Retrofitting Techniques Retrofitting Techniques for Existing Buildings for Existing Buildings

Seismic Rehabilitation Strategy

Concept of Seismic Rehabilitation of Buildings

Behavior of Strengthened Frames

Behavior of Strengthened Frames withSteel Systems

Steel Systems

Load-Displacement Relationship

Current Techniques for Seismic Rehabilitation

Strengthening Existing Frames

Increase the Structural PerformanceIncrease the Structural Performanceof Existing Buildingsof Existing Buildings

1) Increase the StrengthShear Wall, Steel BraceOuter Frame

2) Increase the Deformation CapacityJacketing by RC or SteelCarbon Fiber Wrapping

3) Decrease the Earthquake InputBase IsolationDamping DeviceDecrease the Weight

Retrofitting TechniquesRetrofitting Techniques

1) RC Shear Wall2) Steel Brace3) Outer Frame

4) Jacketing by RC or Steel5) Carbon Fiber Wrapping

6) Joint TechniquesPost-installed AnchorsMortar InjectionHigh-tension Bars

RC Shear WallRC Shear Wall

Roughening Roughening the Face of Concretethe Face of Concrete

Spiral ReSpiral Re--barbar PostPost--Installed AnchorInstalled Anchor

RC Shear WallRC Shear Wall

Spiral ReSpiral Re--barbar

PostPost--Installed AnchorInstalled Anchor

RC Shear WallRC Shear Wall

Steel BraceSteel Brace

Steel BraceSteel Brace

Mortar Injection

Steel BraceSteel BraceMansard typeMansard type

Outer RC FrameOuter RC Frame

Outer Steel FrameOuter Steel Framewith Bracewith Brace

Steel JacketingSteel Jacketingof Columnof Column

Mortar Injection

Welding

Carbon FiberCarbon FiberJacketingJacketingof Columnof Column

Sheet

Strand

Behavior of Reinforced Columns

Aramid Fiber Outer Steel Brace

PCa Wall

Other Retrofitting TechniquesOther Retrofitting TechniquesRelatively New in JapanRelatively New in Japan

1) New Materials2) New Construction Methods3) New Systems

Carbon Fiber Strand

New Material - 1Carbon Fiber Strand/Sheet + Epoxy ResinCRS-CL Research Association

Tel. +81-3-5427-8666

Carbon Fiber Sheet

Carbon Fiber Sheet

(Beam)

New Material - 2Carbon Fiber Sheet + Epoxy ResinMARS Research Association

Tel. +81-29-847-7503

Jacketing Work for Column using

Carbon Fiber Sheet+ Epoxy Resin

ColumnsJacketed with

Carbon Fiber Sheet+ Epoxy Resin

New Material - 3Carbon Fiber Sheet + Meta-Acrylic ResinMitsubishi Rayonne Co. Ltd.

Tel. +81-3-5495-3106

PaintingMeta-Acrylic

Resin on Column Face

Cutting Carbon Fiber

Sheet

Jacketing Workfor Column using

Carbon Fiber Sheet

New Material - 4Carbon Fiber Sheet/Anchor + Epoxy ResinSR-CF Construction Research Association

Tel. +81-3-5441-0123

Carbon Fiber Anchor

CF AnchorHole

Bonded on SheetCF Sheet

CF AnchorCF Sheet

Bonded on CF SheetHole

Column

Column

Beam

ColumnwithWall

Wall

New Material - 5Carbon Fiber Plate + Epoxy Resin + MortarCF-Advanced Construction Council

Tel. +81-3-3263-3575

Carbon Fiber Plate Construction Procedure

New Material - 6Aramid Fiber SheetAF Construction Research Association

Tel. +81-3-3245-5082

AramidFiber Sheet

Jacketing Workfor Column

Columns Jacketed with Aramid Fiber Sheet

New Material - 7Glass Fiber Sheet + Epoxy ResinTYFO Construction Research Association

Tel. +81-3-3293-5290

Jacketing Workfor Column

Column Jacketed with Glass Fiber Sheet

New Material - 8Polyester Fiber SheetStructural Quality Assurance

Tel. +81-3-5274-3431

Jacketing Workfor Column

S

t

r

e

s

s

(

N

/

m

m

2

)

4000

3000

2000

1000

00 2 4 6 8 10

Strain (%)

Carbon Fiber

Aramid Fiber

Polyester Fiber

Stress-StrainRelationships

(Polyester Fiber)

New Material - 9Wire Mesh + Polymer Cement MortarMagnekagaku Co., Ltd.

Tel. +81-92-477-3533

Wire Mash Put Polymer Cement Mortar on

Column FaceAfter Test

New Construction Methods - 1High Tension Bar + Steel PiecesNetsuren Co., Ltd.

Tel. +81-463-55-1448

Construction Procedure

Hole

High Tension BarSteel Piece at the Corner

New Construction Methods - 2Special Joint for Steel JacketingShimizu Corporation

Tel. +81-3-5441-0123

SpecialJoint

Steel Jacketingwithout Welding in Site

MortarInjection

New Construction Methods - 3Steel Brace + Epoxy Resin ConnectionTakenaka Corporation

Tel. +81-3-3542-7100

Existing Concrete

Pipe for AirEpoxy

Injection

Seal

Steel FrameDetails of Connection

Steel Frame

Epoxy Injection

Existing Concrete

Steel Brace

New Construction Methods - 4Pre-Cast Concrete BraceTaisei Corporation

Tel. +81-3-5381-5070

Pre-Cast Concrete Elements

Construction

Pre-Cast Concrete Braceafter Finishing

New Construction Methods - 5Pre-Cast Concrete WallPCa Wall Research Association

Tel. +81-3-3837-6070Joint of PCa Wall High Tension Bar

Post-Installed Anchor

SpiralRe-Bar

MortarInjection

Shear KeyInsert

Bolt

Details of Pre-Cast Concrete Wall

New Construction Methods - 6Outer Steel BraceYokosuka City Office

Tel. +81-468-22-4000

Steel Frame and Brace Details of Connection

Post-Installed Anchor

Column

Beam

Seismic Isolation

Merit

Preservation of building function during construction

Less construction area Preservation of building

facade and interior

Application to:

Critical and essential buildings

Buildings with expensive and valuable contents

Structures where superior seismic performance is required

Supplemental Damping System

Merit

Reduction of seismic response Easy installation Less construction area Less trouble to occupants

Application to:

Flexible buildings where large lateral displacement is expected

Tall buildings Buildings with limited area for

seismic rehabilitation

Response Control for Seismic Rehabilitation

u

F F

u

F

u

F

u

uCuKF &+= )()( )(ufKF =uCF &= uCuCF && = 21 or

u

F F

u

F

u

F

u

uCuKF &+= )()( )(ufKF =uCF &= uCuCF && = 21 or

Viscous Oil Viscoelastic Steel

Shear/Flow Resist.Panel, Box, Cylinder

Flow Resist.Cylinder

Shear Resist.Cylinder, Panel, etc.

Axial/Shear YieldingCylinder, Panel, etc.

Examples of configuration of passive control systems(From K. Kasai, Tokyo Institute of Technology, Japan, 2004)

Examples of configuration of passive control systems(From K. Kasai, Tokyo Institute of Technology, Japan, 2004)

Examples of configuration of passive control systems(From K. Kasai, Tokyo Institute of Technology, Japan, 2004)

Seismic Isolation

Isolators

Seismic Rehabilitation Utilizing Seismic Isolation

Seismic Isolation below Existing Foundation Slab

Seismic Rehabilitation at the Top of First Story Column

Rehabilitated Buildings by Seismic Isolation

R: interstory drift Vmax: maximum velocity

Building Structure Size IsolatorLocation of

Isolator Objective Performance

Museum RCB1 F3

high damping rubber bearing

under foundation

CB

Supplemental Damping System

Energy Dissipating Devices

Buckling Preventive Braces

Friction Damper Steel Yielding Damper

Rehabilitated Buildings by Supplemental Damping System

R: interstory drift Vmax: maximum velocity

Building Structure Size Damping DeviceLocation of

Dampers Objective Performance

Office SRCB1 F10

steel elasto-plastic damper

on the top of steel braces

R

Characteristics of Typical Construction Methods to Strengthen Existing Frames

Concrete Walls Steel Braces Exterior Structures

ConstructionMethod

SuitableBuildings

Attention to

ConstructionPerformanceCost

Steel Brace

Mega-structure

New Piles

Building

Place concrete wallinside existing frame

Place steel brace inside existing frame

Place exterior structuresalong existing building

Many brittle membersSufficient margin in

foundation system

Large window openingAvoid increased weight

Strengthening not insideWide space outside building

Increased building weight Disturbance to

building function

Window opening available Outer space for constructionExtensive construction

Extensive constructionGood Good GoodCheap Moderate Expensive

Good Good

Characteristics of Typical Construction Methodsto Jacket Existing Columns

ConstructionMethod

Buildings with

Attention to

ConstructionPerformanceCost

LateralReinforcement

SteelPlate

MortarGrouting

ContinuousFiber

Small amount of walls Small amount of walls Small amount of wallsFormworksIncreased column sectionand weight

Welding in construction siteConveyance of steel plate

Fire and battingSmoothing corners

Short period Short periodGood Good GoodCheap Expensive Moderate

ConcreteJacketing

Steel Jacketing

Continuous FiberJacketing

Long period

Jacket column with Concrete. Jacket column withand lateral rfmt. Steel Plate

Jacket column withContinuous Fiber

Seismic Isolation Supplemental Damping

Buildings with

Attention to

Construction

PerformanceCost

ConstructionMethod

IsolatorDry Area

New Foundation BeamsExisting Pile

Damper

New Brace

Install isolators belowfoundation beams

Install dampers inside existing frames

High stiffnessStrict requirements for design and functionOuter space for building displacementDetailing for equipments at isolation level

Extensive construction

Significantly reduced seismic response

Expensive due to extensive construction

Low stiffnessStrict requirements for design and functionNew frames for dampersAdequate arrangement of dampers

Extensive construction

Reduced seismic responseExpensive due to new frames

Characteristics of Typical Construction Methodsto Control Building Response

Retrofitting Techniques for Existing Buildings