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.