A BUILDING MAY BE ANALYZED EITHER BY SEISMIC COEFFICIENT METHOD OR BY RESPONSE SPECTRUM (OR MODAL ANALYSIS OR SPECTRAL ACCELERATION) .

EARTH QUAKE LOADS :-- Earthquake or seismic load on a building depends upon its geographical location, lateral stiffness and mass , and is reversible. It's effect should also be considered along both axis of a building taken one at a time . However wind loads and the earthquake loads are assumed not to act simultaneously. Therefore a building should be designed for only one of the two loads which ever is critical. The analysis of a building for earthquake loads is done in accordance with IS:1893--1984 .A building may be analysed either by seismic coefficient method or by response spectrum (or modal analysis or spectral acceleration) method .The seismic coefficient method is simpler than the modal analysis method which involves the knowledge of structural dynamics. The first analysis in the seismic analysis is to determine the horizontal shear at the base of the frame which is also known as base shear and may be obtained by multiplying design seismic coefficient with total dead load and the performance factor depending upon the structural framing system and ductility of Construction.The performance factor related to ductile moment resistant frame confirming to IS:4326 --1976 is taken 1.0 in case of the shear walls and in case of ductile moment resistant frame with infilled concrete panels 1.3 and in case of ordinary moment it is considered 1.6 .The seismic zones , coefficient and factors have been specified for on the basis of various seismic zones .In case of zone V the coefficient is0.08 and factor is 0.40 , In case of zone lV coefficient is 0.05 and factor is 0.25 ,In case of zone lll coefficient is 0.04 and factor is 0.20 , In case of zone ll coefficient is 0.02 and factor is 0.10 and in case of zone number one coefficient is 0.01 and factor is 0.05 .