Sliding fragility of unrestrained equipment in critical facilities

Through the years, seismic design of buildings has been well developed and is continually updated and improved. Yet, nonstructural components housed in buildings are rarely designed with the same degree of consideration as buildings. As a result, buildings that remain structurally sound after a strong earthquake often lose their operational capabilities due to damage to their nonstructural components, such as piping systems, communication equipment and other types of components. The recent 1994 Nothridge, 1995 Kobe and 1999 Turkey and Taiwan earthquakes further demonstrate the importance of controlling damage to nonstructural components, particularly in critical facilities, such as hospitals, in order to ensure their funcionality during and after a major earthquake. Earthquake vulnerability of nonstructural components is usually reduced by fastening or bracing individual objects. However, there are some nonstructural components in buildings which often cannot be restrained for protection from earthquake shaking. The response of these objects will consist of sliding, rocking or jumping. Understanding these response types will allow estimation of vulnerability to earthquake damage and will assist in the design of appropiate mitigation measures. This research concentrates on experimental and analytical studies of the sliding response of freestanding rigid objects subjected to base excitation. Analytical and experimental techniques are combined to allow determination of fragility curves for free-standing rigid equipment under seismic excitations for further improvement of seismic mitigation measures. A discrete system model, an analytical model for two-dimensional sliding under two-dimensional excitation, is developed and analyzed for specific base motions. Shaking table testing with a range of excitations and systems parameters is used to define stability bounds for pure sliding motion. A comparison of the analytical and experimental results is then performed to further verify the validity of the analytical model. Discrepancies in the model assumptions and future improvements of the nonstructural model are also discussed in this report (AU)

Estimación preliminar de la vulnerabilidad sísmica de los hospitales Regional de Temuco y Base de Puerto Montt

La vulnerabilidad sísmica de un centro hospitalario queda determinada por el nivel de servicio que deben garantizar sus servicios clínicos y de apoyo, para satisfacer las demandas de la comunidad durante y después de un evento sísmico severo. El objetivo de esta memoria es realizar una estimación preliminar de la vulnerabilidad sísmica de los Hospital Regional de Temuco y Base de Puerto Montt, como parte de un proyecto más amplio, con participación del Ministerio de Salud y de la Organización Panamericana de la Salud, que persigue conocer el estado actual del Sistema de Salud Pública en Chile ante la amenaza de eventos sísmicos. Para la evaluación de los centros hospitalarios, se divide el estudio en una parte estructural y una no estructural. En el ámbito estructual se utilizan metodologías, basadas en una serie de índices que representan globalmente el comportamiento sísmico de la estructura. En las parte no estructural, se analizan diversos aspectos cualitativos que abarcan desde las características propias del elemento evaluado y de su disposición, hasta su impacto en la función que debe prestar el hospital. Para conseguir el objetivo planteado, se seleccionan en cada hospital las edificaciones que concentran la mayor cantidad posible de capacidad de funcionamiento del centro hospitalario ante un evento sísmico severo. Finalmente, se concluye que la metodología empleada en esta memoria, permite detectar en forma preliminar los aspectos vulnerables que pueden poner en riesgo la adecuada capacidad de respuesta de los hospitales ante un eventos sísmico. (AU)