Use of Different R and D Coefficients for Upper and Lower Pats of Structures with Basement
Symbols
D | Strength Excess Coefficient |
D _{alt} | Strength Excess Coefficient applied to the lower part of the building |
D _{üst} | Strength Excess Coefficient applied to the lower part of the building |
R | Carrier System Behavior Coefficient |
R _{alt} | Structural System Behavior Coefficient applied to the lower part of the building |
(R _{a} ) _{alt} | Earthquake Load Reduction Coefficient applied to the lower part of the building |
(R _{a} ) _{n, alt} | Earthquake Load Reduction Coefficient applied to the lower part of the building in nth vibration mode |
R _{üst} | Structural System Behavior Coefficient applied to the lower part of the building |
( R _{a} ) _{üst} | Earthquake Load Reduction Coefficient applied to the upper part of the building |
(R _{a} ) _{n, üst} | Earthquake Load Reduction Coefficient applied to the upper part of the building in the nth vibration mode |
T | Natural vibration period |
T_{n} | Natural vibration period of the nth mode |
T_{p}^{(X)} | (X) the dominant natural vibration period of the building in the direction of the earthquake |
ν_{n}^{(X)} | The coefficient used in the calculation of the equivalent earthquake load reduction coefficient applied in the nth mode for the lower part of the building |
ν _{alt }^{(X)} | Coefficient used to calculate the reduced internal forces caused by the vibration of the lower part of the building itself |
ν _{n, alt}^{(X)} | Coefficient used to calculate the reduced internal forces from the vibration of the lower part of the building itself in the nth mode |
ν_{üst}^{(X)} | Coefficient used to calculate the internal forces transferred from the upper to the lower part of the building |
ν _{n, üst}^{(X)} | Coefficient used to calculate the internal forces transferred from the upper to the lower part of the building in the nth mode |
4.3.6. Using Different R and D Coefficients in Upper and Lower Sections of Buildings
In buildings where different R and D coefficients are used in the upper and lower sections , calculations will be made according to the rules given in 4.3.6.1 or 4.3.6.2 . According to the definition given in 3.3.1 , these rules can also be applied in buildings with basements surrounded by rigid walls. Alternatively, calculations can be made according to the rules described in 4.7.5 or 4.8.5 .
With the Equivalent Earthquake Load Method explained in 4.3.6.1 - 4.7 , in the calculation made by considering the entire carrier system ( upper section + lower section );
(a) the top section wherein the structural elements corresponding to the ductility internal forces reduced to upper table (4.1) from the selected R _{top} and the D _{top} coefficients and considering the received (X) the natural vibration period prevails in the earthquake direction T _{p }^{(X )} 'e substituted by Eq. (4.1) from the calculated Seismic Load Reduction Factor (R _{a} ) _{top} will be obtained using.
(b) The reduced internal forces corresponding to the non-ductile behavior of the carrier system elements in the upper section will be obtained by multiplying the internal forces obtained in (a) with the _{upper} coefficient D.
(c) The equivalent earthquake load reduction coefficient (R _{a} ) for reduced internal forces corresponding to the ductile behavior of the structural system elements in the _{subsection }shall be determined by _{Sub }Equation (4.4) :
The coefficient ν ^{(X) in} this equation is given below:
Eq. (4.5 A) 'in the first term ν _{top }^{(X)} , the upper portion from the lower portion ' E transmitted reduced forces, the second term (X) ν _{lower }^{(X)} The subsection 'to calculate the reduced forces generated by its own vibration corresponds to the coefficients used. Seismic Load Reduction Coefficient calculated from Equation (4.1) depending on R _{sub} and D _{sub-} coefficients selected from Table (4.1) and T _{p }^{(X)} for the carrier system in _{sub- }subsection (R _{a} ) It shows. ν _{top }^{(X)} is defined as the ratio of the base shear force of the upper section to the base shear of the entire load-bearing system ( upper section + lower section ) under unabated seismic loads .
(d) The reduced internal forces corresponding to the non-ductile behavior of the structural system elements in the subsection shall be obtained by multiplying the internal forces obtained in (c) by the equivalent strength excess coefficient defined below :
:d_czg_alt:
With the Modal Calculation Methods explained in 4.3.6.2 - 4.8 , the calculation made by considering the entire carrier system ( upper section + lower section ),
(a) All operations in Equation (4.4), Equation (4.5) and Equation (4.6) shall be applied for each n th vibration mode and taking into account the relevant natural vibration period T _{n} . In the nth mode , instead of the ratio of base shear forces in Equation (4.5b) , the ratio of modal effective masses corresponding to these shear forces in the same mode can also be used (See 4B.1.4 ).
(b) R is _{lower} <R _{top} in rigid basement systems which, for all modes of Eq. (4.5b) from the ν _{n, parent }^{(X)} 'in case of avoiding to calculate always gives less favorable results ν _{n, parent }^{(X)} = 0 can be assumed. In this case, the following simplifications can be made for the subdivision in the n'th mode:
D _{sub} = 1.5 for basements according to 4.3.2.3 .
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