Importance Factors by Risk Category of Buildings and Other Structures for Snow, Ice, and Earthquake Load per ASCE 7-10, Section 1.5

April 14, 2018 Abdul Siraj, P.E.

In this post, I will provide a brief overview of the importance factors by risk category of buildings and other structures for snow, ice, and earthquake loads that are specified in ASCE 7-10, Section 1.5. 

 

Risk Category I

 

Snow Importance Factor, Is = 0.80

Ice Importance Factor – Thickness, Ii = 0.80

Ice Importance Factor – Wind, Iw = 1.00

Seismic Importance Factor, Ie = 0.80

 

Risk Category II

 

Snow Importance Factor, Is = 1.00

Ice Importance Factor – Thickness, Ii = 1.00

Ice Importance Factor – Wind, Iw = 1.00

Seismic Importance Factor, Ie = 1.00

 

Risk Category III

 

Snow Importance Factor, Is = 1.10

Ice Importance Factor – Thickness, Ii = 1.25

Ice Importance Factor – Wind, Iw = 1.00

Seismic Importance Factor, Ie = 1.25

 

Risk Category IV

 

Snow Importance Factor, Is = 1.20

Ice Importance Factor – Thickness, Ii = 1.25

Ice Importance Factor – Wind, Iw = 1.00

Seismic Importance Factor, Ie = 1.50