modal contribution
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b 2nd Test
• Less interface reinforcement – FRP placed from the start • Equally satisfactory response
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b Conclusions
• Retrofitted specimens fail in flexure, if failure of inadequate lap splicing is precluded (at least at the base section).
• The infilling sustained no damage. • Longitudinal beam cracking needs special measures
• Overall the technique seems structurally reliable and
economically efficient.
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b Forthcoming Tests
Retrofitting substandard buildings
Use Textile Reinforced Mortar (TRM) technique (Triantafillou et. al) to convert existing masonry infill walls into a reliable resisting system
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b Substandard 2-storey structure
Scale 0.7:1
“stiff” side
“flexible” side