Seismic Performance of Three Ancient Stupas in Anuradhapura, Sri Lanka

Abstract

Ruwanweli, Abayagiri and Jetavana stupas situated in Anuradhapura, are three ancient wonders of Sri Lanka. Renovations and restorations of these stupas were started in early parts in the 20th century and carried out until recently. Considering their geometric proportions, cultural and social importance, there is an impending need to assess these stupas for seismic performance to avert any possible damages due to seismic activities that might occur in the future. Further, this requirement has become more important due to some researchers’ predictions on intraplate activities in the behaviour of ancient stupas with respect to possible earthquake accelerations. In this regard, two-dimensional numerical models of the three stupas were prepared using SAP2000 v.14: generalpurpose software package. Both static and dynamic analyses were performed on numerical models for self-weight and two recorded acceleration histories, respectively. Two acceleration histories are from Mahakandarawa, Sri Lanka and Manjil, Iran. Material parameters of ancient bricks were obtained from previous literature works and experimental test results conducted on similar bricks of another ancient stupa in Sri Lanka. Considering the past records of earthquakes that have occurred in Sri Lanka, it was understood that all three stupas are in the safe realm under magnitude 4.7 earthquakes (Peak Ground Acceleration of 5.48x10-5 g). Even referring to the stress distribution with magnitude 7.4 Manjil earthquake (Peak Ground Acceleration of 0.4 g), both Ruwanweli and Jetavana stupas are in safe zone.