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A surface blast generates both air pressure and ground shock on structures. Studies on the relative effects of the air pressure and ground shock on the responses of structures are meagre. In the present study, a preliminary estimate of the relative contributions of the ground shock and air pressure on building responses due to a surface blast is obtained by using an equivalent single-degree-of-freedom (SDOF) model. For this purpose, both linear and non-linear analyses of SDOF models of four reinforced concrete building frames of different heights are performed under different blast scenarios by varying the standoff distance and charge weight. In addition, the criticality of the surface blast in comparison to the free air blast is investigated with the help of the same SDOF models. The study reveals that the contribution of the ground shock is less than that of the air pressure on the responses of low-rise buildings. For high-rise buildings, the opposite trend is observed for smaller standoff distances (R < 15 m). Further, it is shown that the surface blast is more critical as compared to the free air blast for shorter buildings (fewer than six storeys), but the opposite holds good for taller buildings.

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In India, hilly region especially northern part is more seismically active region. Flat Slab systems are widely popular in multi-storey buildings. Flat slab building has more advantages than a regular building like fast construction, free design space, reduced floor to floor height and economical. Flat slab buildings are also being built in high seismicity region. Buildings on hilly ground are vulnerable due to their vertical and horizontal irregularity and they undergo high shear and torsion during the earthquake. Further due to short column and soft storey on uphill side has higher lateral forces that are cause to failure of buildings. In this paper, an attempt has been made to assess the seismic behavior of flat slab resting on hilly slope with soft storey and set back configuration. The methodologies have been adopted are linear dynamic analysis i.e. response spectrum analysis. Building is analyzed and designed by Etabs software. Maximum displacement, maximum inter-storey drift and storey shear are determined as response quantities. It is observed from the study that for flat slab buildings on hill slopes the storey shear is very high in the bottom columns at higher ground level, therefore extra care should be taken to design these columns for earthquake load.

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