TABLE 1-1 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
- Certain temporary facilities
- Minor storage 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 area
- Buildings and other structures with day-care facilities with capacity greater than 150
- Elementary or secondary school facilities with capacity greater than 250
- Colleges & adult education facilities with a capacity greater than 500
- Health care facilities with a capacity greater than 50 resident patients but not having surgery or emergency treatment facilities
- Jails and detention facilities

Buildings and other structures, not includes in Occupancy Category IV, with potential to cause
substantial economic impact and/or mass disruption of day-to-day civilian life in event of failure,
including, but not limited to:

- Power generating stations, water treatment facilities, sewage treatment facilities, and
telecommunication centers
- Buildings and structures not included in Category IV containing sufficient quantities of toxic,
explosive, or other hazardous materials dangerous to the public if released

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
- Fire, rescue and police stations and emergency vehicle garages
- Designated earthquake, hurricane or other emergency shelters
- Designated emergency preparedness, communication, and operation centers and other facilities required for emergency response
- Power-generating stations and other public utility facilities required in an emergency
- Ancillary structures required foroperation of Category IV structures during an emergency
- Aviation control towers, air traffic control centers and emergency aircraft hangars
- Water storage facilities and pump structures required to maintain water pressure for fire suppression
- Buildings and other structures having critical national defense functions
- Buildings and structures containing extremelyhazardous materials where quantity of material exceeds a threshhold quantity established by authority having jurisdiction

IV

(a) Cogeneration power plants that do not supply power on the national grid shall be designated Occupancy Category II.

ASCE 7-05 TABLE 11.5-1
IMPORTANCE FACTORS

IMPORTANCE FACTOR, I, (ICE LOADS)

Occupancy Category

I

I or II

1.0

III

1.25

IV

1.5

*See Section 1.5 and Table 1-1.

ASCE 7-05 TABLE 20.3-1
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

*See Section 1.5 and Table 1-1.

'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.

IBC 2006 TABLE 1613.5.3(1)
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)

(a) - Use straight line interpolation for intermediate values of mapped spectral acceleration at
short period, Ss. (b) - Site-specific geotechnical investigation and dynamic site response analyses shall be
performed to determine appropriate values. See ASCE 7-05 Section 11.4.7.

IBC 2006 TABLE 1613.5.3(2)
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)

(a) - Use straight line interpolation for intermediate values of mapped spectral acceleration at 1-second period, S1. (b) - Site-specific geotechnical investigation and dynamic site response analyses shall be
performed to determine appropriate values. See ASCE 7-05 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 1-second 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 1-second period as determined in IBC 2006 Section 1613.5.4.

IBC 2006 TABLE 1613.5.6(1)
SEISMIC DESIGN CATEGORY BASED ON
SHORT-PERIOD 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

IBC 2006 TABLE 1613.5.6(2)
SEISMIC DESIGN CATEGORY BASED ON
1-SECOND PERIOD RESPONSE ACCELERATIONS

(a) - Occupancy Category I, II, and III structures located on
sites with mapped maximum considered earthquake
spectral response acceleration at 1-second period, S1,
equal to or greater than 0.75g, shall be assigned to
Seismic Design Category E, and Cccupancy Category IV
structures located on such sites shall be assigned to
Seismic Design Category F.

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 seismic-force-resisting system that is used:

CT = 0.028 for moment-resisting frames of steel
CT = 0.016 for moment-resisting 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 seismic-force-resisting system that is used:

x = 0.80 for moment-resisting frames of steel
x = 0.90 for moment-resisting 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 7-05 Section 12.8.2.1, Eqn. 12.8-7

ASCE 7-05 TABLE 12.8-1
COEFFICIENT FOR UPPER LIMIT
ON CALCULATED PERIOD

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 7-05 Table 12.2-1.

The System Overstrength Factor, "Wo", is determined from ASCE 7-05 Table 12.2-1.

The Deflection Amplification Factor, "Cd", is determined from ASCE 7-05 Table 12.2-1.

'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 seismic-force-resisting 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 is 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.