RESPONSE OF BASE ISOLATED BUILDING DURING
THE GREAT EAST JAPAN EARTHQUAKE AND THE
APPLICATION OF BASE ISOLATIONIN TURKMENISTAN
Guvanch Annayev*
MEE12617Supervisor:
Adviser:

Taiki SAITO**
Koichi MORITA***

ABSTRACTTo check performance of the Hachinohe government offices, in use at the time of the Great East Japan
Earthquake of 2011, observation data was analyzed in this study. Numerical simulations using Modified
Bi-Linear Modeling were created of the building, which took into consideration the degradation of thesecondary stiffness and yielding shear force.
From the results of this analysis, it was proved that the base isolation system has non-linear
behavior and the upper-structure behaves in the elastic range. This is because base isolation decouples
movement from ground motion, the displacement concentrates at the isolation level and the upperstructure behaves as a rigid body.
A comparison of isolated and non-isolated building responses was performed in this study, and adesign procedure for base isolated buildings in Turkmenistan is proposed. This procedure is based on therecommendations of the CIB (International Council for Research and Innovation in Building andConstruction), using the preliminary design procedure for seismically isolated buildings (CW2012) andtaking into consideration the Building Seismic code of Turkmenistan.
Keywords: Seismic Isolation, Observation record, Design Procedure.

1. INTRODUCTION
Earthquakes are one of the most dangerous and destructive natural disaster. Usually the earthquake lasts
no more than a few minutes, but despite this it cause massive destruction and human fatalities. Over amillion earthquakes occur each year around the world. Many of occurred earthquakes are too small andcannot be noticed, but some of them can be really strong and may cause huge damage and destruction of
the buildings and structures, and death of the people.
In this sense, Japan is extremely vulnerable to disasters such as earthquakes. Earthquakes are
more common in Japan than in any other country. Because of this Japanese engineers and researchers havemade a lot of studies and researches to make buildings more strong and resistance in case of earthquakes.
Principal engineer, The Scientific Research Institute of Seismic Resistance Construction of the Ministry ofConstruction of Turkmenistan.
**Professor, Toyohashi University of Technology, Japan.
*** Chief Research engineer, Building Research Institute, Japan.

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The territory of Turkmenistan is also characterized by high seismicity. More than 90% of the areaof Turkmenistan is affected by earthquakes from 6 to 9 points on the MSK-64 scale. The most powerfuland destructive earthquakes have occurred in the seismically active zones of Ashgabat and Turkmenbashy,
where major cities and industrial areas are located, and large scale construction projects are beingimplemented.

2. DYNAMIC BEHAVIOR OF SEISMICALLY ISOLATED BUILDINGS
2.1

Types of base isolation devices

This research focused on Lead Rubber Bearings (LRB) the most common elastomeric bearing typeof seismic isolation devices.
2.1.1 Lead Rubber Bearings
Lead Rubber Bearings (LRB), is a widely used form of isolation device for buildings and bridges. They
are composed of thin rubber layers with steel plates and a lead plug core in the middle. The rubbermaterial provides flexibility, and devices can move in a horizontal direction, while the steel plates provide
stiffness vertically, the lead plug works as energy dissipation under all types of load, and it increases thestiffness of devices under low loads, such as wind, traffic and minor earthquake loads. The main
advantage of LRB is that they are flexible under earthquake load, rigid for service loads (e.g. bridges) andhave a damping effect for different types of load. There are also some types of LRB devices with morethan one lead core, this kind of LRB are usually used for bridges.
2.1.2 Bi-linear model of LRB
As mentioned above, LRB are a combination ofrubber material with a lead plug core, hence bilinear hysteresis of LRB will also be a combinationof an elastic linear model for rubber and a plastic
bi-linear model for lead Figure 1.
;

Elasto-plastic (combination)

initial stiffness
secondary stiffnesswhere

β = 10 ~ 15.

Figure 1. Bi-linear model of LRB.

2.1.3 Modified Bi-linear model of LRB
The idea behind the modified bi-linear
model is that calculations of secondary
stiffness and yielding shear force of LRB
devices can be made by using modification

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factors Ckd(γ) and CQd(γ), which depend onstrain level (γ). The equations show thecalculation of modified secondary stiffness
and yielding shear force respectively:
where Ckd(γ), the modification factor,depends on strain level, ϭp and Ap are theyielding shear stress of the lead plug andthe cross sectional area of the lead plug
respectively. Two parameters are used forthe stiffness modification factor and one
modification factor for yielding shear force.

The initial stiffness in the modified
bi-linear model can be obtained in the same
way as the simple bi-linear model.
Using the parameters of themodified bi-linear model for LRB isolators,a comparison between the observed data
and a numerical simulation was performedin this study.
A skeleton curve shown in Figure 2
was produced using the two parameters ofmodification factor for secondary stiffness.
This skeleton curve based on parameters ofLead Rubber Bearings.

Figure 2. Skeleton curve of the Modified Bi-Linear model.

3. RESULTS OF THE ANALYSIS
3.1 Overview of the target building
A ten story steel reinforcement concrete (SRC) typebuilding in Hachinohe, Aomori Prefecture was chosen
as the target building (hereinafter H-building), seeFigure 3. The building is located 292km from theepicenter of the March 2011 Great East JapanEarthquake.
A seismic isolation system was installed
during construction which used LRB devices withdiameters of 1200mm and 1300mm. 12 LRB with adiameter of 1200mm and 2 with a diameter of
1300mm were used.
To record large amplitude ground motion andthe response of the structure to these motions on thebasement, 1st and 10th floors of H-building strong
motion record sensors installed. Three more groundmotion sensors installed at ground level. These threesensors located on the surface, at 30 and 105m deep.

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Figure 3. The H-Building.

Table 1. Obtained results by using Modified Bi-Linear model.
X direction[observed]

Y direction[observed]

Peak acceleration on 1st floor (cm/sec2)

117.5[122.3]91.8[91.4]

Peak acceleration on 10th floor (cm/sec2)

190.7[122.7]151.2[119.6]Max. displacement on 1st floor (cm)

4.7
[4.7]

6.4
[5.4]

Max. displacement on 10th floor (cm)

5.2
[5.7]

6.8
[6.0]

Modified Bi-Linear model analysis

3.1.1 Comparison of analysis
Modified Bi-Linear model gives more close result to observation data in both case (2 shear springs and 6shear springs) than results obtained using Simple Bi-Linear model. Because of this a comparison between
two types of Modified Bi-linear models was done in this sub-chapter.
A comparison of the acceleration response between two shear springs model and observation data,and also between six shear springs model and observation data shown on figures 4, 5, 6 and 7.

a) 2 shear springs model.

b) 6 shear springs model.

Figure 4. Comparison acceleration on the 10th floor Y-direction (Modified Bi-Linear model).

a) 2 shear springs model.

b) 6 shear springs model.

Figure 5. Comparison acceleration on the 1st floor Y-direction (Modified Bi-Linear model).

4a) 2 shear springs model.

b) 6 shear springs model.
thFigure 6. Comparison acceleration on the 10 floor X-direction (Modified Bi-Linear model).

a) 2 shear springs model.

b) 6 shear springs model.

Figure 7. Comparison acceleration on the 1st floor X-direction (Modified Bi-Linear model).

4. PROPOSAL FOR TURKMENISTAN DESIGN CODE.
The design procedure for seismically isolated buildings in Turkmenistan proposed in this research is basedon the recommendations of the CIB (International Council for Research and Innovation in Building andConstruction) using the preliminary design procedure for seismically isolated buildings (CW2012) andRussian Federation Seismic Building Design Code (СНиП II-7-81*, updated edition. Moscow, 2011)
taking into consideration the Turkmenistan Seismic Building Design Code. There are two options for thedesign of seismically isolated buildings; they are the Time History Analysis Method (THAM) and theEquivalent Linear Analysis Method (ELM). This research proposes design procedure using an EquivalentLinear Analysis Method.
4.1 Equivalent Linear Method
Requirements for using the Equivalent Linear Method for assessing of seismically isolated buildings aredescribed as follows: Building height should not be more than 60m;
 Buildings should only be constructed in areas with soil types I or II and ground where there is no
possibility of liquefaction;
 Isolation devices located only in the basement; Maximum mass stiffness center eccentricity is 3%;
 Tension on isolation devices shall not be permitted;
 Yield strength should be more than 0.03W;
 Period range of the isolation system should be T>2.5 sec.

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5. CONCLUSIONSAn analysis of the acceleration data recorded during the Great East Japan Earthquake of 2011 and theModified Bi-Linear Model numerical simulation were made to investigate the nonlinear behavior of thebase isolation systems.
The results of the comparison between the numerical simulation of the building in Hachinohe andobservation data correlated well, showing that the building behaved as should be expected. It is necessary
to continue study in this field to get more accurate results.
From the results of analysis of the residential building in Turkmenistan the effectiveness of using
the seismic isolation systems can possibly be assessed. The main controversy arising in the design ofseismic isolation systems were seen between the reductions of acceleration and limiting relative
displacements at the seismically isolated layer was manifested in the analyzed building.
The study showed that seismic isolation systems are an effective way to lessen the buildings
damages from earthquakes. The primary purpose of seismic isolation systems is to reduce the acceleration
response and relative displacements of structures. Proposed method of design procedure by using theEquivalent linear method allows the assessment of the effectiveness of seismic isolation systems and, tocarry out the selection of parameters of the seismic isolation systems and their reliability.
Finally, base isolation systems can be applied in designing new buildings in Turkmenistan tomitigate the effects of large scale earthquakes.
This technology should be introduced to Turkmenistan, due to the country’s high seismicity andthe huge amount of construction work that is underway.

ACKNOWLEDGEMENTS
I would like to express my deep appreciation to Dr. Toshihide KASHIMA, (Senior Research engineer,Building Research Institute, Japan) for his help and advices during the process of doing my individualstudy. During this study BRI Strong Ground Motion Observation database was used.

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Kashima T., 2010, Proceedings of the 9th U.S. National and 10th Canadian Conference on Earthquake
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Kashima, T., Koyama S., Okawa I. & Iiba M., 2012, Proceeding of the 15th World Conference on
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Kashima T., Koyama S. and Okawa I., 2012, Building Research Data No.135, Building Research Institute(Japanese).
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