As I know because I am close, Düzce municipality wants the Ao value as 0.51. I think it has something to do with the acceleration records of the November 12, 99 earthquake. Soil studies come in this way. In our case, the limit of the relative floor drifts was lowered from 0.02 to 0.01 by the decision of the city council. Relative story displacement parameter is the first value that measures the building stiffness. Even if Ao = 0.51, the relative floor drifts greater than 2 percent indicate that a weak building has been designed. If you have already read the draft of the new earthquake code, the upper floor displacement limit is reduced to 0.008 in cases where infill walls are built together with the building. In cases where infill walls are made with dilatation, the upper limit of relative translation is reduced to 0.016. Moreover, when the parameters in the new regulation such as the element effective stiffness and the coefficient of closeness to the fault come into play, we will have to design much more rigid buildings than now. Best Regards, Jesus SAYI