API 650 Pipe Column Design

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YOUR COMPANY LOGO Pipe Column Design Per AISC / API 650 Rev #

Rev Description

Rev By

Rev Date

1 2 3 4 Notes 1 2 3 4 5

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Pipe Column Design per API 650 A. Introduction API 650 requires that the columns be designed per AISC or other approved standard. These columns are designed using the latest edition of AISC with temperature modification factors per API 650, Appendix M.

B. Geometry Column diameter

Column thickness

dc := 18 ⋅ in

tc := .375 ⋅ in

Length of column

Corrosion allowance

CArc := 0 ⋅ in

Effective length factor

Lc := 50 ⋅ ft

K := 1.0

C. Material Properties Design temperature

Yield stength

Td := 350 ⋅ °F

Fyc := 35 ⋅ ksi

 Td   if Fyc ≤ 45⋅ ksi = 0.87  °F   Td   if Fyc > 55⋅ ksi RY3   °F   Td   otherwise RY2   °F 

RY1 

RFys :=

Yield strength reduction factor for column design per API 650, Appendix M

RFys = 0.87

 Td   = 28000000.00 psi  °F 

Ec := EST 

Modulus of elasticity with temperature modification per API 650, Appendix M

D. Loading Pc := 30000 ⋅ lbs

Total load at base of column

Mc := 10000 ⋅ ft ⋅ lbs

Moment on column

Ωc := 1.67

Safety factor for column design

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Pipe Column Design per API 650 E. Section Properties dcc := dc − 2 ⋅ CArc

dcc = 18.00 in

Column diameter - corroded

tcc := tc − CArc

tcc = 0.3750 in

Column thickness - corroded

π  2 2 Acc := ⋅ d − dcc − 2 ⋅ tcc   4  cc π  4 4 Ic := ⋅ dcc − dcc − 2 ⋅ tcc    64

( ) (

)

( ) (

Sc :=

2 ⋅ Ic

(dcc − tcc)

Ic Acc

.038 ⋅ E c  2  +    dcc  3  Qc := min  RFys ⋅ Fyc ⋅    tcc        1  

Column area - corroded Moment of inertia - corroded

3

Section modulus - corroded

Zc = 116.49 in

π

2

4

Ic = 806.63 ⋅ in Sc = 89.63 ⋅ in

dc

Zc := Acc ⋅

rc :=

)

Acc = 20.764 ⋅ in

3

Plastic section modulus - corroded

rc = 6.23 ⋅ in

Radius of gyration - corroded

Qc = 1.00

Element slenderness reduction factor

F. Check Axial Compressive Stress - Gravity Loads Only 2

Fe :=

π ⋅ Ec

 K ⋅ Lc   rc 

2

Euler buckling stress

Fyc

Fcr :=

.658

Fe

⋅ Fyc if

K ⋅ Lc rc

≤ 4.71 ⋅

Ec Fyc

Critical buckling stress per AISC 360-05 Chapter E

0.877 ⋅ Fe otherwise Fcr = 21415.31 psi RFys Pn := Qc ⋅ Fcr ⋅ Acc = 230321.339 ⋅ lbs Ωc Pc = 13.03 ⋅ % Pn

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Nominal compressive strength of column

Must be less than or equal to 100%

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Pipe Column Design per API 650 G. Check Combined Axial Compressive and Bending Stresses RFys

Mnc :=

Ωc

⋅ Fyc ⋅ Zc if

dcc tcc

≤

.07Ec RFys ⋅ Fyc

Nominal bending strength of column - AISC 360-05, Chapter F

.33 ⋅ Ec Sc dcc .31Ec ⋅ if > dcc Ωc tcc RFys ⋅ Fyc tcc

 .021 ⋅ Ec  Sc  + Fyc ⋅ RFys ⋅ otherwise  dcc  Ωc  t   cc  Mnc = 175.99 ⋅ ft ⋅ kip Coefficient to account for non-uniform moment diagrams and end restraints

Cm := 1.0

INTEc :=

Pc Pn

+

Pc 2 ⋅ Pn Pc Pn

= 13.0 ⋅ %

INTEc = 12.2 ⋅ % K ⋅ Lc rc ⋅ 175

= 55 ⋅ %

Pc 8 Mc ⋅ if ≥ 0.2 9 Mnc Pn +

Mc Mnc

otherwise

Compressive stress check. Value must not exceed 100%. Interaction of bending and axial stress from seismic loading. Value must not exceed 100% Slenderness check. Value must not exceed 100%.

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