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 STRENGTHENING OF RC ARCHES

WITH EXTERNALLY BONDED COMPOSITE MATERIALS

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Reinforced Concrete Arches

INTRODUCTION

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Fibre Reinforced Polymer

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Three arches were tested

Control arch A1

Arches A2 and A3.

Experimental Program

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Cross Section and Edge Details

Edge Details

All units in mm

6All units in mm

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Vertical Displacement – laser sensors & linear digital strain conversion transducers

Applied Load – load cells

Strain Gauges and Monitoring Devices

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For calculating theoretical deflection, three cases takenCase 1 : Perfect loadingCase 2 : Imperfect loading with a maximum error of 7%Case 3 : Cracks considered with an effective area of 0.216 m2

< 0.24 m2

Control Arch A1

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Max Load = 30 kN

Experimental Observations of Control Arch

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arch intrados between the fourth and fifth loading points.

arch extrados between the left support and the first loading point.

Cracking in Control Arch

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Arch A2 was strengthened with CFRP strips located at the center of the arch width.

The CFRP strips are 100 mm wide and 1.2 mm thick

CFRP Strengthened Arch A2

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Arch A3 was strengthened with CFRP in the same pattern as A2.

Strip ends of CFRP are anchored with an 80 mm wide CFRP fabric wrap system.

Extra CFRP at locations of severe cracks.

CFRP Strengthened Arch A3

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No significant change in deflection pattern of arches A3 and A2 with respect to Control Arch.

CFRP strips enter into action once it reaches failure load

CFRP Action and Deflection Pattern

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Failure load of A2 = 37.1 kN ( 21% increase as that of A1 )

Failure load of A3 = 42.8 kN ( 40% increase as that of A1 )

Failure of Arches A1 and A2

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Deflected Shape of Arch A2

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Deflected Shape of Arch A3

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Deflection for Arch A2

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FRP debonding rapidly propagates in FRP-strengthened beams or slabs.

FRP debonding was comparatively slow in arches.It stopped after about 10–15 cm.

Stable Debonding Mechanism

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Stable Debonding Mechanism

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Shifting location of CrackA2

A3

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CASTLEWOOD CANYON BRIDGE, COLARADO

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FRP Strengthening of Arch

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Completely Strengthened Arch

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After strengthening, the bridge strength was increased by 32%.

No loss of performance was detected after one year of service.

FRPs are also very durable.

Study on Castlewood Canyon Bridge

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High strength to weight ratio. High corrosion resistance. Very low maintenance costs over its lifetime. Lower environmental impact. Flexibility

Why FRP in construction?

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CFRP Strengthening of Arches

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CRFP can increase the load carrying capacity.

Can shifted major cracks to locations of minimum CFRP.

Stable Debonding Mechanism.

Economical

Conclusion

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Thank You