Multi-scale analysis of timber framed structures filled with earth and stones

This paper deals with the seismic analysis of timber framed houses filled by stones and earth mortar using a multi-scale approach going from the cell to the wall and then to the house. At the scale of the elementary cells, experimental results allow fitting the parameters of a new versatile hysteretic law presented herein through the definition of a macro-element. Then, at the scale of wall, the numerical simulations are able to predict its behavior under quasi-static cyclic loading and is compared to experimental results allowing validating the macro-element model

Modeling of granular solids with computational homogenization: Comparison with Biot's theory

peer reviewe

Understanding Traditional Anti-Seismic Strategies Beyond Their Disappearance and Distortions: Yazd Qajar Architecture Case Study

Understanding traditional seismic strategies is necessary to conduct appropriate restoration of historic buildings and city centers located in earthquake-prone areas. But, the fast disappearance of vernacular built heritage and of the associated popular knowledge and know-how, along with the spread of inappropriate maintenance works, make it very difficult. To overcome these obstacles, it is suggested to broaden the scope of observations by including both larger geographical areas and elements that do not appear as seismic features at first consideration. This paper illustrates the relevance and the limits of this approach by applying it to the case study of Yazd historic city center. Yazd is located in a moderate seismic area and is famous for its well-preserved historic city center, with a high number of Qajar adobe buildings in various conditions. The authors combined literature review, direct observation of numerous buildings and a deeper study of four Qajar houses to conduct the first part of their research. The data collected mainly relates to the geometrical features, the materials used and the interconnections between elements at different scales. Their analyses led to the elaboration of several assumptions on the seismic behaviour of the studied adobe buildings and vaults and on the distortions some features may have suffered. To validate these assumptions, two methodologies were used. Both are illustrated in this paper through the study of the insertion of baked bricks in adobe vaults. The first one is based on observation campaigns on damaged houses. The second one is based on experimental works, with tests conducted on the shear strengths of masonry made with mud mortars and adobes or baked bricks to better understand how builders benefited from mixing these materials in an adobe vault. Finally, the authors discuss the limits of the method and the extent to which restoration projects can benefit from it

Enhancement of multifiber beam elements in the case of reinforced concrete structures for taking into account the lateral confinement of concrete due to stirrup

International audienceMany researches have been conducted in the structural engineering field in order to develop efficient numerical tools able to reproduce the complex nonlinear behavior of reinforced concrete structures. In the case of slender elements, enhanced beam models have been developed to try to introduce shear effects, but in these models, the transverse steel is sometimes taken into consideration with approximated manner or often not at all. However, as shown by some experimental tests, the amount of transverse reinforcement triggers significantly the behavior of beam elements, especially under cyclic loading. The present study adresses this problem by investigating solutions for an enhanced multifiber beam element, accounting for vertical stretching of the cross-section occurring due to the presence of stirrups. A timoshenko beam element with internal degrees of freedom and higher order interpolation functions is selected. Full 3D stresses and strains are obtained and the construction of the element and sectional stiffness matrices is detailed. The element presented hereafter is suitable for an arbitrary shape cross-section made of heterogeneous materials. Numerical applications on a plain concrete cantilever beam subjected to tension and bending tests respectively are presented. Moreover, as a first application, a dilation effect is added to the concrete fibers in order to highlight the role of transversal rebars. All the numerical results are confronted to the outcomes of stantard 3D finite element computations

Hydromechanical modelling of an initial boundary value problem: Studies of non-uniqueness with a second gradient continuum

A non-uniqueness study for a hydromechanical boundary value problem is performed. A fully saturated porous medium is considered using an elasto-plastic constitutive equations to describe the mechanical behavior of the skeleton. A real hydromechanical experiment which consists in a hollow cylinder test on a Boom Clay sample is modelled. It is shown that the time step discretisation of the numerical problem has an effect on the initialisation of the Newton-Raphson algorithm on a given time step. Different solutions for the same initial boundary value problem can consequently be found

ENHANCEMENT OF MULTIFIBER BEAM ELEMENTS IN THE CASE OF REINFORCED CONCRETE STRUCTURES FOR TAKING INTO ACCOUNT THE LATERAL CONFINEMENT OF CONCRETE DUE TO STIRRUP

International audienceTo assess the seismic vulnerability of existing reinforced concrete structures, a large number of degrees of freedom is involved. Consequently, efficient numerical tools are required. In the case of slender elements, enhanced beam elements have been developed to try to introduce shear effects, but in these models, the transverse steel is sometimes taken into consideration with approximated manner or often not at all. However, as shown by some experimental tests, the amount of transverse reinforcement triggers significantly the behavior of beam elements, especially under cyclic loading. Thus, the main goal of this work is to investigate solutions for an enhanced multifiber beam element accounting for vertical stretching of the cross section, occurring due to the presence of transverse reinforcement. The efficiency of the proposed modeling strategies is tested with results obtained from tension and flexure tests conducted on an elastic linear material

Local second gradient models for thermo-hydro-mechanical coupling in rock like materials

In the design of nuclear waste disposals, an important topic concerns the evolution of an Excavated Damage Zone (EDZ) with a thermal exchanges. In this paper, a new model of local second gradient coupling with a thermo-hydro-mechanical is presented. As for monophasic case, the use of enhanced media induce the objective of the computation but not the uniqueness of the solution. Some classical engineering problems are presented which exhibit several solutions

Hydromechanical modeling of an initial boundary value problem: Studies of non-uniqueness with a second gradient continuum

International audienc