Renato Lancellotta

Identification Technique for Soil-Structure Analysis of the Ghirlandina Tower

Historical towers, in particular medieval towers, are an important part of cultural heritage, and their preservation mandates monitoring and detailed analyses of vulnerability under seismic actions as well as of their long-term performance. Certain aspects of structural nature are linked to the masonry behavior as a unilateral material, and other are aspects related to the interaction with soft soil conditions. This study aims to contribute to the aspects of preservation by exploring the role of the soil-structure interaction in predicting the behavior of the structures, with specific reference to the well-documented case history of the medieval Ghirlandina Tower (Modena, Italy). A significant contribution comes from an experimental identification analysis, performed in the presence of ambient vibration. A novel finding is that the soil structure interaction cannot be neglected, in contrast to most published identification analyses that usually assume the structure to have rigid constraint at base.

Model Updating to Forecast the Dynamic Behavior of the Ghirlandina Tower in Modena, Italy

Historical masonry towers survive at an alarming angle of inclination and may be in danger of leaning instability due to the lack of stiffness of the supporting soil. Therefore, careful investigation is required to estimate the seismic vulnerability as well as its long-term behavior. These problems require a multidisciplinary approach to properly model the behavior of the structure and its interaction with the supporting soil. This article is intended to contribute to these aspects, by showing how identification analyses can highlight the role of soil–structure interaction, and focuses on the model-updating techniques to forecast its behavior under seismic events.

Non-linear consolidation models of clay which change type

This paper deals with the modelling of non-linear consolidation phenomena in a non-homogenous clay characterized by soil properties with change of type going from normal to over consolidation regimes. Some simulations are developed addressed to visualize the main features of the consolidation process. A critical analysis, which gives special attention to research perspectives, concludes this paper.

A constitutive equation for the porosity field

This paper deals with the derivation of an evolution equation for the field here denoted by @Dn, which represents the difference between the porosity in an arbitrary state of a deformable porous medium and its equilibrium value. The equation is obtained assuming that @Dn is a constitutive quantity depending on the history of the fields describing macroscopically a porous material. Moreover, at least in the vicinity of the state of stable equilibrium, the equation obtained for @Dn can be regarded as a balance equation liable to various degrees of approximation, so including various models with additional balance laws known in the literature.

A note on finite deformation consolidation models

This paper deals with the derivation of a finite deformation model in the Lagrangian formulation framework without introducing any a priori partition of the stress tensor between the fluid and the solid skeleton.

Parametric study of cantilever walls subjected to seismic loading

The design of flexible earth retaining structures under seismic loading is a challenging geotechnical problem, the dynamic soil‐structure interaction being of paramount importance for this kind of structures. Pseudo‐static approaches are often adopted but do not allow a realistic assessment of the performance of the structure subjected to the seismic motions. The present paper illustrates a numerical parametric study aimed at estimating the influence of the dynamic soil‐structure interaction in the design. A series of flexible earth retaining walls have been preliminary designed according to the requirements of Eurocode 7 and Eurocode 8—Part 5; their dynamic behaviour has been then evaluated by means of dynamic numerical simulations in terms of bending moments, accelerations and stress state. The results obtained from dynamic analyses have then been compared with those determined using the pseudo‐static approach.

Mathematical Models for Soil Consolidation Problems: a State of the Art Report

The mathematical modeling of the consolidation theory is outlined moving from the fundamentals of the mechanics of porous media. Starting from averaging approaches or from the postulates of the theory of mixtures, we introduce the volume fraction concept, the balance equations for the components of the mixture (written in Eulerian and Lagrangean frames of reference) and the concept of effective stress. Initial boundary value problems are considered for typical geotechnical applications, and in this context Biot’s theory is illustrated. A final discussion concerns the mathematical priciples that are to be accomplished when formulating constitutive relationships.

Finite deformation models and field performance

This paper reports about the derivation of a fully nonlinear model characterized by finite deformations without smallness assumptions. The soil is assumed to be saturated, and no restrictions are introduced on the constitutive laws. Initial boundary value problems are formulated with reference to geotechnical problems, such as consolidation under own weight or sedimentation of solid particles in a quiescent fluid, and back-analyses of field performance of an embankment resting on a soft clay deposit.

Experimental Soil Behaviour: its Testing by Waves and Engineering Applications

This paper is aimed at presenting features of soil behaviour, which can be of relevance when using tests, based on wave propagation, for its characterization. In particular, examples are provided to motivate both in situ and laboratory tests, and some basic aspects related to particulate nature of soils and its anisotropy are also addressed. To motivate the use of seismic methods for site characterization, let start by recalling that coarse grained materials are difficult to sample soils, so that the current practice in Geotechnical Engineering still relies on empirical correlations, mainly related to penetration tests (see Jamiolkowski et al., 1985; Lancellotta, 1995; for a detailed presentation of this subject). To outline shortcomings of these procedures, we consider a practical example concerned with the mechanical characterization of the Messina Gravel formation (Crova et al., 1992). The subsoil of Messina Strait consists of gravel and sand deposits of holocene and pleistocene epoch, superimposed to soft rocks of pliocene and miocene epoch. On the Sicilian shore (see Figure 1), sand and gravel deposits extend to a depth of about 200 m below the actual G.L. In particular, at the location of the anchor block the soil is composed of sand and gravel of middle pleistocene (500.000 to 600.000 years old), whereas at the location of the bridge tower the soil is composed of sand and gravel of holocene epoch (6000 to 15.000 years).