The Effect of Ground Motion Scaling Methods on Steel Braced Frame System Behavior

Abstract

Nonlinear history analysis is one of the most comprehensive methods for assessing structural behavior under earthquake loading. The selection of input parameters used in the analyses is very important as they affect the accuracy and reliability of structural behavior. Among these parameters, the selection and scal-ing of ground motions play a critical role in achieving reliable results. Since real recorded earthquake ground motions used in time history analyses differ in terms of magnitudes, fault distances, source mechanisms, and local ground conditions, scaling is required according to current earthquake codes. According to TSC 2018, two different procedures can be used for scaling real recorded ground motions: the simple scaling method and spectral matching. In this study, the seismic per-formance of a school building with special concentrically braced steel frames is evaluated with nonlinear history analyses. The destructive earthquakes occurred on February 6, 2023, in Kahramanmaraş/Pazarcık and Kahramanmaraş/Elbistan are effective in the selection of ground motion records used in the analyses. After these earthquakes the reports published by universities highlighted the effects of the distance between fault and construction area on the damage levels. Therefore, the ground motions used in this study are selected to reflect earthquakes occurred in high seismic areas with the fault distance less than 10 km. The results of the dynamic analyses indicate that the base shear values obtained using simple scaling and spectral matching methods are largely comparable with no significant differ-ences observed. However, notable differences are observed in the interstory drift ratios, which are substantially higher when the simple scaling method is applied. The ductility demands on brace members are considerably higher under simple scaling methods. In contrast, the spectral matching method more effectively con-trols these demands, maintaining them within the expected performance limits, especially under tensile loading conditions.