Floor Response Spectra: An Investigation on Hospital Building

Seismic protection of hospital buildings is at most important as they belong to lifeline structures. Proper definition of seismic demand is essential for earthquake protection of structural components. Generation of floor response spectra assumes significant in design and analysis of structural contents which require high seismic demand. Limiting the floor acceleration/drift is found to be difficult in most of the times in traditional lateral load resisting system and is period-sensitive in addition to ductility [1]. But decoupling the floor from the building using suitable isolation schemes found to reduce the floor accelerations and displacements [2]. The paper presents an investigation into the seismic demand reduction for a chosen isolation scheme on a 10-storey hospital building which essentially lies in the descending portion of response spectrum [3]. The passive isolation scheme consists of spring and damper assembly connecting isolated floor to the building. Nonlinear time history analysis has been carried out on both the floor isolated and non-isolated building subjected to an earthquake intensity of 0.3 g. Dynamic characteristics of the building were evaluated, and apparent dynamic magnification factors were found out which are useful for generation of floor response spectra. Seismic peak floor acceleration (PFA) is one of the significant parameters influencing performance of the building contents. In addition to PFA, spectral acceleration and displacements were selected as engineering demand parameters. Based on the acceleration and drift demands, suitable floor isolation system is suggested. With the chosen floor isolation scheme, seismic demand has been found to decrease imparting higher efficiency to the system. Accurate recommendation related to displacements and floor acceleration provisions are necessary for the efficient seismic protection design of non-structural elements.