Earthquake Geotechnical Engineering for Protection and Development of Environment and Constructions

Abstract

One of the current main challenges in Geotechnical and Structural Engineering is the analysis of the vertical component of site ground motion. In engineering practice, a simplified formulation of the Biot's equations is usually employed to model the coupled hydro-mechanical behaviour of saturated soils, namely the up formulation that neglects some terms of fluid inertial forces. This is in contrast with more refined formulations such as the u-U formulations that takes all inertial terms into account. The aim of this work is the validation of the up formulation as compared with the u-U formulation by means of numerical simulations, which are performed for different levels of permeability and different dynamic motions. The results are analysed in terms of frequency content and amplification rate, discussing the limits of applicability of the up formulation with respect to the u-U formulation.

On the Effectiveness of Experimentally-Derived Foundation Impedance Functions

“…from Forced-A to -D. The system reaches the highest peak shear strain close to the resonance of the facility, i.e. around 3.0 and 2.5Hz, respectively under the Forced-A and -D tests [19], [35]. In correspondence of these values, f u f u resulted equal to 0.25cm/s and 0.9cm/s, which combined to a VS equal to 100 m/s (see Figure 3a), yields to max eff of the order of 0.0025% for Forced-A (blue hexagon in Figure 6a) and 0.009% for Forced-D (red hexagon in Figure 6) respectively.…”

A multiaxial inertial macroelement for bridge abutments

“…Although the case illustrated in Figure 1 refers to an abutment with a shallow foundation, a recent study demonstrated that a similar roto-translated ellipsoidal shape can be adopted in the case of abutments with deep foundations as well. 7 It can be observed that these first yield and ultimate surfaces can be taken as homothetic to each other. The remaining yield surfaces were then assumed to be all homothetic to the ultimate surface, as shown in Figure 2, such that the analytical expression of the n th yield surface is given by:…”

“…4,5 However, the dynamic amplification of the forces transferred to the deck is limited by the ultimate capacity of the soil-abutment system, that depends strongly on the load direction. 6,7 Nonlinear dynamic analysis is rapidly becoming a common means for seismic assessment of existing structures exhibiting highly nonlinear features. In this context, the plasticity-based macroelements 1,[8][9][10][11] represent a promising approach to characterize realistically the soil-structure interaction effects within dynamic structural analyses, that can be accomplished with manageable computational effort.…”

Cyclic Bi-Axial Tests on Assembly of Metal Rods Under Constant-Volume Condition to Study Re-Liquefaction Behavior

“…As has been summarized by Koseki et al (2019), different types of laboratory tests conducted recently by the authors research group (Wahyudi et al 2015;Aoyagi and Koseki 2017;Teparaksa and Koseki 2018;Morimoto et al, 2019a, b;Iqbal et al 2019) have revealed that the re-liquefaction resistance may not only increase but also decrease as compared with the one in the immediate past liquefaction stage; in particular, Fig. 1 a Excessive settlement of railway embankment.…”