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Structures subjected to cyclic loads show alternative tension–compression stress states; in such a case, even if certain damage (fracture) is reached during the tension cycle, the computational model of the structure should maintain its capacity to withstand subsequent compression based only on the contact effect in the damaged area (opening, closing and reopening of cracks). In order to control this behavior, a phenomenological constitutive model able to consider the contact as a structural limitation is required. From the constitutive point of view, geomaterials have different damage thresholds for tension and compression and, from the structural point of view, it must be ensured that the material damaged in tension still resist compression. In this case, it is accepted that cracks behave as a contact surface at the structural level. To meet the above mentioned phenomenology, a modification of the damage model differentiated in tension and compression proposed by Faria et al. [Faria R, Oliver J, Cervera M. A strainbased plastic viscous-damage model for massive concrete structures. Int J Solids Struct 1998; 35:1533–58] is performed in this paper, considering independent strength thresholds in each of these processes, controlled with two independent discontinuity threshold functions. Also, in this work an elasto-plastic constitutive model is used to represent the behaviour of the steel bars.

A new damage model, based on continuum damage mechanics and simulating the opening, closing, and reopening of cracks in concrete using only one surface of discontinuity, is proposed in this article. The model complies with the thermodynamics principles of nonreversible, 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 controlling the damage variable that should be activated. This new parameter represents the ratio of tensile stress to compressive stress in the damaged material. The continuity of response under complex loads, which is one of the aims of this work, is ensured. An adequate response under different types of loads leads to the conclusion that the proposed model provides a powerful tool to numerically analyze reinforced concrete structures. Validation and illustrative examples are included in the article.

Ferrocement thin walls are the structural elements that comprise the earthquake resistant system of dwellings built with this material. This article presents the results drawn from an experimental campaign carried out over full-scale precast ferrocement thin walls that were assessed under lateral static loading conditions. The tests allowed the identification of structural parameters and the evaluation of the performance of the walls under static loading conditions. Additionally, an isotropic damage model for modelling the mortar was applied, as well as the classic elasto-plastic theory for modelling the meshes and reinforcing bars. The ferrocement is considered as a composite material, thus the serial/parallel mix theory is used for modelling its mechanical behavior. In this work a methodology for the numerical analysis that allows modeling the nonlinear behavior exhibited by ferrocement walls under static loading conditions, as well as their potential use in earthquake resistant design, is proposed. Los muros de ferrocemento de pared delgada son el elemento estructural principal que compone el sistema de resistencia sísmica de las viviendas de ferrocemento. En este artículo se presentan los resultados de una campaña experimental realizada sobre muros prefabricados de pared delgada de ferrocemento construidos a escala real 1:1, los cuales fueron probados bajo carga estática lateral. Estos ensayos permitieron identificar parámetros estructurales y evaluar la capacidad y el desempeño de los muros bajo carga estática. Adicionalmente, se aplicó el modelo de daño isótropo para la modelación del mortero y la teoría de elasto-plasticidad clásica para la modelación de las barras y la malla de refuerzo. El Ferrocemento se puede considerar como un material compuesto y por lo tanto se utilizó la teoría de mezclas serie/paralelo para modelar su comportamiento mecánico. Así, se planteó una metodología para el análisis numérico no lineal que permite modelar el comportamiento no lineal exhibido por los muros de ferrocemento bajo este tipo de cargas y su potencial uso en el diseño de muros de ferrocemento.

The structures subjected to dynamic loads often show alternative tensioncompression states stress; in such a case, even if certain damage (fracture) is reached during the tension cycle, the structure should maintain its capacity to withstand subsequent compression based only on the contact effect in the damaged area. In order to control this behavior requires a phenomenological constitutive model able to consider the contact as a structural limitation. On the other hand, from the constitutive point of view geomaterials have different damage thresholds for tension and compression and, from the structural point of view it must be ensured that the material damaged in tension still can resist compression. In this case, it is accepted that cracks behave as a contact surface at the structural level. To meet the above mentioned phenomenology, a modification of the damage model differentiated in tension and compression of Faria et al. (1998) is performed in this paper, considering independent strength thresholds in each of these processes, controlled with a single discontinuity threshold function.

En Colombia, la albañilería constituye una muy significativa técnica de construcción presente en edificaciones históricas. Sin embargo, ante los cambios de uso que por lo general implican un incremento de las cargas vivas, las fuertes variaciones medioambientales, el incremento de la polución y la presencia de diferentes organismos vivos -entre otros factores-, en los últimos años parece haberse acelerado el nivel de deterioro de los materiales que la conforman (ladrillo y mortero de cal), lo que hace necesario en muchas ocasiones determinar sus propiedades físico - mecánicas y su composición química y mineralógica con el fin de diagnosticar el real estado de la estructura. Este artículo trata de las rutinas apropiadas para tal caracterización de manera que ellas puedan ser aplicadas en el futuro a procesos de restauración de edificios históricos. A partir del estudio de caso que tiene por objeto el puente de arco de mampostería construido en la ciudad de Buga (Valle del Cauca) en la segunda mitad del siglo XIX, se dará cuenta de la manera en que los análisis mecánicos de los ladrillos permiten contar con unos patrones de referencia acerca de su comportamiento resistente; simultáneamente, la caracterización mineralógica permite identificar la composición y temperatura de cocción de los ladrillos empleados originalmente en la construcción. In Colombia, bricklaying is constituted as a very significant construction technique present in historical buildings. However, with changes in their use, which generally implied increased dynamic loads, strong environmental variations, increased pollution, and the presence of different living organisms - among other factors - in recent years have apparently accelerated the deterioration of the materials conforming them (brick and lime mortar), in many occasions making it necessary to determine their physical and mechanical properties along with their chemical and mineralogical composition to diagnose the real state of the structure. This article explores the appropriate routines for such characterization to permit their future application in restoration processes of historical buildings. From the case study involving the masonry brick arch bridge constructed in the city of Buga (Valle del Cauca) during the second half of the 19th century, we will establish how mechanical analysis of the bricks allows having reference patterns of its resistance behavior; simultaneously, mineralogical characterization permits identifying the composition and firing temperature of the bricks originally used in the construction.