Page 199 - Structural Steel Designers Handbook AISC, AASHTO, AISI, ASTM, and ASCE-07 Design Standards

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BUILDING CODES, LOADS, AND FIRE PROTECTION*

BUILDING CODES, LOADS, AND FIRE PROTECTION 4.27

TABLE 4.11 Seismic Use Group Designations
Seismic use group
I II III
Occupancy category I X
(Table 4.10) II X
III X
IV X
Source: From Minimum Design Loads for Buildings and Other Structures,
SEI/ASCE 7-02, American Society of Civil Engineers, Reston, Va., with permission.

TABLE 4.12 Occupancy Importance Factors
Seismic use group I s
I 1.0
II 1.25
III 1.5
Source: From Minimum Design Loads for
Buildings and Other Structures, SEI/ASCE 7-02,
American Society of Civil Engineers, Reston, Va.,
with permission.

TABLE 4.13 Seismic Site Classification
Site class v v s N or N ch s u
A: Hard rock >5000 ft/s Not applicable Not applicable
(>1500 m/s)
B: Rock 2500 to 5000 ft/s Not applicable Not applicable
(760 to 1500 m/s)
C: Very dense soil and soft rock 1200 to 2500 ft/s >50 >2000 lb/ft 2
(370 to 760 m/s) (>100 kPa)
D: Stiff soil 600 to 1200 ft/s 15 to 50 1000 to 2000 lb/ft 2
(180 to 370 m/s) (50 to 100 kPa)
E: Soil <600 ft/s <15 <1000 lb/ft 2
(<180 m/s) (<50 kPa)
Any profile with more than 10 ft of soil having the following characteristics:
—Plasticity index PI > 20
—Moisture context w ≥ 40%
< 500 lb/ft 2
—Undrained shear strength s u
F: Soils requiring site-specific 1. Soils vulnerable to potential failure or collapse
evaluation 2. Peats and/or highly organic clays
3. Very high plasticity clays
4. Very thick soft/medium clays
The following definitions apply, where the bar denotes average value for the top 100 ft of soil. See SEI/ASCE 7-02 for
specific details.

v s = measured shear wave velocity, ft/s
N = standard penetration resistance, blows/ft
= corrected for cohesionless layers, blows/ft
N ch
= undrained shear strength, lb/ft 2
s u
PI = plasticity index
w = liquid limit
Source: From Minimum Design Loads for Buildings and Other Structures, SEI/ASCE 7-02, American Society of Civil
Engineers, Reston, Va., with permission.

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