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Explanation of the Difference in Performance Results Between Versions

CONTRIBUTION OF WALLS WITH INSUFFICIENT CAPACITY TO THE STOREY SHEAR FORCE

  1. In StatiCAD-Yigma VERSION 3, earthquake forces are applied in the X and Y directions. The absolute value of the additional shear forces acting on walls due to torsion is taken. The sum of these forces is added to the storey shear force to obtain the torsional storey shear force. The calculated torsional storey shear force is written in the performance report under the name Qtbi. For each storey, the sum of the shear forces of walls with insufficient capacity in the X or Y direction is divided by the Qtbi value to determine the damage ratios. If the damage ratio exceeds 50% in any storey in any direction, the building is declared at risk.

  2. In StatiCAD-Yigma versions between VERSION 4.0.0.0 and Version 4.0.9.5, the calculation is based on the book "Regulations on Buildings to be Constructed in Earthquake Zones — Explanations and Examples" published by the Ministry of Public Works and Settlement, authored by Prof. Dr. Zekai Celep, Page 617, Example 20. The relevant example can be accessed at http://www.ipkb.gov.tr/ismep/Orneklerkitabi/BolumII/BolumII\_D\_Ornek20\_ZekaiCelep.pdf or by clicking here. In the relevant example, earthquake forces are applied in the (+X), (-X), (+Y), (-Y) directions. The additional shear forces acting on walls due to torsion are calculated. The additional shear forces from torsion are applied to the walls with + and - signs as in the example.

  3. In StatiCAD-Yigma Version 4.1.2.0 and later versions (up to the current release), the solution algorithm was changed in line with the opinion of Prof. Dr. Ahmet YAKUT — provided through the Ministry of Environment and Urbanization — that walls close to the center of rigidity are protected, and in accordance with the solution given at the link http://webdosya.csb.gov.tr/csb/dokumanlar/altyapi0009.pdf.

The additional shear force acting on walls is positive for some walls and negative for others in the relevant direction. When the additional shear forces due to torsion in, for example, the +X direction are summed, the total becomes zero. Similarly in the other directions, positive and negative values cancel each other out. This can be seen from the wall shear force table. Therefore, in VERSION 4 calculations, Qtbi = Qi. In the direction-dependent earthquake calculation, if a wall's capacity is exceeded in one direction, that wall is considered a wall with insufficient capacity (since earthquakes have reversible effects, a wall damaged under the changing direction of an earthquake cannot be assumed to be undamaged). The Ve value of the wall in the relevant direction is included in the sum of Insufficient Ve values. Insufficient Ve values are calculated separately for each storey and each direction, then divided by the storey shear force of the relevant storey. In versions after 4.1.2.0, the torsion-induced shear force due to +/- earthquake directions changes only in new design. This is because the additional eccentricity effect is considered in new design but — in accordance with Section 7 of the earthquake code — is not considered in the evaluation of existing buildings.

If the damage ratio exceeds 50% in any direction in any storey, the building is declared at risk.

Yours sincerely…

ÖZDEMİR YAZILIM