New Iterative method to Calculate Base Stress of Footings under Biaxial Bending

Abstract

Base stresses of the footings should be calculated under biaxial bending especially for structures in seismic zones. However, calculation of the base stresses is not easy for the footings with large eccentricity due to the fact that interaction of the stresses in both directions should be considered and redistribution of stresses is required in zero stress zone.  In this study new iterative method is presented to calculate the base stress of rectangular footings under biaxial bending. A computer program is developed according to this method. A design example (single footing having rectangular shape) is analyzed using the developed program and computed base stresses are compared to previous results in order to test accuracy of the method. The design example is also analyzed using different eccentricities in order to reveal efficiency of the redistribution under biaxial bending.

Keywords

• Biaxial bending,single footings,base pressures,numerical model

References

1. [1] Prakash, S., Saran, S., Bearing capacity of eccentrically loaded footings. Journal of Soil Mechanics & Foundations Div, 1971.
2. [2] Gesund, H., Flexural limit design of column footings. Journal of Structural Engineering, 111(11), 2273-2287, 1985.
3. [3] Saran, S., Agarwal, R., Bearing capacity of eccentrically obliquely loaded footing. Journal of Geotechnical Engineering, 117(11), 1669-1690, 1991.
4. [4] Mahiyar, H., Patel, A., Analysis of angle shaped footing under eccentric loading. Journal of geotechnical and geoenvironmental engineering, 126(12), 1151-1156, 2000.
5. [5] Wieneke, K., Kueres, D., Siburg, C., Hegger, J., Investigations on the punching shear behaviour of eccentrically loaded footings. Structural Concrete, 2016.
6. [6] Gurfinkel, G., Analysis of footings subjected to biaxial bending. Journal of the Structural Division, 96(6), 1049-1059, 1970.
7. [7] Köseoğlu, S., Temeller: statiği ve konstruksiyonu1986; Matbaa Teknisyenleri Basımevi,1986.
8. [8] Csenki, A. Foundation Pressures Beneath Rectengular Footings.Proceedings of the Institution of Civil Engineers, 83, 465-473, 1987.

9. [9] Özmen, G., Determination of Base Stresses in Rectangular Footings under Biaxial Bending. Teknik Dergi, 22(110), 2011.
10. [9] Özmen, G., Determination of Base Stresses in Rectangular Footings under Biaxial Bending. Teknik Dergi, 22(110), 2011.
11. [10] Rodriguez-Gutierrez, J., Aristizabal-Ochoa, J.D., Rigid spread footings resting on soil subjected to axial load and biaxial bending. I: Simplified analytical method. International Journal of Geomechanics, 13(2), 109-119, 2012.
12. [11] Sarkar, B., Analysis of isolated footing subjected to axial load and high biaxial moments and numerical approach for its solution. The Indian Concrete Journal, 2014(6), 60-80, 2014.
13. [12] Guan, Z., Zhang, J., Li, J., A robust computational method for ultimate strength analysis of arbitrary reinforced concrete and composite sections subjected to axial force and biaxial bending. Advances in Structural Engineering, 17(1), 83-96, 2014.
14. [13] Smith-Pardo, J.P., Ortiz, A., Blandon, C.A., Biaxial capacity of rigid footings: Simple closed-form equations and experimental results. Engineering Structures, 69, 149-157, 2014.
15. [14] Code, T.E., Turkish code for buildings in seismic zones, in Turkish Seismic Code, The Ministry of Public Works and Settlement. 2007: Ankara, Turkey.