Page 128 - Çevre Şehir İklim İngilizce - Sayı 4

Seismic Isolation in Earthquake -
Resistant Structural Design for Resilient Cities

10. Isolators must be high-quality and safe products. Thus, it is mandatory
to have CE marking on the isolators.
11. Since the design of the connections of the isolators is the most critical
point for the entire structure, the horizontal and vertical forces based on
this design should be calculated by taking into account the total largest
displacement and increasing all load combinations by 10%. The total
earthquake effect E to be included in the load combinations should
d
be taken into account for the level ground motion in DD-1 earthquake
and by including the vertical earthquake component.
12. In rubber isolators, it is necessary to check if they do not exceed the
limits determined by making unit deformation calculations for various
situations. The unit deformations to be calculated consist of the angular
deformations caused by the possible horizontal displacement due to
pressure and other effects in the non-earthquake state (expansion, wind,
etc.); the unit deformation caused by the relative turning between the
upper and lower plates of the isolator; and the unit deformation caused
by the pressure generated under the impact of earthquake ground
motion and the horizontal displacement. In addition, it is necessary to
check that the buckling load for rubber insulators does not exceed the
limit values.
13. Under certain restrictions and if certain criteria are met, the Effective
Earthquake Load Method or the Mode Coupling Method can be used
for analysis. However, in practice, the design is finalized by performing
time history analyses, which can be applied without any restrictions.
14. There is no rule for limiting floor accelerations in TBDY (2018). On the
other hand, one of the main purposes of buildings with seismic isolation
is to reduce floor accelerations in order to protect vibration sensitive
devices inside the building and to ensure people’s comfort (Alhan and
Şahin, 2011). The limit of floor accelerations should be determined as a
result of consultation with the building owner, taking into account the
purpose of use and the devices inside the building. This level is usually
at around 0.2 g ~ 0.3 g. For hospital buildings in Türkiye, while the
floor acceleration limit was 0.2 g in the circular of the Ministry of Health
Republic of Türkiye published in 2013, this limit was reduced to 0.3 g in
the circular updated in 2018. Achieving these acceleration levels on the
upper floors of multi-storey buildings (above 4-5 floors) can be difficult
in some cases. However, since these floors are usually bearing floors,
values slightly above 0.3 g can be considered as acceptable values.

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