Special Analysis Rules in Basement Structures as per TBDY 2018
- Kemalcan Struja (Unlicensed)
- Zeynep Aladağ
- nurgül Kaya
Modal Response Spectrum Analysis
Modal Response Spectrum Analysis is chosen for the building in accordance with Table 4.4 of TBDY 2018. The building can not be analysed with Equivalent Lateral Force Procedure.
Since the building has basement storys, it is difficult to provide sufficient mode numbers, the mass participation rate of 95%, to be taken into consideration in the Modal Response Spectrum Analysis for the entire upper section above the rigid basement walls and the lower section containing the basement floors. For this reason, in TBDY 2018 4.8.5.1, two stage analysis is done with modal analysis.
In this method, the upper part of the building and the lower part with basement are modeled together as a common structural system and two stage analysis is done. In both load cases, a mass participation ratio of 95% should be achieved.
There are two stages in the analysis of the upper section and the basement floors, as the structural system is flat slabs with special shearwalls. The first stage is the hinged modeling of the columns from the lower and upper ends, and the second stage is the monolithic modeling of the structural elements.
In addition, 4 modal analyzes are performed for each stage, since the accidental torsion is resolved with the dynamic method in the program.
In accordance with TBDY 2018 4.5.10.4 article, it is applied in a full rigid solution to determine accidental torsion in slabs with semi-rigid diaphragm adopted as a shell.
Due to all seismic code requirements listed above, a total of 20 modal analyzes are made for this building and the internal forces to be used for the design are determined.