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Abstract:
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The use of riveted semi-rigid connections was wide spread in building construction in the first half of the 20th century at a time when earthquake design was not required. It is therefore legitimate to question the seismic response of these historic buildings. Recent experimental work has shown that these connections can develop stable hysteretic moment rotation behavior, but must undergo large rotations in order to reach moderate moment capacity. This raises important concerns about the ability of buildings having such connections to withstand earthquakes while undergoing large drifts. An 18-story building located in Eastern Canada has been surveyed and modeled using a non-linear inelastic dynamic analysis program. It was investigated whether this type of building can survive major earthquakes in spite of having low-strength semi-rigid connections such as those described above. Other generic structures of different heights, based on this existing building, have also been considered and modeled. Seismic ground motions typical of Eastern and Western Canada have been used to generalize the results obtained. It was observed that old buildings of the type modeled in this study have much larger masses due to heavier floors and thicker cladding than their modern counterparts. The buildings also have considerably less rigidity, as a result of semi-rigid connections. The ensuing large period favorably impacts their seismic response. However, results demonstrate that small earthquakes cause considerable drifts, which can translate into non-structural damage in spite of the survival of the primary structure. |
