An Experimental Study on the Way Bottom Widening of Pier Foundations Affects Seismic Resistance


  • T. Nagao Research Center for Urban Safety and Security, Kobe University, Japan


The resistance of a pier to horizontal loads, like seismic loads, is due to the flexural rigidity of its foundations and the horizontal subgrade reaction. In the event of a massive earthquake, the latter becomes very small because of the softening of the ground, while the structure may experience a large inertial force and lateral spreading pressure. Therefore, structures with high seismic resistance are required in areas with high seismicity. When a wide caisson is used as a pier foundation, a rotational resistance moment caused by the vertical subgrade reaction acting on the foundation bottom can be expected. Although this rotational resistance moment increases if the foundation is widened, in design practice the subgrade reaction coefficient is evaluated as being low under such circumstances. Therefore, even if the foundation is widened, the rotational resistance moment does not increase greatly. Rotational resistance commensurate with the increased construction cost due to foundation widening cannot be expected. In the present study, horizontal loading experiments were performed at one pier with a normal foundation and at one with widened at the bottom foundation, and the way that the widening affected the seismic performance was examined. The results show that compared with the normal foundation, the bottom-widened one experienced far less displacement and offered higher earthquake resistance.


earthquake resistance, subgrade reaction, pier, displacement


Download data is not yet available.


T. Nagao, D. Shibata, “Experimental study of the lateral spreading pressure acting on a pile foundation during earthquakes”, Engineering, Technology & Applied Science Research, Vol. 9, No. 6, pp. 5021-5028, 2019 DOI:

K. Tokimatsu, Y. Asaka, “Effects of liquefaction-induced ground displacements on pile performance in the 1995 Hyogoken-Nambu Earthquake”, Soils and Foundations, Vol. 38, No. Special, pp. 163-177, 1998 DOI:

PIANC, Seismic design guidelines for port structures, A.A. Balkema Publishers, 2001

G. Mondal, D. C. Rai, “Performance of harbour structures in Andaman Islands during 2004 Sumatra earthquake”, Engineering Structures, Vol. 30, pp. 174–182, 2008 DOI:

R. A. Green, S. M. Olson, R. Brady, B. R. Cox, G. J. Rix, E. Rathje, J. Bachhuber, J. French, S. Lasley, N. Martin, “Geotechnical aspects of failures at Port-au-Prince seaport during the 12 January 2010 Haiti earthquake”, Earthquake Spectra, Vol. 27, No. Suppl. 1, pp. S43–S65, 2011 DOI:

T. Sugano, A. Nozu, E. Kohama, K. Shimosako, Y. Kikuchi, “Damage to coastal structures”, Soils and Foundations, Vol. 54, No. 4, pp. 883–901, 2014 DOI:

G. A. Athanasopoulos, G. C. Kechagias, D. Zekkos, A. Batilas, X. Karatzia, F. Lyrantzaki, A. Platis, “Lateral spreading of ports in the 2014 Cephalonia, Greece, earthquakes”, Soil Dynamics and Earthquake Engineering, Vol. 128, Article ID 105874, 2020 DOI:

T. Nagao, P. Lu, “A simplified reliability estimation method for pile-supported wharf on the residual displacement by earthquake”, Soil Dynamics and Earthquake Engineering, Vol. 129, Article ID 105904, 2020 DOI:

G. Li, R. Motamed, “Finite element modeling of soil-pile response subjected to liquefaction induced lateral spreading in a large-scale shake table experiment”, Soil Dynamics and Earthquake Engineering, Vol. 92, pp. 573-584, 2017 DOI:

I. Towhata, Geotechnical earthquake engineering, Springer-Verlag, 2008 DOI:

M. A. Biot, “Bending of infinite beams on an elastic foundation”, Journal of Applied Mechanics, Vol. 59, pp. A1–A7, 1937

K. V. Terzaghi, “Evaluation of coefficient of subgrade reaction”, Geotechnique, Vol. 5, No. 4, pp.297–326, 1955 DOI:

T. Yoshinaka, “Subgrade reaction coefficient and its correction based on the loading width”, PWRI Report, Vol. 299, pp. 1-49, 1967 (in Japanese)

R. Ziaie-Moayed, M. Janbaz, “Effective parameters on modulus of subgrade reaction in clayey soils”, Journal of Applied Sciences, Vol. 9, pp. 4006-4012, 2009 DOI:

J. Lee, S. Jeong, “Experimental study of estimating the subgrade reaction modulus on jointed rock foundations”, Rock Mechanics and Rock Engineering, Vol. 49, No. 6, pp. 2055–2064, 2016 DOI:

Japan Road Association, Specifications for highway bridges, Part 4, Substructures, Japan Road Association, 2016

S. Iai, “Similitude for shaking table test on soil-structure-fluid model in 1g gravitational field”, Soil and Foundations, Vol. 29, No. 1, pp. 105-118, 1989 DOI:


How to Cite

T. Nagao, “An Experimental Study on the Way Bottom Widening of Pier Foundations Affects Seismic Resistance”, Eng. Technol. Appl. Sci. Res., vol. 10, no. 3, pp. 5713–5718, Jun. 2020.


Abstract Views: 623
PDF Downloads: 437

Metrics Information

Most read articles by the same author(s)