The design of circular pattern anchor bolt group uses the Method 2 Sawcut with h_ef' and Neutral Axis at Center as stated in the
following references

1. ASCE Anchorage Design for Petrochemical Facilities - 2013 Example 2 Step 5(c) on Page 145

2. ASCE 2010 Structural Congress - Concrete Breakout Strength in Tension for Vertical Vessel Anchorage in Octagon Pedestals

The design of circular pattern anchor bolt group is simplified as design of a single anchor bolt with 3 side free edges sawcut at midway between adjacent anchors. The simplified design method uses the following assumptions

1. The moment is resisted only by the anchor bolt group and it does not take into account the contribution of concrete compression force
    against base plate in the moment equilibrium

2. The neutral axis is not shifted and is located at center of vessel

3. It does not consider strain compatibility between the concrete and steel elements which comprise the anchorage.

4. In the assumed 3 side free edges sawcut model, when anchor is located less than 1.5hef from three or more edges, the reduced h_ef' is
    used to calculate concrete projected failure area A_NC

The utilization ratio of simplified method used in this calculation is conservative compared to the accurate but more complex approach.
The detail comparison and analysis of this simplified method is addressed in reference 2 above.

Octagon shape conc mat area

 = 

 = 32101.5

[in²]

Projected conc failure area

 = 

 = 1056.9

[in²]

PIP STE03350 -2008

Factored compression at top of concrete pedestal

 =  + 0.9

 = 135.54

[kips]

Section 4.6.1 Eq 5

Factored shear at base of vessel

 = from user input

 = 29.90

[kips]

Vessel base to concrete support surface friction factor

 = from user input

 = 0.55

Section 4.6.2

Strength reduction factor

 = 

 = 0.75

Section 4.6.2

Factored frictional resistance

 = φ μ P_u

 = 55.91

[kips]

Section 4.6.1 Eq 6

> V_u  shear load taken by the friction

Section 4.6.2 Eq 7

Factored single anchor shear load

 = shear load taken by the friction

 = 0.00

[kips]

Factored base moment - wind

 = from user input

 = 1000.9

[kip-ft]

Vessel empty weight

 = from user input

 = 47.00

[kips]

Factored single anchor tensile load

 =  - 0.9

 = 13.14

[kips]

Section 4.6.1 Eq 4

Factored base moment - seismic

 = from user input

 = 434.20

[kip-ft]

Vessel operating weight

 = from user input

 = 280.80

[kips]

When < 0.9 , there is no tensile load mobilized on anchor

Factored single anchor tensile load

 =  - 0.9

 = 0.00

[kips]

Section 4.6.1 Eq 4

Factored single anchor tensile load - max

 = max ( N_uaw , N_uas )

 = 13.14

[kips]

Check min anchor dimensions as per PIP STE05121 Application of ASCE Anchorage Design for Petrochemical Facilities - 2018   Table 1 as shown below.

This check is NOT a code requirement.   User can turn this check On/Off by changing setting at Anchor Bolt --> Anchor Bolt - Config & Setting --> Check min anchor spacing and edge distance as per PIP STE05121 Table 1

Anchor rod grade and dia

 = F1554 Gr36

 = 1.000

[in]

Anchor sleeve dia and height

 = 3.000

[in]

 = 10.000

[in]

Anchor edge distance

 = 19.675

[in]

 = 12.473

[in]

 = 177.175

[in]

 = 12.473

[in]

Min anchor edge distance required

 = from PIP STE05121 Table 1 below

 = 5.500

[in]

PIP STE05121 Table 1

Min anchor edge distance

 = min(c₁ , c₂ , c₃ , c₄ )

 = 19.675

[in]

 ≥ c_min

OK

Min anchor embedment required

 = from PIP STE05121 Table 1 below

 = 16.000

[in]

PIP STE05121 Table 1

Min anchor embedment depth

 = from user input

 = 18.000

[in]

 ≥ h_min

OK

Table 1 from PIP STE05121 Application of ASCE Anchorage Design for Petrochemical Facilities - 2018

Anchor rod effective section area

 = 0.61

[in²]

 = 58.0

[ksi]

Anchor rod steel strength in tension

 = A_se f_uta

 = 35.15

[kips]

ACI 318-19 17.6.1.2

Anchor group axial tensile force

 = from user load input

 = -13.14

[kips]

in tension

No of anchors in the group

 = 

 = 1

Single anchor tensile force

 = P / n_t

 = 13.14

[kips]

Strength reduction factor

 = 0.75

ACI 318-19 17.5.3(a)

 = 0.75 x 35.15

 = 26.36

[kips]

 = 0.50

 > T

OK

Anchor embedment depth-adjusted

 = from Anchor Forces Calculation above

 = 13.117

[in]

Conc strength & lightweight conc factor

 = 4.4

[ksi]

 = 1.0

ACI 318-19 17.2.4.1

Single anchor concrete breakout strength

 = 24λ √f_c h1.5ef If h_ef < 11" or h_ef > 25"

 = 76.98

[kips]

ACI 318-19 17.6.2.2.1

16λ √f_c h5/3ef   If 11" ≤ h_ef  ≤ 25"

ACI 318-19 17.6.2.2.3

Refer to Vertical Vessel Anchor Forces Calculation above for the details of vertical vessel circular anchor group
and single anchor of that group projected failure area A_NC1 calculation as shown below

 = 

 = 1056.9

[in²]

 = 9 h2ef

 = 1548.4

[in²]

ACI 318-19 17.6.2.1.4

No of anchors in the group resisting tension

 = from Anchor Forces Calculation above

 = 1

 = min( A_Nc1 , n_t A_Nco )

 = 1056.9

[in²]

ACI 318-19 17.6.2.1.1

Eccentricity modification factor

 = from Anchor Forces Calculation above

 = 1.000

ACI 318-19 17.6.2.3.1

Min edge distance

 = min(c₁ , c₂ ,c₃ ,c₄ )

 = 12.473

[in]

Edge modification factor

 = min[0.7 + , 1.0]

 = 0.890

ACI 318-19 17.6.2.4.1

Conc cracking modification factor

 = 

 = 1.00

ACI 318-19 17.6.2.5.1

Conc splitting modification factor

 = 

 = 1.00

ACI 318-19 17.6.2.6.1

Concrete breakout resistance

 =  Ψ_ec,N Ψ_ed,N Ψ_c,N Ψ_cp,N N_b

 = 46.78

[kips]

ACI 318-19 17.6.2.1b

Sum of anchors tensile force in anchor group

 = from Anchor Forces Calculation above

 = 13.14

[kips]

Strength reduction factor

 = 0.75

  supplementary reinft present

ACI 318-19 17.5.3(b)

 = 0.75 x 46.78

 = 35.08

[kips]

Seismic design strength reduction

 = x 1.0   not applicable

 = 35.08

[kips]

ACI 318-19 17.10.5.4(b)

 = 0.37

 > N_u

OK

Anchor head net bearing area & conc strength

 = 1.50

[in²]

 = 4.4

[ksi]

Single bolt pullout resistance

 = 8 A_brg f_c

 = 52.23

[kips]

ACI 318-19 17.6.3.2.2a

Pullout cracking factor

 = for cracked concrete

 = 1.00

ACI 318-19 17.6.3.3.1(b)

Anchor group axial tensile force

 = from user load input

 = -13.14

[kips]

in tension

No of anchors in the group

 = 

 = 1

Single anchor tensile force

 = P / n_t

 = 13.14

[kips]

Strength reduction factor

 = 0.70

 pullout strength is always Condition B

ACI 318-19 17.5.3(c)

 = φ_tc Ψ_cP N_p

 = 36.56

[kips]

Seismic design strength reduction

 = x 1.0   not applicable

 = 36.56

[kips]

ACI 318-19 17.10.5.4(c)

 = 0.36

 > T

OK

Anchor edge distance - min

 = min (c₁ , c₂ , c₁ , c₄ )

 = 12.473

[in]

Anchor embedment depth

 = from user input

 = 18.000

[in]

Side blowout check is required on this edge or not

 = check if h_ef > 2.5 c_a1

 = False

ACI 318-19 17.6.4.1

Side blowout check is NOT required

ACI 318-19 17.6.4.1

Anchor group governing tensile resistance is the minimum value of the resistance values in
the following limit states

No of anchors in anchor group
resisting tension

 = from Anchor Forces Calculation above

 = 1

Anchor rod tensile resistance

 = 1 x 26.36

 = 26.36

[kips]

Anchor concrete breakout resistance

 = from anchor conc breakout calc above

 = 35.08

[kips]

Anchor pullout resistance

 = 1 x 36.56

 = 36.56

[kips]

Anchor side blowout resistance

 = from anchor side blowout calc above

 = N/A

Anchor group governing tensile resistance

 = minimum of above values

 = 26.36

[kips]

There is no shear load from user load input or shear key is used and all shear is taken by shear key, so
Anchor Shear Resistance and Tension - Shear Interaction checks are Not Applicable

Seismic - Tension

    Not Applicable

ACI 318-19 17.10.5.1

Seismic SDC < C or E <= 0.2U , additional seismic requirements in ACI 318-19 17.10.5.3 is NOT required

ACI 318-19 17.10.5.3

Seismic - Shear

    Not Applicable

ACI 318-19 17.10.6.1

There is no shear load applied to anchor/anchor group, so Seismic Shear check is NOT required