Faculty Publications

Permanent URI for this communityhttps://idr.nitk.ac.in/handle/123456789/18736

Publications by NITK Faculty

Browse

Subject: search.filters.subject.Annular raft

Search Results

Now showing 1 - 4 of 4
  • No Thumbnail Available
    Item
    Effect of soil-structure interaction on along-wind response of tall RC chimneys
    (2011) Jayalekshmi, B.R.; Menon, D.; Meher Prasad, A.
    A parametric study has been carried out on tall reinforced concrete industrial chimneys to evaluate the effect of soil-structure interaction on the along-wind response of the structure. Three dimensional fi nite element model of the integrated chimney-raft-soil system under self-weight and wind load has been analysed to estimate the contact pressure distribution and variation of stress resultants in the annular raft. The bending moments in the raft foundation obtained from the soil-structure interaction analysis are compared with those computed assuming the chimney to be fi xed on a rigid foundation. The analysis of results on the effect of fl exibility of supporting soil reveals a considerable reduction in the bending moments in the annular raft foundation.
  • No Thumbnail Available
    Item
    Evaluation of the effect of soil-structure interaction on the raft of tall reinforced concrete chimneys under across wind load
    (Research Publishing Services editorial@rpsonline.com.sg, 2013) Jisha, S.V.; Jayalekshmi, B.R.; Shivashankar, R.
    A three dimensional soil-structure interaction (SSI) analysis of tall reinforced concrete chimneys with piled annular raft and un-piled annular raft subjected to across wind load is carried out in the present study. Effects of SSI were evaluated using four different soil types and three different ratios of external diameter to thickness of the annular raft. The across wind load was computed according to IS:4998 (Part 1)-1992. The integrated chimney-foundation-soil system was analysed by finite element software ANSYS based on direct method of SSI assuming linear elastic behaviour. FE analyses were carried out for two cases of SSI; (I) chimney with un-piled raft and (II) chimney with piled raft. The responses in raft were evaluated for both the cases and compared to that from conventional method of analysis. It is found that due to the addition of piles, there is considerable reduction in the responses in the raft when compared to that in the un-piled raft especially for loose sand and medium sand. © © 2013 APCWE-VIII. All rights reserved. Published by Research Publishing, Singapore.
  • No Thumbnail Available
    Item
    3D soil–structure interaction analyses of annular raft foundation of tall RC chimneys under wind load
    (Springer, 2014) Jisha, S.V.; Jayalekshmi, B.R.; Shivashankar, R.
    Three dimensional soil–structure interaction (SSI) analyses of tall reinforced concrete chimneys with annular raft foundation subjected to wind loads are presented in this paper. Different ranges of height and slenderness ratios of the chimneys and different ratios of external diameter to thickness of the annular raft were selected for the parametric study. To understand the significance of SSI, four types of soils were considered based on the stiffness. The chimneys were assumed to be located in terrain category two and subjected to a maximum wind speed of 50 m/s as per IS:875 (Part 3)-1987. The alongwind and across-wind loads were computed according to IS:4998 (Part 1)-1992. The linear elastic behavior was assumed for the integrated chimney-foundation-soil system and it was analysed using finite element software ANSYS based on direct method of SSI. The radial and tangential moments and settlement of annular raft foundation were evaluated through SSI analysis and compared with that obtained from conventional method of analysis as per IS:11089-1984, assuming foundation system is rigid. From the analysis, it is concluded that the SSI analysis results in higher radial moments and lesser tangential moments as compared to conventional method. All these variations depend on the geometric properties of chimney and annular raft foundations. © Indian Geotechnical Society 2013.
  • No Thumbnail Available
    Item
    Analysis of Foundation of Tall R/C Chimney Incorporating Flexibility of Soil
    (Springer India sanjiv.goswami@springer.co.in, 2017) Jayalekshmi, B.R.; Jisha, S.V.; Shivashankar, R.
    Three dimensional Finite Element (FE) analysis was carried out for 100 and 400 m high R/C chimneys having piled annular raft and annular raft foundations considering the flexibility of soil subjected to across-wind load. Stiffness of supporting soil and foundation were varied to evaluate the significance of Soil-Structure Interaction (SSI). The integrated chimney-foundation-soil system was analysed by finite element software ANSYS based on direct method of SSI assuming linear elastic material behaviour. FE analyses were carried out for two cases of SSI namely, (1) chimney with annular raft foundation and (2) chimney with piled annular raft foundation. The responses in raft such as bending moments and settlements were evaluated for both the cases and compared to those obtained from the conventional method of analysis of annular raft foundation. It is found that the responses in raft vary considerably depending on the stiffness of the underlying soil and the stiffness of foundation. Piled raft foundations are better suited for tall chimneys to be constructed in loose or medium sand. © 2017, The Institution of Engineers (India).