Methodology for Modeling and Seismic Analysis of Four Buildings Representative of Bagan’s Monumental Heritage

This paper presents a comprehensive methodology for assessing the seismic vulnerability of four historic monuments in Bagan, including analysis of their architectural and structural characteristics, an evaluation of their behavior in past earthquakes, and finally finite element (FE) modeling and seismic analysis. The monuments, Myin-pya-gu (1493), Zan-thi (east) (558), Tha-mu-ti-hpaya (844), and Kya-zin-hpaya (1219), are representative of the main structural typologies in Bagan under the scope of the Repair and Seismic Retrofitting of Monuments component of the Bagan Conservation Project. They are defined by the presence or absence of two key features for satisfactory seismic performance: plan symmetry and vertical continuity of the main spire. Nonlinear FE models were developed based on 3D meshes generated from digital scans, incorporating nonlinear constitutive model reflecting Bagan’s historical brick masonry. Seismic performance was assessed through a combination of mass- and mode-proportional nonlinear static pushover analyses. Additionally, nonlinear dynamic time-history analyses were conducted to replicate past damage using natural and physics-based simulated records of the 2016 Chauk earthquake, as well as simulated signals with higher PGA to understand behavior under larger earthquakes. The rationale for the selection of pushover load patterns and ground motion signals for nonlinear static and dynamic analyses, respectively, is discussed highlighting the need to select the nature of analysis based on the exigencies of the structure being modelled.