Browsing by Author "Krishna, S.V."

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    A Study on Settlement Variation in Piled Raft Foundation Under Seismic Loads
    (Springer Science and Business Media Deutschland GmbH, 2022) Krishna, S.V.; Jayalekshmi, B.R.
    Piled raft foundations are usually used to transmit the loads from superstructure to the soil beneath the structure having low or medium bearing capacity to hard or rock strata with a higher bearing capacity and stiffness. This paper investigates the influence of the length and stiffness of the piles on the performance of the raft foundation. For this, a ten storey moment-resisting frame resting on piled raft foundation with different pile length was simulated numerically. Three-dimensional numerical model of the soil medium, piles, raft and the structural elements were created in ANSYS software. Four bay 10 storey building frames having 3 m bay length and storey height of 3 m is with different pile configurations are considered for the study. The column size of 0.5 m × 0.5 m and beam size of 0.3 m × 0.45 m were taken for frames. The dimension of the raft foundation is 14mx14mx1m. This study mainly focuses on the vertical settlement of the raft at various locations along the length of the raft foundation when subjected to El Centro earthquake and time history corresponding to response spectrum given in IS 1893 code. Study was conducted on five types of pile configuration based on pile length. It was found that the settlement at the edges of the raft is minimum for model M1 which is having longest peripheral pile and minimum settlement at the centre is observed for model M5 which has longer central pile compared to peripheral piles. © 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.
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    A Study on the Behavior of Piled Raft Foundation Under Seismic Loading
    (Springer Science and Business Media Deutschland GmbH, 2023) Reddy, D.M.M.; Krishna, S.V.; Jayalekshmi, B.R.
    High rise buildings require strong foundations which should bear heavy loads with less settlement. There has been an increase in the use of combined piled raft foundations because of the effectiveness in bearing heavy loads with comparatively very less settlements. This paper presents the variation in roof displacement, bending moment and shear force of a 10-storey building frame resting on a piled raft foundation having various pile stiffness under earthquake excitations corresponding to El Centro and Loma Prieta earthquakes. Column and beam dimensions of the frame are taken as 0.5 m × 0.5 m and 0.3 m × 0.45 m. The length of the pile is taken as 10 m and the diameter is taken for a range of 0.6 m to 1.2 m. Vertical loading condition is varied by considering different mass at each floor level. Not much variation in the roof displacement is found with a change in the pile stiffness. Variation in the response has been observed for different vertical loading and changes in the pile stiffness. The response of the structure for the two earthquake motions is entirely different. © 2023, The Author(s), under exclusive license to Springer Nature Switzerland AG.
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    Seismic Response of Buildings Resting on Pile-Raft Foundation in Soft Soil
    (Springer Science and Business Media Deutschland GmbH, 2021) Krishna, S.V.; Jayalekshmi, B.R.
    The combined pile-raft foundation is used for high-rise buildings on soft soil since it is an efficient and economical foundation system. The present study deals with evaluation of performance of 15 storey reinforced concrete structures built on piled-raft foundation resting on soft soil under earthquake loads. Finite element analysis of the three dimensional soil-pile-raft-building systems consisting of a combination of long and short piles have been carried out for transient response. The length ratio between the central piles and corner piles is varied from 0.33 to 3 such that the combinations consist of long piles placed at corners or at centre region while short piles are placed at centre or at corners. These systems are subjected to ground motions corresponding to El-Centro and Loma prieta earthquake. The seismic responses of the integrated systems vary with the change in the length of pile. © 2021, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.