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.

  • ECO values ​​scaled with the cutting force are calculated automatically according to Equation (15.1) .


EKO = Impact / Capacity ratio
R a = Earthquake Load Reduction Coefficient
V i = Shear force calculated in the i column

The scaled ECO values ​​with the shear force specified in the clauses (c) and (d) in TBDY Article are calculated with Equation (15.1) .

In the above equation, the column number on the relevant floor is indicated by the index "i". V i is the shear force consisting of the vertical loads calculated in the i column and the earthquake loads ( loading cases ) taken as R a = 1 , (EKO) i is the Impact / capacity ratio calculated in accordance with TBDY Article in the column i . Axial force and biaxial bending interaction are taken into account when calculating ECHO in columns. When creating the interaction diagram, the current material strength is used by considering the information level coefficient .

The line shown in red in the picture below shows the point in the P-M2-M3 three-dimensional system of axial force and biaxial bending consisting of vertical loads and earthquake loads ( load cases ) taken as R a = 1 . It is the curved capacity curve shown with black lines. The length of the line drawn from the starting point to the point PM 2 -M 3 shows the effect value, the length of the line from the starting point to the point that intersects the interaction diagram in the direction of the line drawn to the PM 2 -M 3 point shows the capacity value. ECO value is the ratio of these two values.

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