# 15.5.2.3

Values expressed as *impact/capacity ratio* (ECO) are used to control the application limits of linear performance analysis of existing structures . The ECO value is obtained by dividing the total section moment calculated by taking R _{a} =1 under the effect of vertical loads and earthquakes, by the section moment capacity.

*Impact / capacity ratio*(ECO) values of columns, beams and curtain elements of existing structures are automatically calculated by taking R_{a}= 1.

The direction of the earthquake effect applied in the EKO calculation is automatically taken into account.

Axial force and biaxial bending interaction is automatically calculated by taking the axial forces R

_{a}= 4 in column and wall sections .

In the linear earthquake calculation applied with the ŞGDT approach in the evaluation of existing structures, the *Impact / Capacity Ratios* (ECO) of columns and walls are obtained by dividing the total section moment calculated by taking R _{a} = 1 under the effect of vertical loads and earthquakes by the section moment capacity. However, there is an interaction of axial force and biaxial bending in column and curtain elements as shown in the picture below. The axial forces used to calculate the bending moment capacities in columns and walls are the forces calculated by taking R _{a} = 4 under the effect of vertical loads and earthquakes . Under the influence of this axial force, the moment curvature relation of the section is automatically deduced and the moment capacity is determined. Axial force and biaxial bending interaction. __It__ is obtained by using the__ current material strength in accordance with the knowledge level__

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