Pakistan Table 6

Seismic coefficient C_a

Soil Profile Type¹	Seismic Zone Factor, Z²
Soil Profile Type¹	Z = 0.075	Z = 0.15	Z = 0.2	Z = 0.3	Z = 0.4
S_A	0.06	0.12	0.16	0.24	0.32N_a
S_B	0.08	0.15	0.20	0.30	0.40N_a
S_C	0.09	0.18	0.24	0.33	0.40N_a
S_D	0.12	0.22	0.28	0.36	0.44N_a
S_E	0.19	0.30	0.34	0.36	0.36N_a
S_F	See Footnote4

¹For soil profile types, see Table1-1.
²Seismic Zone factor Z shall be determined from Table7.
³For Near Source Factor N_v, see Table6-1.
⁴Site Specific geotechnical investigation and dynamic site response analysis shall be performed to determine seismic coefficients for Soil Profile Type S_F

Pakistan Table1-1

Soil Profile Types

Soil Profile Type	Soil Profile Name / Generic Description	Average Properties for Top 30 M (100ft) of Soil Profile¹
Soil Profile Type	Soil Profile Name / Generic Description	Shear Wave Velocity, v_s m/sec (ft/sec)	*Standard Penetration Tests, N [or N_CH* for cohesionless soil layers] (blows/foot)**	*Undrained Shear Strenght, s_u* kPa psf**
S_A	Hard Rock	>1,500 (>4,900)	-	-
S_B	Rock	750 to 1,500 (2,460 to 4,920)	-	-
S_C	Very Dense Soil and Soft Rock	350 to 750 (1,150 to 2,460)	>50	>100 (>2,088)
S_D	Stiff Soil Prifile	175 to 350 (575 to 1,150)	15 to 50	50 to 100 (1,044 to 2,088)
S_E¹	Soft soil Profile	<175 (<575)	<15	<50 (<1,044)
S_F	Soil requiring Site-specific Evaluation. See Footnote2.

¹Soil Profile Type S_E also includes any profile with more than 3 m (10 ft) of soft clay defined as a soil with a plasticity index, PI > 20,
w_mc ≥ 40 percent and s_u > kPa (522 psf). The Plasticity Index, PI, and the moisture content, w_mc, shall be determined in accordance with
the latest ASTM procedures.

² Soils requiring site-specific evaluation:

1. Soils vulnerable to potential failure or collapse under seismic loading such as

liquefiable soils, quick and highly sensitive clays, collapsible weakly cemented soils

2. Peats and/or highly organic clays [H > 3 m (10 ft.) of peat and/or highly organic clay

where H = thickness of soil]

3. Very high plasticity clays [H > 7.5 m (25 ft.) with PI > 75]

4. Very thick soft/medium stiff clays [H > 37 m (120 ft.)]

Exception: When the soil properties are not known in sufficient detail to determine the soil profile type, generally Type S_D shall be used. Soil Profile Type S_E need not be assumed for all situations unless the engineer determines that Soil Profile Type S_E may be present at the site or in the event that Type S_E is established by geotechnical data.

Pakistan Table6-1

Near Source Factor N_v¹

Seismic Source Type⁴	Closest Distance to Known Seismic Source^2,3
Seismic Source Type⁴	≤ 2 km	5 km	≥ 10 km
A	1.5	1.2	1.0
B	1.3	1.0	1.0
C	1.0	1.0	1.0

¹The Near Source Factor may be based on the linear interpolation of values for distances other than those shown in the table.
²The location and type of seismic source to be used for design shall be established based on approved geotechnical data.
³The closest distance to seismic sourve shall be taken as the minimum distance between the site and the areas described by the vertical projection of the source on the surface (i.e., surface projection of fault plane). The surface projection need not include portions of the source at depths of 10 km or greater. The largest value of the Near-Source Factor considering all sources shall be used for design.
⁴For Seismic Source Type, See Table1-3.

	1.	Soils vulnerable to potential failure or collapse under seismic loading such as
		liquefiable soils, quick and highly sensitive clays, collapsible weakly cemented soils
	2.	Peats and/or highly organic clays [H > 3 m (10 ft.) of peat and/or highly organic clay
		where H = thickness of soil]
	3.	Very high plasticity clays [H > 7.5 m (25 ft.) with PI > 75]
	4.	Very thick soft/medium stiff clays [H > 37 m (120 ft.)]
	Exception: When the soil properties are not known in sufficient detail to determine the soil profile type, generally Type S_D shall be used. Soil Profile Type S_E need not be assumed for all situations unless the engineer determines that Soil Profile Type S_E may be present at the site or in the event that Type S_E is established by geotechnical data.