Patil et al., International Journal on Emerging Technologies 11(2): 484-494(2020) 484 International Journal on Emerging Technologies 11(2): 484-494(2020) ISSN No. (Print): 0975-8364 ISSN No. (Online): 2249-3255 Vertical Stresses in Soil below a Three Dimensional Structure due to Reinforced Soil Structure Interaction Nayana N. Patil 1 , H.M. Rajashekharswamy 2 and R. Shivashankar 3 1 Assistant Professor, Department of Civil Engineering, Faculty of Engineering and Technology, MS Ramaiah University of Applied Sciences, Bangalore-560058 (Karnataka), India. 2 Professor, Department of Civil Engineering, Faculty of Engineering and Technology, MS Ramaiah University of Applied Sciences, Bangalore-560058, (Karnataka), India. 3 Professor, Department of Civil Engineering, National Institute of Technology, Surathkal (Karnataka), India. (Corresponding author: Nayana N. Patil) (Received 26 December 2019, Revised 08 February 2020, Accepted 14 February 2020) (Published by Research Trend, Website: www.researchtrend.net) ABSTRACT: Numerous problems in civil engineering involve interaction between the structures and the soil. This interaction plays a significant role in the response of a structure and may change the magnitude of displacements, stresses and other responses of a structure in comparison with the non-interactive analysis. In the non-interactive analysis, the structure is assumed to be resting on fixed supports and shall not undergo any relative motions. In Soil Structure Interaction (SSI) analyses, the displacements and stress resultants are found to deviate considerably from non-interactive analysis there by rendering the non- interactive analysis as unrealistic and it is absolutely necessary to consider SSI in the analysis and design of structures. In the present paper, the response of a three dimensional structure is studied in Reinforced Soil Structure Interaction (RSSI). RSSI refers to the interaction between the reinforced soil and the structure. Comparative numerical studies have also been carried out by using finite element analyses to study the effects of a 3D frame resting on unreinforced and reinforced soil by developing programmes, SSI-LIN, SSI-NLIN, RSSI-LIN and RSSI-NLIN for both the linear and non-linear analyses. SSI-LIN and RSSI-LIN are the programs developed to conduct linear analyses and SSI-NLIN and RSSI-NLIN are the programs developed to conduct nonlinear analyses. They are used to study displacements, stresses in soil and member end forces in the structure. The present paper discusses only the effects of SSI and RSSI analyses on stresses in soils. In this study, macro element approach is adopted as modelling the geogrid proves to be very difficult with apertures of size 33 × 25 mm. This is due to limitations of software and prolonged execution time. The vertical pressure at various points are not affected much in non-linear RSSI analysis compared to non-linear SSI. However there is reduction in longitudinal and transverse stresses in non-linear RSSI analysis compared to non-linear SSI. There is also a change in the pressure bulb below foundation level. Hence it is important to conduct RSSI studies. Keywords: Geo-grid, SSI, RSSI, macro-element, FEA, reinforced soil. I. INTRODUCTION Very few researches have been carried out on soil– structure interaction effect by considering three dimensional space frames. SSI studies that consider the yielding of structures and non–linearity of soil are few, especially those involving investigations on the effects of non-linearity of SSI system on the overall behaviour in terms of displacements and stresses [5]. Boudaa et al., (2019) conducted static interaction analysis between beam and layered soil using a two-parameter elastic foundation. They presented shear deformations to show the crucial influence on the beam, on the structure and on the interface behaviors [6]. Few researchers have applied the finite element analysis to study super structure – raft /combined footing soil as a single compatible unit [1, 2]. The SSI studies conducted by a few researchers clearly showed that a two-dimensional plane frame SSI analysis might substantially over or underestimate the actual interaction effect in a space frame [3, 4]. The interactive behaviour of the 3D frame-Isolated footing-soil system was studied [5]. Studies on linear and Non-linear SSI analyses of structure resting on raft foundation showed that the both the maximum and differential settlements in soil tend to be more in non-linear analysis in comparison to the linear analysis. Researchers found that the maximum vertical stresses reduce in non-linear analysis in comparison with the linear analysis. However the stress resultants, in the frame varied (either decreased or increased) based on their location in non-linear analysis when compared to linear analysis [6]. Sufficient studies have been carried out on SSI for structures resting on unreinforced soil. But Reinforced soil-structure interaction (RSSI) involving the structures supported on reinforced soil is still unexplored. The analysis that considers the structure-foundation- reinforced soil as a single system is coined as Reinforced Soil Structure Interaction (RSSI) analysis in the current work. In this study, macro element approach is adopted as modelling the geogrid proves to be very difficult with apertures of e t