Coupled chemical and mechanical processes in concrete structures with respect to aging

Abstract

Accurate prognoses of the durability of concrete structures require a detailed description of the continuously running aging processes and a consideration of the complete load history. Therefore, in the framework of continuous porous media mechanics a model is developed, which allows a detailed analysis of the most important aging processes of concrete as well as a flexible coupling of different processes. An overview of the prediction model and the balance equations is given. The material dependent model equations, the consequences of coupling different processes and the solution scheme are discussed. In two case studies the aging of concrete due to hydration and chloride penetration are presented, which illustrate the capabilities and the characteristics of the developed model.

Thermomechanics failure of RC composites: computational approach with enhanced beam model

“…Extending the proposed formulation to geometrically nonlinear framework can be accomplished by following the footsteps indicated in Ibrahimbegovic et al (2013) and Ngo et al (2014). Another possible line of development will concern combining the proposed structural model with refined material modeling of concrete under fire, such as elaborated upon by (Ostermann andDinkler 2014, Cramer et al 2014).…”

A macroscopic gradient-enhanced damage model for deformation behavior of concrete under cyclic loadings

“…Subsequently, several continuum damage models [9,25,27,28,36] are developed for concrete by introducing a set of internal state variables solely contributing to the post-peak nonlinear softening behavior. On the other hand, there are several other models, namely coupled plastic damage models [23,24,40,42] and multi-surface plastic damage models [7,11,33], that couple plasticity and either isotropic or anisotropic damage theories for concrete.…”

“…In another approach, a total damage is a weighted sum of these damages in tension and compression related to two different loading surfaces, respectively [28]. Occasionally, the total damage is estimated from two damage variables using a multiplicative relation [11,23] to consider elastic stiffness recovery during loading/unloading processes. Likewise, the positive (tension) and negative (compression) parts of effective stresses, which are obtained using spectral decomposition, are sometimes linked to these damage variables [10,42].…”

“…Furthermore, the history variable governing the evolution of damage is usually related to a scalar measure of local deformation via the loading criterion function. It is also noteworthy that there are various definitions available in the literature for the consideration of local measure of deformation [29,36], which can be determined by using damage equivalent strains in terms of either principal stresses [9] or principal strains [27,28], damage energy release rate [10,42], effective stress [26], equivalent effective stress [14] and inelastic strains [7] or sometimes inelastic multipliers [11]. Similarly, there are also different alternatives to express the damage equivalent strain, namely Mazars criterion [28], modified von Mises strain [13,36], and two separate expressions, for cracking and crushing, respectively [27].…”

Numerical analysis of reinforced concrete structures with particular focus on bond behaviour

“…Up to now, a model has been developed, by which numerical simulations of concrete structures can be performed, where the essential influences during lyfe-cycle are considered, see [1] and [2]. Hereby, coupled THMC-processes are modelled for concrete in the framework of continuum mechanics of porous media.…”