Browsing by Author "Valdivieso Cascante, Diego Nicolas"

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    Potential for mitigating hurricane wind impact on informally-constructed homes in Puerto Rico under current and future climate scenarios
    (Elsevier Ltd, 2024) Valdivieso Cascante, Diego Nicolas; Goldwyn B.; Liel A.B.; Javernick-Will A.; López-garcia González, Diego; Guindos P.
    © 2024 Elsevier LtdThis study investigates the resilience of informally-constructed light-frame timber houses in Puerto Rico, a region where households with limited resources face significant risks from climate hazards, notably hurricanes. This study conducts a component-based, performance-based wind engineering assessment of informally-constructed house typologies, defined based on extensive fieldwork, under both existing and projected future climate conditions. Key findings highlight the effectiveness of certain mitigation strategies, such as reinforcing roof-to-wall connections, in significantly reducing the probability of failure. Fully-mitigated cases, which involve applying mitigation measures to the roof envelope, roof-to-wall connections, and shear walls, exhibited annual probabilities of failure that are much closer to, but do not necessarily meet, the threshold targeted by American building standards (i.e., ASCE 7). The results also show a dramatic increase in probability of failure of these houses projected by the adopted climate change model scenarios, driven by the increased frequency and intensity of hurricanes in Puerto Rico. Results from feedback from those working in the informal construction sector also identify challenges hindering the effective implementation of mitigation measures in Puerto Rican communities, including a lack of knowledge about how to implement the mitigation strategies and barriers related to real and perceived costs. Taken together these results underscore the urgent need for changes in building practices and revising building standards and suggesting potentially feasible mitigation strategies to improve those practices.
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    Reinforcement Effects and Parametric Study of the Lateral Response of Multilayered Wood-Frame Shear Walls: An Experimental and Numerical Investigation
    (American Society of Civil Engineers (ASCE), 2025) Valdivieso Cascante, Diego Nicolas; López-Garcia González, Diego; Liel, Abbie; Guindos Bretones, Pablo
    In the seismic design of light-frame timber buildings (LFTBs), the use of strong shear walls (SSWs) is crucial for providing lateral resistance. While the contribution of finish layers, such as Type X gypsum wallboard (GWB), has generally been conservatively ignored, recent experimental and numerical studies have demonstrated that these finish layers can significantly enhance the cyclic lateral performance of SSWs, leading to the concept of multilayered strong shear walls (MLSSWs). The effect of the finish layers cannot be solely attributed to additional layers and fasteners. There is also an additional reinforcement effect from deeply screwed Type X GWB that prevents nails from pulling out during hysteresis cycles that has not been previously investigated. The primary objective of this study is to explore the reinforcement effect and evaluate MLSSWs across a broad range of configurations. The research combines experimental tests (monotonic and cyclic) and numerical simulations, with connection-level tests used to calibrate the numerical models. The simulations interrogate the influence of the reinforcement effect and investigate the effects of various parameters, including wall aspect ratio, number of Type X GWB layers, multilayered connection type (screwed or stapled), and overturning anchorage systems. The findings demonstrate the positive effect of finish layers on strength and stiffness. The reinforcement effect of screws and Type X GWB layers is shown to modify the response of nailed OSB-to-frame connections, preventing nail pullout and improving fatigue resistance and deformation capacity. The study shows that the other important parameters that control the strength, stiffness and deformation capacity of MLSSW are multilayered connection type and number of Type X GWB layers. This research enhances the understanding of the role of Type X GWB finish layers on the lateral response of MLSSWs for improved design and construction.
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    Testing of strong multi-layered wood frame shear walls with non-structural layers
    (Springer International Publishing, 2023) Valdivieso Cascante, Diego Nicolas; López-García González, Diego; Montaño Castañeda, Jairo Alonso; Guindos Bretones, Pablo
    In areas of high seismic activity it is important to provide Light Frame Timber Buildings (LFTBs) with enhanced levels of lateral stiffness and strength, as well as to prevent excessive levels of non-structural (NSC) damage. Chilean wood-frame shear walls are usually sheathed at both sides with OSB and covered by one/two-ply type X gypsum wallboard (GWB) fastened to the frame with narrow patterns of nails or screws. The result is a multi-layered strong shear wall (MLSSW), which is not considered as such by design codes and mechanical models. The objective of this paper is to report an experimental evaluation of typical Chilean MLSSWs, with emphasis on the influence of NSCs. Connection-level and assembly-level of 1:1 aspect ratio shear walls were evaluated through experimental tests. Results showed increments of 53% and 160% in elastic stiffness and maximum capacity, respectively, while keeping virtually the same deformation capacity and energy dissipation of equivalent bare (non-GWB finished) shear walls. It is postulated that such increases may arise from the high embedment strength of the GWB, and that the deeply screwed GWB may prevent nails from pulling out during hysteresis cycles. It is concluded that GWBs have a significant structural influence on MLSSWs, and such influence should be taken into account in structural design.
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    Testing of strong multi-layered wood frame shear walls with non-structural layers
    (2023) Valdivieso Cascante, Diego Nicolas; López-García González, Diego; Montaño Castañeda, Jairo Alonso; Guindos Bretones, Pablo
    In areas of high seismic activity it is important to provide Light Frame Timber Buildings (LFTBs) with enhanced levels of lateral stiffness and strength, as well as to prevent excessive levels of non-structural (NSC) damage. Chilean wood-frame shear walls are usually sheathed at both sides with OSB and covered by one/two-ply type X gypsum wallboard (GWB) fastened to the frame with narrow patterns of nails or screws. The result is a multi-layered strong shear wall (MLSSW), which is not considered as such by design codes and mechanical models. The objective of this paper is to report an experimental evaluation of typical Chilean MLSSWs, with emphasis on the influence of NSCs. Connection-level and assembly-level of 1:1 aspect ratio shear walls were evaluated through experimental tests. Results showed increments of 53% and 160% in elastic stiffness and maximum capacity, respectively, while keeping virtually the same deformation capacity and energy dissipation of equivalent bare (non-GWB finished) shear walls. It is postulated that such increases may arise from the high embedment strength of the GWB, and that the deeply screwed GWB may prevent nails from pulling out during hysteresis cycles. It is concluded that GWBs have a significant structural influence on MLSSWs, and such influence should be taken into account in structural design.
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    Testing the influence of 3D coupling effects on the lateral response of non-planar T-shape wood frame shear walls
    (2023) Valdivieso Cascante, Diego Nicolas; López-García, González Diego; Almazán Campillay, José Luis; Montaño Castañeda, Jairo Alonso; Guindos Bretones, Pablo
    Cumulative shear wall overturning (CSWO) is a common response of structural models of multistory Light-Frame Timber Buildings (LFTBs) under lateral loads. Governed by holdown uplift and shear wall (SW) bending, large CSWO occurs in LFTBs due to the light self-weight of wood and the dominant rocking flexibility of stiff SWs. Even though CSWO is paramount in seismic design because of its effect on the flexibility of LFTBs (making hard to achieve the inter-story drift limits), this phenomenon is not incorporated into the structural models of LFTBs. For instance, in the design of LFTBs for lateral loads it is assumed that SWs behave as planar isolated elements. However, CSWO may be influenced by 3D coupling effects (3D-SWCE) in non-planar SWs such as T or L assemblies. This paper describes a large full-scale experiment of a 7.32 m x 5.1 m assembly, performed to gather insight into 3D-SWCEs through the cyclic evaluation of a non-planar T-shape SW. Results showed an asymmetric behaviour of the T-shape SW with increments of 20% and 98% in elastic stiffness and maximum capacity, respectively, with respect to those of a planar SW. It is concluded that 3D-SWCEs have a significant structural influence on the response of LFTBs.
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    Testing the influence of 3D coupling effects on the lateral response of non-planar T-shape wood frame shear walls
    (Springer International Publishing, 2023) Valdivieso Cascante, Diego Nicolas; López-García, González Diego; Almazán Campillay, José Luis; Montaño Castañeda, Jairo Alonso; Guindos Bretones, Pablo
    Cumulative shear wall overturning (CSWO) is a common response of structural models of multistory Light-Frame Timber Buildings (LFTBs) under lateral loads. Governed by holdown uplift and shear wall (SW) bending, large CSWO occurs in LFTBs due to the light self-weight of wood and the dominant rocking flexibility of stiff SWs. Even though CSWO is paramount in seismic design because of its effect on the flexibility of LFTBs (making hard to achieve the inter-story drift limits), this phenomenon is not incorporated into the structural models of LFTBs. For instance, in the design of LFTBs for lateral loads it is assumed that SWs behave as planar isolated elements. However, CSWO may be influenced by 3D coupling effects (3D-SWCE) in non-planar SWs such as T or L assemblies. This paper describes a large full-scale experiment of a 7.32 m x 5.1 m assembly, performed to gather insight into 3D-SWCEs through the cyclic evaluation of a non-planar T-shape SW. Results showed an asymmetric behaviour of the T-shape SW with increments of 20% and 98% in elastic stiffness and maximum capacity, respectively, with respect to those of a planar SW. It is concluded that 3D-SWCEs have a significant structural influence on the response of LFTBs.
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    Toward resilient and sustainable communities: performance evaluation of light frame timber residential structures subjected to seismic and hurricane hazards
    (2024) Valdivieso Cascante, Diego Nicolas; Abbie B., Liel; Guindos Bretones, Pablo; López-García, González Diego; Pontificia Universidad Católica de Chile. Escuela de Ingeniería ; University of Colorado Boulder
    Esta tesis ofrece un análisis profundo sobre el comportamiento estructural y la modelización de estructuras de entramado ligero de madera. Destaca la importancia de un modelado en 3D que refleje con precisión el comportamiento real, frente a las aproximaciones simplificadas en 2D comúnmente usadas en el ámbito profesional. El objetivo principal de esta tesis es profundizar en el entendimiento de las respuestas estructurales ante riesgos sísmicos y huracanados en Chile y Puerto Rico, respectivamente. Esta mayor comprensión podría potenciar la resiliencia de las comunidades en estas zonas ambientalmente sensibles, haciendo al mismo tiempo que la construcción con madera sea más competitiva y factible como opción sostenible en el tiempo. Centrándose en la sostenibilidad, este estudio subraya el importante papel de la madera en la disminución del déficit habitacional y en la reducción de las emisiones de gases de efecto invernadero a nivel mundial. Basada en desempeño para evaluar los riesgos relacionados con los vientos huracanados. También se consideran los posibles impactos del cambio climático en la frecuencia e intensidad de los huracanes en la isla. Esta tesis integra varios aspectos del comportamiento de los edificios de madera bajo cargas sísmicas y de vientos huracanados, desafiando los enfoques de diseño convencionales y abogando por prácticas sostenibles y socialmente responsables. Las conclusiones y recomendaciones establecen un camino para el desarrollo de prácticas de construcción robustas, eficientes y sostenibles en áreas propensas a amenazas naturales. Se espera que investigaciones futuras expandan sobre los efectos de sistema y los efectos de las capas no estructurales para desarrollar la información necesaria para que los profesionales y académicos consideren tales efectos en el análisis de estructuras de madera. Las investigaciones futuras también deberían centrarse en desarrollar modelos integrales de cambio climático para la evaluación del riesgo ante múltiples amenazas, promoviendo así la resiliencia en comunidades vulnerables a nivel global