## 4 Comparison of Structural Analyses
Each story has an equal height of 3 m.  
C25-S420 was taken into consideration for all RC building models. Yield strength (f\({}_{\text{s}}\)) value was taken as 483 MPa, and concrete compressive strength (f\({}_{\text{c}}\)) was taken as 33 MPa according to material models used in this study. The transverse reinforcements were selected as \(\phi\)10/10 in columns and \(\phi\)10/15 in beams in all stories. The reinforcements used in all columns were selected as 4\(\phi\)20 in corners, 4\(\phi\)16 in top-bottom sides, and 4\(\phi\)16 in left-right sides. The reinforcements used in all beams were selected as 4\(\phi\)16 in lower, 5\(\phi\)18 in upper, 2\(\phi\)12 in sides, 4\(\phi\)10 in lower-slab, and 6\(\phi\)10 in upper-slab. Column and beam cross-sections used in the RC buildings are given in Figure 10. The selected RC building was analyzed using horizontal design spectrum curves, which were obtained from DD-2 since it is the standard design earthquake ground motion level. The base shear forces were obtained for each province. Three different points on the idealized curve as displacement values were calculated. Figure 5: Flow chart of the adaptive pushover method (modified from [78]). Figure 6: Material models for concrete and steel considered in the study [80]. Figure 8: Two- and three-dimensional models of the selected 3-story RC building. Figure 7: The blueprint of sample reinforced-concrete (RC) building. Figure 9: Three- and two-dimensional models of the selected 6-story RC building. While creating all structural models, force-based plastic hinge frame elements (infrmFBPH) were used for columns and beams. These elements model the spread inelasticity based on force and only limit the plasticity to a finite length. The ideal number of fibers in the cross section should be sufficient to model the stress-strain distribution in the cross section [82]. In total, 100 fiber elements are defined for the selected sections. This value is sufficient for such sections. Plastic-hinge length (Lp/L) was chosen as 16.67%. The base shear force, which occurs at the ground level of the buildings due to the earthquake and is equal to the total lateral load acting along the building height, was calculated separately for each province. The displacements were obtained for three different points on the idealized curve. The first value refers to yield displacement (d\({}_{\rm y}\)), while the second and third values refer to the intermediate displacement (d\({}_{\rm int}\)) and the target (or ultimate) displacement (d\({}_{\rm t}\)), respectively. The stiffness values of RC structural elements differ from the predicted stiffness values under the effect of an earthquake. Therefore, effective cross-sectional stiffness values are used in the design and analysis of these structural elements. The stiffness of cracked sections is taken into account to determine RC structural systems' performance under earthquake loads. The effective stiffness of cracked sections was obtained by using the prescribed stiffness reduction coefficients of the elastic stiffness value [83; 84; 85]. The elastic stiffness value (K_elas) and effective stiffness (K_eff) values for each structural model were obtained directly using the stiffness reduction coefficients predicted in the algorithm. It is crucial to determine the target displacements for damage estimation when certain performance limits of structural elements are reached in performance-based earthquake engineering. In the structural analysis, the limit states given in Eurocode-8 (Part 3) [86; 87] were taken into consideration for damage estimation used worldwide. The limit states for damage estimation are presented in Table 7, according to Eurocode-8. All displacements calculated for structural analysis are shown in Figure 4:0  
The natural vibration period of buildings is an important parameter in earthquake resistant design and performance evaluation.