| Summary: | 碩士 === 中興大學 === 土木工程學系所 === 99 === Early school building was built under brick walls strengthened type of structures, and classrooms were divided by brick walls. Furthermore, there was no restriction against seismic included in the previous building design, nor the ductility of the structures were considered. Most of the structures at that time, as described above, were classified as the weak column strong beam structures. To improve the building against the earthquake and to buy times for victims of earthquake disaster running out of building, columns of buildings were retrofitted. There were many types of structures strengthening, and two of columns reinforcing were: additional wing walls, and enlarged columns. By strengthening the column, weak column strong beam was transformed into strong column weak beam. In addition, the ductility of the structures was increased. The strategy to maintain the building against earthquake and to improve its ductility was relatively correct with strong column weak beam model. The model was built with plastic hinges assigned to both ends of beams. Plastic hinges would appear first on both ends of beams, rather than on columns. However, after careful observation of retrofitted model’s curvature, the column behaved as a cantilever column, and model’s curvature was not relatively similar to the basic column plastic hinge double curvature assumptions.
This paper was based on a case study. A building model was created using ETABS program and run for stress analysis in both before and after retrofitted condition. Then, the result of the stress analysis was processed further by using a tool provided by National Earthquake Engineering Research Center Report No.: NCREE-09-023. The final result was the performance ground acceleration of the existing building before and after retrofitted. Another after retrofitted building model was run under shear building type of structures. Shear building structures was modeled to find out if it was similar to the existing retrofitted building. After the results were obtained, plastic hinges attached to beam model was compared to shear building model. The comparison was done under several different time scales and to compare the effectiveness and the result of both models to the existing retrofitted building behavior. From the results, shear building model had curvature that was close to the basic column plastic hinge double curvature assumptions, its lateral displacement was small, and its base shear was relatively large. Therefore, the shear building retrofitted column model had got effective performance ground acceleration. On the other hand, the model with plastic hinges attached to both ends of beams, having a cantilever column behavior, would cause ineffectiveness in retrofitting.
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