Numerical study of ultimate bearing capacity of rectangular footing on layered sand

Author(s):  
V. Panwar ◽  
R.K. Dutta

Purpose: The purpose of this study is to investigate the ultimate bearing capacity of the rectangular footing resting over layered sand using finite element method. Design/methodology/approach: Finite element analysis was used to investigate the dimensionless ultimate bearing capacity of the rectangular footing resting on a limited thickness of upper dense sand layer overlying limitless thickness of lower loose sand layer. The friction angle of the upper dense sand layer was varied from 41° to 46° whereas for the lower loose sand layer it was varied from 31° to 36°. Findings: The results reveal that the dimensionless ultimate bearing capacity was found to increase up to an H/W ratio of about 1.75 beyond which the increase was marginal. The results further reveal that the dimensionless ultimate bearing capacity was the maximum for the upper dense and lower loose sand friction angles of 46° and 36°, while it was the lowest for the upper dense and lower loose sands corresponding to the friction angle of 41° and 31°. For H/W = 0.5 and 2, the dimensionless bearing capacity decreases with the increase in the L/W ratio from 0.5 to 6 beyond which the dimensionless ultimate bearing capacity remains constant for all combinations of parameters. The results were presented in nondimensional manner and compared with the previous studies available in literature. Research limitations/implications: The analysis is performed using a ABAQUS 2017 software. The limitation of this study is that only finite element analysis is performed without conducting any experiments in the laboratory. Further the study is conducted only for the vertical loading. Practical implications: This proposed numerical study can be used to predict the ultimate bearing capacity of the rectangular footing resting on layered sand. Originality/value: The present study gives idea about the ultimate bearing capacity of rectangular footing when placed on layered sand (dense sand over loose sand) as well as the effect of thickness of top dense sand layer on the ultimate bearing capacity. The findings could be used to calculate the ultimate bearing capacity of the rectangular footing on layered sand.

Author(s):  
S. Nazeer ◽  
R.K. Dutta

Purpose: The purpose of this study is to estimate the ultimate bearing capacity of the E-shaped footing resting on two layered sand using finite element method. The solution was implemented using ABACUS software. Design/methodology/approach: The numerical study of the ultimate bearing capacity of the E-shaped footing resting on layered sand and subjected to vertical load was carried out using finite element analysis. The layered sand was having an upper layer of loose sand of thickness H and lower layer was considered as dense sand of infinite depth. The various parameters varied were the friction angle of the upper (30° to 34°) and lower (42° to 46°) layer of sand as well as the thickness (0.5B, 2B and 4B) of the upper sand layer. Findings: The results reveal that the dimensionless ultimate bearing capacity was found to decrease with the increased in the H/B ratio for all combinations of parameters. The dimensionless ultimate bearing capacity was maximum for the upper loose sand friction angle of 34° and lower dense sand friction angle of 46°. The results further reveal that the dimensionless bearing capacity of the E-shaped footing was higher in comparison to the dimensionless bearing capacity of the square footing on layered sand (loose over dense). The improvement in the ultimate bearing capacity for the E-shaped footing was observed in the range of 109.35% to 152.24%, 0.44% to 7.63% and 0.63% to 18.97% corresponding to H/B ratio of 0.5, 2 and 4 respectively. The lowest percentage improvement in the dimensionless bearing capacity for the E-shaped footing on layered sand was 0.44 % at a H/B = 2 whereas the highest improvement was 152.24 % at a H/B = 0.5. Change of footing shape from square to E-shaped, the failure mechanism changes from general shear to local shear failure. Research limitations/implications: The results presented in this paper were based on the numerical study conducted on E-shaped footing made out of a square footing of size 1.5 m x 1.5 m. However, further validation of the results presented in this paper, is recommended using experimental study conducted on similar size E-shaped footing. Practical implications: The proposed numerical study can be useful for the architects designing similar types of super structures requiring similar shaped footings. Originality/value: No numerical study on E-shaped footing resting on layered sand (loose over dense) were conducted so far. Hence, an attempt was made in this article to estimate the bearing capacity of these footings.


2012 ◽  
Vol 193-194 ◽  
pp. 1461-1464
Author(s):  
Bai Shou Li ◽  
Ai Hua Jin

Based on the characteristics of the special-shaped concrete-filled steel tubes and consideration of material nonlinearity of constitutive relation, stimulation of 6 T-shaped thin-walled ribbed and un-ribbed concrete-filled steel tube short columns is implemented, as well as comparable analysis of stress, strain, displacement and bearing capacity, through the finite element analysis software ANSYS. The result indicates that the rib can effectively improve the ductility, delaying the buckling occurs, which enhances the core concrete confinement effect, so as the stimulated ultimate bearing capacity which is greater than nominal ultimate bearing capacity.


2021 ◽  
Vol 31 (3) ◽  
pp. 152-176
Author(s):  
Priyanka Rawat ◽  
Rakesh Kumar Dutta

Abstract The aim of the present numerical study was to analyse the pressure settlement behaviour and bearing capacity of asymmetric plus shaped footing resting on loose sand overlying dense sand at varying embedment depth. The numerical investigation was carried out using ABAQUS software. The effect of depth of embedment, friction angle of upper loose and lower dense sand layer and thickness of upper loose sand on the bearing capacity of the asymmetric plus shaped footing was studied in this investigation. Further, the comparison of the results of the bearing capacity was made between the asymmetric and symmetric plus shaped footing. The results reveal that with increase in depth of embedment, the dimensionless bearing capacity of the footings increased. The highest increase in the dimensionless bearing capacity was observed at embedment ratio of 1.5. The increase in the bearing capacity was 12.62 and 11.40 times with respect to the surface footings F1 and F2 corresponding to a thickness ratio of 1.5. The lowest increase in the dimensionless bearing capacity was observed at embedment ratio of 0.1 and the corresponding increase in the bearing capacity was 1.05 and 1.02 times with respect to the surface footing for footings F1 and F2 at a thickness ratio of 1.5.


Author(s):  
V. Panwar ◽  
R.K. Dutta

Purpose: The study presents the numerical study to investigate the bearing capacity of the rectangular footing on layered sand (dense over loose) using ABAQUS software. Design/methodology/approach: Finite element analysis was used in this study to investigate the bearing capacity of the rectangular footing on layered sand and subjected to inclined load. The layered sand was having an upper layer of dense sand of varied thickness (0.25 W to 2.0 W) and lower layer was considered as loose sand of infinite thickness. The various parameters varied were friction angle of the upper dense (41° to 46°) and lower loose (31° to 36°) layer of sand and load inclination (0° to 45°), where W is the width of the rectangular footing. Findings: As the thickness ratio increased from 0.00 to 2.00, the bearing capacity increased with each load inclination. The highest and lowest bearing capacity was observed at a thickness ratio of 2.00 and 0.00 respectively. The bearing capacity decreased as the load inclination increased from 0° to 45°. The displacement contour shifted toward the centre of the footing and back toward the application of the load as the thickness ratio increased from 0.25 to 1.25 and 1.50 to 2.00, respectively. When the load inclination was increased from 0° to 30°, the bearing capacity was reduced by 54.12 % to 86.96%, and when the load inclination was 45°, the bearing capacity was reduced by 80.95 % to 95.39 %. The results of dimensionless bearing capacity compare favorably with literature with an average deviation of 13.84 %. As the load inclination was changed from 0° to 45°, the displacement contours and failure pattern shifted in the direction of load application, and the depth of influence of the displacement contours and failure pattern below the footing decreased, with the highest and lowest influence observed along the depth corresponding to 0° and 45°, respectively. The vertical settlement underneath the footing decreased as the load inclination increased, and at 45°, the vertical settlement was at its lowest. As the load inclination increased from 0° to 45°, the minimum and maximum extent of influence in the depth of the upper dense sand layer decreased, with the least and highest extent of influence in the range of 0.50 to 0.50 and 1.75 to 2.00 times the width of the rectangular footing, respectively, corresponding to a load inclination of 45° and 0° Research limitations/implications: The results presented in this paper were based on the numerical study conducted on rectangular footing having length to width ratio of 1.5 and subjected to inclined load. However, further validation of the results presented in this paper, is recommended using experimental study conducted on similar size of rectangular footing. engineers designing rectangular footings subjected to inclined load and resting on layered (dense over loose) sand. Originality/value: No numerical study of the bearing capacity of the rectangular footing under inclined loading, especially on layered soil (dense sand over loose sand) as well as the effect of the thickness ratio and depth of the upper sand layer on displacement contours and failure pattern, has been published. Hence, an attempt was made in this article to investigate the same.


2011 ◽  
Vol 243-249 ◽  
pp. 1737-1742 ◽  
Author(s):  
Ke Chen ◽  
Jian Yong Song ◽  
Shuo Zhang

The externally prestressed bridge finite element analysis module redeveloped based on ANSYS software is introduced,realizing finite element analysis method for externally prestressed concrete bridge. It is able to build the externally prestressed bridge finite element model, combined with Solid65 and Solid45 simulated concrete, and Link8 or Link10 simulated prestressed tendon. It is also able to bring material and geometric nonlinear effects into the analysis, for analyzing ultimate bearing capacity and local stress characterization of the externally prestressed structure. A bridge model is generated as an example for verifying the application of the module. Based on it, the model then is equipped with different allocation arrangements of internal and external tendons to analyze the mechanical characteristics of externally prestressed concrete bridge. Research is conducted for the effect on ultimate bearing capacity by allocation arrangement of tendons, and providing design suggestion and theoretic basis.


2013 ◽  
Vol 78 (686) ◽  
pp. 763-770
Author(s):  
Kazuhiro KANEDA ◽  
Satoru OHTSUKA ◽  
Yoshimasa SHIGENO ◽  
Masamichi AOKI ◽  
Junji HAMADA ◽  
...  

2012 ◽  
Vol 446-449 ◽  
pp. 533-536
Author(s):  
Xiu Li Wang ◽  
Peng Chen ◽  
Wen Wei Yang

In this paper,the ultimate bearing capacity of unstifened overlapped CHS K-joints is investigated by using the finite element method with influence of weld and non-weld on joint ultimate capacity under brace different bearing capacity. with angle of chord and brace is increasing ultimate capacity to lowed more and more small,which hidden weld is non-weld by one brace is pulled and other is pressured. ultimate capacity no influence to hidden welded and non-welded by both brace is pulled.


2014 ◽  
Vol 488-489 ◽  
pp. 365-369
Author(s):  
Xiao Guang Song ◽  
Zuo Yun Mei ◽  
Jia Lv

With the rapid development of the Chinese railway in recent years, the construction of so many large railway stations are needed. Because the roof and the canopy should be convenient for the passengers and goods to get through, the column spacing and span is large. In order to achieve the functional and aesthetic requirements of the railway stations, the dendritic column is developed. Dendritic structure is the building structure which is designed by the principle of zoology and undertaking force of tree among nature. It has particular appreciation and practicability. In order to determine the critical load and buckling behavior of the dendritic column from stable balance to unstable balance condition, the finite element model is established by the finite element analysis program ANSYS. And the linear overall stability, geometrical nonlinear overall stability, geometrical and material nonlinear overall stability were studied. Through changing such factors as the stiffness ratio and the height ratio between the trunk and the branch, span to height ratio of branch, etc., the authors further studied the nonlinear stability behavior of this new type structure. It is showed that the ultimate bearing capacity of the Y-shape column is high. And we got the conclusion that how these three parameters influence the ultimate bearing capacity of the dendritic column. And the results can offer reference for the design of the dendritic column. Your manuscript will be reduced by approximately 20% by the publisher. Please keep this in mind when designing your figures and tables etc.


1974 ◽  
Vol 11 (2) ◽  
pp. 223-229 ◽  
Author(s):  
G. G. Meyerhof

The ultimate bearing capacity of footings resting on subsoils consisting of two layers has been investigated for the cases of dense sand on soft clay and loose sand on stiff clay. The analyses of different modes of soil failure are compared with the results of model tests on circular and strip footings and some field observations of foundation failures.


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