International Journal of Civil Engineering and Technology (IJCIET)
Volume 10, Issue 1, January 2019, pp.285–296, Article ID: IJCIET_10_01_027
Available online at http://www.iaeme.com/IJCIET/issues.asp?JType=IJCIET&VType=10&IType=1
ISSN Print: 0976-6308 and ISSN Online: 0976-6316
©IAEME Publication Scopus Indexed
U. Wijaya
Department of Civil Engineering, Universitas Tarumanagara, Jakarta, Indonesia
R. Soegiarso
Department of Civil Engineering, Universitas Tarumanagara, Jakarta, Indonesia
Tavio
Department of Civil Engineering, Institut Teknologi Sepuluh Nopember (ITS),
Surabaya, Indonesia
ABSTRACT
The Lombok and Palu Earthquakes that have recently occurred in Indonesia caused significant damage. Earthquakes are closely related to damage, landslide, and the loss of life and economy. However, the causes of these things are not solely due to the earthquake itself. The cause loss of life and economy caused solely due to the collapse of buildings that built by humans during an earthquake. To reduce impact loss of life and economy, Performance Based Seismic Design (PBSD) using based isolator can be one of the solution. By using PBSD economic considerations the cost of repair after an earthquake can be predicted. In this study, modeling 12-storey reinforced concrete buildings located in Yogyakarta Indonesia stands on soft soil using base isolator High
Damping Rubber type (HDR HH090X4S, thickness 20 cm product of Bridgestone). The average of non-linear dynamic time history analysis of seven ground motion respectively
Denali earthquake 2002, Imperial Valley 1940, Kobe 1995, Loma Prieta 1989,
Northridge 1994, San Fernando 1971, Superstition Hills 1987 was conducted. Seismic response modification coefficient R was taken respectively 2.5, 3.5, 5.5, and 8. From these coefficients, the performance of the building is obtained with R 2.5 and R 3.5 performance building in the category of immediate occupancy, R 5.5 and R 8 Category damage control. Thus the building with R 2.5 and R 3.5 according to FEMA 273 will produce a building with a repair cost of 25% and repair time only 1 day, so that after the earthquake the building can resume normal operation.
Keywords : earthquake, PBSD, time history analysis, base isolator.
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U. Wijaya, R. Soegiarso, and Tavio
Cite this Article: U. Wijaya, R. Soegiarso and Tavio, Seismic Performance Evaluation of A Base-Isolated Building, International Journal of Civil Engineering and Technology
(IJCIET), 10 (1), 2019, pp. 285–296. http://www.iaeme.com/IJCIET/issues.asp?JType=IJCIET&VType=10&IType=1
Indonesia is located at the subduction zone of tectonic plates, the Eurasian Plate, the Indo-
Australian Plate and the Pacific Plate. In the most recent earthquake in Indonesia, the earthquake in Lombok and Palu caused significant damage. Earthquake s are closely related to damage, landslide, and the of loss of life and economy. However, the causes of these things are not solely due to the earthquake itself. The cause loss of life and economy caused solely due to the collapse of buildings that built by humans during an earthquake. To reduce impact loss of life and economy, Performance Based Seismic Design (PBSD) using based isolator can be one of the solution. By using PBSD economic considerations the cost of repair after an earthquake can be predicted.
Rubber Base Isolator is the most effective tools to reduce earthquake force that is transmitted to the building. Separating structures from the effects of earthquakes is the main goal in using this device [1-2]. In principle, rubber base isolator can extend the fundamental period of the structure far beyond the period of the high energy period of an earthquake when it was deformed. For low-rise buildings under fifth floors can use the type hyperelastic low damping rubber where it obtained from recycled rubber material, but for buildings higher than fifth floors can use the type of hyperelastic high damping rubber combined with steel plate material to get certain rigidity [3].
In this study modeling 12-storey reinforced concrete buildings located in Yogyakarta
Indonesia stands on soft soil using a High Damping Rubber type isolator (HDR HH090X4S thickness 20 cm product of Bridgestone were used) [4].
Average of non-linear dynamic time history analysis of seven ground motion respectively
Denali earthquake 2002, Imperial Valley 1940, Kobe 1995, Loma Prieta 1989, Northridge
1994, San Fernando 1971, Superstition Hills 1987. According to ASCE 7-16, Seismic response modification coefficient for the design of earthquake resistant buildings using a base isolator was taken to respond the elastic conditions (R 2.5). Basically, base isolators can extend the fundamental period of a building structure. Since the fundamental period of the building extended, the acceleration response will be reduced and it will minimize building damage [5-
7]. However, from the regulations of ASCE 7-16 limiting the coefficient of seismic response modification is only R 2.5 so that in the economic value with the base isolator the economic value of building prices will increase, but building performance will also increase [8]. Therefore in this paper It will study buildings using base isolators designed in elastic responses (R 2.5),
R3.5, R5.5 and inelastic response (R 8.0) regarding the performance due to damage and building repair costs after the earthquake according to FEMA 273.
According to ASCE 7-16 the base isolators design considered is based on seismic elastic response. Maximum consideration earthquake is 2500 years return period. For base isolator design, there is no seismic response coefficient reduction. Regarding PBSD in this paper tried to study the seismic response coefficient until reach inelastic condition (reduce factor up to 8). http://www.iaeme.com/IJCIET/index.asp 286 editor@iaeme.com

Seismic Performance Evaluation of A Base-Isolated Building
The horizontal rubber bearing stiffness can be shown in equation (1) and (2) as follows [9]:
=
(1)
Where: G = shear modulus of elastomer (MPa). t
A r
= section area (mm).
= total thickness of rubber (mm).
D = maximum horizontal displacement (mm).
γ = maximum shear strain.
=
The vertical rubber bearing stiffness can be described in equation (3) as follows [6]:
=
(2)
(3)
Where: E c
= compression modulus of composite rubber-steel plate (MPa)
Design displacement of base isolator can be illustrated in equation (4) and (5) as follows [10]:
=
Where: D
D
= design displacement at the center of rigidity at the DBE (mm) g = gravity acceleration.
T
D
= isolated period (sec).
C
VD
= seismic coefficient.
B
D
= damping coefficient for DBE .
=
Where: D
M
= design displacement at the center of rigidity at the MCE (mm)
g = gravity acceleration.
T
M
= isolated period (sec).
C
VM
= seismic coefficient.
B
M
= damping coefficient for MCE
(4)
(5)
Composite damping coefficient of base isolator can be illustrated in equation (6) as follows
[11]:
=
"
∑
(6)
Where: β = base isolator damping ratio
K
D
= effective stiffness of isolation system
D
D
= design displacement at the center of rigidity at the DBE (mm) http://www.iaeme.com/IJCIET/index.asp 287 editor@iaeme.com

U. Wijaya, R. Soegiarso, and Tavio
E
D
= effective linear properties from cyclic load
Base shear of base isolator can be illustrated in equation (7) as follows [7]:
V b
= K
Dmax
D
D
Table 1 Isolator Properties
HH070X4S
Outer Diameter (mm)
Weight (kN)
Mass (tonf)
Compressive Stiffness (10
3 kN/m) Kv
Initial Stiffness (10
3
kN/m) Ki
Post yield Stiffness (10
3
kN/m)
Characteristic Strength (kN)
Equivalent shear Stiffness (10 3 kN/m)
Equivalent Damping Ratio
700
7.90
0.80
2290
4.42
0.44
61.50
0.75
0.24
(7)
Figure 1 High Damping Rubber Bearing (Product catalogue Bridgestone )
In this research study the seismic area was located at Yogyakarta Indonesia and the response spectrum can be illustrated in Figure 3. Site class categorized as soft soil based on soil investigation data as illustrated in Table 2. http://www.iaeme.com/IJCIET/index.asp 288 editor@iaeme.com

Seismic Performance Evaluation of A Base-Isolated Building
Response Spectrum D.I. Yogyakarta
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
0 1 2
Period (s)
3 4
Figure 2 D.I.Yogyakarta Response Spectrum – Soft Soil [12]
Table 2 Site Class [12]
Sites Class
A-Hard Rock
B-Rock
C-Very dense soil and soft rock
D-Stiff soil
E- Soft soil
Vs (m/sec)
>1500
750 to 1500
350 to 750
175 to 350
< 175
N
N/A
N/A
>50
15 to 50
< 15
Su (kPa)
N/A
N/A
> 100
15 to 100
< 50
Seven ground motion records list in Table 3 and illustrated in Figures 4(a) to (n) [13].
Table 3 Selected Earthquake the Ground Motions
Earthquake
Imperial Valley
Denali
San Fernando
Superstition Hills
Kobe
Loma Prieta
Northridge
Year
1940
2002
1971
1987
1995
1989
1994
Magnitude
6.95
7.9
6.61
6.84
6.9
6.93
6.69
Distance (Km)
2.66
270.25
11.34
5.02
38
1.81
5.61
Vs 30 (m/s)
223.03
212.48
256
1070.34
349.6
2016.13
362.38
(a) http://www.iaeme.com/IJCIET/index.asp 289
(b) editor@iaeme.com

U. Wijaya, R. Soegiarso, and Tavio
(c) (d)
(e) (f)
(g) (h)
(i) (j) http://www.iaeme.com/IJCIET/index.asp 290 editor@iaeme.com

Seismic Performance Evaluation of A Base-Isolated Building
(k) (l)
(m) (n)
Figure 3 Selected Ground Motion
According to ASCE 7-16, the target ordinate response spectrum for structures using a base isolator is in the range of 0.5 TD to 1.25 TM. Each of graph should be composite with Indonesia earthquake code (SNI 1726:2012) as shown in Table 4 and Figures 5(a) to (d). The pseudoacceleration target for site class was taken as the median of the damping 5% pseudoacceleration spectrum response that corresponds to the average horizontal component of the record that is not scaled can be illustrated in equation (8) as follows [14]:
# = ∑ .
&/
$%
&
' ()*. %
&
,-
(8)
Where A i
and
A i
are the target spectral acceleration and record's (unscaled) spectral acceleration, respectively. The legend i th is spectral period, and n is the number of periods from
0.5TD up to 1.25TM. The purpose is to determine Scale Factor (SF) that decrease the erratum using equation (9) as follows [14]:
)* 0∑ .
&/
%
&
%
&
1/(∑ .
&/
%
&
%
&
,
(9)
From Equation (9), it produces an optimal scale factor to ensure a scale spectrum that matches the target spectrum from 0.2TI up to 1.5TI. The ground motion record scale factor according to
Equation (9) is shown in Table 4 [14]. http://www.iaeme.com/IJCIET/index.asp 291 editor@iaeme.com

Earthquake
Denali
Imperial Valley
Kobe
Loma Prieta
Northridge
San Fernando
Superstition Hills
U. Wijaya, R. Soegiarso, and Tavio
Year
2002
1940
1995
1989
1994
1971
1987
Table 4 Scaling Factor of Ground Motion
Station
TAPS Pump Station
#10
El Centro Array #9
Amagasaki
Los Gatos -
Lexington Dam
Anaverde Valley -
City R
Pacoima
Superstition Mtn
Camera
Magnitude
7.9
6.95
6.9
6.93
6.69
6.61
6.84
X
Direction
Y
12.974
1.339
0.977
0.708
12.424
1.683
0.832
0.743
8.955
0.474
0.998
8.955
0.509
0.634
(a) (b)
(c) (d)
Figure 4 Selected Ground Motion
ANALYSIS PROCEDURE
A mathematical model of the structure is determined to get seismic response using base isolator. Computer program that will be used is ETABS non-linear v16.2.1. Analytical procedure is determined as follows [9]:
1.
Determined Risk Category.
2.
Determined Importance factor ( I e
). http://www.iaeme.com/IJCIET/index.asp 292 editor@iaeme.com

Seismic Performance Evaluation of A Base-Isolated Building
3.
Site specific ground motion procedure.
4.
Determined Site soil class ( S
A
S
F
).
5.
Determined Site coefficient short and long period ( F a
, F v
).
6.
Design spectral acceleration parameter ( SD
S
, SD
1
).
7.
Determined Seismic Design Category ( A F ).
8.
Determined Seismic response modification coefficient.
9.
Determined base isolator properties.
10.
3D dynamic non-linear time history analysis.
11.
Base isolator PBSD method.
In this study, the building data as follows:
1. Building function : Apartment.
: 43 m. 2. Building height
3. First floor level
4. Floor level 2 nd – 12 th
: 4.5 m.
: 3.5 m.
5. Floor numbers
6. Location
: 12 storey (43 m).
: Yogyakarta.
7. Material
8. Concrete grade ( f’ c
)
: Reinforced concrete.
: 35 MPa.
9. Reinforcement grade ( f y
) : 420 MPa.
10. Thickness of floor
11. Thickness of roof
12. Column (K1)
13. Primary beam (B1) x-x
14. Primary beam (B2) y-y
15. Secondary beam (B3)
16. Thickness of Shear wall
17. Base isolator (BI)
18. Thickness of BI
19. Ground Motion
20. Soil type
: 12 cm.
: 12 cm.
: 60 x 60 cm.
: 40 × 60 cm.
: 50 × 70 cm.
: 25 × 35 cm.
: 35 cm.
: HDR HH090X4S (Bridgestone product).
: 20 cm.
: Denali Earthquake 2002, Imperial Valley 1940,
Kobe 1995, Loma Prieta 1989, San Fernando
1971, Superstition Hills 1987.
: Soft Soil. http://www.iaeme.com/IJCIET/index.asp 293 editor@iaeme.com

U. Wijaya, R. Soegiarso, and Tavio
Figure 5 Plan view twelve storey building
From non-linear time history analysis, it obtained that twelve stories building with height 43 m, sitting at soft soil, isolated with HDR HH070X4S product of Bridgestone Japan at each column support. Analysis of seismic modification coefficient of R 2.5; R3.5; R 5,5 and
R 8.0 were calculated and illustrated in Figures 6(a), (b), 7(a), and (b). http://www.iaeme.com/IJCIET/index.asp 294 editor@iaeme.com

Seismic Performance Evaluation of A Base-Isolated Building
12
11
10
9
8
7
6
5
4
3
2
1
0
R =
2.5
R =
3.5
Displacement (m)
(a)
12
11
10
9
8
7
6
5
4
3
2
1
0
Drift
R = 2.5
R = 3.5
R = 5.5
R = 8
(b)
Figure 6 Displacement and drift elastic - inelastic X direction
(a)
(b)
12
11
10
9
8
7
6
5
4
3
2
1
0
R = 2.5
R = 3.5
R = 5.5
R = 8
12
11
10
9
8
7
6
5
4
3
2
1
0
R = 2.5
R = 3.5
R = 5.5
R = 8
Displacement (m) Drift
Figure 7 Displacement and drift elastic - inelastic Y direction
Figures 6(a), (b), 7(a), and (b) explain the building deformation occurred when using seismic response modification coefficient, R, i.e. 2.5 and 3.5 It obtained performance level
Immediate Occupancy (IO) with repair costing 25% and repair time only one day, otherwise for seismic response modification coefficient R 5.5 and R 8, it can be obtained the performance level damage control with repair costing 50% and repair time is between 7 days to 30 days as shown in Figure 8. All of the coefficient fulfills the minimum requirement for PBSD for base isolator. http://www.iaeme.com/IJCIET/index.asp 295 editor@iaeme.com

U. Wijaya, R. Soegiarso, and Tavio
Figure 8 Illustration of PBSD [15]
This paper obtained the result of performance based seismic design for building that is use base isolator. According to that illustrated, the following below is the conclusion of this study:
1.
PBSD using base isolator for seismic response modification coefficient R 2.5 (elastic condition) got the best performance IO and only need one day repair and 25% of repair costing during the earthquake, after that the building can be use and operate.
2.
PBSD using base isolator for seismic response modification coefficient R 8 (inelastic condition) got the performance damage control and need 7-30 days repair and 50% of repair costing during the earthquake, after that the building can be use and operate.
3.
Seismic response modification coefficient R 8 is the maximum level that is allowed for
PBSD using base isolator, but using this method, investment for base isolator will be useless because level of damage is 50% and need to repair more than 30 days.
The authors would like to gratefully acknowledge for all the facilities and the supports received to make this research possible.
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Seismic Performance Evaluation of A Base-Isolated Building
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