HAL-Ecole des Ponts ParisTech

    Ornament and its users From vitruvian tradition to the digital age

    No full text
    International audienc

    Universal expositions, utopias, and architecture

    No full text
    International audienc

    Factors affecting the thermo-chemo-mechanical behaviour of massive concrete structures at early-age

    No full text
    International audienceDifferent factors related to construction site conditions must be accounted for when designing concrete massive structures in order to accurately predict the cracking risks at early-age. Detailed descriptions of the thermal and mechanical boundary conditions as well as analyses accounting for the coupling between damage and creep may lead to computationally expensive simulations campaign. On the other hand, simplified modelling strategies have been extensively used but may not capture accurately key aspects of such analysis. Based on a previous chemo-thermal analysis by Honorio et al. (Eng Struct 80:173–188, 2014), the present study focuses on the mechanical behaviour of a specific structure by making use of a coupled thermo-chemo-creep-damage model. Simplified modelling strategies to treat the external restraints and some thermal boundary conditions are compared to more realistic ones. The risks of cracking are assessed by means of a cracking index (CI) and a damage model. Restraint conditions in which the ground is not represented leads to cracking risks in different zones if compared to the case with the ground. It is shown that, the ambient temperature affects directly the tensile stresses reached and the oscillation of the temperature within a day may play a non-negligible role. The effect of damage and its coupling with creep are analysed, and a strong influence of the corresponding coupling parameter on the cracking initiation and propagation is observed

    Should We Be Wary of Mitigation Banking? Evidence Regarding the Risks Associated with this Wetland Offset Arrangement in Florida

    No full text
    International audienceThis paper describes and analyzes the risks associated with using mitigation banking for the conservation of wetlands in Florida in the United States. First, we attempt to identify and summarize the main ecological and socio-economic risks regarding mitigation banking that have been discussed in previous studies. Then we analyze the institutional responses adopted by US regulators to limit these risks. We have used empirical evidence including interviews and data analysis to assess the effectiveness of these responses. Our main findings are that the recent regulatory responses adopted to face risks associated with mitigation banking seem to be more effective than what is often assumed. These responses are underpinned by the emergence of a hybrid mode of governance that combines market characteristics and regulatory constraints, and which contributes to enforcing wetland compensation in Florida. However, we also observed some risks inherent in this system, in particular the redistribution of ecosystem services, as the distance between impact sites and compensation sites seems to have increased in Florida in the last several years. In addition, the question is still pending regarding whether or not No Net Loss of wetlands is really achieved through mitigation banking

    Macroeconomic modelling of electrified mobility systems in 2030 European Union

    No full text
    This working paper details in 3 sections (i) the data collection and treatment that were necessary to apply IMACLIM-P to a 28-country European Union (EU); (ii) the particulars of a version of IMACLIMP dedicated to a prospective outlook on the penetration of electric passenger cars in the EU, including how results of the PAN-EU TIMES model of energy systems can be imported in IMACLIMP, together with the complete set of equations of the model; (iii) model implementation

    Higher order elastoplastic beam model

    No full text
    International audienceBridge decks, metallic meshes or concrete beams have long been numerically described by beam models with a simple kinematic. Those classic models can capture elementary deformations like traction or bending moment. But when it comes to wide decks or thin beams, higher order effects become non negligible. Moreover, plasticity in the structure is associated to an infinitely large number of degrees of freedom, which are not provided by the classic models. Added to the computational cost of a full volumic computation, this has motivated the development of higher order beam models. Based on the elastic beam model developed by Ferradi et al. [1], a new elastoplastic beam model is presented here. As for the model described in [1], the kinematic of the beam is extended using the asymptotic expansion method [2]. Degrees of freedom specific to the geometry of the section of the beam and specific to the loading applied on the structure are added to the kinematic. In the elastoplastic model presented here, new degrees of freedom specific to the plasticity are also introduced: at each iteration of the plasticity algorithm, the updated plastic strain field is considered as an eigenstrain loading the beam. The asymptotic expansion method yields new degrees of freedom from these new external loads. Unlike many POD-like plastic reduced models, this elastoplastic beam model does not need any a priori knowledge on the solution of the problem. This is a systematic method in which the degrees of freedom are specific to the plastic strains, these latter being updated at each iteration of the algorithm. This model shows similar results to volumic computations, with much higher time performances

    A model reduction technique for beam analysis with the asymptotic expansion method

    No full text
    International audienceIn this paper, we apply the asymptotic expansion method to the mechanical problem of beam equilibrium, aiming to derive a new beam model. The asymptotic procedure will lead to a series of mechanical problems at different order, solved successively. For each order, new transverse (in-plane) deformation and warping (out of plane) deformation modes are determined, in function of the applied loads and the limits conditions of the problem. The presented method can be seen as a more simple and efficient alternative to beam model reduction techniques such as POD or PGD methods. At the end of the asymptotic expansion procedure, an enriched kinematic describing the displacement of the beam is obtained, and will be used for the formulation of an exact beam element by solving analytically the arising new equilibrium equations. A surprising result of this work, is that even for concentrated forces (Dirac delta function), we obtain a very good representation of the beam’s deformation with only few additional degrees of freedom

    Discrimination in public procurements: A cost-reducing guide (joint with Philippe Jehiel), VOX-EU (CEPR)

    No full text
    Bid preferences and set-asides are popular discriminatory practices in US public procurement, but are prohibited in the EU. This column argues that discrimination can be cost-reducing provided it is targeted to favour those firms whose participation is more responsive to the auction procedure. Situations when set-asides may be cost-reducing are also discussed
    HAL-Ecole des Ponts ParisTechis based in FR
    Repository Dashboard
    Do you manage HAL-Ecole des Ponts ParisTech? Access insider analytics, issue reports and manage access to outputs from your repository in the CORE Repository Dashboard!