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 Wall reinforcement

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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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A

A

B

B

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b Scheme A

• Dowels (16mm,130+130mm) • Anchors (10/8 mm, 130+590mm)

A

A

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16mm bars acting both as dowels & anchors Embedment length 130+590mm

B

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b Acquisition - visualization

• 96 acquisition channels • 13 network cameras • Photogrammetry at ground floor

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b Measurement system

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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 Frame-wall separation

1st test 2nd test

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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 Past activities – Deficient Columns

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b Substandard 2-storey structure

Scale 0.7:1

“stiff” side

“flexible” side

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20

0 m

m

150

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b Retrofitting techniques

FRP

Soft storey

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RC jacket

Textile-Reinforced Mortar (TRM)

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Free vibration

test

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