Luc Davenne

Prediction of crack pattern distribution in reinforced concrete by coupling a strong discontinuity model of concrete cracking and a bond‐slip of reinforcement model

Purpose – To provide a reinforced concrete model including bonding coupled to a classical continuum damage model of concrete, capable of predicting numerically the crack pattern distribution in a RC structure, subjected to traction forces.Design/methodology/approach – A new coupling between bonding model and an alternative model for concrete cracking is proposed and analyzed. For concrete, proposes a damage‐like material model capable of combining two types of dissipative mechanisms: diffuse volume dissipation and localized surface dissipation.Findings – One of the most important contributions is the capacity of predicting maximal and minimal spacing of macro‐cracks, even if the exact location of cracks remains undetermined. Another contribution is to reiterate on the insufficiency of the local damage model of concrete to handle this class of problems; much in the same manner as for localization problem which accompany strain‐softening behavior.Practical implications – Bonding becomes very important to ev...

Efficient approaches to finite element analysis in earthquake engineering

Abstract This paper deals with the modeling of reinforced concrete structures subjected to earthquake ground motion. Due to the complex behavior of both materials and structures, efficient numerical tools are developed herein in order to keep accuracy and robustness for large scale computations. We focus our attention on the use of simplified multifiber beam element describing the response of structural components and on macro-element accounting for soil–structure interaction.

Modélisation jusqu'à rupture de murs en maçonnerie chargés dans leur plan

ABSTRACT This paper deals with modeling of mechanical behaviour of masonry walls submitted to in-plane loading. The adopted strategy consists of modelling separately the appropriate local failure mechanisms of thoug elements and mortar joints. A particular attention is dedicated to brick crushing mechanisms which were captured with strong displacement discontinuities within the framework of incompatible mode method. A perfect plasticity model including di-latancy has been employed for the joints modeling. This model has been compared with two experimental results. We show that we are able to well reproduce the global behaviour of such structure (stiffness and peak load) and thus construct reliable predictive model of the masonry walls by using only the experimental characteristics of their components.

Saint‐Venant multi‐surface plasticity model in strain space and in stress resultants

Purpose – To present a new constitutive model for capturing inelastic behavior of brittle materials.Design/methodology/approach – The multi‐surface plasticity theory is employed to describe the damage‐induced mechanisms. An original feature in that respect concerns the multi‐surface criterion which limits the principle values of elastic strains, which is equivalent to Saint‐Venant plasticity model. The latter allows to represent the damage both in tension and in compression.Findings – Provides a quite realistic description of cracking phenomena in brittle materials, with a very few parameters, leading to a very useful tool for analyzing practical engineering problems.Originality/value – The model is recast in terms of stress resultants and employed within a flat shell elements in order to provide a very efficient tool for analysis of cellular structures. Moreover, a detailed description of the numerical implementation is given.

Fire Induced Damage in Structures and Infrastructure: Analysis, Testing and Modeling

In this work we first review the statistical data on large fires in urban areas, presenting a detailed list of causes of fires, the type of damage to structures and infrastructure built of reinforced concrete. We also present the modern experimental approach for studying the fire-resistance of different structural components, along with the role of numerical modeling to provide a more detailed information on quantifying the temperature and heat flux fields. In the last part of this work we provide the refined models for assessment of fire- induced damage in structures built of reinforced concrete, the most frequently used construction material. We show that the refined models of this kind are needed to provide a more thorough explanation of damage and to complete the damage assessment and post-fire evaluations.

Modeling thermomechanical behaviour of cellular structure made of brittle material

Publisher Summary This chapter discusses the modeling of thermo-mechanical behavior of brittle material using shell elements. The structures of this kind are encountered in many practical engineering problems and their uses are widespread in civil engineering. From a physical point of view, the material exhibits brittle behavior in traction and in compression. Moreover, considering that cracking appears perpendicularly to load direction in tension and in parallel to this direction in compression, it has been noted that the failure of such material is mainly driven by positive strains. According to such experimental aspect, Rankine like plasticity model was written, which contrary to standard approach employs the yield criterion based on strain tensor principal values and not on the stress tensor.

Performance Based Earthquake-Resistant Design: Migrating Towards Nonlinear Models and Probabilistic Framework

In this work we present our recent works that follow two modern tendencies in modelling and design of engineering structures for extreme loading such as earthquakes: (i) fine scale models for providing the simplest, fine-scale interpretation of inelastic damage mechanisms at the origin of energy dissipation and damping phenomena, as opposed to coarse scale of stress resultants; (ii) the role of probability in this kind of modelling approach. We consider application of these ideas first to structures, especially irreplaceable structures, such as nuclear power plants, and move onto the complex systems such as water networks.

NONLINEAR TRANSIENT ANALYSIS AND DESIGN OF COMPLEX ENGINEERING STRUCTURES FOR WORST CASE ACCIDENTS : EXPERIENCE FROM INDUSTRIAL AND MILITARY APPLICATIONS

In this work we address some of the present threats posed to engineering structures in placing them under extreme loading conditions. The common ground for the problems studied herein from the viewpoint of structural integrity is their transient nature characterized by different time scales and the need to evaluate the consequence for a high level of uncertainty in quantifying the cause. The pertinent issues are studied in detail for three different model problems: i) the worstcase scenario of system functioning failure accident in a nuclear power plant causing the loss of cooling liquid, ii) the terrorist attacks brought explosion and impact of large aeroplane on a massive structure, iii) devastating fire and sustained high temperatures effects on massive cellular structures. By using these case studies, we discuss the issues related to multi-scale modelling of inelastic damage mechanisms for massive structures, as well as the issues pertaining to the time integration schemes in presence of different scales in time variation of different sub-problems brought by a particular nature of loading (both for a very short and a very long loading duration) and finally the issues related to model reduction seeking to provide an efficient and yet sufficiently reliable basis for parametric studies employed within the framework of a design procedure. Several numerical simulations are presented in order to further illustrate the approaches proposed herein. Concluding remarks are stated regarding the current and future research in this domain.