5. Stresses
In Sri Lanka, where seismic effects are minimal,
the main loading on a stupa is its self weight.
Finite element studies done on stupas [Ranaweera
1993, 1998, 2000, 2001] have shown that, under
self weight, most parts of a stupa are under
compression. Few tensile zones are present in the
square chamber and the cylinders, and at the outer
surface of the domes having shapes other than the
paddy-heap.
For paddy-heap shape domes the stresses are all
compressive, making them the most stable from a strength point of view [Ranaweera 1998]. In the
paddy-heap shaped dome of Jetavana, the largest
stupa ever built, the maximum compressive stress
occurs at the centre at foundation level and its
value is 839 kPa (Fig. 17), around one tenth of the
compressive strength of the ancient bricks used
(Table 4). Hoop and radial stresses in Jetavana
dome are also compressive having a maximum of
280 kPa at base centre. Pot shape domes have the
largest tensile hoop stress region, as in the case of
Tissamaharama stupa.