Seismic Rocking Analysis of Monuments in Bagan Archaeological Site

An analytical framework for seismic rocking analysis of nonstructural elements in the monuments of the archaeological site of Bagan, identified as vulnerable in past earthquakes, is presented. While the overarching study focuses on four structural typologies, a nonlinear kinematic analysis incorporating a finite compressive-strength rocking model is adopted specifically for the susceptible rocking elements of three selected representative monuments. Seismic demand is evaluated using three definitions: the recorded 2016 Chauk earthquake ground motion, monument-specific simulated records, and the design spectrum based on Myanmar’s National Building Code of 2020 (MNBC 2020). The floor spectra are computed for each rocking element using the procedure based on Italian norms for construction (CNTC 2019) accounting for height-dependent acceleration amplification. Results show that the main spires of all three monuments are the most vulnerable elements, with amplification factors of 1.65–2.45 relative to ground level. A comparison of the three demand definitions reveals distinct outcomes: The design spectrum definition consistently yields the most conservative demand estimate due to its higher peak ground acceleration, while the spatial variability captured by monument-specific simulated records reveals significant inter-monument differences not apparent from the single record of Chauk earthquake.