Seismic Vulnerability of Existing R.C. Structures with Special Focus on High-Priority Buildings in Central America
Verbicaro, Maria Isabella (2009) Seismic Vulnerability of Existing R.C. Structures with Special Focus on High-Priority Buildings in Central America. [Tesi di dottorato] (Inedito)
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As part of a regional cooperation project on the reduction of earthquake risk in the Central American countries Guatemala, El Salvador, and Nicaragua (RESIS-II), one of the major work tasks consists in the identification of the structural and non-structural seismic vulnerability of schools, hospitals and health centres. The regional cooperation project RESIS II (Reduccion de Riesgo Sismico) is focused on earthquake risk reduction for the Central American countries Guatemala, El Salvador and Nicaragua, project funded by the Norwegian Embassy in Managua (Nicaragua) and headed by NORSAR (Norway). Beside a number of project tasks dealing with seismic hazard and risk assessment, a main part of the project is allocated to earthquake vulnerability studies of those buildings that are of major importance to the society: schools and hospitals. The integrity of schools and hospital buildings during an earthquake disaster is of utmost importance. As given by PAHO (2004) the safety of a health facility (hospital) is determined by four different modules: geographic location (natural and man-made hazards or dangers, geotechnical properties of soils at the site); structural safety (structural vulnerability determined by the building’s design and primary structural system); non-structural safety (non-structural elements such like infill walls, equipment, installations or furniture may not influence the building’s stability but it may put people and the contents of the building at risk and increases the follow-up losses during evacuation); and functional capacity (how hospital personnel is trained and organized in disaster situations is crucial in order to assess the hospitals functionality after the event). As for any building, the assessment of the structural vulnerability is of utmost importance in order to get an idea about the building’s exposure to suffer structural damage as a direct effect of earthquake shaking. However, especially for high-priority structures like hospitals and schools non-structural and functional vulnerability can lead to severe follow-up losses in the direct aftermath of an event and in the weeks or months to follow. In this work a study on the seismic vulnerability of existing reinforced concrete structures is presented, with special focus on schools and hospitals in Central America. The evaluation of seismic risk is an actual problem, many earthquakes all over the word occur each day, so it is important the assessment and the reduction of seismic risk; it can be evaluated as the product with hazard and vulnerability. This work has two goals: do vulnerability analysis for representative buildings of analysed schools and hospitals with a mechanical model; and check a survey card formulated ad hoc and the correspondent method for vulnerability evaluation based on questionnaires. For each category (schools and hospitals), representatives buildings are chosen following to surveys done ad hoc in Central America, which have allowed to chose really representative buildings, and to have all necessary information about geometry, structural peculiarities and materials. Detailed analysis are used to compute structural vulnerability of reinforced concrete existing structures; suitable structural models and the corresponding non-linear lumped plasticity models are generated. The seismic capacity is determined via pushover analysis and by the transformation of the equivalent SDOF capacity curve into bilinear form. The resulting lateral strength and displacement capacity are considered for selected limit states; also the effective period is retrieved. Combining structural capacity with seismic demand through Capacity Spectrum Method, fragility functions are derived for each representative building of schools or hospitals.
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