Project 1_Comparative study of different storey buildings for Seismic forces
- Buildings oscillate during earthquake shaking. The oscillation causes inertia force to be induced in the building.
- The intensity and duration of oscillation, and the amount of inertia force induced in a building depend on features of buildings, called their dynamic characteristics, in addition to the characteristics of the earthquake shaking (beyond the control of an engineer) itself.
- The important dynamic characteristics of buildings are modes of oscillation and damping (assumed constant in most practical cases). A mode of oscillation of a building is defined by associated Natural Period and Deformed Shape in which it oscillates.
- Every building has a number of natural frequencies (how many?), at which it offers minimum resistance to shaking induced by external effects (like earthquakes and wind) and internal effects (like motors fixed on it).
- Each of these natural frequencies and the associated deformation shape of a building constitute a Natural Mode of Oscillation.
- The mode of oscillation with the smallest natural frequency (and largest natural period) is called the Fundamental Mode; the associated natural period T1 is called the Fundamental Natural Period.
- Regular buildings held at their base from translation in the three directions, have two fundamental translational natural periods, Tx1 and Ty1, associated with its horizontal translational oscillation along X and Y directions, respectively, and one fundamental rotational natural period Tθ1 associated with its rotation about an axis parallel to Z axis.
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Structural Element Sizes
- Beams : 300 × 400 mm
- Columns : 400 × 400 mm
- Slab : 150 mm thick
Material Properties
- Grade of Concrete : M30
- Grade of Steel Reinforcement Bars : Fe 415
Loading
- Dead Load on beams from infill wall : 10 kN/m
- Live load on floor : 3 kN/m2
(what is the seismic mass?)
Buildings are assumed to be pinned at base