44 research outputs found
Numerical simulation of liquefaction effects on seismic SSI
No full textInternational audienceThe present paper deals with the influence of soil non-linearity, introduced by soil liquefaction, on the soil-foundation-structure interaction phenomena. The objective is to reveal the beneficial or unfavourable effects of the non-linear SSI on both structural drift and settlement of a given structure. Factors such as the signal modification due to liquefaction, and ratios of fundamental frequencies of soil, structure and signal may play an important role on the damage of the structure. The importance of each of these factors is evaluated through a significant parametric study. A 2D coupled finite element modelling is carried out using an elastoplastic multi-mechanism model to represent the soil behaviour. This paper presents the research work we did in the framework of the European Community project NEMISREF (New methods of mitigation of seismic risk on existing foundations, GRDI-40457), to study possible retrofitting measures using GEFDYN computational tools
Numerical modelling of rainfall effects on the slow movement of slopes
No full textThis paper concerns the assessment of rainfall-induced slow movement of slopes.
The effects of the rainfall intensity and the geometric slope conditions on the induced
displacements are studied via a parametric finite element simulation. For some given initial slope conditions, a model assessing the expected displacement due to a rainfall intensity level
is proposed
Uncertainties in the Estimation of the Torsion Effect in Buildings Subjected to Seismic Loading
No full text
One-Dimensional response of a borehole station during the 2005 West off Fukuoka Prefecture earthquake : observation and simulation
No full textInternational audienceThe objective of this paper is to present a one-dimensional response of a soil column at a borehole station during the 2005 west off Fukuoka prefecture, Japan, earthquake. The borehole station is located in Fukuoka City where the sediment's thickness reaches 56 meters. First, we have confirmed that according to the rupture process the major axis is north 32 degrees east by calculating the observed energy distribution at several stations around the epicenter. Then we have computed, in the major and minor axes, surface-to-borehole spectral ratios using the S-wave portion of the main shock and 12 aftershocks. As for the aftershocks, the fundamental resonant peaks lie in the frequency range of 1.5 to 1.9 Hz, and are quite stable. As for the main shock, the resonant peak is 1.3 Hz showing a nonlinear effect. To simulate the main shock, we have first inverted by genetic algorithm S-waves velocities and damping coefficients of the soil column as well as incident angle of the upcoming wave using Thomson-Haskell propagator matrix for SH and P-SV waves. Inverted values of S-waves velocities are consistent with the P-S logging provided by CTI Engineering and inverted incident angle is also consistent with observed particle orbit in the vertical plane. Simulations at the borehole station show a good agreement with observations
