## 2 Materials and Methods
### Nonlinear Modeling and Determining Collapse Points of Structures  
As previously mentioned, the reinforcement designs for the reinforced concrete elements of the buildings were carried out in accordance with the TEC-1975 earthquake regulations for the older buildings and the TEC-1998 earthquake regulations for the newer buildings. However, the section damage limits outlined in TBEC-2018 were utilized to assess the seismic performance of the buildings. Although TBEC-2018 also includes building performance limits for beams, this study only considered column elements when determining building performance limits. In other words, when the buildings were evaluated in the study, the performance of the beams, whether Limited Damage (LD) or Collapse  
Figure 1: Sample floor plan of theoretical building created in study. Figure 2: Calculated natural vibration periods of buildings. Prevention (CP), did not affect the overall building performance. The rationale behind this is that the failure of a column significantly increases the probability of loss of life in a building. Table 2 presents the threshold values corresponding to the damage limits. To capture the nonlinear behavior of the structural members, lumped fiber-hinge elements were employed, where the hinges were directly characterized by material nonlinearity. In this approach, each hinge is described by fiber models, with stiffness evaluated directly from the material's nonlinearity. According to [16], a single hinge at each end is sufficient to model biaxial bending. The hinge length was applied as 0.5 of the section height, as recommended by [16]. The compressive strength of the concrete was assumed to be 25 MPa for the new buildings and 16 MPa for the old buildings, and the yield strength of both the longitudinal and transverse reinforcements was assumed to be 420 MPa for the new buildings and 220 MPa for the old buildings. The calculations also accounted for the post-yield strengthening of the reinforcement. The longitudinal reinforcement ratios varied between 1.1% and 1.65% for the reinforced concrete columns. No cross-sectional or reinforcement reduction was employed for either the old or new structures, which are widely used in buildings designed under TEC-1975 [8]. After the nonlinear definitions of the buildings were made, the structure models were subjected to static pushover analysis and the building performance limits were determined according to TBEC-2018. Both the x and y capacities of the buildings were determined, and the collapse status of the buildings was assessed separately in both directions. The performance points were determined based on the rotations of the relevant structural elements, and the corresponding section damage limits were used to define overall building performance levels, taking into account the distribution of these damages throughout the structure. Within this framework, only column damage was considered in defining total building collapse, excluding beam damage from the collapse criteria. Figure 3 illustrates the capacity curves (in dimensionless form) and associated damage states for two 6-story new building models (6N1X and 6N1Y). The obtained capacity curves and the means of the subjected categories are shown in Figures 3-9, with the relevant damage limits indicated by dots along two lines. The averages of the relevant damage limits are shown as immediate occupancy (IO) to ultimate capacity (C) in Table 3. This table shows that the empirical buildings examined represent Turkish buildings in terms of both horizontal strength ratios and horizontal drift capacities, and are consistent with building models in past studies [12; 17; 18; 19]. In their 2008 study, [PERSON] et al. [17] modeled representative buildings (referred to as REF buildings) based on structural characteristics observed in the Turkish building stock, including both 4- and 7-story reinforced concrete buildings.