24.01.2020 Sivrice Earthquake and Seismic Isolation
Date:
24.2.2021
24.01.20 After the Sivrice Earthquake, we conducted several examinations for 3 days in the cities of the region. In the meantime, we also had the opportunity to examine 3 seismically isolated hospitals. The structural and earthquake isolation systems project designs of 2 of the hospitals have been performed by Ülker.
The maximum displacement demand of one of the facilities, the Elazığ Hospital, calculated under 0.82g S1 MCE spectral acceleration is 44.8 cm. Its isolation unit displacement capacity is 52 cm. during the Sivrice Earthquake, movements varying between 6 cm and 2 cm were observed in the isolators. The permanent displacements are between 2 and 0 cm.
When we look at the calculations, it should be about 4 cm in nominal and about 6 cm with lower limit parameters. S1 value for calculations is approximate as we do not have instrumental data.
In the video below, you can see the movement of the contents first in a conventional structure, and then in the seismically isolated Elazig hospital during the Sivrice Earthquake. The difference clearly shows that the isolation system works successfully.
Based on the example of a seismically isolated city hospital we have designed, which passed its first test in the Sivrice earthquake, I have listed the issues that should be considered as follows:
1. The lower and upper limit parameters in isolation systems should be determined correctly. In this example, the displacement estimate has been achieved with lower limit values (lambda = 0.7). Today, the high lambda values such as 0.9 given by the builders in many projects, which is obviously not achieved in the tests, should be questioned.
2. The isolated buildings should be monitored by equipment such as accelerometer/ displacement meter etc. to be able to accurately monitor the behavior of the isolation units.
3. In this example it is clear that the building is "pivoting". This seriously changes the behavior of the isolation system. Thus, all structural / non-structural elements that prevent the movement of isolation systems should be removed as soon as possible.
4. There may be permanent displacement in the building according to the selected isolation system. An undesirable situation can be prevented by routine control performed after earthquakes.
