•Seismic coefficient method
The seismic coefficient method is one of the static procedures for earthquake resistant design of structures.
•Horizontal and/or vertical forces, which are calculated as products of the seismic coefficients H K , V K and the weight of the structures are applied to the structures.
•This approach is also known as "pushover" analysis.
•Three basic methods are available for analyzing the responses of a structure subjected to seismic ground wave: Static analysis. Response spectra analysis. Time history analysis.
Steps for seismic coefficient method
•Step-I Calculation Design base shear
VB=Ah*W
Ah –Design horizontal acceleration coefficient
Ah=Z*I*Sa
2*R*g
VB-Base shear
W-Seismic weight of building
Z-Zone factor (Annex E pg no. 36,37 IS 1893-2016)
I-Importance factor (Table 8, pg no.-19 IS 1893-2016
Important service and community building or structures (e.g. critical governance building, school) signature building, monument building, lifeline and emergency building (hospital , telephone exchange building, television station building, bus station, radio station, airport, food storage building, fuel station, fire station, large community hall like cinema hall, shopping malls, assembly hall)-1.5
Residential or commercial building (other than those listed in sr. 1) with occupancy more than 200 persons-1.2
All other building-1
R-Response reduction factor (Table 9, pg no.-20 IS 1893-2016
Lateral load resisting system
Moment frame system
RC building with ordinary moment resisting frame (OMRF)-3
RC building with special moment resisting frame (SMRF)-5
Steel building with ordinary moment resisting frame (OMRF)-3
Steel building with special moment resisting frame (OMRF)-5
Sa/g-Design acceleration coefficient for different soil type ,normalized with peak ground acceleration corresponding to natural period T of structure (pg no.-9 IS 1893-2016)
T-Natural time period of oscillation (pg no.-21 IS 1893-2016)
•Moment resisting frame (without any masonry infill wall)
Ta-0.075 h0.75 (for RC MRF building)
Ta-0.080 h0.75 (for RC steel composite MRF building)
Ta-0.085 h0.75 (for steel MRF building)
•Moment resisting frame (with any masonry infill wall)
Ta=0.09h/Γd
Step II- Calculation Seismic weight of building
•Seismic load=Dead load + live load + floor finish
Ø Dead load-sum of dead load of all floor
Ø Live/Imposed load-Percentage of Imposed load to be considered in calculation of seismic weight
Step III-Calculate Base shear
•VB=Ah*W
Step IV Determine lateral force
•lateral force
•Q= VB * wihi2
€wihi2
• wi seismic weight of floor
hi height of floor I measure from base
