Amplitude Scaling for Ground Motion Modification Using Firefly Algorithm

One step in the nonlinear response time history analysis technique used in designing earthquake-resistant structural buildings is the selection and modification of ground motion. In Indonesia, this clause is found in SNI 8899:2020, which deals with procedures for selecting and modifying surface ground motion for designing earthquake-resistant buildings. This research will discuss ground motion modification based on historical earthquake recordings and spectrum targets. Amplitude scaling and spectral matching are the two common techniques utilized in ground motion modification. Amplitude scaling is a straightforward technique that lowers computing costs. The firefly algorithm will be used in this study to approximate the scale factor in the amplitude scaling method. Eleven sets of earthquake recordings were utilized, following the examples found in SNI 8899:2020. The objective function is taken as reducing the limit ratio between the target spectrum and the average spectrum of recorded earthquakes. A comparison will be made between the scale factor found in SNI 8899:2020 and the scale factor obtained by the firefly method. The scale factors in the periods 0.2T1(B) - 2T1(A) and 0.2T1(B) - 1.5T1(A) are the two that will be compared.