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NUMERICAL INVESTIGATIONS ON THE
SEISMIC RESPONSE OF MULTI-STOREY
HYBRID PRECAST CONCRETE FRAMES
WITH NON-TEARING FLOOR CONNECTIONS
By Alejandro Amaris, Stefano Pampanin,
Des Bull, Athol Carr.
New Zealand Society of Earthquake Engineering.
Christchurch, 2009
IntroductionProblems associated with Beam sidesway
Mechanism of Plastic deformation
Sidesway Mechanism and beam elongation effects for precast frame systems.
(fib Bulletin 27, 2003)
Alternative innovative solutions to
reduce damage in the floor
SOLUTION B
Non-gapping frame system
(recently proposed)
+
Standard floor solution
SOLUTION A
“Gapping” frame system
(traditional Jointed ductile
connection)
+
Articulated (jointed) floor
External energy dissipaters
Tendon profile
Top Mono Hinge
External Dissipater
T-Shape steel plate
CorbelExperimental investigations
SOLUTION B Non-Gapping frame SystemInnovative “no-gapping”and “no-tearing” jointed
ductile connection + standard floor solution
Building Description
PRESSS Design Handbook (NZCS, 2009)
Numerical Investigations on a Multi-
storey, multi-bay Hybrid Precast
Frame Systems
Building Description
•Building Location: Wellington
•Soil type: C (shallow soil)
•Importance level: 2
•Return period: 500 year
•Near fault effects within 2km
•Design: DBD procedures for
Monolithic system
•Target interstorey drift: 2.0%
5 Storeys at 3.8 m, total height 19.0 m
m
30.0
Numerical Investigations:
Monolithic Beam Column Models excluding
and including beam elongation.
The plastic hinge is modeled as
a rotational spring using a
Takeda hysteresis behaviour.
q (1/m)
M (kNm)Mon model
Beam elongation is modeled as
series of inelastic truss
elements representing the
concrete and reinforcing steel
Mon_beam-elong model
D
F (kN)
Concrete element
(Multi-spring element)
D
F (kN)
Reinforcing steel
(compound element)
Elastic column
Elastic Beam
Elastic column
Elastic Beam
Linear elastic
-
Bi-linear inelastic
The connection is
modeled with the
combination of moment
rotation contributions of
two springs in parallel.
q (1/m)
M (kNm)
M (kNm)
q (1/m)
Hy_non-tear model
Numerical Investigations:
Hybrid Beam Column Models with non-
tearing connection.
Elastic column
Elastic Beam
Hy modelHybrid Connection is modeled as
combination of the moment
rotation contributions of two
springs in parallel
M (kNm)
q (1/m)
Bi-Linear elastic Bi-linear inelastic
M (kNm)
q (1/m)
D
F (kN)
Concrete element
(Multi-spring element)
Reinforcing steel
(compound element)
D
F (kN)
D
F (kN)
Hy_beam-elong modelBeam elongation is modeled as
series of inelastic truss
elements representing the
concrete, reinforcing steel and
post-tensioned tendons Post-tensioned tendons (Linear elastic)
Numerical Investigations:
Hybrid Beam Column Models excluding
and including beam elongation.
Numerical Investigations
Adaptive Push over Analysis
Adaptive push over analysis with an
initial inverted triangular shape.0 0.4 0.8 1.2 1.6 2 2.4
Roof Drift (%)
0
500
1000
1500
2000
La
tera
l Fo
rce
(kN
)
0 100 200 300 40050 150 250 350 450
Roof Displacement (mm)
Hy_
Hy
Hy_
Mon
Mon_
non-tear
beam-elong
beam-elong
Numerical Investigations-Time History
Analysis: Mean and maxima inter-
storey drift ratio
Far field
0 0.5 1 1.5 2 2.50
1
2
3
4
5
Interstorey Drift, %
Sto
rey
Mean
Max.
Hy-non-tear
0 0.5 1 1.5 20
1
2
3
4
5
Interstorey Drift, %
Sto
rey
Mean
Max.
Hy-non-tear
Near field
0 0.5 1 1.5 20
1
2
3
4
5
Interstorey Drift, %
Sto
rey
Mean
Max.
Mon-beam-elong
0 0.5 1 1.5 20
1
2
3
4
5
Interstorey Drift, %
Sto
rey
Mean
Max.
Mon-beam-elong
0 0.5 1 1.5 20
1
2
3
4
5
Interstorey Drift, %
Sto
rey
Mean
Max.
Hy-beam-elong
0 0.5 1 1.5 20
1
2
3
4
5
Interstorey Drift, %
Sto
rey
Mean
Max.
Hy-beam-elong
Numerical Investigations-Time History
Analysis: Mean and cumulative
storey shear
Mean and cumulative storey shears for far field set of Earthquakes
0
1
2
3
4
5
0 200 400 600 800 1000Storey Shear (kN)
Sto
rey
MonMon_beam-elongHyHy_beam-elongHy_non-tear
0
1
2
3
4
5
0 1000 2000 3000Cumulative Shear (kN)
Sto
rey
MonMon_beam-elongHyHy_beam-elongHy_non-tear
Conclusions
In general, the response of the hybrid system using non-tearing
connection was very satisfactory under push-over and THA.
Push over analysis indicates that lateral stiffness was lower for the
hybrid with non-tearing connections when compared with the traditional
hybrid systems. However, the total base shear (for the same imposed drift
level) was similar.
Additionally, push over analysis indicate that beam elongation were
higher in the 2nd floor of the frames were plastic hinge was 7.1% and 5.1%
of the beam depth for the monolithic and hybrid systems respectively.
THA indicate that no excessive increase on inter-story drift response
when compared to the targeted 2% of drift was found for all the models
except the set of near field earthquakes which were more severe for the
Hybrid with non-tearing connections.
Conclusions
Beam elongation effects change the distribution of moments, shears and
inter-storey drifts throughout the frames specially the first two storeys.
For the hybrid with non tearing solution the storey shears remain
constant.
A series of numerical investigations are under-going to provide further
confirmations of the behaviour of this type of systems using non-tearing
connections.
Acknowledgments
The financial support provided by the New
Zealand Foundation of Research, Science and
Technology (FRST) under the “Future Building
System” research project is greatly
appreciated.
http://www.frst.govt.nz/