Open AccessSeismic behavior of existing elevated water tanks resting on different type of foundations
Author(s) -
P Kodanda Rama Rao,
S R K Reddy,
AHL Swaroop,
K Nagarjuna
Publication year - 2022
Publication title -
iop conference series. earth and environmental science
Language(s) - English
Resource type - Journals
eISSN - 1755-1307
pISSN - 1755-1315
DOI - 10.1088/1755-1315/982/1/012082
Subject(s) - foundation (evidence) , geotechnical engineering , soil water , seismic analysis , seismic loading , water tanks , pore water pressure , engineering , structural engineering , geology , soil science , archaeology , history , marine engineering
It has been well recognized that heavy structures built on soft soils, experience significant impact on seismic response, because of considerable foundation movements and hence, the effect of Soil-Structure-Interaction (SSI) can be a major factor while analyzing important structures like; nuclear power plants, elevated water tanks, chimneys, etc. against seismic forces. In general, elevated water tanks that were constructed on different type of soils in seismic regions, prior to the revision of seismic codes, must be checked on behavior and safety of such structures against earthquake loads as per present codes. In this paper, two similar elevated R.C. circular water tanks, each of 4.0 lakh liters capacity supported by two types of foundations; one with circular ring raft below the columns of tank resting on sandy soils, and the other with circular ring raft supported by piles embedded in black cotton soils, are chosen for carrying out seismic analysis. In the analysis, the water tank is idealized as a system with three degrees of freedom, treating the staging of tank as one spring attached to the mass of the water tank and the soil is treated with two springs; one in horizontal and the other in rocking mode, both attached to the soil mass and the response parameters like; time periods, base shears and displacements are worked out against earthquake loads. Results indicate that, irrespective of type of foundation, the soil play important role on seismic response of elevated water tanks by virtue of their configuration with top heavy mass and slender staging; particularly displacements are found high when they rest on loose soils. According to the new guidelines provided in the revised IS 1893 (Part-1) 2016 code, SSI effect should be considered in seismic analysis when the structure rests on loose or soft soils.