Overview of T-BAGS Base Isolation Method for Building Foundation
Lai Lai Oo #1, Kinji Takeuchi#1, Yasuo Tomono#1, Yohei Okimoto #1#1

Takeuchi Construction Inc.
4-2-14 Enichi-cho, Mihara-shi, Hirosima 723-0015, Japan1

mail@takeuchi-const.co.jp

Abstract —Tension BAGS (T-BAGS) can reduce seismic effectand earlier restoration from an earthquake disaster. It is safe
and secure in low-cost construction method. Two-layer of TBAGS can reduce earthquake vibration by top and bottombags sliding. This paper describes general conception of TBAGS Base Isolation System for building foundation withspecification of the T-BAGS and the construction processincluding its characteristics, effectiveness and model results.
According our study, T-BAGS Base Isolation Method canreduce the earthquake vibration from 800 gal of input toapproximate 250 gal as its response motion and also reducethe 80% cost of the existing method to introduce.
Keywords —Base Isolation, Earthquake, Building Foundation,
T-BAGS, Seismic Effects

I. INTRODUCTION
Recently, earthquakes happen all around the world and it
is difficult to know its scale, it will happen where and whenin advance. For example, a 7.3 magnitude earthquake
occurred in Nepal in May 2015. After that, a series ofearthquakes including a magnitude of 7.0 struck in
Kumamoto City in Kyushu Region, Japan in April 2016.
Due to this earthquake, 49 people were killed and several
people were injured. In here, numerous structures weredamaged, and the resident evacuated from their home dueto this disaster (1). Recently, a 6.8 magnitude earthquake
struck in central Myanmar in August 2016 and at least 185
ancient Buddhist pagodas were damaged in Bagan (2).
We have already registered our construction methods toPatent Office in Japan. Almost of our construction methods
are related with base isolation of building and it includes
the ability to reduce the earthquake effect. Now, we will
explain one of our patented technologies, “T-BAGS Base
Isolation Method” (3) using the sand bags as the baseisolation device. We have already conducted 17 buildings
construction projects by using this method in Japan, andthis method has four benefit points which are low cost,safety, secure and friendly for the environment. Although,there are many seismic base isolation methods, most ofthem are expensive but T-BAGS is a low-cost method toinstall.
II. SPECIFICATIONS of T-BAGS
T-BAGS is composed of geotextiles, filled with sandand these are widely used in the reinforcement of soft
ground as a foundation.
There is approximately 400mm length, 400mm width and80mm height shown in the Fig. 1(a) and Fig.1 (b). Creeplife of the bags material is 250 years under the foundation.
These bags are laid out both under the building foundationand the floor. The bags are piled up as two layers shown in
the Fig. 2, and it is more effective to put a sheet between
two piled bags for isolation of buildings from earthquake
energy.

Fig. 1 (a) Specifications of T-BAGS

Fig. 1 (b) Photograph of T-BAGS

Fig. 2 Layout of T-BAGS two layers

III. GENERAL CONCEPTION OF BASE ISOLATIONFOR BUILDING(3) Low-cost Method for Installation
Installation cost of T-BAGS Base Isolation
Method is one-fifth of rubber seismic isolation equipmentin Japan.

A base isolation system is one of most powerfulsystem for earthquake, which separates main structure ofbuildings from ground. An example of base isolation
system is described in the following Fig. 3. In this system,
isolator and net pole damper are included.

(4) Free Maintenance
T-BAGS Based Isolation Method does not require
regular maintenance because it has high durability.

(5) To Simplify Superstructure
In the case of buildings installed rubber seismic
isolation system need stiffening member to be reinforced
because the stress concentrate in the narrow area (point)
vicinity of the seismic isolation system. On the other hand,
T-BAGS Base Isolation Method supports buildings’ loads
by surface, thus it has no stress concentration and reduce
the loads of buildings.
V. MODEL RESULTS
We have conducted a vibration test of T-BAGS
Base Isolation device at Tsukuba Building Research Test
Laboratory, Center for Better Living in Japan. Thefollowings are the conditions of the test and the maximum
response acceleration value as its results.

Fig. 3 Example of Base Isolation System for building

In our method, T-BAGS, is different from themechanism of general system but the same effectiveness toreduce earthquake vibration. T-BAGS works as baseisolation and its effective factors and characteristics arebeing now evaluated by Tsukuba Building Research TestLaboratory, Center for Better Living in Japan. In thepresent paper, we introduce outline of T-BAGS Base
Isolation Method for buildings.

(1) CONDITION

Fig. 5 Experiment image (Unit : mm)
Fig. 4 Position of T-BAGS for building foundation

The vertical load is set up 14.3 kN (1.46 ton×9.8m/s2). The friction coefficient is estimated to be 0.19 byexperimental result. 105 mm space is set up between the TBAGS and oscillating body, and rubber chips are charged
as collision cushioning (W100mm×H400mm×D80mm) atthe space. Input vibration sine-wave, acceleration andfrequency are as shown in the following table

IV. CHARACTERISCTICS AND EFFECTIVE FACTOR
OF T-BAGS BASE ISOLATION METHOD
Characteristics and effective factors of T-BAGS
Base Isolation Method are described in the following.
(1) Effectiveness Against Earthquake
T-BAGS can suppress 300 gal ～ 800 gal ofearthquake vibration to under 250 gal.
(2) Suitable for Soft GroundBy combination of T-BAGS Base Isolation
Method and TNF method (New raft foundation construction
method for soft ground) enables you to construct buildings
on soft ground without pile.

2(2) RESULTExperiment
No.
12
3
45
678

(2) Compaction of the first layer is as shown in the Fig. 8.

Table 1. Experimental Results
Input Earthquake Motion
Max. Response Residual
Acceleration Displacement
Acceleration
Frequency
2[mm][m/s 2 ][Hz][m/s ]
3.0
3.0
3.0
1.5
4.5
4.5
1.0
2.0

4.0
6.2
7.1
4.0
4.3
9.2
2.75.7

2.00
2.02
2.05
2.59
1.93
2.06
1.87
2.08

-0.72
2.84
1.04
16.76
-13.08
-1.52
13.16
10.16

Fig. 8 Compaction situation of first layer(3) The slip sheet is laid on the first layer. After that,
T-BAGS of second layer is laid on the sheet.

Fig. 6 Experimental results of acceleration

Fig. 9 Form of laid T-BAGS of second layer(4) Then, compaction of the second layer is shown in theFig. 10.

VI. CONSTRUCTION PROCESS OF T-BAGS BASE
ISOLATION METHOD
The construction process of T-BAGS Base
Isolation Method is expressed in the following.
(1) Fixing position of T-BAGS layout under the foundationand then
T-BAGS are laid at first layer as shown to the Fig. 7.

Fig. 10 Compaction situation of second layer

Fig. 7 First layer of T-BAGS are laying out

3(5) Completed form of T-BAGS layers under foundation isshown in the Fig. 11.

(8) Completed form of second T-BAGS layers of under thefloor is shown in the Fig. 14.

Fig. 11 Completed form of second layer

Fig. 14 Laying form of second layer under the floor(9) Completed Building is shown in Fig. 15.
(6) Building foundation constructed on the T-BAGS layers
are shown in the Fig.12.

Fig. 15 Completed buildings construction
Fig. 12 Completed form of concrete foundation

VII. CONCLUSIONS
A method of T-BAGS base isolation for building
foundation was described in overview of its specifications
and construction process. This method is simple but it can
reduce earthquake vibration of buildings. Hereafter, we will
provide further information and experimental results of TBAGS Base Isolation Method.

T-BAGS are laid also under the floor. The process
is the same as that under building foundation and it
describes briefly in the following.
(7) Laying T-BAGS of first layer under the floor is asfollows.

VI. REFERENCES[1] http://earthquake.usgs.gov/[2] http://www.abc.net.au/news/[3] 減震基礎構造体及びそれを用いた減震工法,
Patent Number (JP) 5196059

Fig. 13 Laying form of first layer of T-BAGS under the floor4