2nd Annual Construction Excellence: Prefab, Precast and Modular Buildings, event held at Grand Hyatt, November 2017

1. Dr. Naveed Anwar
Delving into the Application of Precast
Prestressed Concrete buildings in High
Seismic Regions
Naveed Anwar, PhD
Prof. Pennung Warnitchai, PhD
Punchet Thammarak, PhD

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Main Structural Concerns
Stability and
Integrity
01
Strength and
Servicibility
02
Local
Deformation
03
Drift
04
Ductility
05
Energy
Dissipation
06
Motion
Perception
07

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Key areas to
“Delve” in
• Gravity, Wind and Earthquake are different
• Monolithic and Precast are different
• Reinforced and Prestressed are different

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Loading
4
Wind
Earthquake
Gravity

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• Both value and direction are known reliably
• Suitable for load balancing and stress balancing
• Ideally suited for PT
Gravity Loads
• Value can be estimated and assumed static
• Direction can reverse
• PT can be designed within elastic range
Wind Load
• Value is not known well and can be much larger than design value
• Direction is not known, and effects are both lateral and vertical
• Changes rapidly with time
• Traditional PT will not work
Seismic Load

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Seismic LoadWind Load
m
ügv
A
 Excitation is an applied
displacement at the base
 force will be distributed along
interior and exterior lateral load
resisting elements
 Excitation is an applied pressure
or force on the facade
 force will act mainly on exterior
frames then transferred to floor
diaphragms

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 For most buildings, dynamic wind response may
be neglected
 Structures are designed to respond elastically
under factored loads
 Structures are designed to respond in elastically
under factored loads
 it is not economically feasible to design structures
to respond elastically to earthquake ground
motion
Design for Seismic EffectsDesign for Wind Load

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Structural systems are designed to be monolithic,
with continuity and consistent stiffness, strength and
deformability
Monolithic
Emulation
Planes of significantly reduced stiffness and strength
exist at the interface between adjacent precast
concrete structure
Jointed Precast

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Typical RC and PC Design
• Prestressed/ Post tensioned
concrete typically designed for
serviceability and stress
control
• Checked for strength
• Not suitable for ductility and
stress reversal
• Reinforced concrete is typically
designed for strength
• Checked for serviceability
• Detailed for ductility and stress
reversal

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Other
Important
Issues in PC
• Inadequate diaphragm action of PC Floors for
seismic load transfer
• PC elements to foundation connection
• The overall “integrity” of PC components and
tying forces
• Reduced redundancy compared to RC
monolithic

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Design
Expectations
• Building Codes (and the public) expect
“similar” performance from RC and PC
structure for seismic resistance
• For higher performance in seismic
design, pre-cast and prestressed needs
to be designed for ductility, energy
dissipation, and stress reversal

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Design Concept
• Divide structure into
• Elements that remain elastic
• Connections that can provide
ductility, deformability while
remaining stable
• Use pre-stress that is not loading-
direction dependent

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Some
selected
approaches
explored at
Asian Institute
of Technology
(AIT)
• Use Frames with “Rocking” joints
• Use self centering bearing/ shear Walls
• Use hybrid of frames and walls
• Add separate energy dissipater elements
• Improve precast cast joints for ductility
• Use hybrid of RC and PC wall systems

14. Dr. Naveed Anwar
Rocking Joints in Frames
Yooprasertchai, E., & Warnitchai, P. (2016). An application of precast hybrid moment-resisting frames for seismic
improvement. Magazine of Concrete Research, 68(20), 1051-1069.

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Precast Hybrid Moment Resisting Frame (PHMRF)
Ref:
Stone et al. 1995; Cheok et al. 1997;
Stanton et al. 1997; Priestley et al. 1999

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Precast Hybrid Moment Resisting Frame (PHMRF)
Reinforcing Bars Moment + Energy Dissipation
PT steels  Moment + Self Centering
Compressive Strength  Friction ForceVertical Shear

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Precast Hybrid Moment Resisting Frame (PHMRF)

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Required Behavior of PHMRF
Elastic beam
Elastic Column
Seismic Load
Gap Opening at Interior Beam-Column Joint
Gap Opening at Exterior
Beam-Column Joint
Gap Opening at Column
Foundation Joint
Note:
Special mild steels at joints are not shown
for clarity.

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Testing Hybrid Joints with Slab System
U=1.2D+0.5L+E

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Precast Hybrid Moment Resisting Frame (PHMRF)
-100
-80
-60
-40
-20
0
20
40
60
80
100
-8 -6 -4 -2 0 2 4 6 8
SDR (%)
Numerical Analysis Results
Lateralforce(kN)
-100
-80
-60
-40
-20
0
20
40
60
80
100
-8 -6 -4 -2 0 2 4 6 8
SDR (%)
Lateralforce(kN)
Experimental Results
The drift capacity is much larger than RC Frames
(Typical maximum demand is 2% -3%)

21. Dr. Naveed Anwar
Precast Hybrid Rocking Walls
Yooprasertchai, E., Hadiwijaya, I. J., & Warnitchai, P. (2015). Seismic performance of precast concrete
rocking walls with buckling restrained braces. Magazine of Concrete Research, 68(9), 462-476.

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Precast Rocking Walls
An innovative solution to resist large, cyclic seismic excitation without damage
Providing damping, and energy absorbtion
Simpler construction
Pre-cast concrete wall panel
Post-tensioning strands
Mild stel rebar dowels, partially grouted

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Precast Hybrid Rocking Walls
Pinching

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Precast Hybrid
Rocking Walls
• PCRW can deform to large displacement
without damage on the member.
• Higher stiffness (Yield  0.15% drift).
• High self centering feature.
• Lack of energy dissipation  need
energy dissipating devices.

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Precast Hybrid Rocking Walls + BRBs

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Buckling Restrained Braces - BRB

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Precast Rocking Walls + BRB
Reduced Pinching

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Combined Frame and Wall System
Yooprasertchai, E., & Warnitchai, P. (2016). An application of precast hybrid moment-resisting frames for
seismic improvement. Magazine of Concrete Research, 68(20), 1051-1069.

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Combined Hybrid Frame-Rocking Wall

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Combined
Hybrid
Frame-
Rocking Wall

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Combined Hybrid Frame-Rocking Wall

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Modeling of
Combined
Hybrid
Frame-
Rocking Wall

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Dynamic Behavior of Precast Post-Tensioned
Rocking Wall Structures
Source: Qureshi, I. M., & Warnitchai, P. (2016). Computer modeling of dynamic behavior of
rocking wall structures including the impact-related effects. Advances in Structural
Engineering, 19(8), 1245-1261.

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Impact-induced Dynamic Responses in Rocking Walls is Important
Toranzo (2002)
Horizontal Acceleration Spikes (HAS)
Vertical
Acceleration
Spikes (VAS)
Belleri (2010)

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Detailed Numerical Models
𝐌𝐮𝐥𝐭𝐢 − 𝐬𝐩𝐫𝐢𝐧𝐠 𝐅𝐢𝐛𝐞𝐫 𝐦𝐨𝐝𝐞𝐥 𝐅𝐢𝐧𝐢𝐭𝐞 𝐄𝐥𝐞𝐦𝐞𝐧𝐭 𝐦𝐨𝐝𝐞𝐥

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During rocking motion, the gap at wall-
foundation joint can be considered to be almost
always open.
As the gap opens in Rocking walls, the lateral
stiffness suddenly reduces to a much lower level
compared to the initial stiffness. This change in
stiffness in conventional structures is gradual.
Simplified Models and Conclusions

37. Dr. Naveed Anwar
Experimental Study on Welded-Splice Connection in
Typical Beam-Column Precast Frames in Thailand
Source: Chuachart, S. An Experimental Study on welded-splice connection in
typical beam-column precast frames in Thailand under reversed cyclic load.

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Typical PC Frame in Thailand

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Test Program to Compare PC and RC Connections
Control specimen Precast specimen

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RC Specimen

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Precast Specimen

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Failure Mode and Crack Pattern
RC specimen at Max Drift Precast specimen at Max Drift

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Ductility and Energy
0
2000
4000
6000
8000
10000
0.00 1.00 2.00 3.00 4.00
Energydisspation(N-m)
%Drift ratio
0
1000
2000
3000
4000
5000
6000
0.00 1.00 2.00 3.00 4.00
Energydisspation(N-m)
%Drift ratio

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R & D and Application
Some Selected Projects

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A Rational Approach for Developing New Systems
Calibration of Connection for Finite Element Analysis
Full 3D Finite Element Modeling of Typical Structures
Evaluate the Performance Acceptance of Real Sites
Experimental Study Connections and Details

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Calibration Process
Test Model FE Model
Connection to test

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Localization for Site Specific Criteria
FoundationsResponse Spectrum

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R&D for Systematic Determination of Shortcoming

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Project Overview
108.60
m
(37
Stories)
Transfer Beams
Residential Floors
Cast-in-Place Shear Walls
Precast Concrete Walls
Car Parking Floors
Roof
Precast Concrete Slabs
Post-tensioned slabs
15.4 m (5 Stories)
RC Columns

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Linear and Nonlinear Models
ETABS (Linear) PERFORM 3D (Nonlinear)
X
Y
X
Y

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Nonlinear Dynamic Analysis

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Performance Based Evaluation of PC-RC Hybrid Building

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Project Overview
Elevation View
Plan View

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Finite Element Modeling
3D FEM Model
Structural System for Lateral Load
2nd Floor to Roof  Precast walls + Cast-in-place RC wall
Cast-in-place RC wall
Plan View Elevation View

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Finite Element Modeling
Modeling of Precast Wall Connection
Precast Wall
(Shell Element)
Link Element
Transfer Beam
(Shell Element)
Cast-in-place
Wall
(Shell Element)
Link beam

58. Dr. Naveed Anwar
Seismic Performance Evaluation of
Precast Bearing Wall System

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Finite Element Modeling
Structural Member Finite Element
Pile Cap
Shell Element with
Hinged Support at Pile
Location
Beams and Columns Frame Element
Slab Panels Shell Element
Cast-in-Place Wall Panels Nonlinear Shell Element
Precast Wall Panels Frame Element
Precast Wall Connection
(Wall-Wall Vertical
Connection)
Nonlinear Link Element
(from Previous Study)
Precast Wall Connection
(Top-Bottom Wall Connection)
Nonlinear Link Element
(from Previous Study)

60. Dr. Naveed Anwar
Concluding
Remarks
The seismic performance of Precast
Buildings can be improved by
addressing:
• Integrity and load transfer
• Ductility
• Energy dissipation
Using
• Rocking concepts
• Hybrid systems

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References
• Yooprasertchai, E., & Warnitchai, P. (2016). An application of precast hybrid moment-resisting
frames for seismic improvement. Magazine of Concrete Research, 68(20), 1051-1069.
• Yooprasertchai, E., Hadiwijaya, I. J., & Warnitchai, P. (2015). Seismic performance of precast
concrete rocking walls with buckling restrained braces. Magazine of Concrete Research, 68(9),
462-476.
• Qureshi, I. M., & Warnitchai, P. (2016). Computer modeling of dynamic behavior of rocking wall
structures including the impact-related effects. Advances in Structural Engineering, 19(8), 1245-
1261.
• Chuachart, S. An Experimental Study on welded-splice connection in typical beam-column
precast frames in Thailand under reversed cyclic load.
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