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Dr. Oyarzo-Vera, Claudio
Research Outputs
Seismic and coastal vulnerability assessment model for buildings in Chile
2021, Quiñones Bustos, Catalina, Bull-Torres, Maria, Oyarzo-Vera, Claudio
This article proposes a vulnerability assessment model for evaluating buildings’ expected seismic performance, as well as their vulnerability to tsunamis. The objective of this assessment is to provide appropriate information for decision makers regarding the need of repairs and reinforcement of buildings or other mitigation measures that need to be applied in a territory. A procedure for assessing seismic vulnerability and another methodology for evaluating tsunami vulnerability faced by coastal structures is presented. Finally, a method that integrates both procedures is proposed, providing a combined index of vulnerability. The assessment model was applied to the central area of the city of Talcahuano, Chile, which was affected by the 2010 Maule earthquake and tsunami.
Non-Destructive assessment of the elastic properties of Low-Grade CLT panels
2021, Dr. Maureira-Carsalade, Nelson, Dr. Oyarzo-Vera, Claudio, Opazo-Vega, Alexander, Benedetti, Franco, Nuñez-Decap, Mario
The use of cross-laminated timber panels (CLT) made of low-grade structural timber has steadily increased in developing countries. These panels usually present several natural defects, which can cause a high local variation of their orthotropic elastic properties, generating future structural serviceability problems. Our work aims to estimate the local variability of the elastic properties in low-grade CLT panels by combining nondestructive transverse vibration testing, numerical simulations, and regional sensitivity analysis (RSA). Four three-layer Radiata pine CLT panels were subjected to transverse vibration tests with supports at four points. Besides, a series of numerical simulations of the panels, considering the local variability of the elastic properties of the panels in eight zones, were carried out using the finite element method. Then, RSA analysis was performed to study in which ranges of values the panels’ elastic properties generated lower differences between the measured versus simulated dynamic properties. Finally, a structural quality control indicator was proposed for the CLT panels based on keeping low the probability that the elastic properties in the central zones do not exceed minimum acceptable values. The results obtained suggest that the proposed methodology is suitable for segregating CLT panels with high concentrations of defects such as pith presence.
Damping assessment of lightweight timber floors under human walking excitations
2019, Opazo-Vega, Alexander, Muñoz-Valdebenito, Francisco, Oyarzo-Vera, Claudio
Vibrations on timber floors are among the most common serviceability problems in social housing projects. The presence of low damping levels on these floors could cause excessive vibrations in a range of frequency and amplitude that generate discomfort in users. This study focuses on the influence of the damping ratio in the dynamic serviceability of social housing timber floors due to walking excitations. More than 60 human-walking vibration tests were conducted on both laboratory and in-situ timber floors. The floors were instrumented with accelerometers, and fundamental modal damping ratios were estimated by applying Enhanced Frequency Decomposition Domain (EFDD) and Subspace Stochastic Identification (SSI) methods. The vibration dose value (VDV) was used to estimate the dynamic serviceability of floors. The results indicated that timber floors had an impulsive-type vibration response, with fundamental damping ratios between 1.9% and 14.8%, depending on their constructive characteristics. The in-situ floors had damping ratios between two to three times greater than the laboratory floors due to the presence of non-structural elements. Finally, it was possible to demonstrate that the floors with the highest damping ratios reached lower vibration dose values and, therefore, a better dynamic serviceability performance.
Non-Destructive assessment of the dynamic elasticity modulus of Eucalyptus nitens timber boards
2021, Dr. Oyarzo-Vera, Claudio, Opazo-Vega, Alexander, Rosales-Garcés, Víctor
Eucalyptus nitens is a fast-growing wood species with a relevant presence in countries like Australia and Chile. The sustainable construction goals have driven the search of structural applications for Eucalyptus nitens; however, this process has been complicated due to the defects usually presented in these timber boards. This study aims to evaluate the dynamic elasticity modulus(Exd) of Eucalyptus nitens timber boards through non-destructive vibration-based tests. Thirty-six timber boards with different levels of knots and cracks were instrumented and tested in a simply supported condition by measuring longitudinal and transverse vibrations. In the first stage, the Exd was calculated globally through simplified normative formulas. Then, in a second stage, the local variability of the Exd was estimated using operational modal analysis (OMA), finite element numerical simulations (FEM), and regional sensitivity analysis (RSA). The positive correlation found between the global static modulus of elasticity and Exd suggests that non-destructive techniques could be used as a reliable and fast alternative for the assessment of bending stiffness. Finally, the proposed method to estimate the local variability of Exdt based on the combination of OMA, FEM,and RSA techniques was useful to improve the structural selection process of timber boards forlightweight social housing floors.
Damage assessment of the May 31st, 2019, Talcahuano tornado, Chile
2020, Dr. Aranguiz-Muñoz, Rafael, Dr. Oyarzo-Vera, Claudio, Dr. Nuñez-Castellanos, Eduardo, Dra. Bull-Torres, Maria, Saez, Boris, Gutierrez, Gladys, Quinones, Catalina, Bobadilla, Romina
On May 31st, 2019, a tornado hit the city of Talcahuano, Chile, generating significant damage to structures and leaving one person dead. The objective of the present paper is to report on damage to structures in Talcahuano. A preliminary survey was performed by the Municipality of Talcahuano and covered the entire affected area with a cellphone web application used to report the severity and distribution of damage. A more comprehensive damage survey was conducted in the Brisa del Sol neighborhood in the Medio Camino area by the UCSC team to assess the damage distribution within an area with well-defined and homogeneous building typologies. The results of the field surveys showed that the tornado behaved as a skipping tornado and that most damage to houses consisted of wall opening damage, roof sheathing failure, and wall cover removal (EF0), followed by partial roof removal(EF1). It was noticeable that self-built systems (house additions) were more damaged than original houses, which may be explained by the fact that such structures do not always meet minimum building standards. It is recommended that field surveys conducted by municipalities and the Ministry of Social Development considertypical damage types rather than just categories such as minor, moderate, or major. Finally, it is recommendedthat the feasibility of implementing mitigation measures such as stricter wind load provisions and dual-objective tornado design philosophy in the Concepci´on-Talcahuano area be analyzed.
Vibration-based damage identification of an unreinforced masonry house model
2017, Dr. Oyarzo-Vera, Claudio
Non-destructive vibration-based damage identification techniques are especially attractive for assessing damage in structures of high historical and architectural value. So far, most studies have focused on slender structures built using relatively homogeneous materials. In this study, global damage identification methods based on vibration response parameters were applied for identifying damage in an unreinforced masonry full-scale house model (non-homogeneous material and non-slender structure). The house model was dynamically loaded using an eccentric-mass shaker. Structural damage to the walls was initiated by increasing the amplitude of the applied load. At each damage state, a modal test was performed by impacting the walls with a calibrated hammer. Statistically significant variations of modal frequencies and the modal assurance criteria were considered as suitable parameters to identify damage. It was concluded that different sets of modes can be found for different states of damage because of material degradation, change in the support and connectivity conditions, and breaks in the members continuity generated by damage. All these changes are reflected in variations of modal frequencies and modal assurance criteria. It was also established that prior to identifying the damage distribution on the entire building, it was necessary to determine how the modal frequencies were related to each wall.
Monotonic response of exposed base plates of columns: Numerical study and a new design method
2020, Díaz, Héctor, Nuñez-Castellanos, Eduardo, Oyarzo-Vera, Claudio
This paper describes a numerical study of the behavior of exposed base plates of columns under the action of axial and bending loads. The aim of this research is to evaluate numerically the failure mechanisms on stiffened and non-stiffened base plates and propose a new design method. The effects of base plate thickness, location of anchor rods, location of stiffeners and tensile strength of anchor rods were considered in the analysis. Sixteen finite elements simulations were performed considering different combinations of the above mentioned parameters. The results show a fragile response in the base plates when high resistance anchor rods are used. The anchor rods worked as fuse elements in base plates with a large thickness or many stiffeners. Additionally, the models with anchor bars located outside of the column flanges showed lower flexural strength and rotational stiffness compared to the models with anchor rods located between column flanges. The simulations showed that the base plate strength was determined by the simultaneous failure mechanisms of two or more components, different to what is stated in current design guides. Finally, the new method is suitable to design base plates with stiffened and not stiffened configurations, which unlike traditional design methods, show a good adjustment with numerical models.
Damage identification of unreinforced masonry panels using Vibration-Based Techniques
2017, Dr. Oyarzo-Vera, Claudio, Nawawi, Chouw
Several damage indicators based on changes in modal properties validated for homogeneous materials were applied to detect damage in an unreinforced masonry cantilever panel. Damage was created by a “clean diagonal cut” at the center of the specimen which length was progressively extended towards the specimen’s corners. Numerical simulations were employed to determine the modal response at several damage states and this data was used to calculate the damage indicators. Those indicators presenting a good performance were then applied to identify damage on a physical specimen tested in the laboratory. The outcomes of this study demonstrated that vibration-based damage detection in unreinforced masonry structures can be satisfactorily performed.However, the identification of the damage spatial distribution using vibration-based methods in unreinforced masonry structures is still difficult. To improve the prediction of damage distribution, a large number of measurement points need to be considered to obtain an acceptable level of resolution.
Diagnóstico estructural de un edificio de hormigón armado basado en su perfil bio-sísmico y un análisis dinámico incremental
2020, Dr. Oyarzo-Vera, Claudio, Olivera-López, Juan
En este estudio se presenta la evaluación global de la salud estructural de un edificio habitacional de 14 pisos de altura, potencialmente vulnerable a sufrir daños significativos debido a terremotos y tsunamis. Este edificio fue construido en el año 2013 y está ubicado en la zona costera de Concepción (Chile), en el área afectada por el terremoto Mw = 8.8 del Maule 2010. La evaluación estructural se realizó combinando ensayos destructivos (extracción y ensayo de testigos) y no-destructivos (esclerómetro). Utilizando la información obtenida experimentalmente se generó un modelo numérico lineal del edificio, el cual fue utilizado para evaluar la salud global del edificio mediante una metodología llamada perfil bio-sísmico y un análisis dinámico incremental. Los resultados de este estudio demuestran que el edificio presentaría un buen desempeño frente a eventos sísmicos de gran envergadura,pero sería susceptible a presentar daño producto de los desplazamientos que experimentaría, ya que estos superan el rango de desplazamiento permitido por las juntas de expansión sísmica.
Aprendizaje servicio aplicado a la gestión de desastres en establecimientos educacionales municipales
2017, Mg. Cea-Echeverria, Patricio, Mg. Muñoz-Venegas, Marcia, Dra. Bull-Torres, Maria, Dr. Oyarzo-Vera, Claudio, Dr. Sanhueza-Espinoza, Frank
Este trabajo presenta una experiencia de educación en ingeniería orientada a la prevención de desastres, a través de la revisión y adecuación de los planes integrales de seguridad escolar en tres establecimientos educacionales de la comuna de Talcahuano, Chile, a solicitud del Departamento de Educación Municipal. La experiencia se desarrolló en el contexto del curso Desastres naturales y cultura de la prevención de las carreras de Ingeniería Civil e Ingeniería Civil Geológica de la Universidad Católica de la Santísima Concepción, mediante la aplicación de la metodología aprendizaje servicio. El objetivo de la experiencia es que los estudiantes del curso y la comunidad escolar estudiada reconozcan de manera eficaz los riesgos generados por el entorno natural, describan las etapas asociadas a gestión de desastres y colaboren en la generación de una cultura de prevención y preparación frente a ellos. Los resultados obtenidos corresponden a la entrega de planes integrales de seguridad escolar adecuados a los establecimientos estudiados con un diagnóstico de vulnerabilidades y mapa s de riesgo. La experiencia de aprendizaje servicio desarrollada muestra el fomento del compromiso social en los estudiantes y la importancia del aprendizaje orientado a resolver necesidades reales, con una visión integral en su formación profesional.