Page 132 - Çevre Şehir İklim İngilizce - Sayı 4

Seismic Isolation in Earthquake -
Resistant Structural Design for Resilient Cities

Initial rigidity, k , is taken into account as a virtual rigidity, which is a very
1
high value in calculations. The secondary rigidity, as given in Equation (1)
(TBDY (2018), Equation 14B.2) is calculated as such:

In the sample model, the average P (G+nQ) load imposing on the insulators
is 4992.62 kN. Characteristic strength for the selected nominal effective friction
coefficient 0.08 and the effective radius of curvature R =6.9 m is calculated
c
as F =0.08×4992.6=399.4 kN and k =4992.62/6.9=723.6 kN/m. Another
Q
2
parameter, k the value that is needed in the computer model can be taken a
1
high value (for example, 400~500 times of F ).
y
Effective rigidity (k ) as given in Equation (3) (TBDY (2018), Equation 14B.3),
e
the effective damping ratio ( β ) as given in Equation (4) (TBDY (2018), Equation
e
14B.4), the radius of curvature can be obtained depending on the coefficient
of friction and displacement:

In this case, at the DD1 earthquake level, if the target displacement is
considered to be 40.4 cm using nominal characteristics (the final value is
obtained as a result of iteration), it is found as k =1697.7 kN/m and β =0.365.
e
e
Damping Scaling Coefficient (η), is calculated as given in Equation (5) (TBDY
(2018), Equation 14.32) depending on the the effective damping percentage
(ζ) calculated for isolator displacements at the DD1 and DD2 earthquake
ground motion levels:

Here, at the DD1 earthquake level, ζ= 36.5% was achieved by the above
calculation made with nominal parameters, but according to Article 14.14.3.5
of the TBDY (2018) the effective damping ratio is limited to ζ=30%, the
damping scaling value using this value is obtained as η=0.535.

Year 2 / Issue 4 / July 2023 121