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Pecol P.,ParisTech National School of Bridges and Roads | Dal Pont S.,University Paris Est Creteil | Erlicher S.,EGIS Industries | Argoul P.,ParisTech National School of Bridges and Roads
Annals of Solid and Structural Mechanics | Year: 2011

The aim of this paper is to develop on discrete models that reproduce the behavior of a crowd of people in several emergency evacuation situations. The first step in this study is to determine how to treat contacts between pedestrians. For that, three already existing discrete approaches, one smooth and two non-smooth, originally proposed to simulate the collisions of granular assemblies, are first analyzed both from the theoretical and the numerical point of view. The solving algorithms are presented and the numerical formulation of the two non-smooth approaches is compared to standard plasticity in order to point out the common theoretical framework. The next step is to adapt these discrete approaches to represent pedestrians. The key point is to introduce a "willingness" for each particle through a specific desired velocity. These adapted discrete approaches are able to handle local interactions, like pedestrian-pedestrian or pedestrian-obstacle contacts, in order to reproduce the global dynamic of pedestrian traffic. Finally, results of several simulations in emergency configurations are presented as well as compared to real exercise ones. © 2011 Springer-Verlag.

Huguet M.,Ecole Centrale Nantes | Voldoire F.,Electricite de France | Kotronis P.,Ecole Centrale Nantes | Erlicher S.,EGIS Industries
11th World Congress on Computational Mechanics, WCCM 2014, 5th European Conference on Computational Mechanics, ECCM 2014 and 6th European Conference on Computational Fluid Dynamics, ECFD 2014 | Year: 2014

A new nonlinear stress resultant global constitutive model for RC panels is presented. Concrete damage, concrete stress transfer at cracks and bond-slip stress are the main nonlinear effects identified at the local scale that constitute the basis for the construction of the stress resultant global model through an analytical homogenization technique. The closed form solution is obtained using general functions for the previous phenomena.

Ceravolo R.,Polytechnic University of Turin | Erlicher S.,EGIS Industries | Zanotti Fragonara L.,Polytechnic University of Turin
Journal of Sound and Vibration | Year: 2013

When subjected to events such as earthquakes, engineering structures typically exhibit a nonlinear and hysteretic behaviour with stiffness and strength degradations. Though a reliable evaluation of safety conditions should take into account the nonlinear dynamic and evolutionary nature of the structural response, the experimental identification of a nonlinear behaviour under dynamic and seismic loading is, to date, an open problem. The present research aims at evaluating the potential of different restoring force models for simulating the seismic response of hysteretic structural systems, with special emphasis on the two main problems encountered when applying this approach to full-scale structures under intense excitation: (a) a markedly time-dependent behaviour; (b) need to compare among different restoring force models, either expressed in a parametric or polynomial form. In particular, polynomial models will be formulated both in terms of restoring force and its derivative, in order to present a comprehensive discussion of different strategies. The nonlinear identification technique employed in this paper is required to account for a time-dependent behaviour. In fact, in presence of degradation or any other time-varying characteristics, instantaneous identification certainly constitutes an enhancement of the classical restoring force based approach, and may as well provide checks on the consistency of the assumed models. © 2013 Elsevier Ltd.

Trovato A.,University of Calabria | Kumar A.,Indian Institute of Technology Roorkee | Erlicher S.,EGIS Industries
Annals of Solid and Structural Mechanics | Year: 2014

In this article, the entrained response of the modified hybrid Van der Pol/Rayleigh (MHVR) oscillator undergoing a periodic excitation is analyzed. Based on a large experimental database, this self-sustained oscillator was originally proposed by the authors to model the lateral ground force of a pedestrian walking on a rigid floor. In this situation, there is no external excitation on the oscillator (autonomous regime). In a successive development, the authors used the MHVR oscillator in the non-autonomous regime to model the lateral oscillations of a pedestrian walking on a periodically moving floor. In the same work, the MHVR oscillator was analyzed in terms of amplitude of the entrained response, i.e. a solution having constant amplitude and the same frequency as the one of the given periodic excitation. The main goal of the present paper is the stability analysis of entrained responses. Some theoretical results are first discussed. Then, these theoretical notions are applied to the pedestrian modelling problem: the conditions allowing stability of the solution are used to compute the percentage of pedestrians of a given population that can synchronize their walk with a given periodic floor motion. Finally, these model predictions are compared with experimental results concerning pedestrians walking on a periodically moving floor. © 2014, Springer-Verlag Berlin Heidelberg.

Kabalan B.,University Paris Est Creteil | Argoul P.,University Paris Est Creteil | Jebrane A.,Cadi Ayyad University | Cumunel G.,University Paris Est Creteil | Erlicher S.,EGIS Industries
Annals of Solid and Structural Mechanics | Year: 2016

One of the main objectives of crowd modeling is to optimize evacuation and improve the design of pedestrian facilities. In this work, a sensitivity analysis is performed to study the effect of the parameters of a 2D discrete crowd movement model on the nature of pedestrian’s collision and on evacuation times. After presenting the proposed model in its full version (three degrees of freedom for each individual), a pedestrian–pedestrian collision is considered. We identified the parameters that govern this type of collision and studied their effects on it. Then an evacuation experiment of a facility with a bottleneck exit is introduced and its configuration is used for numerical simulations. It is shown that without introducing a social repulsive force, the obtained flow rate values are much higher than the experimental ones. For this reason, we introduced the social force as defined by Helbing and performed a parametric study to find the set of optimized values of this force’s parameters that enables us to achieve simulation results close to the experimental ones. Using the values of the parameters obtained from the parametric study, the evacuation simulations give flow rate values that are closer to the experimental ones. The same optimized model is then used to find the density in front and inside the bottleneck and to reproduce the lane formation phenomenon as was observed in the experiment. Finally, the obtained results are analyzed and discussed. © 2016 Springer-Verlag Berlin Heidelberg

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