2015 10 06_sem_pref_watanabe_chile_presentationoct2015(part1)

ReinforcedconcretePrecastandprestressedconcreteReinforcedconcretePrecastandprestressedconcrete 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
watanabe.fumio@takenaka.co.jp
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
00

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

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
02

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

2
215 /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.
04

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)
05

ud i t i oQ W ZR AC=
oC =standard base shear coefficient and 1.0 for major earthquake
Z
iW
=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. 0
Ground 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
R
t
Natural period of a building T in sec.
Hard soil
Medium soil
Soft soil
(Eq. 2)
06

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
07

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
SpectralAcceleration
T=0.5sec
T=1.0sec
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
08

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

Beam column arrangement
Beam bar welding
10

(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
11

(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
12

Monolithic pair
specimen
Japanese tests on equivalent monolithic
precast beam-column assemblage
(Courtesy of Dr. Masaru Teraoka at Fujita Cooperation)
Precast
specimen
13

Precast Wall Specimen tested by Hassane Ousalem at Takenaka Corporation
14

Testing Setup and Obtained Load Displacement Curve
Hassane Ousalem et al ;Journal of Structural Engineering, Vol.61B, March 2015
15

Testing Setup and Obtained Load Displacement Curve
Hassane Ousalem et al ;Journal of Structural Engineering, Vol.61B, March 2015
15-1

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
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
16

Requirements for Rebar Splice for Seismic Connection (Rank A)
Grout
injection
Grout
Coupler
Re-bar
2 yε 5 yε
4 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

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)
18

( / )u
a
V C M j V V
j
µ µ µ= = = >
Design condition
(4)
a
j
µ >
(1) Friction (shear strength)
Friction resistance due to flexural compression
19

( )u s y oτ µ ρ σ σ= +
µ
sρ
oσ
yσ
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)
(2) Shear Friction (shear strength)
20

sσ
: Stress ratio of re-bar
2 '
1.3dowel b c yQ d f σ=
2 ' 2
1.3 (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
(3) Dowel Action (shear strength)
(7)
Qdowel
Qdowel
21

'
1
1
n
l cl i i
i
V f w xβ
=
= ∑
1 1( )bearing r lV Smaller of V or V=
'
1
1
n
r cr i i
i
V f w xβ
=
= ∑
Concrete bearing
ix
ix
iw
β
Height of a key
Width of a key
Bearing strength factor: 1
(8-1)
(4-1) Shear Key (shear strength)
(8-2)
22

'
2
1
0.5
n
l cl i i
i
V f w a
=
= ∑
2 2( )shear r lV Smaller of V or V=
'
2
1
0.5
n
r cr i i
i
V f w b
=
= ∑
Concrete shear
(9-1)
iaix
iw
ib
'
0.5 clf
Width of a key
Bottom length of a key
Tens. strength
of concrete
(4-2) Shear Key (shear strength)
(9-2)
23

( , )shear bearingSmaller of V V
Shear strength of a set of
shear keys is given by
'
1 1
0.1
n m
u c i i j y
i 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)
(4) Shear Key (shear strength)
(10)
24

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
25

Most popular and well established beam column
arrangement in Japan
Courtesy of Dr. Masaru Teraoka at Fujita Corporation26

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

Beam hinging
28

Beam hinging
Continuous beam unit with
beam-to-column joint
29

Beam hinging
One Directional Continuous Beam Unit
Beam unit is put on column
30

One Directional Continuous Beam Unit
Courtesy of Dr. Tsutomu Komuro at Taisei Corporation
Beam-to-beam Joint
Strong Joint
31

Courtesy of Prof. Makoto Maruta at Kajima Corporation
Two Directional continuous Beam Unit
32

Post tensioned precast prestressed beam
33

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
34

Mechanical coupler
Exterior surface of
precast beam unit Casting concrete at site
Roughened surface
35

No protruding
re-bar
Only grout
injection
Grout injection
Grout outlet
Threaded splice
36

37
Construction work

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
Joint examples of frame system (Connection Interface)
38

Joint examples of wall system
(Wall-beam Unit + Column Unit + Cast-in-situ Concrete at Connections)
Cast in Place Concrete
39

Cast-in-place
beam-column
joint and slab
Panel’s hor. &
v e r t .
reinforcement

Precas
t

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
reinforcemen
t

Mainly for apartment buildings of middle rise height
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
40

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
41

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
42

Beautiful Historic Bridge in Switzerland
Built in 1930
Good materials, careful detailing and affectionate construction
Intermission
43

2015 10 06_sem_pref_watanabe_chile_presentationoct2015(part1)

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