...
In buildings classified as Building Height Class BYS ≤ 6 and DTS = 1a, 2a according to TBDY Article 4.3.4.1 (b) , ductility level mixed structural systems cannot be used.
With the TBDY 2018 Wizard , ductility level limitations are made automatically according to the classifications in 4.3.4.1 (a) and (b) and the selection of these carrier systems is not allowed with the TBDY 2018 Wizard .
The following picture shows the structural ductility level selection for DTS = 1a. According to 4.3.4.1 (a) , for DTS = 1a, since carrier systems with limited ductility level are not used, the "Limited" option is not used.
...
The following picture shows the ductility level selection screen for a structure with DTS = 1a and BYS = 5. According to 4.3.4.1 (a) , carrier systems with limited ductility level are not used for DTS = 1a . Besides, according to 4.3.4.1 (b) , for buildings with DTS 6 and DTS = 1a, mixed ductility load-bearing systems are not used. Since both items (a) and (b) are applied for a structure with DTS = 1a and BYS = 5, ductility level is limited and mixed options cannot be used in the TBDY 2018 Wizard.
...