2015 10 06_sem_pref_watanabe_chile_presentationoct2015(part1)

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ete Reinforced concrete Precast and prestressed concrete Reinforced concrete Precast and prestressed concrete Reinforced concrete

Fumio Watanabe Emeritus Professor of Kyoto University Executive Technical Advisor of Takenaka Corporation

[email protected]

Structural Design and Construction Practice of

Precast Concrete Buildings in Japan

International Seminar on Design and Construction of Precast Structures in Seismic Regions October 2015, Chile

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I would like to express my hearty thanks to Prof. Patricio Bonelli (University Frederico Santa Maria, Valparaiso) and Dr. August Holmberg (President of Chilean Cement and Concrete Institute), who kindly invited us to nice country Chile in the southern hemisphere.

JAPAN CHILE

01

I would express my hearty sympathy to the Chilean

people who suffered the heavy losses during the great

earthquake on September 16.

Seismic Countries

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Part 1 1. Outline of Japanese Seismic Design Method 2. Requirements for Structural Equivalency to Monolithic Construction 3. Design Equations fro Interface Shear 4. Typical Detailing of Precast Connection

Dr. Tsutomu Komuro at Taisei Corporation Prof. Makoto Maruta at Shimane University (Kajima Corporation) Prof. Minehiro Nishiyama at Kyoto University Dr. Masaru Teraoka at Kure National Collage of Technology (Fujita) Dr. Hideki Kimura at Takenaka Corporation Mr. Hisato Okude at Takenaka Corporation Dr. Yuuji Ishikawa at Takenaka Corporation Dr. Hassane Ousalem at Takenaka Corporation

Part 2 5. Design Example of Precast Connection 6. Example of Precast Reinforced Concrete Building 7. Example of Precast Prestressed Concrete Building 8. Example of Precast Prestressed Concrete Stadium 9. Structural Damage in Past Earthquake

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Part 1 - 1. Outline of Japanese Seismic Design Method

Hukui Earthquake (1948, M7.1) Establishment of modern seismic design code (Building Standard Law) (1951)

Tokachi-Oki Earthquake (1968, M7.9)

Intensification of the requirement to lateral reinforcement (1971)

Miyagiken-Oki Earthquake (1978, M7.4)

Drastic revision of Building Standard Law (1981: currently used)

Hyogo-Ken Nanbu (Kobe) Earthquake (1995, M7.2)

Partial revision of 1981 Building Standard Law (1995) Adoption of performance based design process (2000) 03

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2215 /N mm for deformed bar≤

' / 3cf=

'2 / 3cf=specified yield strength≤

Flexural Design

Flexural Design


Design for Gravity Load Allowable stress design Allowable stress of concrete Allowable stress of re-bar

A: Conventional Seismic Design Method

(most widely used in Japan and completely revised in 1981) Conditions: Buildings less than 60 meters and without isolation systems, damping

devices and other response control devices

Allowable stress design for minor earthquake Allowable stress of concrete Allowable stress of re-bar

Capacity design for major earthquake Lateral story shear strength should be greater than the code

specified story shear strength which depends on the structural ductility.

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A: Conventional Seismic Design Method Capacity design for major earthquake

Required lateral strength at each story is determined based on the

elastic response for design base shear coefficient of unit and the lateral story shear distribution function.

Required lateral strength at each story can be reduced depending on the structural ductility. This reduction factor ranges from 0.30 (for special ductile moment frames) to 0.55 (for elastic　responding structures).


un s es udQ D F Q=

=required story shear strength

=elastic story shear response

=coefficient for structural irregularity

=reduction factor based on the structural ductility

udQ

esF

sD

unQ

1.0 esF≤

0.3 0.55sD≤ ≤

0.55sD =

0.30sD =

(Eq. 1)

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A: Conventional Seismic Design Method Capacity design for major earthquake

ud i t i oQ W ZR AC=oC =standard base shear coefficient and 1.0 for major earthquake ZiW

=zoning coefficient and ranged from 0.7 to 1.0 =weight of building above i-th story

0 1 2 3 4 5 6

0

0.2

0.4

0.6

0.8

1.0Ground level

αi

Lateral story shear distribution factor Ai

Roof level

T=0

T=0.1 sec.T=0.5 sec.

T=4.0 sec.

0

0.2

0.4

0.6

0.8

1

0 0.5 1 1.5 2 2.5

Rt

Natural period of a building T in sec.

Hard soil

Medium soil

Soft soil

(Eq. 2)

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B: Advanced Verification Procedure (Revised in 1981) All types of buildings can be designed by this procedure Dynamic time history analysis against earthquake ground motion is required to assure the design criteria for structural responses such as maximum inter-story drift, story ductility, member ductility and others. As input ground motions, past strong ground motion records and artificial waves are used, where artificial waves should meet the code specified standard design spectrum at the engineering bedrock. Phase, duration time and site condition (surface geology) are also considered. The engineering bedrock is defined as a thick soil stratum that shear wave velocity is not less than 400 meter/sec.

Standard Design Spectrum at Engineering Bed Rock

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C: Performance based design method (Newly established in 2000)

Required lateral strength and structural ductility are given at an intersection point (performance point) of the demand spectrum at building base and the capacity spectrum for superstructure.

The keys of design are the proper evaluation of equivalent damping factor of a superstructure and the reliable estimation of input ground motion at building base. Because the standard design spectrum (response spectrum) is given at the engineering bedrock

Spectral Displacement

Spe

ctra

l Acc

eler

atio

n

T=0.

5sec

T=1.0se

c

T=2.0sec

0.2g

0.4g

1/200

h=0.3

h=0.1

h=0.05

Demand spectra for different damping values calculated

Performance point

Determination of Performance Point

S /S =1.5/(1+10h)h 0 . 0 5

Demand Spectra for Different Damping Values Calculated

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Part 1 - 2. Requirements for Structural Equivalency to Monolithic Construction

In Japan, precast concrete building structures are being constructed that attempt to emulate seismic performances of cast-in-place monolithic structures. The reason is that Japanese Building Standard Law and Enforcement Order for structural design have been established based on the structural behavior of monolithic reinforced and prestressed concrete structures. Equivalent monolithic structural behaviour is generally demonstrated by tests on precast beam-column sub-assemblages and other structural sub-assemblies. Experimentally observed data is compared with that of simultaneously constructed pair specimen or with past experimental data in view of lateral stiffness, lateral strength, structural ductility and hysteretic behaviour (energy dissipation). 09

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Beam column arrangement

Beam bar welding


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(1) Lateral strength at yielding should be greater or equal to that of emulated monolithic construction (2) Drift at yielding should be greater than 0.8Ry and not greater than 1.2Ry of emulated monolithic construction (3) These condition should be satisfied up to 2 % drift


AIJ proposal for structural equivalency

(a) Envelop curve

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(b) Degradation and (c) Energy dissipation

With regard to the degradation of load carrying capacity during seismic load cycling, the maximum load in the second cycle should be greater than 80% of that in the first cycle in the same drift amplitude. Energy dissipation of a precast system in second loading cycle should not be smaller than 80% of that of emulated monolithic construction


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Monolithic pair specimen

Japanese tests on equivalent monolithic precast beam-column assemblage (Courtesy of Dr. Masaru Teraoka at Fujita Cooperation)

Precast specimen


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Part 1 - 2. Requirements for Structural Equivalency to Monolithic Construction Precast Wall Specimen tested by Hassane Ousalem at Takenaka Corporation

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Part 1 - 2. Requirements for Structural Equivalency to Monolithic Construction Testing Setup and Obtained Load Displacement Curve Hassane Ousalem et al ;Journal of Structural Engineering, Vol.61B, March 2015

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Part 1 - 2. Requirements for Structural Equivalency to Monolithic Construction Testing Setup and Obtained Load Displacement Curve Hassane Ousalem et al ;Journal of Structural Engineering, Vol.61B, March 2015

15-1

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Epoxy injection

Mortar Grout Type Grout injection

無収縮グラウト

1. Weather condition 2. Temperature range 3. Correct materials 4. Usable time after mixing of grout or epoxy materials 5. Correct insert length of re-bar into sleeve 6. Perfect injection of grout or epoxy 7. Fixing re-bar and sleeve until hardening of grout or epoxy

Part 1 - 2. Requirements for Structural Equivalency to Monolithic Construction Example of Rebar Splice for Seismic Connection

Threaded Screw Type

Grout outlet

Seal material

Non-shrink grout

Re-bar Sleeve

Specifications approved by the Authority

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Part 1 - 2. Requirements for Structural Equivalency to Monolithic Construction Requirements for Rebar Splice for Seismic Connection (Rank A)

Grout injection

Grout

Coupler

Re-bar

2 yε 5 yε4 cycles 4 cycles

20 cycles Elastic

Slip<0.3mm Slip<0.9mm

Re-bar

One Example Final fracture should occur at the base material 17

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Part 1 - 3. Design Equations fro Interface Shear AIJ proposal : Basic design equations for joint (1) Friction (shear strength)

( )u n uV Nτ µσ µ= =

Friction Coefficient (ACI310-02)

Normal stress

(3)

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( / )uaV C M j V Vj

µ µ µ= = = >

Design condition

Part 1 - 3. Design Equations fro Interface Shear

(4)

aj

µ >

AIJ proposal : Basic design equations for joint (1) Friction (shear strength)

Friction resistance due to flexural compression

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( )u s y oτ µ ρ σ σ= +

µ

sρ

oσyσ

Reinforcement ratio

Yield strength of reinforcement (less than 800MPa)

'0.3u cfτ <'cf Compressive strength of concrete

Normal stress Friction coefficient (ACI318-02)

To suppress the slip deformation at maximum strength less than 0.5 mm, the shear strength should be taken as a half of calculated one (excepting for ultimate limit state design).

(5)

AIJ proposal : Basic design equations for joint (2) Shear Friction (shear strength)

Part 1 - 3. Design Equations fro Interface Shear

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sσ: Stress ratio of re-bar

2 '1.3dowel b c yQ d f σ=

2 ' 21.3 (1 )dowel b c yQ d f σ α= −

/s yα σ σ=

: Yield strength of re-bar (MPa) : Bar diameter (mm)

: Tension stress of re-bar (MPa)

(6)

: Concrete strength (MPa)

yσ

α

bd'cf

Part 1 - 3. Design Equations fro Interface Shear AIJ proposal : Basic design equations for joint (3) Dowel Action (shear strength)

(7)

Qdowel

Qdowel

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'1

1

n

l cl i ii

V f w xβ=

= ∑

1 1( )bearing r lV Smaller of V or V=

'1

1

n

r cr i ii

V f w xβ=

= ∑

Concrete bearing

ixixiw

βHeight of a key Width of a key

Bearing strength factor: 1

(8-1)

Part 1 - 3. Design Equations fro Interface Shear AIJ proposal : Basic design equations for joint (4-1) Shear Key (shear strength)

(8-2)

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'2

10.5

n

l cl i ii

V f w a=

= ∑

2 2( )shear r lV Smaller of V or V=

'2

10.5

n

r cr i ii

V f w b=

= ∑

Concrete shear

(9-1)

iaixiwib'0.5 clf

Width of a key Bottom length of a key Tens. strength of concrete

Part 1 - 3. Design Equations fro Interface Shear AIJ proposal : Basic design equations for joint (4-2) Shear Key (shear strength)

(9-2)

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( , )shear bearingSmaller of V V

Shear strength of a set of shear keys is given by

'

1 10.1

n m

u c i i j yi j

V f w x a σ= =

= +∑ ∑

Japanese empirical equation for shear strength of a set of keys with joint reinforcement (Mochizuki et al)

(11)

Part 1 - 3. Design Equations fro Interface Shear AIJ proposal : Basic design equations for joint (4) Shear Key (shear strength)

(10)

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Part 1 - 4. Typical Detailing of Precast Connections

Beam hinging

Joint examples of frame system (Ductile connection 1)

Beam top bars are arranged at site

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Part 1 - 4. Typical Detailing of Precast Connections Joint examples of frame system (Ductile connection 1)

Most popular and well established beam column arrangement in Japan Courtesy of Dr. Masaru Teraoka at Fujita Corporation 26

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Beam hinging


Beam bottom bars are anchored in a joint with 90 degree hooks 27

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Beam hinging


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Beam hinging


Continuous beam unit with beam-to-column joint

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Beam hinging

One Directional Continuous Beam Unit

Beam unit is put on column


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One Directional Continuous Beam Unit

Courtesy of Dr. Tsutomu Komuro at Taisei Corporation

Beam-to-beam Joint Strong Joint

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Courtesy of Prof. Makoto Maruta at Kajima Corporation

Two Directional continuous Beam Unit

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Part 1 - 4. Typical Detailing of Precast Connections Joint examples of frame system (Ductile connection 3) Post tensioned precast prestressed beam

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Part 1 - 4. Typical Detailing of Precast Connections Joint examples of frame system (Beam to Beam; Strong connection)

Courtesy of Dr. Masaru Teraoka at Fujita Corporation

Casting concrete at site

Re-bar welding

Shear key

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Mechanical coupler

Exterior surface of precast beam unit Casting concrete at site

Roughened surface

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No protruding re-bar

Only grout injection

Grout injection Grout outlet

Threaded splice

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Part 1 - 4. Typical Detailing of Precast Connections

37

Joint examples of frame system (Beam to Beam; Strong connection) Construction work

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Composite column section

Composite Beam section

Bottom reinforcement is buried in precast unit

Bottom reinforcement is placed at site

Internal cross tie is buried in precast unit

Internal cross tie is placed at site

Inner surface is roughened

Inner surface is roughened

Part 1 - 4. Typical Detailing of Precast Connections Joint examples of frame system (Connection Interface)

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Part 1 - 4. Typical Detailing of Precast Connections Joint examples of wall system (Wall-beam Unit + Column Unit + Cast-in-situ Concrete at Connections)

Cast in Place Concrete

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Cast-in-place beam-column joint and slab Panel’s hor. &

v e r t . reinforcement

Precast column

C a s t - i n -p l a c e vertical joint

Lap splicing

Precast panel

G r o u t h o r i z o n t a l joint

Story i

Mechanical s p l i c e device

Story i+1

Story i+2

Cast-in-place part

Cast-in-place part

Cast-in-place part

Cast-in-place part

I n t e g r a t e d beam

M o r t a r s l e e v e joint

S h e a r key

Slab & beam reinforcement

Mainly for apartment buildings of middle rise height

Part 1 - 4. Typical Detailing of Precast Connections Joint examples of wall system

Courtesy of Dr. Hassane Ousalem at Takenaka Corporation

Precast Wall Panel +

Precast Colum Unit +

Cast-in-situ Beam Column Joint

+ Cast -in-situ Floor Slab

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Part 1 - 4. Typical Detailing of Precast Connections Joint examples of Half Precast Slab System

Top reinforcement: Enough buckling strength is required to prevent buckling during construction process.

Truss bar: Slab shear and lateral stability of top reinforcement

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Part 1 - 4. Typical Detailing of Precast Connections Joint examples of Precast Prestressed Half Slab System

Precast Pre-tensioned Prestressed Concrete Unit

Top Reinforcement Arranged at Site

Prestressing Strand Void Wire Mesh

Top Reinforcement Arranged at Site

Cast-in-situ Concrete

Rough Surface

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Beautiful Historic Bridge in Switzerland Built in 1930

Good materials, careful detailing and affectionate construction

Intermission

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