Enter the value of the importance factor that you wish the program to use. The importance factor accounts for the degree of hazard to life and property. The software will use this value directly without modification.
Values of typical importance factors for ASCE 7-93, ASCE 7-95/98/02 and UBC 1997 standards are listed in the following tables.
The following values are used for ASCE 7-93. In general, this value ranges from .95
to 1.11.
|
Category |
100 mi from Hurricane Oceanline |
At Oceanline |
|
I |
1.00 |
1.05 |
|
II |
1.07 |
1.11 |
|
III |
1.07 |
1.11 |
|
IV |
0.95 |
1.00 |
Category Classification:
|
I |
buildings and structures not listed below |
|
II |
buildings and structures where more than 300 people congregate in one area |
|
III |
buildings designed as essential facilities, hospitals etc. |
|
IV |
buildings and structures that represent a low hazard in the event of a failure |
Most petrochemical structures are 1, Importance I. ASCE-7-95/98/02: In general this
value ranges from .77 to 1.15. It is taken from table 6-2 of the ASCE 95 standard
or table 6-1 from the 98 standard.
|
Category |
Importance Factor (I) |
|
I |
0.87 |
|
II |
1.00 |
|
III |
1.15 |
|
IV |
1.15 |
In the 98 standard for Wind Speeds > 100 mph for category I, the importance factor can be 0.77.
Category Classification:
|
I |
buildings and other structures that represent a low hazard to human life in the event of failure |
|
II |
buildings and structures except those listed in categories I, III and IV |
|
III |
buildings and structures that represent a substantial hazard in the event of a failure |
|
IV |
buildings designed as essential facilities, hospitals, and so on. |
Most petrochemical structures are 1, Importance I. For UBC 1997 code these values
are listed in the following table.
|
Category |
Importance Factor (I) |
|
I, Essential facilities |
1.15 |
|
II, Hazardous facilities |
1.15 |
|
III, Special occupancy structures |
1.00 |
|
IV, Standard occupancy structures |
1.0 |