Enter the value of the importance factor that you want the program to use. The importance factor accounts for the degree of hazard to life and property. Please note the program will use this value directly without modification. Values of typical importance factors are listed below for ASCE 7-93, ASCE 7-95/98/02 and UBC 1997 standards.
ASCE7-93: 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 |
1.0 |
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 and so on.
-
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 etc.
Most petrochemical structures are 1, Importance I.
UBC: UBC 1997 code values are listed as follows:
|
Category |
Importance Factor (I) |
|
I, Essential facilities |
1.15 |
|
II, Hazardous facilities |
1.15 |
|
III, Special occupancy structures |
1.00 |
|
IV, Standard occupancy structures |
1.00 |