innovative retrofit of concrete and masonry...

Innovative Retrofit of

Concrete and Masonry

Buildings Murat Saatcioglu, PhD., P.Eng.

Distinguished University Professor and

University Research Chair

Department of Civil Engineering

University of Ottawa

Ottawa CANADA

Seismic Retrofit Strategy?

Retrofit individual non-ductile elements for

improved strength and deformability

(jacketing, surface-bonded FRP etc.).

System level retrofit for structural bracing and

lateral drift control (bracing by added shear

walls, steel braces, active control,

supplementary damping devices etc.)

Shear Deficiency

Kobe Earthquake1995

Chi Chi Earthquake 1999

Deficiencies in Concrete Columns

Lack of Confinement

San Fernando 1971

Nortridge 1994


Splice Deficiency


FRP Wrapping of Columns

Lightly Loaded Square Bridge

Column (P = 0.15Po)

-800

-600

-400

-200

0

200

400

600

800

-8% -6% -4% -2% 0% 2% 4% 6% 8%

Drift Ratio

Mo

men

t, M

(kN

-m)

BR-SS-R

Short Square Column

L = 1500 mm

Continuous bars

3 CFRP plies (wrapping)

Axial Load = 1160 kN (15% P0)

h = 500 mm

M

PF

M=FL+P

L

BR-SS-R

Short Square Column

L = 1500 mm

Continuous bars

3 CFRP plies (wrapping)

P = 1160 kN (15% Po)

RS-5

-300

-250

-200

-150

-100

-50

0

50

100

150

200

250

300

-5.3 -4.0 -2.7 -1.3 0.0 1.3 2.7 4.0 5.3

Displacement Ductility (mD)

Mo

men

t (k

N.m

)-8 -6 -4 -2 0 2 4 6 8

Lateral Drift (%)

Heavily Loaded Square Building

Column (P = 0.35Po)

The Canadian Standards

Association CSA S806

“Design and Construction

of Building Structures with

Fibre-Reinforced

Polymers” has design

provisions.

FRP Design

Comparisons with Experimental Data

Hardware required

External Prestressing (RetroBelt)

1

2

3 4

Installation on a Circular

Column

Installation on a Square

Column

Shotcrete Cover

-100-80 -60 -40 -20 0 20 40 60 80 100

Lateral Displacement (mm)

-600

-400

-200

0

200

400

600

-6 -4 -2 0 2 4 6

Drift (%)

BR-S1

M

PF

D

L

-6-6

12 # 25 Bars

#10 Hoops @ 300

mm

Shear Deficient Column

-100 -80 -60 -40 -20 0 20 40 60 80 100

Lateral Displacement (mm)

-600

-400

-200

0

200

400

600

-6 -4 -2 0 2 4 6

Drift (%)

Ext. Prestressed to 25% of ultimate with a spacing of 150 mm

BR-S2

M

PF

D

L

Retrofitted Shear Deficient Column

-120 -100 -80 -60 -40 -20 0 20 40 60 80 100 120

Lateral Displacement, D (mm)

-600

-400

-200

0

200

400

600

Mo

me

nt,

M (

kN

·m)

-6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6

Drift (%)

BR-C6

FP

L

DM = FL + PD

L = 2000 mm

P = 15% Po

Confinement Deficient

Column

-120 -100 -80 -60 -40 -20 0 20 40 60 80 100 120

Lateral Displacement, D (mm)

-600

-400

-200

0

200

400

600

Mo

me

nt,

M (

kN

·m)

-6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6

Drift (%)

BR-C7

FP

L

DM = FL + PD

L = 2000 mm

P = 15% Po

Retrofitted for Confinement

End of test(5% Drift)

-800

-600

-400

-200

0

200

400

600

800

-10% -8% -6% -4% -2% 0% 2% 4% 6% 8% 10%

Drift Ratio

Mo

men

t, M

(kN

·m)

Splice Deficient Column

-800

-600

-400

-200

0

200

400

600

800

-10% -8% -6% -4% -2% 0% 2% 4% 6% 8% 10%

Drift Ratio

Mo

men

t, M

(kN

·m)

After the test(10% Drift)

Retrofitted Splice-Deficient Column

Use of High Strength Packaging

Straps for Transverse Prestressing

Pneumatic Tensioner

Pneumatic Sealer

Seal



Precast concrete raiser units were manufactured

to complete square and rectangular sections to

circular and elliptical shapes,

Use of High

Strength

Packaging Straps

for Transverse

Prestressing

Flexure-dominant circular

column

Shear-dominant square

column

A large number of reinforced concrete frame

structures, with or without masonry infill

walls, are seismically deficient. They were

either designed prior to the enactment of

modern seismic codes, or built in areas

where code enforcement poses challenges.

Non-ductile R/C Frames

Bracing by Diagonal Prestressing

Bracing by Diagonal Prestressing

Unretrofitted

capacity : 270 kN

250 kN

Buckling Restrained Brace (BRB)

for R/C Frames

Masonry Infill Walls

Retrofitted Frame with Infill Wall

Fiber anchor,

inserted into hole

in column with

epoxy

Strip width: 2 feet

FRP Anchors

Anchors

Predrilled holes

Wooden guides

FRP anchors in place

FRP Anchors

-800

-600

-400

-200

0

200

400

600

800

-60 -40 -20 0 20 40 60

Force-Displacement Hysteretic Relationship

Retrofitted Specimen

(1%) (2%)

(-1%)(-2%)(-3%)

Force, kN

(3%)

Displacement, mm

(Drift)

Retrofitted

Unretrofitted

BL-2

Retrofit with Diagonal FRP Strips

-800

-600

-400

-200

0

200

400

600

800

-60 -40 -20 0 20 40 60

Force-Displacement Hysteretic Relationship Retrofitted Specimen

(1%) (2%)

(-1%)(-2%)(-3%)

Force, kN

(3%)Displacement, mm

(Drift)

Retrofitted

Unretrofitted

BL-3

Reference specimen, reflecting

as built conditions

Retrofitted specimen, diagonally

prestressed to 30% of ultimate on

both sides

Retrofitting by Diagonal

Prestressing

-800

-600

-400

-200

0

200

400

600

800

-80 -60 -40 -20 0 20 40 60 80

Force-Displacement Hysteretic

Relationship

BR-2

(-4%) (-2%) (-1%)

(1%) (2%) (3%) (4%)

(-3%)

Displacement, mm

(Drift)

Retrofitted

Unretrofitted

Retrofitting Walls with Steel

Strips

Reinforced Concrete Walls

Unreinforced Masonry Walls

Reinforced Masonry Walls

Seismically Deficient Reinforced

Concrete Wall

Reinforced

Concrete

Wall

Without

Retrofit

With

Retrofit

Unreinforced

Masonry

Wall

Without

Retrofit

With

Retrofit

Reinforced

Masonry

Wall

Without

Retrofit

With

Retrofit

PRM Wall – FRP Retrofit with FRP Anchors

FRP Anchors

Rounding of FRP


Unretrofitted Wall

Envelop


URM Walls – FRP Retrofit with Ductile

Steel Sheet Anchors

Stainless steel developed 60% elongation prior to

tensile rupture


Steel Sheet Anchors


Steel Sheet Anchors

Foundation concrete was cut

FRP anchors were

placed and epoxy

glued. They were

also bolted to

delay buckling

URM Wall – FRP Retrofit with Ductile Steel

Sheet Anchors

URM Wall – FRP Retrofit with Ductile Steel

Sheet Anchors

Unretrofitted

capacity : 55 kN

Thank You…

Questions and Comments?

innovative retrofit of concrete and masonry...

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