About the dynamic strength enhancement of concrete-like materials in a split Hopkinson pressure bar test

The saturated hydraulic conductivity of a soil can be predicted using empirical relationships, capillary models, statistical models, and hydraulic radius theories. A well-known relationship between...

On the use of the KozenyCarman equation to predict the hydraulic conductivity of soils

This paper assesses methods to predict the saturated hydraulic conductivity, k, of clean sand and gravel. Currently, in engineering, the most widely used predictive methods are those of Hazen and t...

Predicting the saturated hydraulic conductivity of sand and gravel using effective diameter and void ratio

Numerical simulation of drained triaxial test using 3D discrete element modeling

https://yade-dem.org/w/images/3/30/CMAME_YADE_2008.pdf

A new open-source software developed for numerical simulations using discrete modeling methods

This paper presents a non-linear soil–structure interaction (SSI) macro-element for shallow foundation on cohesive soil. The element describes the behaviour in the near field of the foundation under cyclic loading, reproducing the material non-linearities of the soil under the foundation (yielding) as well as the geometrical non-linearities (uplift) at the soil–structure interface. The overall behaviour in the soil and at the interface is reduced to its action on the foundation. The macro-element consists of a non-linear joint element, expressed in generalised variables, i.e. in forces applied to the foundation and in the corresponding displacements. Failure is described by the interaction diagram of the ultimate bearing capacity of the foundation under combined loads. Mechanisms of yielding and uplift are modelled through a global, coupled plasticity–uplift model.

The cyclic model is dedicated to modelling the dynamic response of structures subjected to seismic action. Thus, it is especially suited to combined loading developed during this kind of motion. Comparisons of cyclic results obtained from the macro-element and from a FE modelization are shown in order to demonstrate the relevance of the proposed model and its predictive ability. Copyright © 2001 John Wiley & Sons, Ltd.

Cyclic macro-element for soil–structure interaction: material and geometrical non-linearities

A new nonlinear soil-structure interaction macro-element is presented. It models the dynamic behaviour of a shallow strip foundation under seismic action. Based on substructured methods, it takes into account the dynamic elastic effect of the infinite far field, and the material and geometrical nonlinear behaviour produced in the near field of the foundation. Effects of soil yielding below the foundation as well as uplift at the interface are considered. Through the concept of macro-element, the overall elastic and plastic behaviour in the soil and at the interface is reduced to its action on the foundation. The macro-element consists of a non linear joint element, expressed in the three degrees of freedom of the strip foundation, reflecting the limited bearing capacity of the foundation. This model provides a practical and efficient tool to study the seismic response of a structure in interaction with the surrounding soil medium. Applications to a bridge pier show the potentialities of this kind of model.

Modelling of nonlinear dynamic behaviour of a shallow strip foundation with macro-element

High strain rate unconfined compressional tests on concrete are simulated by a 3D discrete element method. The laboratory data set was provided by three unconfined experiments on a split Hopkinson pressure bar apparatus at very high strain rates (350–700 s\u–¹). This numerical method was chosen because it is well adapted to problems involving the characterization of fracturing and fragmentation in geomaterials. The simulations input data are the recorded experimental velocities, whereas the simulations output data are the computed forces that are compared with the experimental ones. The fit between the experimental and the numerical data is quite good. Based on this fit, it is shown that the strain rate dependency of the material strength can be explained by inertial effects.

Numerical Study of Compressive Behavior of Concrete at High Strain Rates

Confinement effects on the steel–concrete bond strength and pull-out failure

Fragility curves are generally developed using a single parameter to relate the level of shaking to the expected structural damage. The main goal of this work is to use several parameters to characterize the earthquake ground motion. The fragility curves will, therefore, become surfaces when the ground motion is represented by two parameters. To this end, the roles of various strong-motion parameters on the induced damage in the structure are compared through nonlinear time-history numerical calculations. A robust structural model that can be used to perform numerous nonlinear dynamic calculations, with an acceptable cost, is adopted. The developed model is based on the use of structural elements with concentrated nonlinear damage mechanics and plasticity-type behavior. The relations between numerous ground-motion parameters, characterizing different aspects of the shaking, and the computed damage are analyzed and discussed. Natural and synthetic accelerograms were chosen/computed based on a consideration of the magnitude-distance ranges of design earthquakes. A complete methodology for building fragility surfaces based on the damage calculation through nonlinear numerical analysis of multi-degree-of-freedom systems is proposed. The fragility surfaces are built to represent the probability that a given damage level is reached (or exceeded) for any given level of ground motion characterized by the two chosen parameters. The results show that an increase from one to two ground-motion parameters leads to a significant reduction in the scatter in the fragility analysis and allows the uncertainties related to the effect of the second ground-motion parameter to be accounted for within risk assessments.

https://hal-brgm.archives-ouvertes.fr/hal-00558781/document

Luc Davenne

Papers

Cyclic macro-element for soil–structure interaction: material and geometrical non-linearities

Modelling of nonlinear dynamic behaviour of a shallow strip foundation with macro-element

Numerical Study of Compressive Behavior of Concrete at High Strain Rates

Confinement effects on the steel–concrete bond strength and pull-out failure

Development of seismic fragility surfaces for reinforced concrete buildings by means of nonlinear time-history analysis