Fondation (construction)

Résumé

Une fondation se définit comme la partie d'un bâtiment ou d'un ouvrage de travaux publics qui assure la transmission dans le sol des charges (poids propre, forces climatiques, sismiques et charges d'exploitation) de celui-ci. Les fondations d’un bâtiment représentent un enjeu essentiel de sa construction, car elles forment la partie structurelle qui assure sa portance et permet de contrôler les tassements dus aux charges qu'il applique au sol et les infiltrations dues à la présence éventuelle d'eau dans le terrain. Suivant la capacité portante du sol, l'environnement de l'ouvrage à fonder, les forces mises en jeu et les tassements admissibles, le constructeur choisira une solution du type fondation superficielle, semi-profonde ou profonde, qui diffèrent par leur niveau de fondation, leur géométrie et leur fonctionnement. En dernier recours, si le sol en place ne possède pas les qualités suffisantes pour qu'on puisse y fonder l'ouvrage, des techniques de renforcement des sols sont u

Source officielle

https://fr.wikipedia.org/wiki/Fondation_(construction)

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Publications associées (6)

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Concepts associés (19)

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Cours associés (16)

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Séances de cours associées (41)

Séances de cours associées

Chargement

Development of Dissipative Steel Column-Base Connections for Steel Moment-Resisting Frames under Seismic Loading

Hiroyuki Inamasu

In capacity-designed steel moment resisting frames (MRFs), column base connections feature a strong-base/weak-column design philosophy. Prior studies on fixed-end wide flange steel columns featuring seismically compact cross sections subjected to coupled axial load and lateral drift demands suggest that columns may experience considerable residual axial shortening due to nonlinear geometric instabilities (e.g., local buckling). Column axial shortening is challenging to be repaired in the aftermath of earthquakes; thus, it may result in building demolition. Fixed end columns are conventionally realized with either exposed or embedded column bases (ECBs). In the latter, that forms the primary focus of this PhD thesis, ECBs are conceived as ideally fixed and non-dissipative. However, they do have an inherent flexibility and often exhibit unintentional inelastic deformations as revealed from field observations after earthquakes. While both phenomena are neglected in seismic design procedures of steel MRFs, they seem to have a beneficial effect on the earthquake response of first story steel MRF columns. This suggests that innovative yet simple concepts should be developed and validated so as to prevent local buckling in steel MRF columns. Within such a context, the primary objectives of this thesis are: 1) to develop a novel ECB connection, termed dissipative ECB that promotes a stable hysteretic behavior during earthquake shaking, thereby minimizing local-buckling induced residual axial shortening in steel columns; and 2) to comprehend by means of simulation-based engineering the steel column-ECB interaction in steel MRFs, which provides the basis of the dissipative ECB connection development. This thesis first explores the nonlinear interaction between embedded bases and wide flange steel columns by means of extensive continuum finite element simulations. The simulation results facilitate the development of refined design procedures for conventional non-dissipative ECBs. Moreover, the benefits of balancing the inelastic deformation demands between the steel column and the embedded base are highlighted. Based on these findings, a novel dissipative ECB connection is developed that defies the current paradigm in capacity-designed steel MRFs (i.e., weak-base/strong-column). In the proposed concept, a dissipative zone is introduced as part of the embedded portion of the steel column. This zone is decoupled from the concrete foundation with a debonding material layer. The dissipative zone is engineered such that the steel column does not experience nonlinear geometric instabilities at the column base and the reinforced concrete foundation itself remains practically undamaged during earthquake loading. The proposed concept is validated with large-scale quasi-static experiments and supplemental finite element analyses. It is demonstrated that, contrary to its conventional counterpart, the dissipative ECB connection is resilient to local buckling-induced axial shortening. A simple non-degrading mechanics-based model is sufficient to describe the hysteretic response of the dissipative ECB for performance-based design and assessment of steel MRFs under earthquake loading.

EPFL2021

Chargement

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In this paper we use the novel Disturbed Stress Field Model (DSFM) from Facconi et al. (2013) to model the lateral in-plane behaviour of different unreinforced masonry (URM) walls which we tested at the laboratory of the EPF Lausanne, Switzerland. The model uses the failure criterion developed by Ganz (1985) for URM and is implemented in the software VecTor 2. In the first part of this article, we show that the DSFM gives good estimates for the initial stiffness of the walls but underestimates the displacement and force capacity of our URM walls. This is due to the confinement of the mortar base joint which is confined by the wall foundation. However, we show that this phenomenon can be accounted for by replacing the compression strength of the masonry of the first brick layer by the strength of the brick itself. Using this improved model, we compare the numerical results to the experimental results with regard to displacements and strains. We show that the simplification of the masonry to a continuous material is correct when comparing the global engineering demand parameters (EDPs), e.g., force-displacement behaviour of the walls or crack pattern. However, when comparing local EDPs, e.g., strains and crack widths, significant differences can be obtained. These differences are mainly caused by the torque of the bricks inside the walls (Mann and Müller, 1982). We show that this distortion gets less important with increasing shear span and that for a wall with higher shear span the assumption of a continuous material gives reasonable results even at the local level.

2014

Chargement

Experimental investigation of soil - structure interaction for transition slabs of integral bridges

Olivier Burdet, Jürgen Einpaul, Aurelio Muttoni

This paper presents the results of an experimental test series on the soil-structure-pavement interaction in the vicinity of the transition slab at the end of an integral bridge. The main function of transition slabs is to ease the transition between the bridge deck and the embankment in case of differential settlements. Additionally, in the case of integral bridges, they can solve the problem of moderate imposed longitudinal deformations at the bridge ends. In this case, the displacements imposed to the transition slab can lead to vertical and longitudinal surface displacements and to cracking of the pavement. Based on the observed behaviour, some recommendations are proposed for the geometry and surface conditions to optimise the behaviour of the transition slabs.

Structural Concrete2015

Chargement

Development of Dissipative Steel Column-Base Connections for Steel Moment-Resisting Frames under Seismic Loading

Hiroyuki Inamasu

EPFL2021