☑ In detail Step for solving multistory structures by seismic coefficient method

•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