Floor acceleration spectra estimation in reinforced concrete frames

Non-structural elements that are considered primarily sensitive to and subject to damage from inertial loading are classified as acceleration-sensitive elements. The response of acceleration-sensitive non-structural components in buildings is therefore directly affected by the floor acceleration demand that they experience during ground shaking. Reducing seismic damage to these elements is of primary importance not only for economic reasons, but also for maintaining the functionality of the building immediately after the earthquake. The purpose of this paper is to study the floor acceleration demand variation along the height of concrete frame buildings and how the sophistication of the structural modeling can be reduced in such estimation. In fact, development of probabilistic seismic demand models, that usually involve the use of methods such as the incremental dynamic analysis, the cloud analysis, and multiple stripe analysis requires a large number of non-linear analyses of the structure to be run. To reduce the numerical effort, a simplified methodology based on the modal pushover analysis procedure will be proposed and used for the characterization of floor spectra. To this purpose the seismic response of a selected case study, consisting in a six-storey three-bay frame of a reinforced concrete building, dimensioned to be representative of an existing structure designed according to a past seismic code (using the one in force in Italy between 1996 and 2008), will be analyzed. The estimates of peak absolute acceleration and response spectra at each floor level will be compared and contrasted.