Comparative Study Of Structure Response Isolated Base And Not Isolated Base on IHF School Cimanggis

Along with technological developments in the field of civil engineering, various systems are used to reduce the impact of earthquakes on the structure. One system that has long been developed is a passive prevention system consisting of seismic isolation. Buildings that use seismic dumper are expected to fail structure when an earthquake occurs. This study discusses the comparison of internal forces in buildings using base isolation and without base isolation. The building which is the case study is the Indonesian Heritage Foundation school building in Cimanggis. The analysis uses the 2016 ETABS program. Earthquake analysis uses the Spectrum Response method. From the research results, it is known that the building which was installed with an insulator shakes the structure to 1,344 seconds. The vibration period of the structure increased 41% from the vibration period of the structure which still used a fixed base of 0.796 seconds. Seen from the intersection between floors the maximum direction of X can be reduced by 15.4% by installing an insulator. The same thing happened to the maximum inter-floor deviation for the Y direction deviation is muted by 27.75%. Base isolation installation reduces the moment in a column by 36% in the earthquake X direction and 61% in the earthquake Y direction. For column shear force is reduced by 58% in the earthquake X direction and 75% in the earthquake Y direction. Base isolation can reduce basic shear force in buildings by 24.49% in the X direction of the building and 22.24% in the Y direction.


Introduction
The ideas behind the concept of base isolation are very simple, namely how to separate the building base related to the ground and the structure of the upper structure, so that the movement of the soil is not directly transferred to the upper structure. The concept of seismic isolation is a significant development in earthquake engineering in the last 20 years. This system has been widely used by countries that have a high risk of earthquakes such as Japan, Italy, the United States, Turkey, China, Taiwan, and Indonesia. This system will separate the building or structure from a relatively small horizontal component between the upper building and the foundation. As a result of the acceleration of the earthquake that works on the building becomes smaller. The first vibrating range of buildings only causes lateral deformation in the isolator system, while the upper part will behave as rigid body motion. The higher vibrational variations that cause deformation in the structure are orthogonal to the first variance and ground motion so that these vibrational variations do not participate in the structural response, or in other words earthquake energy is not dissipated to the building structure (Neim and Kelly, 1999 ).
In a strong earthquake, an insulator with relatively small horizontal stiffness will cause the natural period of the building to be larger, (generally between 2 -3.5 seconds). In this period the earthquake acceleration was relatively small, especially in hard ground. Connecting with the insulator will reduce acceleration in building structures. However, the reverse will cause an increase in displacement in the building. To limit displacement to the acceptable limits, the isolation system is also equipped with elements capable of diminishing energy. Apart from that, the isolation system also has the ability to return to its original position after the appearance of a cynical movement. Whereas in small earthquakes or due to wind the horizontal stiffness of the insulator system must be adequate, so as not to cause vibrations that cause the discomfort of its inhabitants (Kelly, 2001)

Metodholgy
The research method used will use the analysis method in building structure modeling where the plan will use Base Isolation with reference to applicable regulations such as the Indonesian National Standard (SNI).
This research method uses the case study analysis method. The case study method is in the form of re-planning with a model made according to the condition of the building. The research method used has stages of input, VOLUME 2 │ NUMBER 2 │ MARCH 2020 Available online at http://proceedings.worldconference.id. ISSN: 2656-1174 (online) analysis, and output. At the input, stage will be explained about the structure geometry, dimensions, and specifications of structural elements, the determination of the burden of working with 3-dimensional modeling. The stages of analysis include structural modeling using the 2016 ETABS software The final stage is the output stage which discusses the comparison of buildings without Base isolation and buildings with Base isolation.

Structure Geomethry
The building that will be planned using the Base isolation system has the following planning data: a.

Dimension of Base Isolation
Based on the calculation using the design step, obtained property dimensions from the Bridgestone-Seismic isolation product line-up catalog. So Base isolation suitable for use in IHF school buildings is High damping rubber bearing type HH080X4S.

Conclusion
Based on the purpose of writing this thesis and based on the results of structural analysis obtained using ETABS 2016, the authors can draw the following conclusions : 2. The building which was installed with an insulator shakes its structure to 1,344 seconds. The vibration period of the structure increased 41% from the vibration period of the structure which still used a fixed base of 0.796 seconds.
3. The maximum inter-floor deviation of X direction can be reduced by 15.4% by installing an insulator. The same thing happened to the maximum inter-floor deviation for the Y direction deviation is muted by 27.75%.
4. Installation of base isoalation can reduce the moment in the column by 36% in the X direction earthquake and 61% in the Y direction earthquake. For the reduced shear force of the column by 58% in the X direction earthquake and 75% in the Y direction earthquake.
5. Installation of base isoalation can reduce the moment on the beam by 59% in the X-direction earthquake and 52% in the Y direction earthquake. For the column shear force is reduced by 59% in the X-direction earthquake and 53% in the Y direction earthquake.
6. The installation of base isolation in the IHF school building can reduce the basic shear force in buildings by 24.49% in the X direction of the building and 22.24% in the Y direction.