PERFORMANCE EVALUATION OF
RC HIGHRISE BUILDINGUNDER LONG PERIOD GROUND MOTION AND
FORMULATION OF NONLINEAR MODELINGS.Murugan ∗MEE08170

Supervisor: Taiki Saito ∗∗ABSTRACTThis study proposed new models for beam and column elements based on experimental results whichenable to consider the strength degradation by long period loading. The performance evaluation of a 36story model RC highrise building was conducted by adopting the proposed element models under long
period ground motions.
The dynamic analysis was conducted using STERA 3D software by inputting El Centro 50Kine, BCJ-L2, Osaka and Sannomaru ground motions. It was found that the performance of thebuilding was within the safety criteria of design standard except that under Sannomaru ground motion.
Under Sannomaru ground motion, 75% of beams were damaged and it may require a large amount ofrepair work. To avoid such severe damage, retrofitting of highrise building will be necessary.
Keywords: Highrise building, long period ground motion, STERA 3D.
INTRODUCTION
Highrise building is one option in the rapid industrialized world to fulfill housing and commercialneeds within limited land space. These buildings are considered as safe structure in seismic region
when compared with small buildings. But, the 1985 Mexico earthquake changed this thought and it
damaged many highrise buildings. This incident changed direction of many researchers and to think
about the vulnerability of the highrise buildings. It has been observed that these highrise buildings
have long natural period and those will respond largely to the ground motions having the period sameas that of the natural period of the highrise buildings. These ground motions are called long period
ground motions. Long period ground motions are produced in the large river basins having soft andthick layer of sediment deposits due to large distant earthquake by means of path and site effects.
It is very essential to know the performance of highrise building under long period groundmotions. So it is important to have an accurate analytical method for conducting the performance studyof the highrise buildings. This study mainly focuses on the formation of element model for beam andcolumn elements of RC highrise building. Also the objective of this study is performance evaluation ofRC highrise building under long period ground motion and damage estimation.
CONSTRUCTION OF TRILINEAR SKELETON MODEL
Study on Beam:
The experiment study on beam specimens was conducted by the joint research team comprised ofBuilding Research Institute and six private companies in March 2008. As shown in the Table 1 eighttypes of beams specimens were used for the experiment. Here N indicates normal loading representing
the short period ground motion and L indicates long period loading representing long period groundmotion. The beam details are given in Table 1 and the cross section of the beam is given in Figure 1.
The experimental data were obtained from this research team was used in this study.
∗Thanthai Periyar Government Institute of Technology, Vellore, Tamil Nadu, India.
International Institute of Seismology and Earthquake Engineering, Building Research Institute, Japan.

∗∗1WithSlabWith
outslab

Table 1 Types of beam
BeamMain bar
TypeSD490
B1-N
Top 6-D19
B1-L
B2-L
Bottom 4-D19
B2-N
B3-L
B4-L
Top 6-D19
B4-N
Bottom 6-D19
B5-L

Tie bar
UHY6854-D6@75
4-D6 @150
4-D6 @75

Figure 1 Cross section of beams

4-D6 @150
Loading for the study:
Two types of loads were used in
the experiment, namely normal
loading and long period loading.
Here normal loading represents theshort period ground motion andlong period loading represents thelong period ground motions. As
shown in Figure 2 in thisexperiment the story drift ratio(R=δ/a)ismaintainedas
1/400, 1/200, 1/100, 1/50, 1/33,

Figure 2 Normal and Long Period Loading

1/25, 1/20 and each ratio was maintained for 2 cycles for normal loading. Then the story drift ratio wasmaintained as R= 1/200, 1/100, 1/50 and 1/33 and 10 cycles were given for long period loading
The trilinear skeleton models were400
constructed based on the experiment results.
300
The skeleton models of the specimens are
200
shown in Figure 3.
kN

100

-80

0-60-40-20-100

020-200-300
-400

mm

Figure 3 Trilinear skeleton model for beam
1400
1200

Force (kN)

1000
800
600
400
200
00

Figure 4 cross section

Study on Column:
Two types of column specimens were used forthe study namely C1 and C2 with same cyclicloading as given before and axial load of
2880kN and 4800kN respectively. Twocolumns from each type namely C1-N, C1-L,C2-N, C2-L were prepared for normalloading (N) and long period loading (L).
The cross section of
the column is shownin Figure 4. Main barof 16-D19 and tie barof4-D6@40mm
spacing were used.
Same cyclic loading
C1-L
wasappliedfor
C1-N
C2-L
columns and tri
C2-Nlinear skeletons were1015
2025
Displacement (mm)prepared as shown inFigure 5.

60 B1-L80
B1N
B2-LB2-N
B3-L
B4-L
B4N
B5-L

40

5Figure 5 Trilinear skeleton model2

FORMATION OF ELEMENT MODEL
Formation of element model for beam:
The hysteresis model of the beam as given in
Figure 6 is governed by the parameters R1,R2, R3 and Sy. The unloading stiffness kr isgoverned by the parameter R1. The slip
stiffness ks is governed by the parameter R2.
The strength degradation depends on theparameter R3. The constructed trilinear
skeleton model is adopted in this model andanalysis was done for all the specimens byadopting the same load which is applied in
the experiment. The governing parameters
were optimized in this analysis by fitting thehysteresis obtained from analysis with thehysteresis obtained from experiment. The
fitted hysteresis and the optimized parameters
are shown in Figure 7. This beam element
model is proposed for further analysis of themodel building
Figure 6 Hysteresis model for the Beam
B2-L300

B2-N
300

200

200

200

100

100

100

00

50.0

100.0-100-200.0-400.0mm-50-400mm

R20.7

R30.005

Sy-0.01-100-50 -100 0

R10.1

R20.5-400mm

R30.005Sy-0.03

R10.05400200

300

300

100

200

2000100

100-100050

100-100-300-400mm

R10.1

R20.5

B4-L-100 0-300-400mm

Sy-0.03100-1000-50 -100 050

100-100

R10.4

analysis
Experiment

R20.5

R30.005-300-400mm

Sy-0.01-50 -100 0-300

ExperimentR20.5-400mm

R30.01Sy-0.01

R10.4

50

analysis
Experiment

R20.4

R30.005200
1000-10050

100-50-100050

100-200-300

Analysis
Experiment

R20.5

R30.01Analysis
Experiment-400mm

Sy0.1

R10.6R20.5

Figure 7 Hysteresis fitting
Formation of element model for column:
The column is divided into nine subsections as shown in Figure 8 and the nonlinear spring ineach subsection also shown in the figure. The subsections from 1to 8 consist of both steel and concrete
springs and the 9th subsection consists only of concrete. The hysteresis models of steel and concrete areshown in Figures 9 and 10.

3100

B5-L
300-200
Analysis

R10.1

B4-N

0-200

Analysis
ExperimentR30.01400

0-50

50-200-300

analysis
Experiment

B3-L
300-200Sy-0.01

100-200-300kN

kN-100R10.3

50-200analysis
Experiment-300.0

Sy-0.01-50 -100 0

kN-50.0-100.0 0.0

kN-100.00.0

kN

kN

100.0

kN

B1-N300

200.0

kN

B1-L
300.0

R30.01( )= s1 2 f y(dm= s2 d m − d yFigure 8 Multi spring model)

Figure 9 Hysteresis model for Steel spring

S1 is the factor control the unloading stiffness and the factor S2 controls the slip stiffness.
The other parameters controls the column models are given as follows.

⎛dp ⎞dm' = dm⎜⎜1 + r ⎟⎟dy ⎠ dm’ dm⎝dp

Ps - Factor to control
the initial stiffness.
ay - Factor to control
yield displacement.
Ku/Ko - Degradation
Ratio of concrete
fc/fy(s)–ratio of crack&yielding force-steel
fc/fy(c)-ratio of crack
and yielding force
concretedcfc
fy
Figure 10 Trilinear hysteresis model for concrete spring

1500

C1-L
1500

1000

1000

500

500

C1-N

0-80-60-40-20-500

020

40-1500ay
0.3

Fc/fy(s)0.7080-100-50

Analysis
Experiment-1000

Ps
0.160

Fc/fy(c)0.6

Ku/K0-0.02R0.1-500 0-1000
-1500

S10.7

S20.7Psay

Fc/fy(s)

0.07

0.3

0.55

C2-L
1500

1000

1000

500500kN

kN

0-40-20 -500 020-1500mm

ay

0.06

0.5

Fc/fy
(s)
0.8

Fc/fy(c)0.840-6060-20 -500 0-1000-1500mmKu/K0R

S1S2

Ps

ay-0.01

0.1

0.8

0.8

0.05

0.4

Fc/fy(s)0.8

Figure 11 Hysteresis fitting for column

4

Ku/K0R

S1

S2

-0.01

0.03

0.8

0.8

0-40Analysis
Experiment

-1000

Ps

Fc/fy(c)
0.55

1500

C2-N-6050100Analysis
Experiment

Fc/fy(c)0.8204060Analysis
Experiment

Ku/K0R

S1

S2

-0.01

0.05

0.8

0.8

Figure 10 shows the tri linear hysteresis model for concrete spring. The strength degradationof the concrete due to cyclic loading is included in the model. The cyclic loading applied in theexperiment is taken for the model analysis of the column specimens. The controlling parameters wereoptimized by fitting the hysteresis arrived from this analysis and the hysteresis arrived from theexperiment. The optimized parameters and hysteresis are shown in the Figure 11.
PERFORMANCE EVALUATION AND RESULTS

A 36 story RC highrise building located in Tokyo is
selected as a model building. The plan of the building isshown in Figure 12. The 3D model of the building wasdeveloped in the STERA 3D software and it was foundthat the dynamic analysis of 3D model takes more time
to complete the analysis. So it was decided to form 2-D
model to overcome this time constraint with the samecharacteristics as that of the 3-D model. So the 2Dmodel is used for further analysis

Figure 12 Plan of the building
Input Ground motions:
The ground motions given in Table 2 are selected as input ground motion for the dynamic analysis ofthe model building
Table 2 Input Ground Motions
Earthquake
Type of earthquake
Characteristics
El Centro 50 Kine
Famous and Design
1940 El Centro earthquake NS component.
earthquake
PGA 505cm/sec2 and PGV 50 cm/sec
BCJ-L2
Design earthquake.
Artificial wave developed by Building
Centre of Japan (level 2),
PGA 355 cm/sec2, PGV 50 cm/sec
Sannomaru
Long period ground
Artificial wave simulated formotion
Tokai-Tonankai earthquake in Nagoya city
Osaka
Long period ground
Artificial wave simulated for Nankai
motionearthquake in Osaka city
Results:
The performance of the model building was studied and the response of the building under various
ground motions is given in Table 3. It is seen that the story drift ratio obtained from various earthquake
for the model building are within the design limit of 1/100 except for the Sannomaru earthquake. The
max story drift obtained for the Sannomaru earthquake at 11th floor is 1/73 which exceeds the design
limit of 1/100.
Table 3 Max drift, displacement and ductility
Max displacement @ top Max Ductility
Max Drift
Max Drift Ratio
Earthquake(cm)(cm)(rad)
El Centro 50 Kine 2.35@ 22F
1/134
66.1
1.47
BCJ-L22.59@ 19F
1/122
71.8
1.61Sannomaru
4.41 @11F
1/73108
3.19
Osaka
0.8 @12 F
1/400
22.8
0.48

540403535301510Osaka
Sannamaaru
BCJ-L2El Centro

50050cm100Figure 13 Story Drift

35252015Sannamaru
BCJ-2
El Centro

25201510105500150

Osaka

30
No. of story

No. of story

No. of Story

2040Sannamaaru
BCJ-L2El Centro

3025Osaka02cm46Figure 14 Max top displacement

0500 cm/s2 1000

1500

Figure 15 Max Acceleration

The story drift distribution for each earthquake is given inFigure13. The maximum story drift is produced by the Sannomaru
earthquake with the value of 4.41cm. The story drift ratio for this drift
is 1/73. This is over the design safety limit of 1/100.
The maximum top story displacement given by the modelbuilding under various input ground motions is shown in Figure 14. It
is also seen that highest top displacement for the model building was
found under Sannomaru earthquake than the other three earthquake
considered for this study. The maximum top story displacement isobserved from the Sannomaru earthquake and the value is 108 cm
The distribution hinges developed due to Sannomaru
earthquake is shown in Figure 16. It is estimated that 75% of beams
were damaged due to Sannomaru earthquake. This study implies thatthe performance of model building satisfies the design standard exceptthat under Sannomaru earthquake.

Figure 16 Distribution of hinges
CONCLUSIONSIn this study new element models were proposed for beam and column elements based on
experimental results which enable to consider the strength degradation by long period loading.
Dynamic analysis of the 36 RC highrise building was conducted adopting proposed element models
under long period ground motions. It was found that the performance of the building was within safety
criteria of design standard except that under Sannomaru earthquake. 75% of beams damaged underSannomaru earthquake and it may require a large amount of repair work. To avoid such severe damage,retrofitting of highrise building will be necessary.
REFERENCE:Aoyama.H, Design of modern highrise reinforced concrete structures, Imperial College Press,2001
Park.R and Paulay.T, Reinforced Concrete Structures, Wiley Interscience Publication, 1974
Seismic Evaluation and Retrofit Tech. Manual, The Japan Building Disaster prevention Association
STERA 3D software link: http://iisee.kenken.go.jp/net/saito/stera3d/index.html

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