Browsing by Author "Vargas Carvajal, Laura Andrea"

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    Design of partially grouted reinforced masonry shear walls in an earthquake-prone area: Proposal based on the LRFD approach
    (2025) Vargas Carvajal, Laura Andrea; Aguilar,Víctor; Calderón, Sebastián; Araya Letelier, Gerardo Andrés; Sandoval Mandujano, Cristián
    There is a lack of reliability assessment of modern structural masonry design. Hence, a novel reliability-based calibration of the in-plane shear ultimate limit state for partially grouted reinforced masonry shear walls (PGRMSWs) is presented. This calibration allows for the proposal of a load and resistance factor design (LRFD) methodology oriented to in-plane shear design, responding to the need to update the reinforced masonry Chilean code, which is currently based on the allowable stress design (ASD) format. An extensive database of material and assembly tests and numerical research that made this code update proposal feasible are summarized. The reliability-based calibration was performed aiming to define a target reliability index (βT) and the corresponding strength reduction factors (φ) were recommended. A value of βT = 2.5 is defined based on the reliability analysis of representative existing structures against earthquake-induced shear force. The results allow for recommending φ = 0.60 for walls made of multi-perforated clay bricks and φ = 0.70 for walls made of hollow concrete blocks. Additionally, φ = 0.85 and φ = 0.65 are recommended for flexural and axial strength of compression-controlled walls by adapting international standards to Chilean practice. Comparisons of the required horizontal reinforcement between ASD and LRFD methodologies are presented for a 4-story case study building. The results show that the total reinforcement quantities from ASD and LRFD methodologies are similar, which means the proposal does not imply a more restrictive and expensive design; yet, the LRFD proposal provides designs with a uniform reliability level across various load scenarios.
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    Experimental and Numerical Assessment of the In-Plane Behaviour of PG-RM Walls with Openings
    (Springer, 2025) Vargas Carvajal, Laura Andrea; Sandoval Mandujano, Cristian; Bertolesi, Elisa; Tarque, Nicola; Calderón, Sebastián
    This paper investigates how openings affect the in-plane response of partially grouted masonry (PG-RM) walls. The effect of the openings was assessed regarding shear capacity and failure mode through the cyclic test of four façadetype walls constructed with different opening sizes and with and without asymmetry. The results show that the shear capacity decreases with the opening’s height or width increment. It is also observed that geometric asymmetry generates differences between the lateral resistances of both in-plane loading directions. In addition, a two-dimensional finite element macro model using Abaqus was validated against the experimental results. The numerical strategy implemented satisfactorily represented the shear strength and failure mode of the tested walls. Considering the high complexity of representing the PG-RM behaviour, the proposed model is suitable for reproducing the PG-RM walls’ shear resistance and could be subsequently used further to investigate the effect of openings with different configurations.
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    Numerical strategy and openings-focused sensitivity study of the seismic behavior of partially grouted masonry shear walls with openings
    (Elsevier Ltd, 2025) Vargas Carvajal, Laura Andrea; Sandoval Mandujano, Cristián; Bertolesi, Elisa; Tarque, Nicola
    Partially grouted reinforced masonry (PG-RM) is a commonly used structural system in several seismic-prone countries. In recent years, experimental and numerical investigations have been conducted to identify the main parameters that influence their seismic performance. However, little attention has been devoted to investigating the influence of openings on their structural response. Although experimental tests have provided valuable insights into their behavior, numerical simulations have emerged as a complementary strategy for lower economic costs and logistical requirements. In this context, a two-dimensional finite element macro-model is implemented to simulate the in-plane behavior of PG-RM walls containing openings. The concrete damage plasticity (CDP) model is used to describe masonry's nonlinear response. The model is validated against the experimental results of four full-scale PG-RM walls previously tested by the authors. Then, considering both loading directions, an openings-focused sensitivity study is conducted to investigate their effect on the in-plane lateral response. The implemented model was capable of simulating the in-plane behavior of PG-RM walls containing openings, as good agreement was achieved between numerical results and experimental tests in terms of lateral strength and failure mode. As expected, sensitivity analysis indicated that the wall shear capacity decreased when the openings' height or width or the number of openings increased. Based on the results, this work proposes an effective height to estimate the shear capacity of PG-RM walls with openings, where the height of the pier is established as the average of the heights that constrain the pier on its sides.
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    Seismic behavior and design criteria of partially-grouted reinforced masonry walls with openings
    (2024) Vargas Carvajal, Laura Andrea; Sandoval Mandujano, Cristián; Pontificia Universidad Católica de Chile. Escuela de Ingeniería
    El sistema estructural compuesto por muros de albañilería armada parcialmente rellena (PG-RM por sus siglas en inglés) es comúnmente utilizado en regiones de sismicidad media y alta (por ejemplo, Chile, Canadá, Estados Unidos y Nueva Zelanda) debido a su economía y eficiencia. En los últimos años se han realizado investigaciones experimentales y numéricas para identificar los principales parámetros que influyen en su comportamiento sísmico. Sin embargo, se ha dedicado poca atención al estudio del efecto de las aberturas en su respuesta estructural, a pesar de que en estructuras reales generalmente se presentan diferentes configuraciones de muros con aberturas (por ejemplo, fachadas frontales con ventanas y puertas), y su respuesta sísmica difiere de la de los muros sólidos (sin aberturas). La poca investigación sobre este tema ha llevado a la existencia de expresiones de corte que provienen de muros sin aberturas y a una falta de disposiciones que consideren el efecto de las aberturas en los procesos de diseño. En este contexto, esta investigación tiene como objetivo principal proponer un criterio de diseño para muros PG-RM que considere el efecto de las aberturas. Para lograr este objetivo, esta investigación se dividió en tres partes. La primera parte consistió en caracterizar la respuesta experimental de muros PG-RM con aberturas sometidos a una acción combinada de carga axial constante y carga lateral cíclica. El efecto de las aberturas se evaluó en términos de las curvas de histéresis y de fuerza-desplazamiento. Además, los campos de deformaciones principales y patrones de agrietamiento se monitorearon con un sistema de correlación digital de imágenes (DIC por sus siglas en inglés) 2D. Luego, se llevó a cabo un estudio de sensibilidad enfocado en las aberturas para analizar más a fondo la influencia de su tamaño en la respuesta lateral de muros tipo fachada con configuraciones asimétricas. Por lo tanto, se desarrolló y validó un macromodelo de elementos finitos con los resultados experimentales de cuatro muros PG-RM a escala real ensayados previamente. La validación numérica se realizó en términos de su capacidad para representar la resistencia a corte y modo de falla de los muros. En general, se observó una buena correlación entre las respuestas experimentales y las simulaciones numéricas. Los resultados experimentales y numéricos indican que las variaciones en el tamaño de las aberturas afectan la capacidad de corte del muro. La capacidad de carga de los muros PG-RM con aberturas se reduce cuando aumenta su altura o su ancho o cuando aumenta el número de aberturas. Además, se observó que la direccionalidad de la carga lateral juega un papel fundamental en la evolución del daño. Por lo tanto, estos hallazgos se utilizaron para proponer un enfoque para determinar la altura efectiva de los piers (segmentos de muro) para calcular la capacidad de corte de los muros PG-RM con aberturas. La definición de una altura efectiva tiene como objetivo capturar los efectos de la direccionalidad de la carga en los patrones de falla del muro. Finalmente, se presentó una propuesta de actualización del código chileno para el diseño de muros PG-RM —NCh1928. Of1993 Mod.2009—, pasando del formato de Diseño por Esfuerzos Admisibles (ASD por sus siglas en inglés) a una metodología de diseño de factores de carga y resistencia (LRFD por sus siglas en inglés). Se realizó una calibración basada en confiabilidad utilizando simulaciones de Montecarlo para definir un índice de confiabilidad objetivo y factores de reducción de resistencia apropiados para diseñar muros PG-RM por corte. Esta transición en la metodología proporciona diseños con un índice de confiabilidad y una probabilidad de falla uniformes, enfatizando un comportamiento consistente en varios escenarios de carga.
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    Seismic behavior of partially grouted masonry shear walls containing openings: Experimental testing
    (2023) Vargas Carvajal, Laura Andrea; Sandoval Mandujano, Cristián; Bertolesi, Elisa; Calderón Díaz, Sebastián Andrés
    This article presents an experimental study aimed at understanding the effect of openings on the seismic response of partially grouted reinforced masonry (PG-RM) walls. For this purpose, four full-scale PG-RM walls with different opening sizes were built and tested under the combined action of constant axial compression and cyclic lateral loading. All the specimens had the same external dimensions. The effect of openings was assessed in terms of wall hysteresis and force–displacement curves and the quantification of different seismic parameters such as shear capacity, degradation of lateral stiffness, energy dissipated, equivalent viscous damping ratio, and displacement ductility. A 2D Digital Image Correlation (DIC) system was implemented to monitor principal strain fields and cracking patterns during the tests. The paper also includes the assessment of the shear capacity of the tested walls according to three existent approaches developed for in-plane shear panels, which rely on the definition of an effective height of piers. The results indicate that the shear capacity of the walls decreased when the aspect ratio of the piers increased. From DIC analysis results, it was observed that damage extended beyond piers also covering spandrels and that directionality of shear loads played a fundamental role in the damage development. Therefore, the identification of the pier’s effective height and direction of seismic loads should be incorporated into the estimation of the shear capacity. Finally, the performance of the selected shear expressions and different approaches to estimate the effective height of the piers was evaluated. It was concluded that the most accurate approach was to define an effective piers height according to Augenti (2006)’s proposal using the Calderón et al. (2022) shear expression to assess piers’ lateral resistance.
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    Seismic strengthening of partially grouted masonry walls with openings: Evaluation of ferrocement and BTRM solutions
    (2024) Pérez Pinedo, Luis Elías; Sandoval Mandujano, Cristián; Alvarado Funes, Rolando José; Vargas Carvajal, Laura Andrea; Calderón Díaz, Sebastián Andrés; Bernat, Ernest
    This paper presents an experimental study on the seismic performance of partially grouted reinforced masonry (PG-RM) walls strengthened with two solutions: Ferrocement coating (welded wire steel mesh embedded in cementitious mortar, WWM) and Basalt Textile Reinforced Mortar (BTRM) layer. For this purpose, two full-scale walls were built with hollow concrete units, with identical geometry and construction details of a previously reported tested wall, which acts as the control specimen (unstrengthened case) in this study. The walls, with a window-type opening and another door-type opening, were strengthened on one of their sides and tested under the combined action of constant axial compression and cyclic lateral loading up to failure. The experimental results show that both strengthening solutions increased the investigated walls' initial stiffness and lateral capacity. The increase in lateral capacity of both solutions was similar, about 37%. The 2D-DIC analysis implemented during the tests was instrumental in highlighting the areas on the strengthened walls where high strains were developed. The damage registered on the BTRM layer was more consistent with what was observed on the surface of the unstrengthened wall. Meanwhile, the damage reported on the wall strengthened with WWM did not exhibit apparent damage at higher drift levels due to the detachment between the ferrocement coating and the masonry substrate. Finally, the performance of some procedures to compute the contribution of the studied strengthening solutions was also assessed.
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    Shear design equation and updated fragility functions for partially grouted reinforced masonry shear walls
    (2022) Calderón Díaz, Sebastián Andrés; Vargas Carvajal, Laura Andrea; Sandoval Mandujano, Cristián; Araya Letelier, Gerardo Andrés; Milani, Gabriele
    This paper proposes specific ultimate shear strength expressions for partially-grouted reinforced masonry (PG-RM) shear walls that are bed-joint reinforced (BJR) and made with either multi-perforated clay bricks (MPCLBs) or hollow concrete blocks (HCBs). For each unit type, a set of constant coefficients of an arbitrary mathematical expression is optimized to minimize the error against experimental databases of walls made with the same unit types. Additionally, the assembled databases are employed to calculate lognormal empirical fragility functions, following performance-based earthquake engineering (PBEE) methodologies. For this, two different engineering demand parameters (EDPs) (story drift ratio, SDR, and normalized diagonal shear demand, NDSD) are proposed, and two damage states (DS) (named DS4 for moderate damage and DS5 for severe damage) are investigated. The proposed shear formulae are used in the normalization of calculated NDSD values. Moreover, databases are sorted by a selected design parameter (aspect ratio) to calculate design parameter-sensitive fragility functions. Overall, the results indicate that the proposed expressions are more accurate than the corresponding expressions proposed by the American and Canadian codes when assessing BJR-PG-RM shear walls in terms of the average error and dispersion of relative prediction error. All the fragility curves adjusted to the whole database pass the Lilliefors goodness of fit test (). Comparing SDR-based curves of walls of a different unit type, DS4 curves present a smaller difference in the median value () than DS5 curves. Additionally, the variations in the of NDSD-based curves of walls of different units are smaller than those observed in SDR-based fragility functions, indicating that NDSD represents a less variant EDP to describe the probability of shear damage at DS5 when a proper expression is employed for the normalization. Regarding design parameter-sensitive fragility functions, sorting databases reduces the number of data points used to calculate the functions, which produced two SDR-based and one NDSD-based function to fail the Lilliefors test (). In general, the value of SDR-based curves increases in proportion to the aspect ratio. Additionally, classifying the databases by a design parameter (aspect ratio) corroborated that the proposed expression has acceptable accuracy based on the adjusted NDSD-based DS5 fragility functions. It is highlighted that calculating design parameter-sensitive functions might increase the accuracy of PBEE assessments (e.g., loss estimations) when an EDP insensitive to design parameters normalization (e.g., SDR) is employed.