The document discusses the PreWEC self-centering seismic resistant system. PreWEC consists of a single precast concrete wall connected to two end columns through unbonded post-tensioning strands and energy dissipating connectors. Experimental studies showed the system concentrated inelastic deformation at the wall base with minimal damage and was able to self-center after a drift of 3%. Finite element models were also able to accurately capture the system's force-displacement behavior. The performance of the energy dissipating connectors was found to be effective with some limited yielding of strands observed at design drifts.

1. Guided by, Presented by,
Ms. Sreekala C K Krishnapriya K
Assistant Professor Roll No:KNR18CECS12
GCEK GCEK

2. INTRODUCTION
PreWEC SYSTEM
EPERIMENTAL STUDIES ON
PreWEC SYSTEM
CONCLUSION
REFERENCE
2

3.  GENERAL
•Earthquake damages
•Structural concrete walls
WHAT IS SELF CENTERING?
•Reduce or prevents structural damage.
•Return the structure to the upright
position.
3

4. 4
Unbonded post-tensioned wall
Source:Henry R S et.al

5. 5
ROCKING WALL
•Clamped to the foundation using unbonded
post tensioned strands.
•Rock about the corners
•No cracking
•Concentrated gap opens at the wall base.

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Comparison of rocking wall with cast-in-place structural walls
(Source: Quingzhi Liu et.al)

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PreWEC SYSTEM
 New arrangement for self centering system
(Developed by researchers at Iowa state university)
System consists:-
 Single precast wall
 Two steel or concrete end column
 Unbonded PT strand
 End connectors

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PreWEC System
Source:Henry R S et.al

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CONNECTOR REQUIREMENTS:
Transfer forces between the wall and column
 Primary source of energy dissipation
Maintain a stable force-displacement response
Maximize energy dissipation
Welded between end column and concrete wall

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(a) Installed on PreWEC system (b)Subjected to drift
Source: Maryam Nazari et.al

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Condition of the bottom O-connector with increase in drift levels
Source: Maryam Nazari et.al

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Both are secured to the foundation using
prestressing
End columns are horizontally connected to the
wall with O-connectors
End columns are designed so as not to buckle.
End columns may be positioned at the end or on
the sides of the wall panel.

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The floor shell elements which is reinforced were tied to
the wall at the joint
 Lateral loading causes inertia forces in the floor
diaphragms
Subsequently transfer the forces into wall systems.
Area of the cracked concrete covers the yield strain in
excess of 30% of the floor area
The strains exceeding the yield strain marked by the
white shaded region

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(a)Extend of concrete cracking on the top surface (b)Yielding in the top layer of
reinforcing steel
(Figure 2.4 Predicted damage to the cast in place floor slab
Source:R.S. Henry et.al)

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Increased moment capacity.
Energy dissipating elements can be replaced.
Placement of connectors up to the height of the wall
Energy dissipating element can be added as required
without compromising the wall performance.
End column arrangement improves seismic resilience of the
building

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oPROTOTYPE BUILDING
(Source: Quingzhi Liu et.al)

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six-story office building developed by a practicing
structural engineer in the State of California.
one-third scale single frame line of the building
selected for testing

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Figure 3.4:Test setup
Source: Sri Sritharan et.al,

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TEST RESULTS
Inelastic deformation concentrated at a single crack that
opened up at the wall base and minimal damage resulted.
(a)PreWEC at 3% lateral drift (b)RC wall after 2.5% lateral drift
Source: Quingzhi Liu et.al

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ANALYTICAL MODELLING
Finite element model of test specimen developed in ABAQUS
3D FEM for PT concrete wall & O connector
 The precast concrete wall panel was modeled with 3D solid
brick elements
The wall material was modeled using the “concrete damaged
plasticity model”

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(a) Assembly (b) Deformed shape
Figure 3.6: FEM of a PreWEC system
Source:R.S. Henry et.al

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FEM predicted force-displacement envelope compared to PreWEC test result
Source:R.S. Henry et.al

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The lateral load behaviour of PreWEC subjected to
simulated seismic loading was satisfactory
If there any damage occurs or appears will be repairable
Some improvements to the wall base can be adopted to
ensure continuous use of the wall after it experiences a
lateral drift about 3%.
The performance of the specially designed , energy
dissipating O-connector was good.
Some times limited yielding of the strands was observed
at the design drift ratio.

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1.Andre FILIATRAULT, Jose RESTREPO and constantin
CHRISTOPOULOS (2004), “Development of Self-centering Earthquake
resisting systems”, 13th World Conference on Earthquake Engineering Paper
no:3393
2.Dimitrios Kalliontzis and Sri Sritharan (2016), “A simple analytical model
for the rocking PreWEC system” Magazine of Eccomass Congress 2016
3.Henry R S, Aaleti, S Sritharan, S.,and Ingham ,J.M. “Seismic analysis of a
low-damage precast wall with end columns (PreWEC) including interaction with
floor diaphragms”, Civil, Construction and Environmental Engineering
Publications, vol 25, pp 69-81.
4.Maryam Nazari, A.M. ASCE, and Sritharan , M.ASCE (2018) , “Dynamic
Evaluation of PreWEC Systems with Varying Hysteretic Energy Dissipation”,
ASCE Journal of Structural Engineering vol 144 ,pp 04018185 5-04018185 15
5.Qingzhi Liu, Catherine W. French, and Sri Sritharan (2018), “Study of
interaction between a PreWEC System and Surrounding Structure” ACI
Structural journal ,
Vol 115, pp 1407-1417

25. 25
6.R.S. Henry, S. Sritharan , J.M. Ingham (2016), “Finite element analysis of
the PreWEC self-centering concrete wall system”, Engineering Structures ,
vol 115, pp 28-41
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concrete wall with end columns (PreWEC) for earthquake resistant design” ,
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pp 2075-2092
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friction connectors” Engineering Structures, vol 161 pp 192-206
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Restrepo, Richard S Henry, Ned M Cleland, S K Ghosh and Patricio
Bonelli (2018) “Seismic-Resistant Precast Concrete Structures: State of the
Art” ASCE Journal of Structural Engineering vol 144 (4) ,pp 03118001-
031180018

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