A new tension-compression damage model applied to modeling the ferrocement thin walls under cyclic loads

J. A. PAREDES; S. OLLER; A. BARBAT; D. BEDOYA

Congreso; USACM's 12th U.S. National Congress on Computational Mechanics; 2013

A new damage model, based on continuum damage mechanics, simulating the opening, closing and reopening of cracks in concrete using only one surface of discontinuity, is proposed in this article. This model will be used to modeling the ferrocement thin walls under cyclic loads. Ferrocement thin walls are the main components of the seismic system of the ferrocement dwelling houses. The model complies with the thermodynamics principles of non-reversible, isothermal and adiabatic processes. Two scalar internal variables have been defined: a tensile damage variable "d+" and a compressive damage variable "d-" ; the threshold of damage is controlled by only one surface of discontinuity and a new parameter which controls the damage variable which should be activated.This new parameter represents the ratio of the tensile stress to the compressive stress in thedamaged material. The continuity of response under complex loads, which is one of the aims of this work, is ensured. The proposed model allows to represent the structural response due to cyclic loads that shows alternate tension-compression stress states. If tensile damage (fracture) is reached during a tension cycle, the model is able to maintain the compressive strength during the compressive cycle. An adequate response under different types of loads allows concluding that the proposed model provides a powerful tool for the numerical analysis of reinforced concrete structures. The model validation is carried out in four sequential steps: 1) the numerical result for increasing monotonic compressive axial loads are compared with the experimental results of Kupfer et al. [1]; 2) the results under increasing monotonic tensile axial load are compared with the experimental data published by Gopalaratnam and Shah [2]; 3), the numerical results are validated for cyclic loads; 4) the results are validated for shear states and compared with the experimental data published by Kupfer et al [1]. The results obtained with the new constitutive model are compared with those of the work of Arrea and Ingraffea [3], in which a concrete beam was subjected to complex loading.