Some engineering aspects of ancient stupas in Sri Lanka

Stupas in Sri Lanka are solid brick structures built since the third century BC, and over the years, they have grown in size to become some of the largest brick structures in the world. Jetavanaya stupa, built during the third century AD, reached a height of 122 m, making it the third tallest structure in the world at that time. Presently, it has a total volume of bricks in excess of 300 000 m³, making it the most voluminous brick structure in the word. While constructing these megastructures, the ancient builders of Sri Lanka have shown some remarkable engineering innovations and skills far ahead of their times. This paper deals with the development of these historical structures and some technological aspects related to their architecture, materials, stresses and construction techniques and methods used for their protection from the elements. Stupa components are discussed, as well as the brick mortar and plaster used and their properties. Stresses found from finite-element analyses are also shown, followed by techniques used in stupa construction. Protection techniques include an innovative device used for lightning protection of these tall structures and methods used to prevent corrosion of the metallic objects inside the relic chamber.