Base Plate Verification Example - asdip Plate Verification... · V / Vn/Ω Shear Design Ratio ........

60 / DESIGN GUIDE 1, 2ND EDITION / BASE PLATE AND ANCHOR ROD DESIGN

2. Assume a 14-in. 14-in. base plate. The effective ec-centricity is

Then, e > ekern; therefore, anchor rods are required to resist the tensile force. The anchor rods are assumed to be 1.5 from the plate edge.

3. Determine the length of bearing.

thus,

8. Determine required plate thickness:

Note: Since the Mpl is expressed in units of kip-in./in., the plate thickness expressions can be formatted with-out the plate width (B) as such:

9. Use plate size:

N = 19 in.

B = 19 in.

t = 14 in.

B.5.2 Example: Large Moment Base Plate Design, Triangular Pressure Distribution Approach

Design the base plate shown in Figure B.4 for an ASD and LRFD required strength of 60 and 90 kips, respectively, and moments from the dead and live loads equal to 480 and 720 kip-in., respectively. The ratio of the concrete to base plate area (A2/A1) is 4.0. Bending is about the strong axis for the wide flange column W831 with d = bf = 8 in.; Fy of the base plate and anchor rods is 36 ksi and fc of the concrete is 3 ksi.

1.

LRFD ASD

tM

Fu requ crit

y

kip-in.

ksi in.

=

=

=

4

4 11 1

0 90 361 17

.

..

tM

Fa reqa crit

y

kip-in.

ksi in.

=

=

=

4

4 7 68 1 67

361 19

. .

.

LRFD ASD

P

M

P

A

u

u

p

=

=

=

90

720

0 60 0 85 3 0 2

0 60 1 71

kips

kip-in.

. ( . )( . )( )

. ( . )(( . )3 0

P

M

P

A

a

a

p

=

=

=

60

480

0 85 3 0 2

2 50

1 7 3 01

kips

kip-in.

( . )( . )( )

.

( . )( . ))

.

.

2 50

2 041

P

Ap

= ksi

LRFD ASD

e = 720 kip-in./90 kips = 8.00 in. e = 480 kip-in./60 kips = 8.00 in.

Figure B.4. Design example with large eccentricity.

LRFD ASD

=

=

f3 06 14 12 5

2268

. . ksi in. in.

kips

=

=

f 2 04 14 12 5

2178

. . ksi in. in.

kips

LRFD ASD

A=

( )+

268268 4

3 06 146

90 5 5 720

3 06 143

2 .

.

.

= in.5 27.

A=

( )+

178178 4

2 04 146

60 5 5 480

2 04 143

2 .

.

.

= in.5 27.

PA

p

1

3 06= . ksi

AISC Design Guide 1, 2nd EditionBase Plate and Anchor Rod Design

Verification Example

DESIGN GUIDE 1, 2ND EDITION / BASE PLATE AND ANCHOR ROD DESIGN / 61

Anchor rods are placed at a 12-in. edge distance. The required moment strength, Mu pl or Ma pl, for a 1-in. strip of plate due to the tension in the anchor rods is

The required moment strength due to the bearing stress distribution is critical.

The required plate thickness is:

Use a 14 14 1-in. base plate.

4. Determine the required tensile strength of the anchor rod.

5. Determine the required plate thickness.

The moment for this determination is to be taken at the critical plate width. This is determined by assuming that the load spreads at 45 to a location 0.95d of the col-umn. The width is then taken as twice the distance from the bolt to the critical section for each bolt, provided that the critical section does not intersect the edge of the plate.

The critical section, as shown in Figure B.5, is at 14 0.95(8)/2 = 3.2 in.

The required moment strength, Mu pl or Ma pl, for a 1-in. strip of plate, determined from the bearing stress distri-bution in Figure B.4, is

LRFD ASD

T

T T

u

rod u

=

== =

3.06 ksi 5.27 in. 14 in. kips

kips2

90

22 8

2 11

.

/ ..4 kips

T

T T

a

rod a

=

== =

2.04 ksi 5.27 in. 14 in. kips

kips2

60

15 2

2 7

.

/ .660 kips

LRFD ASD

Mu pl =( )

+

1 20 3 2

2

3 06 1 20

2

23

. .

( . . )

ksi in.

ksi ksi ( . )3 2

2

2 in.

= 12.5 in-kips/in.

Ma pl ksi in.

ksi ksi

=( )

+

0 80 3 2

2

2 04 0 80

2

23

. .

( . . )) ( . ) 3 22

2 in.

= 8.33 in-kips/in.

LRFD ASD

M u pl =

kips in. in.

in in.

22 8 3 2 1 5

2 3 2 1 5

. ( . . )

( . . . )

in.-kips/in.=11 4.

M a pl =

=

kips in. in.

in. in.

i

15 2 3 2 1 5

2 3 2 1 5

7 60

. ( . . )

( . . )

. nn.-kips/in.

LRFD ASD

t p = =

4 12 5

0 90 361 24

( . )

..

in.-kips

ksi in. t p = =

4 8 33 1 67

361 24

( . )( . ).

in.-kips

ksi

Figure B.5. Critical plate width for anchor bolt (tension side).

Project:

Engineer:

Descrip:


Javier Encinas, PE

Base Plate Verification

Page # ___

7/20/2014

ASDIP Steel 3.2.5 STEEL BASE PLATE DESIGN www.asdipsoft.com

GEOMETRY

Column Section .................

Width Length

Column ..........

Plate ..............

ConcreteSupport

Rod Offset .....

Thickness of Grout ............

Wp1

Wp2

Lp1

Lp2

W8X31

8.0 8.0

14.0 14.0

14.0 14.0

14.0 14.0

5.5 5.5

1.5

in

in

in

in

in

in

OK

OK

OK

OK

SERVICE LOADS (ASD)

Vertical Load P ................

Bending Moment M .........

Horizontal Load V ............

Design Eccentricity e .......

Design Eccentricity Is > L/2

60.0

40.0

0.0

8.0

kip

k-ft

kip

in

MATERIALS

Plate Steel Strength Fy ....

Pier Concrete Strength f'c

36.0

3.0

ksi

ksi

AXIALLY LOADED PLATES

Cantilever Model

Bearing Stress fp .............

Critical Section @ Long m

Critical Section @ Short n

Plate Thickness tp ..........

0.31

3.20

3.80

0.64

ksi

in

in

in

OK

Thornton Model

Bearing Strength Fp/ .....

Critical Section @ Int n' .

Design Moment @ Plate ...

Plate Thickness tp ............

2.04

0.81

0.10

0.14

ksi

in

k-in/in

in

BASE PLATES WITH MOMENT

Blodgett Method

Max. Bearing Stress fp ......

Bearing @ Critical Section

Moment @ Critical Section

Moment due to Rod Tension

Design Moment @ Plate ....

Plate Thickness tp .............

1.64

0.88

7.11

4.86

7.11

1.15

ksi

ksi

k-in/in

k-in/in

k-in/in

in

OK

DeWolf Method

Max. Bearing Stress fp ......

Bearing @ Critical Section

Moment @ Critical Section

Moment due to Rod Tension

Design Moment @ Plate ....

Plate Thickness tp .............

2.04

0.80

8.34

3.86

8.34

1.24

ksi

ksi

k-in/in

k-in/in

k-in/in

in

OK

1

Project:

Engineer:

Descrip:


Javier Encinas, PE


Page # ___

7/20/2014


ANCHORAGE DESIGN

Rod Material Specification .........

Anchor Rod Size ..

F1554-36

(4) Rods , fya = 36.0 ksi, futa = 58.0 ksi

1" diam. x 16.0 in emb.

Concrete Is Cracked at Service Load Level

Tension Analysis (kip)

Total Tension Force N ..........

Tension Force per Rod Ni ....

Anchor Reinf: Use 2 Bars #5 per Rod

15.4

7.7

kip

kip

Failure Mode Nn N / Nn/

Steel Strength Nsa

Rebars Strength Nrg

Conc. Breakout Ncbg

Pullout Strength Npn

Side Blowout Nsbg

N / Nn/ Tension Design Ratio .... OK

2.00

2.00

2.00

2.00

2.00

35.1

74.4

N.A.

36.0

N.A.

0.44

0.41

N.A.

0.43

N.A.

0.44

Shear Analysis (kip)

Shear Taken by Anchor Rods only

Total Shear Force V ........... 0.0 kip

Shear Force per Rod Vi ...... 0.0 kip

All Anchor Rods Are Effective

No Reinforcing Bars Provided

Failure Mode Vn V / Vn/

Steel Strength Vsa

Rebars Strength Vrg

Conc. Breakout Vcbg

Conc. Pryout Vcpg

2.31

2.31

2.14

2.14

16.9

N.A.

11.9

52.8

0.00

N.A.

0.00

0.00

0.00V / Vn/ Shear Design Ratio ...... OK

Tension-Shear Interaction

Combined Stress Ratio ........... 0.25 OK

SUMMARY OF RESULTS

Design Moment @ Plate ...

Plate Thickness tp ............

Max. Bearing Stress fp .....

Bearing Strength Fp/ ......

fp / Fp/ Design Ratio ..............

8.3

1.24

2.04

2.04

1.00

k-in/in

in

ksi

ksi

OK

DESIGN IS DUCTILE

DESIGN CODES

Steel design .............

Base plate design ....

Anchorage design ...

AISC 360-10 (14th Ed.)

AISC Design Series # 1

ACI 318-11 Appendix D

2

Project:

Engineer:

Descrip:


Javier Encinas, PE


Page # ___

7/20/2014


Tension Breakout Shear Breakout

3

Project:

Engineer:

Descrip:


Javier Encinas, PE


Page # ___

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Column Section .................

Width Length

Column ..........

Plate ..............

Concrete

Support

Rod Offset .....

Thickness of Grout ............

Wp1

Wp2

Lp1

Lp2

in

in

in

in

in

in

OK

OK

OK

OK

Vertical Load P ................

Bending Moment M .........

Horizontal Load V ............

Design Eccentricity e .......

Design Eccentricity Is > L/2

8.0

kip

k-ft

kip

in

Plate Steel Strength Fy ....

Pier Concrete Strength f'c

ksi

ksi

Bearing stress 60.0 / (14.0 * 14.0) = 0.3 ksi

Bearing strength = 0.85 * 3.0 * = 5.1 ksi ACI 10.14.1

Under-strength factor = 2.50 ACI 9.3.2.4

Bearing strength ratio = =0.3

2.0 / 2.50= 0.15 < 1.0 OK

Critical section m =

Critical section n =

0.5 * (14.0 - 0.95 *8.0) = 3.2 in

0.5 * (14.0 - 0.80 *8.0) = 3.8 in

AISC-DG#1 3.1.2

[4 * 8.0 * 8.0

(8.0 + 8.0)] * 0.15 = 0.15 AISC-DG#1 3.1.2

=+ -

= 0.40

= = 2.0 in

Controlling section Max (3.2, 3.8, 0.40 * 2.0) = 3.8 in

Plate moment 0.3 * 3.8 / 2 = 2.2 k-in/in

Plate thickness = 3.8 * = 0.64 in AISC-DG#1 3.1.2

1

Project:

Engineer:

Descrip:


Javier Encinas, PE


Page # ___

7/20/2014


Eccentricity 40.0 * 12 / 60.0 = 8.0 in > L / 6 = 14.0 / 6 = 2.3in

Bearing length

Y = 1.5 * (14.0 / 2 + 5.5) - 0.5 * [ + ] - = 5.3 in AISC-DG#1 B.4.2

Max bearing stress 2.0 ksi

Tension 2.0 * 5.3 * 14.0 / 2 - 60.0 = 15.4 kip AISC-DG#1 B.4.2

Bearing at critical section 2.0 * (1 - 3.2 / 5.3) = 0.8 ksi

Moment due to bearing

Mb = 0.8 * 3.2 / 2 + (2.0 - 0.8) * 3.2 / 3 = 8.3 k-in/in

Moment due to tension

Mt = 7.7 * [3.2 - (14.0 / 2 - 5.5)] / [2 * (3.2 - (14.0 / 2 - 5.5))] = 3.9 k-in/in

Plate thickness = = 1.24 in

AISC-DG#1 3.1.2

2

Project:

Engineer:

Descrip:


Javier Encinas, PE


Page # ___

7/20/2014


Rod Material Specification ...... F1554-36 , Use (4) Rods , fya = 36.0 ksi, futa = 58.0 ksi

Anchor Rod Size .... 1" diam. x 16.0 in emb. , Ase = 0.61 in , Abrg = 1.50 in

ACI D.5

Total tension force N = 15.4 kip , # of tension rods = 2 , Tension force per rod Ni = 7.7 kip

- Steel strength of anchors in tension ACI D.5.1

Steel strength 0.606 * 58.0 = 35.1 kip ACI Eq. (D-2)

Under-strength factor = 2.00 ACI D.4.3

Steel strength ratio = =7.7

35.1 / 2.00= 0.44 ACI D.4.1.1< 1.0 OK

- Concrete breakout strength of anchors in tension ACI D.5.2

Anchor reinforcement: Use 2 bars #5 per rod

Bar strength 0.31 * 2 * 2 * 60 = 74.4 kip

Under-strength factor = 2.00 ACI D.5.2.9

Bar strength ratio = =15.4

74.4 / 2.00= 0.41 ACI D.4.1.1< 1.0 OK

Effective embedment 19.50 / 1.5 = 13.00 in ACI D.5.2.3

Anchor group area

Anc = (19.5 + 8.5) * (8.5 + 11.0 + 8.5) = 784.0 in ACI D.5.2.1

Single anchor area 9 * (13.0) = 1521.0 in Eq. (D-5)

Single anchor strength = 24 = 61.6 kip Eq. (D-6)

Eccentricity factor 1.00 (No eccentric load) ACI D.5.2.4

Edge effects factor = 0.7 + 0.38.5

1.5 * 13.0= 0.83 ACI D.5.2.5

Cracking factor 1.00 (Cracked concrete at service load level) ACI D.5.2.6

Breakout strength

784.0

1521.01.00 * 0.83 * 1.00 * 61.6 = 26.4 kip Eq. (D-4)


Breakout strength ratio = =15.4

26.4 / 2.00= 1.17 ACI D.4.1.1> 1.0 NG

Bar strength ratio controls (0.41 < 1.17) ACI D.5.2.9

- Concrete pullout strength of anchors in tension ACI D.5.3

Single anchor strength 8 * 1.50 * 3.0 = 36.0 kip ACI Eq. (D-14)


Pullout strength 1.00 * 36.0 = 36.0 kip ACI Eq. (D-13)


Pullout strength ratio = =7.7

36.0 / 2.00= 0.43 ACI D.4.1.1< 1.0 OK

3

Project:

Engineer:

Descrip:


Javier Encinas, PE


Page # ___

7/20/2014


- Concrete side-face blowout strength of anchors in tension ACI D.5.4

Side-face blowout Nsbg = N.A. (Embed < 2.5 Ca , 16.0 < 2.5 * 8.5 = 21.3) ACI D.5.4.1

Tension Design Ratio = = 0.44 < 1.0 OK ACI D.4.1.1

ACI D.5

Shear resisted by Anchor Rods only

Total shear force V = 0.0 kip , Shear per rod Vi = 0.0 kip ,

(anchor rods are welded to the base plate)

(all anchor rods are effective)

- Steel strength of anchor rods in shear

Steel strength 0.6 * 0.61 * 58.0 * 0.80 = 16.9 kip ACI D.6.1.2


Steel strength ratio = =0.0

16.9 / 2.31= 0.00 < 1.0 OK ACI D.4.1.1

- Concrete breakout strength of anchors in shear ACI D.5.2

No Reinforcing bars provided

Anchor group area

Avc = (1.5 * 8.00) * (8.50 + 11.00 + 8.50) = 336.0 in ACI D.6.2.1

Single anchor area 4.5 * (8.00) = 288.0 in Eq. (D-32)

Single anchor strength

Vb = Vb = 11.2 kip Eq. (D-33)

Eccentricity factor 1.00 (No eccentric load) ACI D.6.2.5

Edge effects factor = 0.7 + 0.38.50

1.5 * 8.0= 0.91 ACI D.6.2.6


Thickness factor ACI D.6.2.8

Breakout strength

336.0

288.01.00 * 0.91 * 1.00 * 1.00 * 11.2 = 11.9 kip Eq. (D-31)


Breakout strength ratio = =0.0

11.9 / 2.14= 0.00 < 1.0 OK ACI D.4.1.1

Breakout strength ratio controls (0.00 < 0.00) ACI D.6.2.9

4

Project:

Engineer:

Descrip:


Javier Encinas, PE


Page # ___

7/20/2014


- Concrete pryout strength of anchors in shear

Pryout strength 2.0 * 11.9 = 52.8 kip ACI D.6.3.1


Pryout strength ratio = =0.0

52.8 / 2.14= 0.00 < 1.0 OK ACI D.4.1.1

Shear Design Ratio = = 0.00 < 1.0 OK ACI D.4.1.1

Combined Stress Ratio =

Combined Stress Ratio = + = 0.25 < 1.0 OK ACI RD.7

Anchorage design is ductile

Steel design ...................

Base plate design ..........

Anchorage design .........

AISC 360-10 (14th Ed.)

AISC Design Series # 1

ACI 318-11 Appendix D

5

Base Plate Verification Example - asdip Plate Verification... · V / Vn/Ω Shear Design Ratio ........

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