Browsing by Author "Calderón, Sebastián"

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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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    Influence of Joint Reinforcement on the Shear Behavior of Masonry Panels: Experimental and Numerical Assessment
    (Springer Nature, 2025) Calderón, Sebastián; Fredes Siervo, José Ignacio; Sandoval Mandujano, Cristián
    In seismic-prone regions, providing shear reinforcement is crucial for controlling the damage to masonry structural elements. In this context, shearresistant behavior has been the focus of several investigations due to its complexity and importance to withstand seismic demands. Different studies have intended to understand more in-depth how shear reinforcement improves the performance of reinforced masonry; despite these efforts, many questions remain open. For instance, it has been observed that shear reinforcement starts interacting with masonry only after cracks are developed. However, the pre-cracking behavior of reinforced and unreinforced masonry walls somewhat differ. Furthermore, it has been proven that the behavior of masonry built with different unit types (i.e., multi-perforated clay bricks, hollow concrete blocks, and solid clay bricks) may exhibit significant variations, implying that masonry built with all unit types must be evaluated. Motivated by this knowledge gap, this study assesses the behavior of masonry panels about 0.8 × 0.8 m made of multi-perforated clay brick, with and without shear reinforcement, and subjected to diagonal compression. Ladder-type steel reinforcement was placed at the mortar bed-joints. The experimental results are complemented with numerical simulations (detailed micro-models) to extend the achieved understanding. The study concluded that the horizontal reinforcement ratio did not significantly influence the behavior of the panels based on the findings that shear strength, shear strain, and shear modulus did not exhibit significant differences. Also, the reinforcement started collaborating with masonry only after the shear strength was achieved when specimens were too damaged to gain higher stresses.
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    Shear behavior of single- and triple-thickness masonry panels strengthened by bed-joint structural repointing
    (2021) Sandoval, Cristián ; Serpell, Ricardo; Araya-Letelier, Gerardo ; Calderón, Sebastián
    Bed-joint structural repointing is a widely used strengthening technique in historic masonry constructions, particularly in applications where the material appearance needs to be preserved. Despite its wide use, limited research is available on the effectiveness of this technique in masonry elements of greater thickness subjected to in-plane shear loading. In the reported study, the shear behavior of single-and triple-thickness masonry panels strengthened with Near Surface Mounted (NSM) steel bars was investigated. Masonry panels were built following the material characteristics and bonding types of a reference case and tested in diagonal compression. Two lime-based mortar mixes with different compressive strength were employed to assess the effect of existing mortar quality on the strengthening technique performance. The investigated parameters were the number of courses with reinforcement in single-thickness panels, and the depth of the reinforcement and number of the faces reinforced in those of triple-thickness. The technique proved effective in improving the shear deformation capacity regardless of specimen thickness and, in panels of triple-thickness, both the eccentricity (result of reinforcing one or two faces) and depth of reinforcement were observed to significantly affect shear behavior. CO 2021 Elsevier Ltd. All rights reserved.