Assessing Seismic Risk in Sagaing City: A Case Study of Incremental Dynamic and Pushover Analyses on Multi-Span Reinforced Concrete Bridge Pier

Abstract Sagaing City, situated along the highly active Sagaing Fault, faces significant seismic hazards, necessitating rigorous evaluation of its critical infrastructure. This study explores the seismic performance of a multi-span reinforced concrete bridge pier through a comparative analysis of Incremental Dynamic Analysis (IDA) and Pushover Analysis (POA). These methodologies are employed to capture both the dynamic and static responses of the structure, offering insights into its vulnerability under varying seismic intensities. IDA, leveraging real earthquake ground motion records, provides a detailed depiction of the bridge's nonlinear dynamic behavior, including elastic deformation, energy dissipation, and collapse thresholds. In contrast, POA highlights the structure's capacity limits under monotonically increasing lateral loads, identifying key parameters such as yield and ultimate displacements. Results from IDA reveal that seismic events induce steep drift escalations and collapse at peak ground accelerations ranging from 0.5g to 1.5g. This indicates significant energy input challenges the ductility and reserve capacity of the hollow pier. Meanwhile, POA establishes yield and maximum displacements of 0.135 meters and 0.255 meters, respectively, along the longitudinal axis, complemented by capacity curves that delineate the structure's load-bearing thresholds. A critical comparison between IDA and POA underscores their complementary nature: while IDA captures dynamic effects like resonance and material degradation under seismic excitation, POA provides a simplified yet effective evaluation of structural stiffness and ultimate capacity. The study further emphasizes the directional variability of seismic responses, with longitudinal displacements exhibiting lower thresholds than transverse ones, reflecting inherent structural asymmetries. These findings highlight the necessity of enhanced seismic design strategies that incorporate dynamic energy dissipation mechanisms and robust detailing. Integrating insights from both IDA and POA, this research advocates a hybrid framework for seismic assessment, tailored to the unique challenges posed by near-fault seismicity in Sagaing City. By addressing the interplay between dynamic and static seismic demands, this study contributes to a deeper understanding of structural performance, paving the way for sustainable and resilient urban development in earthquake-prone regions.