Earthquake-resistant design technologies have come to the agenda with the destruction caused by the earthquake. A technology that eliminates the earthquake effect in a high amount and is in everyone's language is “Seismic Isolators”.
What is a Seismic Isolator?
The reason why structures are damaged in natural disasters and destroyed at advanced levels is that unexpected loads that are added to the existing building load are earthquakes. The majority of structural damage in earthquake zones occurs when non-structural loads that subsequently affect the structure disrupt the rigidity of the structure, resulting in the formation and movement of high acceleration.
Seismic isolators are structural systems that control the vibrations affecting the structure during an earthquake and ensure that the structure is affected by an earthquake at the lowest level. Seismic insulators are located at the base of the structure. It works as a vibration-absorbing barrier between the foundation and the structure above it, controlling the earthquake vibrations from the ground without transmitting them to the upper floors of the structure, which decays the earthquake effect.
To go into more detail, seismic insulators are applied to the columns located between the basement and the ground decking of the building. Columns are cut from certain places according to the characteristics of the system and gaps are created. Seismic insulators are placed in these cavities. Seismic insulators not only contribute to the load-bearing system of the structure without reducing the bearing property of the column but also prevent vibrations from the foundation from reaching the upper floors. By separating the structure from the ground, the earthquake effect cannot manifest itself throughout the structure and a much safer structure is formed for users compared to normal carrier systems.
Before choosing seismic insulators, you should make sure that there are insulators with a steel casing that has been tested and certified for resistance to earthquake loads coming from all directions to the structure.
How Do Seismic Isolators Work?
The main principle of Seismic Insulators is the protection of the structure by absorbing disaster loads such as earthquakes. This absorption can be achieved by using materials with high elastic properties. Seismic insulators must have adjustable steel springs or rubber wedges inside. The behavior of these two materials contained in the insulator body against earthquakes is different.
Rubber; receives high-frequency vibrations. By ensuring the horizontal movement of the structure during an earthquake, it ensures that the structure located on it remains standing independently of the earthquake movement.
Steel springs; when high-vibration insulation is required, they are preferred so that they can meet heavy loads. That is, they carry the axial forces from the structure.
The body material of the insulator should be coated with high-strength paint in closed areas and galvanized in open areas. If there are steel springs inside the body, these springs should also be covered with PVC. It should be noted that a thin layer of rubber should be kept at the base of the springs.
Types of Seismic Insulators
Passive Seismic Insulators; In this type of insulator, vibrations caused by an earthquake are absorbed by the system, reducing the amount of force acting on the structure. It filters out high-frequency vibrations and ensures minimal damage to the structure. The most common of these types of insulators are ELASTOMERIC pillows. Pillows made of polymeric materials are formed by placing a series of elastomeric sheets on top of each other.
Active Seismic Isolators; In addition to passive seismic isolators, they interfere with the tremors, reducing the amount of vibrations affecting the structure. There are actuators in the insulator that apply a controllable force. These controlled forces applied to the structure reduce the earthquake force acting on the structure during an earthquake.
The Benefits of Seismic Isolators
Seismic isolators create safe living spaces for users inside the structure by reducing the destructive effects of earthquakes at a high rate in the structures where they are used. When we look at the big picture, the cost of repair works to be carried out after an earthquake in structures where a seismic insulator is not made is much higher than the cost of applying a seismic insulator. Seismic isolators are both an economical solution for users while offering living spaces with a high amount of earthquake resistance at the same time.
Strength Capacity
Seismic insulators may vary in their strength capacities depending on their types and the materials used. In insulators, which are applied with high-quality materials and a professional team, resistance to earthquakes of about 9 magnitudes can be provided comfortably. In Japan, which is the best example of today's earthquake and disaster prevention measures, structures equipped with seismic insulators were minimally affected by the earthquake in the 9th magnitude 2011 earthquake.
Seismic isolators can be applied at the initial construction stage of the structure, as well as they can be added after the structure is completely completed. The part that needs to be taken into account here is that seismic insulators added later may cause some structural changes due to their operating principles. The simplest example of these changes is to place a temporary disconnection insulator in the columns where the insulators will be placed. When the necessary changes are implemented by a professional team, a solid foundation can be created without any problems in the structure.