Per IBC 2006 and ASCE 705 Specifications
Using Equivalent Lateral Force Procedure for Regular SingleLevel Building/Structural Systems
Input Data
Occupancy Category =  [?]  IBC 2006, Table 1604.5, page 281 
Importance Factor, I =  ASCE 705 Table 11.51, page 116  
Soil Site Class =  IBC 2006 Table 1613.5.2, page 303  
Location Zip Code =  
Spectral Accel., SS =  ASCE 705 Figures 221 to 2214  
Spectral Accel., S1 =  ASCE 705 Figures 222 to 2214  
Long. Trans. Period, TL =  sec. ASCE 7 Fig's. 2215 to 2220  
Structure Height, hn =  ft.  
Total Seismic Weight, W =  kips ASCE 705 Section 12.7.2  
Actual Calc. Period, Tc =  sec. from independent analysis  
Seismic Resist. System = 
Result Data
Seismic Base Shear
(Regular Bldg. Configurations Only)
Occupancy Category of Buildings and Other Structures for Flood, Wind, Snow, Earthquake, and Ice Loads
Nature of Occupancy Occupancy Category 


Buildings and structures that represent a low hazard to human life in the event of failure including, but not limited to: Agriculture facilities 
I 
Buildings and other structures except those listed in Categories I, III and IV  II 
Buildings and other structures that represent a substantial hazard to human life in the event of failure including, but not limited to: Buildings and other structures where more than 300 people congregate in one areaBuildings and other structures, not includes in Occupancy Category IV, with potential to cause substantial economic impact and/or mass disruption of daytoday civilian life in event of failure, including, but not limited to:  Power generating stations, water treatment facilities, sewage treatment facilities, and telecommunication centers 
III 
Buildings and other structures designated as essential facilities including, but not limited to: Hospitals and health care facilities having surgery or emergency treatment facilities 
IV 
IMPORTANCE FACTORS
IMPORTANCE FACTOR, I, (ICE LOADS)  

Occupancy Category  I 
I or II  1.0 
III  1.25 
IV  1.5 
ASCE 705 TABLE 20.31 SITE CLASSIFICATION 


SITE CLASS  Soil Shear Wave Velocity, vs, (ft/s)  Standard Penetration Resistance, N  Soil Undrained Shear Strength ,su, (psf)  
A.  Hard Rock  vs > 5000  Not Applicable  Not Applicable 
B.  Rock  2500 <= vs <= 5000  Not Applicable  Not Applicable 
C.  Very Dense Soil & Soft Rock  1200 <= vs <= 2500  N > 50  su > 2000 
D.  Stiff Soil  600 <= vs <= 1200  15 <= N <= 50  1000 <= su <= 2000 
E.  Soft Clay Soil  vs < 600  N < 15  su < 1000 
Any profile with more than 10 feet of soil having the following characteristics: 1. Plasticity Index, PI > 20 2. Moisture Content, w >= 40% and 3. Undrained shear strength, su < 500 psf 

F.  Soils requiring site response analysis per Section 21.1  See Section 20.3.1 
'W' = The effective seismic weight of the structure, including the total
dead load and other loads listed below:
 In areas used for storage, a minimum of 25% of the reduced floor live load (floor live load in public garages and open parking structures need not be included).
 Where an allowance for partition load is included in the floor load design, the actual partition weight or a minimum weight of 10 psf of floor area, whichever is greater.
 Total operating weight of permanent equipment.
 20% of flat roof snow load where flat roof snow load > 30 psf.
VALUES OF SITE COEFFICIENT, Fa, AS A FUNCTION OF SITE CLASS
AND MAPPED SPECTRAL RESPONSE ACCELERATION AT SHORT PERIODS (Ss)(a)
SITE CLASS  MAPPED SPECTRAL RESPONSE ACCELERATION AT SHORT PERIODS 

Ss<=0.25g  Ss=0.50g  Ss=0.75g  Ss=1.00g  Ss>=1.25g  
A  0.8  0.8  0.8  0.8  0.8 
B  1.0  1.0  1.0  1.0  1.0 
C  1.2  1.2  1.1  1.0  1.0 
D  1.6  1.4  1.2  1.1  1.0 
E  2.5  1.7  1.2  0.9  0.9 
F  Note (b)  Note (b)  Note (b)  Note (b)  Note (b) 
(b)  Sitespecific geotechnical investigation and dynamic site response analyses shall be performed to determine appropriate values. See ASCE 705 Section 11.4.7.
VALUES OF SITE COEFFICIENT, Fv, AS A FUNCTION OF SITE CLASS
AND MAPPED SPECTRAL RESPONSE ACCELERATION AT 1 SECOND PERIOD (S1)(a)
SITE CLASS  MAPPED SPECTRAL RESPONSE ACCELERATION AT 1 SECOND PERIOD 

S1<=0.1g  S1=0.2g  S1=0.3g  S1=0.4g  S1>=0.5g  
A  0.8  0.8  0.8  0.8  0.8 
B  1.0  1.0  1.0  1.0  1.0 
C  1.7  1.6  1.5  1.4  1.3 
D  2.4  2.0  1.8  1.6  1.5 
E  3.5  3.2  2.8  2.4  2.4 
F  Note (b)  Note (b)  Note (b)  Note (b)  Note (b) 
(b)  Sitespecific geotechnical investigation and dynamic site response analyses shall be performed to determine appropriate values. See ASCE 705 Section 11.4.7.
'SMS' is the maximum considered earthquake spectral response accelerations for short period as determined from IBC 2006 Section 1613.5.3.
'SM1' is the maximum considered earthquake spectral response accelerations for 1second period as determined from IBC 2006 Section 1613.5.3.
'SDS' is the design spectral response acceleration at short periods as determined in IBC 2006 Section 1613.5.4.
'SD1' is the design spectral response acceleration at 1second period as determined in IBC 2006 Section 1613.5.4.
SEISMIC DESIGN CATEGORY BASED ON
SHORTPERIOD RESPONSE ACCELERATIONS
VALUE OF SDS  OCCUPANCY CATEGORY 

I or II  III  IV  
SDS < 0.167g  A  A  A 
0.167g <= SDS < 0.33g  B  B  C 
0.33g <= SDS < 0.50g  C  C  D 
0.50g <= SDS  D  D  D 
Seismic Design Category to be used shall be the the highest (most critical) category as determined from IBC 2006 Table 1613.5.6(1) using 'SDS' and IBC 2006 Table 1613.5.6(2) using 'SD1'.
'CT' is the building period coefficient, and is dependent on the type of seismicforceresisting system that is used:
CT = 0.028 for momentresisting frames of steel
CT = 0.016 for momentresisting frame systems of reinforced concrete
CT = 0.030 for eccentrically braced steel frames
CT = 0.020 for all other building systems
'x' is the building period formula exponent, and is dependent on the type of seismicforceresisting system that is used:
x = 0.80 for momentresisting frames of steel
x = 0.90 for momentresisting frame systems of reinforced concrete
x = 0.75 for eccentrically braced steel frames
x = 0.75 for all other building systems
'Ta' is the approximate fundamental period of the building, in seconds.
Ta = CT*hn^(x), ASCE 705 Section 12.8.2.1, Eqn. 12.87
Design Spectral Response
Acceleration at 1 Second Period, SD1  Coefficient, Cu 
>=0.4  1.4 
0.3  1.4 
0.2  1.5 
0.15  1.6 
<=0.1  1.7 
The Response Modification Coefficient, "R", is determined from ASCE 705 Table 12.21.
The System Overstrength Factor, "Wo", is determined from ASCE 705 Table 12.21.
The Deflection Amplification Factor, "Cd", is determined from ASCE 705 Table 12.21.
'CS' is the seismic response coefficient.
'V' is the total Seismic Base Shear, and it may be minimized by any of the following means:
 Using a seismicforceresisting system with a larger Response Modification Factor, 'R'. The total Seismic Base Shear, 'V', is inversely proportional to the the value of 'R'.
 Using a lower site class if possible
 Minimizing the weight of the structure.
Disclaimer: This calculator are not intended to be used for the design of actual structures, but only for schematic (preliminary) understanding of structural design principals. For the design of an actual structure, a competent professional should be consulted.
‘Calculations courtesy of Alex Tomanovich, PE ’