# Site Coefficients per ASCE 7-16 with ideCAD

How does ideCAD define site coefficients, according to ASCE 7-16?

• The site class is chosen by the user.

• According to ASCE 7-16 Section 20.3. 1, site response analysis must be performed for F site classes.

• Spectrum parameters are determined automatically using Equations 11.4-3 and 11.4-4.

SYMBOLS

Fa = Short-Period Site Coefficient
Fv = Long-Period Site Coefficient for a period of 1.0 seconds
SMS = Short-period design spectral response acceleration parameter [dimensionless]
SM1 = Design spectral response acceleration parameter for a period of 1.0 seconds [dimensionless]
SS = the mapped MCER spectral response acceleration parameter at short periods as determined in accordance with Section 11.4.2,
S1 = the mapped MCER spectral response acceleration parameter at a period of 1 s as determined in accordance with Section 11.4.2
SD1 = Design spectral response acceleration parameter for a period of 1.0 seconds
SDS = Design earthquake spectral response acceleration parameters at short periods

Site Coefficients

In ASCE 7-16 Table 20.3-1, the soil class is determined according to the top 100 ft (30 m) of the soil profile. It has been defined as six classes, from A to F , according to Table 20.3-1.

Depending on the site classes defined in ASCE 7-16 11.4-1, site coefficients Fa and Fv are given in Table 11.4-1 and Table 11.4-2. Straight-line interpolation is performed for intermediate values ​​of site coefficients in the tables.

Short-Period Site Coefficient, Fa

Site Class

Ss ≤ 0.25

Ss = 0.5

Ss = 0.75

Ss = 1.0

Ss = 1.25

Ss ≥ 1.5

A

0.8

0.8

0.8

0.8

0.8

0.8

B

0.9

0.9

0.9

0.9

0.9

0.9

C

1.3

1.3

1.2

1.2

1.2

1.2

D

1.6

1.4

1.2

1.1

1.0

1.0

E

2.4

1.7

1.3

11.4.8

11.4.8

11.4.8

F

11.4.8

Long-Period Site Coefficient, Fv

Site Class

S1 ≤ 0.25

S1 = 0.2

S1 = 0.3

S1 = 0.4

S1 = 0.5

S1 ≥ 0.6

A

0.8

0.8

0.8

0.8

0.8

0.8

B

0.8

0.8

0.8

0.8

0.8

0.8

C

1.5

1.5

1.5

1.5

1.5

1.4

D

2.4

2.2

2.0

1.9

1.8

1.7

E

4.2

11.4.8

11.4.8

11.4.8

11.4.8

11.4.8

F

11.4.8

JavaScript errors detected