Seismic performance evaluation of arch segments on Rumbai Jaya bridge using incremental dynamic analysis method

Abstract

Steel arch bridges are critical transportation infrastructures whose seismic reliability must be rigorously evaluated, particularly in high-seismicity regions such as Indonesia. Despite the widespread application of performance-based seismic assessment, probabilistic evaluations of existing steel arch bridges using Incremental Dynamic Analysis (IDA) remain limited. This study investigates the seismic performance and reliability of the Rumbai Jaya Bridge using Incremental Dynamic Analysis (IDA) within the Performance-Based Earthquake Engineering (PBEE) approach. A three-dimensional finite element model was subjected to twelve spectrally matched ground-motion records representing multiple seismic source mechanisms, with excitation intensities progressively scaled from 0.1g to 1.0g. Structural performance was quantified through drift-based limit states and seismic fragility curves following the NCHRP Synthesis 440 criteria. The analytical model exhibited a fundamental period of 0.48 s dominated by transverse vibration, while demand-to-capacity ratios of 0.40, 0.61, and 0.39 for bending moment, shear, and axial force, respectively, confirmed adequate structural capacity prior to seismic excitation. The IDA results revealed considerable record-to-record variability, with the Tohoku ground motion producing the most critical response, reaching a maximum drift of 12.33%. Nevertheless, the mean structural response remained below the Near Collapse threshold, exhibiting an average drift of only 4.64% at the maximum intensity of 1.0g. Fragility analysis further demonstrated that, under the site-specific design peak ground acceleration of 0.151g, the probabilities of exceeding the Operational and Collapse limit states were only 11.67% and 0.21%, respectively, indicating a substantial seismic safety margin. These findings demonstrate the robustness of the Rumbai Jaya Bridge against design-level earthquakes and highlight the effectiveness of IDA-based fragility assessment as a reliable method for performance evaluation and risk-informed management of steel arch bridges in high-seismic regions.