base plate anchor bolt design

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"BASEPLT9" --- STEEL COLUMN BASE PLATE ANALYSIS

Program Description:

"BASEPLT9" is a spreadsheet program written in MS-Excel for the purpose of analysis of steel column base plates. Specifically, wide flange column base plates may be subjected to axial loads (compression or tension), with or without major-axis column bending, plus major-axis shear. Base plate bearing pressure is checked as well as bolt tension, if applicable. If shear is present, bolt shear as well as interaction of bolt tension and shear, if applicable, are calculated. Finally, the required base plate thickness is calculated. There is a separate worksheet for base plate shear lug design, when shear load is high and cannot be effectively handled by bolts. This program is a workbook consisting of four (4) worksheets, described as follows:

Worksheet Name

Description

Doc This documentation sheet

Base Plate Steel column base plate analysis

Shear Lug Steel column base - shear lug analysis

Base Plate (Table) Multiple steel column base plate analysis (table format)

Program Assumptions and Limitations:

1. This program follows the procedures and guidelines of the AISC 9th Edition Allowable Stress (ASD) Manual (2nd Revision, 1995) for wide flange column base plates subjected to axial compressive load only.

2. This program uses a "cubic equation" method of solution for column base plates subjected to axial compression or tension load with major axis column bending as presented in the reference:

"Design of Welded Structures" - by Omer W. Blodgett (James F. Lincoln Arc Welding Foundation) 3. For interaction of anchor bolt tension and shear, this program follows the article:

"Design Aid: Anchor Bolt Interaction of Shear and Tension Loads", by Mario N. Scacco AISC Engineering Journal, 4th Quarter - 1992.

4. User has option to take out some of the total shear though friction between column base and grout based on column dead load and coefficient of friction, thus reducing amount of shear to be taken by anchor bolts. 5. This program uses the database of member dimensions and section properties from the "AISC Shapes Database", Version 3.0 (2001) as well as the AISC 9th Edition (ASD) Manual (1989).

6. This program assumes that the base plate is sufficiently rigid to assume linear distribution of load to the base plate and/or anchor bolts. (Note: adequate base plate rigidity is most likely assured if the distance from the face of the column to the edge of the base plate is <= 4*tp. See "General Anchorage to Concrete", TVA Civil Design Standard DS-C1.7.1 (Rev. 1984), page 25.)

7. Additional assumptions used in this program are as follows: a. The column is centered on the base plate in both directions. b. Axial column load, 'P', can be = 0 for the case with moment. c. The minimum area of concrete support is: A2(min) = N*B. d. For a base plate supported on a slab or mat, use A2 = 4*(N*B).

e. Two (2) total rows of anchor bolts are allowed, one row outside of each column flange. f. There must be an equal number of anchor bolts in each of the two (2) rows.

8. For cases with anchor bolt tension and base plate bearing, this program calculates the bending moment in the base plate at two locations. One, at the column flange in compression using the bearing pressure distribution, and the other at the column flange in tension using the tension in one bolt distributed over an assumed width effective plate width based on edge distances and bolt spacing. At both locations, the moment and resulting base plate thickness are calculated using a "cantilever" length equal to the calculated "m" distance from the AISC code. Then, the larger of the two calculated thickness values is used for the required base plate thickness. (Note: this program assumes that the anchor bolts are not located in plan significantly beyond the ends of the column flange, so that corner-type plate bending does not control.) 9. The "Shear Lug" worksheet follows the AISC "Steel Design Guide Series #1 - Column Base Plates".

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column bases or column load combinations. Refer to that worksheet for list of specific assumptions used. 11. This program contains numerous “comment boxes” which contain a wide variety of information including explanations of input or output items, equations used, data tables, etc. (Note: presence of a “comment box” is denoted by a “red triangle” in the upper right-hand corner of a cell. Merely move the mouse pointer to the desired cell to view the contents of that particular "comment box".)

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"BASEPLT9.xls" Program

Version 3.2

STEEL COLUMN BASE PLATE ANALYSIS

Version 1.1

Per AISC 9th Edition Manual (ASD) and "Design of Welded Structures" (O. Blodgett)

For Axial Load with or without Moment

Job Name:

Subject:

Job Number:

Originator:

Checker:

Input Data:

Column Size:

Column Properties:

Select:

HE120A

A =

3.92

in.^2

Column Loadings:

d =

4.488

in.

Axial Load, P

(total)

=

-2.50

kips

tw =

0.197

in.

-11.10

KN

Axial Load, P

(DL)

=

0.00

kips

bf =

4.724

in.

0.00

KN

Shear Load, V

(total)

=

0.81

kips

tf =

0.315

in.

3.60

KN

Moment @ Base, M =

4.83

ft.-kips

58.00

In.-kips

Design Parameters:

Base Plate Length, N =

18.000

in. ED1=50.8

Base Plate Width, B =

18.000

in.

Plate Yield Stress, Fy =

36.00

ksi ED2=2 n=7.11

Concrete Strength, f 'c =

3.000

ksi.

Bearing Area, A

2

=

1296.00

in.^2

Shear Coef., C =

1.85

B=457.2 0.80*bf

Coef. of Friction,

m

=

0.55 Anchor Bolt/Rod Data:

Total No. of Bolts, Nb =

4

n=7.11

Bolt Diameter, db =

0.750

in.

Anchor Bolt Material =

F1554 (36)

m=6.87 0.95*d m=6.87

Bolt Edge Dist., ED

1

=

2.000

in.

Bolt Edge Dist., ED

2

=

2.000

in. N=457.2

19.050 mm

Results:

Plan

Eccentricity, Bearing Length, and Bearing Pressures:

e = M*12/P = 23.234

Eccentricity, e =

23.234

in.

Length, Xc =

4.491

in. P(total) =

Fp =

2.100

ksi -2.4953799

fp

(max)

=

0.129

ksi (-down)

fp

(min)

=

0.000

ksi

Fp >= fp(max), O.K.

HE120A Col.

Anchor Bolt/Rod Tension and Shear:

Ft =

19.10

ksi

Ta =

8.44

k/bolt tp=14.918

Tb =

1.35

k/bolt

Ta >= Tb, O.K.

fp(max)=0.129

Fv =

9.90

ksi T= Xc=4.491

Va =

4.37

k/bolt Tb*(Nb/2)

V

(bolts)

=

0.81

= V(total)-1/2*m*P(DL) N=457.2

Vb =

0.20

k/bolt

Va >= Vb, O.K.

Elevation

(Interaction) S.R. =

0.246

= Tb/Ta+(C*Vb)/Va

S.R. <= 1.0, O.K.

Base Plate Thickness:

Suggested plate thickness for rigidity:

tp

(req'd)

=

0.587

in.

tp

(min)

=

1.778

in. tp(min) >= max. of m/4 or n/4

14.918 mm

45.150 mm

be

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Version 3.2

STEEL COLUMN BASE - SHEAR LUG ANALYSIS

Per AISC 9th Edition Manual (ASD), AISC "Steel Design Guide Series No. 1"

and AC1 318-99 Code

Job Name:

Subject:

Job Number:

Originator:

Checker:

Input Data:

Column Loadings:

Shear Load, V

(total)

=

17.25

kips

Axial Load, P

(DL)

=

-7.00

kips P(DL)=-7

Base and Shear Lug Data:

Column

Base Plate Length, N =

18.000

in.

Base Plate Width, B =

18.000

in.

Base Plate Thk., tp =

1.5000

in. V=17.25

Grout Thickness, G =

2.00

in. tp=1.5

Lug Height, H =

4.00

in. G=2

Lug Width, W =

9.00

in. Grout H=4

Lug Thickness, t =

1.250

in.

w

Weld Size,

w

=

0.0000

in. Shear Lug

Lug Yield Stress, Fy =

36.00

ksi t=1.25

Coef. of Friction,

m

=

0.55 Pier Length, Lpx =

20.000

in.

Pier Width, Lpy =

20.000

in.

Nomenclature

Concrete Strength, f 'c =

3.000

ksi

Results:

Shear Lug Design Loads:

Shear, V(lg) =

15.33

kips

V(lg) = V-1/2*

m

*ABS(P

(DL)

)

Moment, M(lg) =

5.11

in-kips

M(lg) = (V(lg)/W)*(H+G)/2

Shear Lug Thickness:

t

(req'd)

=

1.065

in.

t(req'd) = SQRT(6M(lg)/(0.75Fy)) <= t <= tp

t(req'd) <= t, O.K.

Concrete Bearing at Lug:

fp =

0.851

ksi

fp = V/(W*(H-G))

Fp =

1.050

ksi

Fp = 0.35*(f'c)

Fp >= fp, O.K.

Concrete Shear in Front of Lug:

Vu =

26.05

kips

Vu = 1.7*V(lg) (assume L.F. = 1.7)

EDx =

9.375

in.

EDx =(Lpx-t)/2

EDy =

5.500

in.

EDy =(Lpy-W)/2

Av =

209.50

in.^2

Av = (2EDy+W)(H-G+EDx)-2*W

f

Vc =

39.01

kips

f

Vc = 40.85SQRT(f'c1000)/1000Av (allowable)

Vu <= V(allow), O.K.

Shear Lug Welding:

s =

1.250

in.

s = t+2(1/3)

w

(moment arm between C.G. of welds)

Rw =

4.174

k/in.

Rw = SQRT((M(lg)/s)^2+(V(lg)/(2*W))^2)

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"BASEPLT9.xls" Program Version 3.2

STEEL COLUMN BASE PLATE ANALYSIS

Per AISC 9th Edition Manual (ASD) and "Design of Welded Structures" (O. Blodgett) Assumptions: 1. Program follows the procedures and guidelines of the AISC 9th Edition Allowable Stress (ASD) Manual (2nd Revision, 1995) pages 3-106 to 3-110 for wide

For Axial Load with or without Moment flange column base plates subjected to concentric axial compressive load only.

Job Name: Subject: 2. Program uses a "cubic equation" method of solution for column base plates subjected to axial compression or tension load with major axis column bending

Job Number: Originator: Checker: e = M*12/P as presented in "Design of Welded Structures" - by Omer W. Blodgett (James F. Lincoln Arc Welding Foundation), pages 3.3-6 to 3.3-10.

3. The total number of anchor bolts on both sides of the column flanges is 'Nb'. Anchor bolts MUST be in only 2 rows, one row outside of each column flange.

Input Data: ED1 4. Permitted anchor bolt diameters are: 5/8", 3/4", 7/8", 1", 1-1/8", 1-1/4", 1-3/8", 1-1/2", 1-3/4", 2", 2-1/4", 2, 1/2", 2-3/4", and 3".

P 5. For case of concentric axial compression load without moment:

Base Plate Yield Stress, Fy = 36.00 ksi n (-down) P = -P (which was input) for use in equations below

Concrete Compressive Strength, f'c = 3.000 ksi fp = P/(N*B) , m = (N-0.95*d)/2 , n = (B-0.8*bf)/2 , n' = SQRT(d*bf)/4 , q = 4*fp*d*bf/((d+bf)^2*Fp) < 1.0 , l = 2*(1-SQRT(1-q))/SQRT(q) <= 1.0 Anchor Bolt/Rod Material = F1554 (36) Col. tp = 2*c*SQRT(fp/Fy) , where: c = maximum of: m, n, or l*n'

Shear Coefficient, C = 1.85 B 0.80*bf 6. For case of axial load (compression or tension) plus moment resulting in anchor bolt tension, with eccentricites (e) as shown below:

P = -P (which was input) for use in equations below

tp ABS(e) = M*12/P > N/2-Xc/3 (for P = compression) , ABS(e) = M*12/P > N/2-ED1 (for P = tension) Page breaks may be placed at rows 460, 536, 612, 688, etc., in n MR = Es/Ec = 29000/(57*SQRT(f'c*1000)) , As = (Nb/2)*p*db^2/4 increments of 76 rows for full page printouts as required.

fp(max) Xc^3 + 3*(e-N/2)*Xc^2 + 6*MR*As/B*((N/2-ED1)+e)*Xc - 6*MR*As/B*(N/2+(N/2-ED1))*((N/2-ED1)+e) = 0 , and solve cubic equation for Xc

m 0.95*d m T= Xc T = -P*(N/2-Xc/3-e)/(N/2-Xc/3+(N/2-ED1)) , Tb = T/(Nb/2) , fp(max) = 2*(P+T)/(Xc*B)

Tb*(Nb/2) 7. Plate bending is calculated due to both plate bearing stress and anchor bolt tension, where effective plate width used for anchor bolt tension is as follows:

N N be = Minimum of: (m-ED1) or (B-2*ED2)/(2*(Nb/2-1)) + Minimum of: (m-ED1) or (B-2*ED2)/(2*(Nb/2-1)) or ED2

8. For interaction of anchor bolt tension and shear, this program follows the article: "Design Aid: Anchor Bolt Interaction of Shear and Tension Loads", Plan Elevation by Mario N. Scacco, AISC Engineering Journal, 4th Quarter - 1992. Anchor bolt interaction formula is as follows: Tb/Ta + (C*Vb)/Va <= 1.0.

COLUMN LOADS DESIGN DATA RESULTS

COLUMN COLUMN Case 1: Maximum Load Condition Case 2: Minimum Load Condition Base Plate Data Pier Data Anchor Bolt Data Eccentricities and Bearing Lengths Bearing Pressure Check Plate Thk. Check Bolt Tension Check Bolt Shear Check Interaction

LOCATION SIZE Axial Shear Moment Axial Shear Moment Length Width Thickness Length Width Total No. Diameter Edge Dist. Edge Dist. Eccentricity Brg. Length Eccentricity Brg. Length fp(max) Fp S.R. = tp S.R. = Tb Ta S.R. = Vb Va S.R. = S.R. =

P V M P V M N B tp Lpx Lpy Nb db ED1 ED2 e(case 1) Xc(case 1) e(case 2) Xc(case 2) (actual) (allowable) fp(max)/Fp (req'd) tp(req'd)/tp (actual) (allowable) Tb/Ta (actual) (allowable) Vb/Va Tb/Ta +

(kips) (kips) (ft-kips) (kips) (kips) (ft-kips) (in.) (in.) (in.) (in.) (in.) (in.) (in.) (in.) (in.) (in.) (in.) (in.) (ksi) (ksi) (in.) (kips) (kips) (kips) (kips) C*Vb/Va

A-1 W10x100 -525.00 0.00 0.00 -525.00 0.00 0.00 19.000 17.000 2.000 28.000 28.000 4 1.000 1.500 1.500 0.000 19.000 0.000 19.000 1.625 1.636 0.994 1.861 0.931 0.00 15.00 0.000 0.00 7.78 0.000 ---A-2 W12x106 -600.00 0.00 0.00 -600.00 0.00 0.00 19.000 16.000 1.750 34.000 34.000 4 1.000 1.500 1.500 0.000 19.000 0.000 19.000 1.974 2.048 0.964 1.579 0.902 0.00 15.00 0.000 0.00 7.78 0.000 ---A-3 W10x100 -360.00 20.00 60.00 -360.00 20.00 60.00 19.000 17.000 2.000 36.000 36.000 4 1.250 2.000 2.000 2.000 19.000 2.000 19.000 1.818 2.100 0.866 1.845 0.922 0.00 23.44 0.000 5.00 12.15 0.412 ---A-4 W14x90 -130.00 20.00 59.58 -130.00 20.00 59.58 28.750 24.000 1.750 36.000 36.000 4 1.250 2.000 2.000 5.500 26.641 5.500 26.641 0.407 1.439 0.283 1.561 0.892 0.02 23.44 0.001 5.00 12.15 0.412 0.762 A-5 W14x90 -130.00 20.00 175.00 -130.00 20.00 175.00 28.750 24.000 2.500 36.000 36.000 6 1.750 2.500 2.500 16.154 15.532 16.154 15.532 0.928 1.439 0.645 2.265 0.906 14.30 45.94 0.311 3.33 23.81 0.140 0.570 A-6 W14x90 0.00 20.00 175.00 0.00 20.00 175.00 28.750 24.000 2.250 36.000 36.000 6 2.000 2.750 2.750 (Infinite) 10.602 (Infinite) 10.602 0.735 1.439 0.511 2.161 0.961 31.16 60.00 0.519 3.33 31.10 0.107 0.718 A-7 W14x90 150.00 0.00 0.00 150.00 0.00 0.00 28.750 24.000 2.250 36.000 36.000 6 1.375 2.000 2.000 0.000 0.000 0.000 0.000 0.000 1.439 0.000 2.132 0.947 25.00 28.36 0.881 0.00 14.70 0.000 ---A-8 W14x90 150.00 5.00 50.00 150.00 5.00 50.00 28.750 24.000 2.500 36.000 36.000 6 1.750 2.500 2.500 4.000 0.000 4.000 0.000 0.000 1.439 0.000 2.314 0.925 33.42 45.94 0.727 0.83 23.81 0.035 0.792 A-9 W14x90 130.00 20.00 175.00 130.00 20.00 175.00 28.750 24.000 2.750 36.000 36.000 6 2.250 3.500 3.500 16.154 5.762 16.154 5.762 0.425 1.439 0.296 2.541 0.924 53.14 75.94 0.700 3.33 39.36 0.085 0.856

be ED2

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2

3

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Profile

A

d

Tw

cm^2

in^2

mm

inch

mm

inch

HE100AA

15.6 2.4180

91 3.5827

4.2 0.1654

HE140AA

23.0000

3.5650

128.0000

5.0394

4.3000

0.1693

HE140AA

44.1000

6.8355

186.0000

7.3228

5.5000

0.2165

HE120A

25.3000

3.9215

114.0000

4.4882

5.0000

0.1969

HE220A

64.3000

9.9665

210.0000

8.2677

7.0000

0.2756

HE240A

76.8000

11.9040

230.0000

9.0551

7.5000

0.2953

HE260A

86.8000

13.4540

250.0000

9.8425

7.5000

0.2953

HE300A

113.0000

17.5150

290.0000

11.4173

8.5000

0.3346

HE320A

124.0000

19.2200

310.0000

12.2047

9.0000

0.3543

HE360A

143.0000

22.1650

350.0000

13.7795

10.0000

0.3937

HE400A

159.0000

24.6450

390.0000

15.3543

11.0000

0.4331

HE400B

198.0000

30.6900

400.0000

15.7480

13.5000

0.5315

HE600B

270.0000

41.8500

600.0000

23.6220

15.5000

0.6102

PIPX100

16.1000

10.7500

0.5000

PIPX120

19.2000

12.7500

0.5000

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