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Even if the special condition given in 7.6.1.3 is fulfilled, you receive this message because the wall thickness is less than 200 mm.
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Solution:
Give the size of the curtain with the name and floor at least 200 mm.
Choose curtains, curtains
Enter the properties.
In the general settings tab, increase the curtain width and click the OK button.
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Icons
ΣAg = The sum of the cross-sectional areas of the structural system elements working as a curtain parallel to the earthquake direction considered at any floor.
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