Faculty Publications
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Item Effects of prestressing the reinforcement on the behavior of reinforced granular beds overlying weak soil(Elsevier Ltd, 2014) Shivashankar, R.; Jayamohan, J.The effects of prestressing the reinforcement on the strength improvement and settlement reduction of a reinforced granular bed overlying weak soil are being investigated through a series of laboratory scale bearing capacity tests. The influences of parameters such as strength of underlying weak soil, thickness of granular bed, magnitude of prestressing force, direction of prestressing forces and number of layers of reinforcement are being examined. Finite element analyses are carried out using the FE program PLAXIS to study the effect of prestressing the reinforcement. Results obtained from finite element analyses are found to be in reasonably good agreement with the experimental results. © 2013 Elsevier Ltd.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.Item Response in piled raft foundation of tall chimneys under along-wind load incorporating flexibility of soil(Higher Education Press, 2015) Jayalekshmi, B.R.; Jisha, S.V.; Shivashankar, R.The present paper deals with the numerical analysis of tall reinforced concrete chimneys with piled raft foundation subjected to along-wind loads considering the flexibility of soil. The analysis was carried out using finite element method on the basis of direct method of soil-structure interaction (SSI). The linear elastic material behavior was assumed for chimney, piled raft and soil. Four different material properties of soil stratum were selected in order to study the effect of SSI. The chimney elevation and the thickness of raft of piled raft foundation were also varied for the parametric study. The chimneys were assumed to be located in terrain category 2 and subjected to a maximum wind speed of 50 m/s as per IS:875 (Part 3)-1987. The along-wind loads were computed according to IS:4998 (Part 1)-1992. The base moments of chimney evaluated from the SSI analysis were compared with those obtained as per IS:4998 (Part 1)-1992. The tangential and radial bending moments of raft of piled raft foundation were evaluated through SSI analysis and compared with those obtained from conventional analysis as per IS:11089-1984, assuming rigidity at the base of the raft foundation. The settlements of raft of piled raft foundation, deflection of pile and moments of the pile due to interaction with different soil stratum were also evaluated. From the analysis, considerable reduction in the base moment of chimney due to the effect of SSI is observed. Higher radial moments and lower tangential moments were obtained for lower elevation chimneys with piled raft resting on loose sand when compared with conventional analysis results. The effect of SSI in the response of the pile is more significant when the structure-foundation system interacts with loose sand. © 2015, Higher Education Press and Springer-Verlag Berlin Heidelberg.Item Shear Response of Pervious Concrete Column Improved Ground(Springer, 2021) Rashma, R.S.V.; Shivashankar, R.; Jayalekshmi, B.R.This study deals with numerical analysis of the shearing resistances of pervious concrete column improved ground vis-à-vis ordinary stone column improved ground. Analysis is done by numerically simulating a large shear test model, representing pervious concrete column improved ground. The parameters varied in this study are the depth of pervious concrete column/pile, floating and end-bearing piles, diameter, single pile and two-pile group and distance from the edge of loading area in the model. The shear response of improved ground is quantified by the applied strain controlled vertical load to the entire width of large shear test model that induces shear movements within the tank model. It is observed that the pervious concrete column improved ground shows better shear performance than ordinary stone column improved ground. It is also found that the pervious concrete column undergoes very small lateral deflections. It is also observed that more number of pervious concrete columns, and closer they are to the loaded area, better is the shear performance. © 2020, Indian Geotechnical Society.Item Liquefaction Mitigation Potential of Improved Ground Using Pervious Concrete Columns(Springer, 2022) Rashma, R.S.V.; Jayalekshmi, B.R.; Shivashankar, R.In this study, liquefaction mitigation potential of improved ground using pervious concrete column is being investigated. The seismic performance of pervious concrete column improved ground is compared with conventional stone column improved ground. Three-dimensional finite element analysis using OpenSeesPL software is conducted to study the ground lateral deformation and excess pore water pressure generation of pervious concrete column improved ground on a mildly sloping soil strata of infinite extent under seismic loading. The soil strata considered is fully saturated sand with an inclination of 4°. The parameters influencing seismic performance of improved ground like area ratio, founding depth of columns, diameter of columns and hydraulic conductivity of columns are considered. It is found from various response parameters that the pervious concrete column improved ground has better seismic performance than conventional stone column improved ground. The lateral deformation profile of pervious concrete column is found to be similar to that of concrete pile, allowing excess pore water pressure to dissipate through the pores of pervious concrete column. It is also concluded that pervious concrete columns could be used as an alternative to conventional stone columns to mitigate liquefaction to a larger extent. © 2021, Indian Geotechnical Society.