THE DEVELOPMENT OF THE SEISMIC FRAGILITY CURVES FOR EXISTING BRIDGES IN INDONESIA.

• Main Author: Citra Simanjuntak, Veby
• Format: Dissertations
• Language: Indonesia
• Subjects: Teknik sipil
• Online Access: https://digilib.itb.ac.id/gdl/view/75039
• Institution: Institut Teknologi Bandung

Seismic regulations have been updated from time to time to accommodate an increase in seismic hazards. Updating of seismic regulations certainly has implications for tighter provisions on bridge seismic detailing. These implications raise questions regarding the seismic performance of the existing bridges especially those located in high seismic zones that were designed and built many years ago, but are still operating now. Therefore, this research aimed to identify the seismic detailing from different versions of Indonesian bridge design codes before 1990 until now and to present the significant changes in the seismic performance level of the existing bridges built in different design eras through analytical fragility curves. Fragility curves show the magnitude of the probability value of a level of damage that occurs to the bridge due to various earthquake intensity levels. In this study, seismic fragility curves were developed using incremental non-linear time history analysis and more holistically according to the actual strength of concrete and steel material in Indonesia to determine the uncertainty factor of structural capacity, ?c. From the research that has been carried out, it was found that in Indonesia’s bridge code before SNI 2833:2016, inadequate confinement and limited ductility were the main issues. The performance of older bridges would typically be less than more recently designed structures. Based on the current seismic load in SNI 2833:2016/Seismic Map 2017 (7% probability of exceedance in 75 years), the performance level of the bridge in the era before SNI 2833:2016 was Operational- Life Safety whereas the performance level of the bridge designed with SNI 2833:2016 was Elastic– Operational. The potential for more severe damage occurs in greater earthquake intensity. For exceedance probability >50%, collapse condition occurs at As = FPGA x PGA value of bridge Era I = 0,93 g ; Era II = 1,03 g; Era III = 1,22 g ; Era IV = 1,54 g. Furthermore, the fragility analysis was also developed with geometric variations (span length and pier height) in the same bridge class (type of pier, deck, pier to deck connection) to see the effect of these variations on the fragility, which is the basis for making bridge risk maps in Indonesia.