Anchor Bolt Design Spreadsheet Anchor Reinforcement ACI318-08 Appendix D ACI 349-06 CSA-A23.3-04 Annex D Concrete Anchorage CCD Method Shear Lug Shear Key Base Plate Anchor Stud

Anchorage to concrete Concrete Capacity Design (CCD) Method was first introduced in ACI 318-02 and ACI 349-01 Appendix D, followed by CSA A23.3-04 Annex D. Anchorage design provisions in ACI 318-08 and ACI 349-06 Appendix D, CSA A23.3-04 Annex D are similar except that ACI 349-06 imposes a more severe penalty on non-ductile anchor design (ACI 349-06 D3.6.3) and also ACI 349-06 provides additional provisions for shear transfer using friction and shear lugs.

Since ACI 318-02 the ACI has released ACI 318-05, ACI 318-08, and recently ACI 318-11. In ACI 318-08 the definition for Anchor Reinforcement is introduced, and the strength of Anchor Reinforcement used to preclude concrete breakout in tension and in shear is codified (ACI 318-08 D.5.2.9 and D.6.2.9.), guidance for detailing the Anchor Reinforcement is given in ACI 318-08 RD.5.2.9 and RD.6.2.9.

Since CSA A23.3-04 CSA has released several updates to catch up ACI’s revisions on anchorage design, with the latest CSA A23.3-04 (R2010, Reaffirmed 2010) partially incorporated Anchor Reinforcement (CSA A23.3-04 R2010 D.7.2.9). It’s expected that the same Anchor Reinforcement provisions as ACI 318-08 will be amended in the next revision of CSA A23.3-04 update.

This technical writing includes a series of design examples covering mainly the anchorage design of grouped anchors and studs, in both ACI 318-08 and CSA A23.3-04 R2010 code. The design examples are categorized in Anchor Bolt and Anchor Stud, with Anchor Reinforcement and without Anchor Reinforcement, with moment presence and without moment presence.

Anchor Bolt and Anchor Stud

The main difference between anchor bolt and anchor stud is the way how they attach to the base plate. For anchor bolt normally the anchor bolt holes on base plate are much bigger than anchor bolt diameter due to cast-in anchor bolt construction tolerance, while the anchor stud is rigidly welded to the base plate. This different approach of attachment will cause the difference on shear transfer mechanism during anchorage design (ACI 318-08 RD.6.2.1(b)).

Anchor Reinforcement and Supplementary Reinforcement

In all concrete failure modes, the tensile and shear concrete breakout strengths are most of the time the lowest strengths among all concrete failure modes. The concrete breakout strength limits the anchor design strength and make anchor bolt design not practical in many applications such as concrete pedestal, which has limited edge distances surrounding anchor bolts.

In ACI 318-08 the definition for Anchor Reinforcement is introduced, and the strength of Anchor Reinforcement used to preclude concrete breakout in tension and in shear is codified (ACI 318-08 D.5.2.9 and D.6.2.9.), guidance for detailing the Anchor Reinforcement is given in ACI 318-08 RD.5.2.9 and RD.6.2.9. The use of Anchor Reinforcement in many times is the only choice to make a practical anchor bolt design in applications such as concrete pedestal.

Anchor Reinforcement for Tension ACI 318-08 RD.5.2.9	Anchor Reinforcement for Shear ACI 318-08 RD.6.2.9

The use of supplementary reinforcement is similar to the anchor reinforcement, but it isn't specifically designed to transfer loads. If supplementary reinforcement is used, the concrete strength reduction factor f is increase 7% from 0.70 to 0.75, which is not that significant in terms of increasing concrete breakout strength.

Supplementary Reinforcement ACI 318-08 Condition B

Supplementary Reinforcement ACI 318-08 Condition A

Anchor Ductility

When an anchor’s overall design strength, for both tension and shear, is equal to the design strength of anchor rod steel element, and all potential concrete failure modes have design strengths greater than the anchor rod steel element design strength, this anchor design is considered as ductile anchor design.

Anchor’s ductility is its own characteristic related to anchor rod material, embedment depth, anchor bolt spacing and edge distances etc, and has nothing to do with the applied loadings. If high strength anchor rod material is used, it would be more difficult to achieve the ductile design as deeper embedment depth, larger edge distances are required for concrete failure modes design strengths to surpass anchor rod material design strength. The high strength anchor bolt material shall only be used when it’s necessary, such as for anchorages required pre-tensioned or subjected to dynamic impact load in cold temperature environment (A320 Grade L7). In most cases the anchorage design won’t benefit from the high strength bolt material as the concrete failure modes will govern, and the use of high strength bolt will make the anchor ductile design almost impossible.

For anchorage design in moderate to high seismic zone (ACI 318-08 SDC>=C and CSA A23.3-04 R2010 I_EF_aS_a(0.2)>=0.35) ductile anchor design is mandatory as specified in ACI 318-08 D.3.3.4 and CSA A23.3-04 R2010 D.4.3.6.

For anchorage design in low seismic zone (ACI 318-08 SDC<C and CSA A23.3-04 R2010 I_EF_aS_a(0.2)<0.35), the non-ductile anchor design is permitted, but when calculating anchor bolt force distribution, the plastic analysis approach is not permitted for non-ductile anchor as specified in ACI 318-08 D.3.1 and CSA A23.3-04 R2010 D.4.1.

2.0 DESIGN EXAMPLES

Example 01: Anchor Bolt + Anchor Reinft + Tension & Shear + ACI 318-08 Code

N_u= 20 kips ( Tension ) V_u = 25 kips

Concrete f_c’= 4 ksi Rebar f_y= 60 ksi

Pedestal size 16” x 16”

Anchor bolt F1554 Grade 36 1.0” dia Hex Head h_ef= 55” h_a =60”

Seismic design category >= C

Anchor reinforcement Tension à 8-No 8 ver. bar

Shear à 2-layer, 4-leg No 4 hor. bar

Provide built-up grout pad

Example 02: Anchor Bolt + Anchor Reinft + Tension & Shear + CSA A23.3-04 Code

N_u= 89 kN ( Tension ) V_u = 111.2 kN

Concrete f_c’= 27.6 MPa Rebar f_y= 414 MPa

Pedestal size 406mm x 406mm

Anchor bolt F1554 Grade 36 1.0” dia Hex Head h_ef= 1397mm h_a =1524mm

Seismic design I_EF_aS_a(0.2) >= 0.35

Anchor reinforcement Tension à 8-25M ver. bar

Shear à 2-layer, 4-leg 15M hor. bar

Provide built-up grout pad

Example 03: Anchor Bolt + Anchor Reinft + Tension Shear & Moment + ACI 318-08 Code

M_u = 35 kip-ft N_u= 10 kips (Compression) V_u = 25 kips

Concrete f_c’= 4 ksi Rebar f_y= 60 ksi

Pedestal size 26” x 26”

Anchor bolt F1554 Grade 36 1.25” dia Hex Head h_ef= 55” h_a =60”

Seismic design category < C

Anchor reinforcement Tension à 2-No 8 ver. bar

Shear à 2-layer, 2-leg No 4 hor. bar

Provide built-up grout pad

Example 04: Anchor Bolt + Anchor Reinft + Tension Shear & Moment + CSA A23.3-04 Code

M_u = 47.4 kNm N_u= -44.5 kN (Compression) V_u = 111.2 kN

Concrete f_c’= 27.6 MPa Rebar f_y= 414 MPa

Pedestal size 660mm x 660mm

Anchor bolt F1554 Grade 36 1.25” dia Hex Head h_ef= 1397mm h_a =1524mm

Seismic design I_EF_aS_a(0.2) < 0.35

Anchor reinforcement Tension à 2-25M ver. bar

Shear à 2-layer, 2-leg 15M hor. bar

Provide built-up grout pad

Example 11: Anchor Bolt + No Anchor Reinft + Tension & Shear + ACI 318-08 Code

This example taken from Example 8 on page 71 of ACI 355.3R-11 Guide for Design of Anchorage to Concrete: Examples Using ACI 318 Appendix D

N_u = 12 kips (tension), V_u=4 kips, f_c’ = 3 ksi

Anchor bolt d_a=3/4 in ASTM F1554 Grade 55 h_ef =12 in h_a=24 in Anchor head à Hex

Supplementary reinforcement Tension à Condition B Shear à Condition A Y_c,V =1.2

Provide built-up grout pad Seismic is not a consideration

Field welded plate washers to base plate at each anchor

Example 12: Anchor Bolt + No Anchor Reinft + Tension & Shear + CSA A23.3-04 Code

This example taken from Example 8 on page 71 of ACI 355.3R-11 Guide for Design of Anchorage to Concrete: Examples Using ACI 318 Appendix D

N_u = 53.4 kN (tension), V_u=17.8 kN, f_c’ = 20.7 MPa

Anchor bolt d_a=3/4 in ASTM F1554 Grade 55 h_ef =305mm h_a=610mm Anchor head à Hex

Supplementary reinforcement Tension à Condition B Shear à Condition A Y_c,V =1.2

Provide built-up grout pad Seismic is not a consideration

Field welded plate washers to base plate at each anchor

Example 13: Anchor Bolt + No Anchor Reinft + Tension Shear & Moment + ACI 318-08 Code

M_u = 25 kip-ft N_u= 10 kips (Compression) V_u = 10 kips

Concrete f_c’= 5 ksi

Anchor bolt F1554 Grade 36 1.25” dia Heavy Hex Head h_ef= 16” h_a =20”

Oversized holes in base plate

Seismic design category < C

Supplementary reinforcement Tension à Condition A

Shear à Condition A Y_c,V = 1.2

Provide built-up grout pad

Example 14: Anchor Bolt + No Anchor Reinft + Tension Shear & Moment + CSA A23.3-04 Code

M_u = 33.9 kNm N_u= 44.5 kN (Compression) V_u = 44.5 kN

Concrete f_c’= 34.5 MPa

Anchor bolt F1554 Grade 36 1.25” dia Heavy Hex Head h_ef= 406mm h_a =508mm

Oversized holes in base plate

Seismic design I_EF_aS_a(0.2) < 0.35

Supplementary reinforcement Tension à Condition A

Shear à Condition A Y_c,V = 1.2

Provide built-up grout pad

Example 21: Welded Stud + Anchor Reinft + Tension & Shear + ACI 318-08 Code

N_u= 20 kips ( Tension ) V_u = 25 kips

Concrete f_c’= 4 ksi Rebar f_y= 60 ksi

Pedestal size 16” x 16”

Anchor stud AWS D1.1 Grade B 1.0” dia h_ef= 55” h_a =60”

Seismic design category >= C

Anchor reinforcement Tension à 8-No 8 ver. bar

Shear à 2-layer, 4-leg No 4 hor. bar

No built-up grout pad for embedded plate.

Note: The stud length used in this example may not be commercially available and it’s for illustration purpose only.

Deep anchor stud embedment h_ef is required for anchor reinforcement to develop resistance on both sides of the

failure plane.

Example 22: Welded Stud + Anchor Reinft + Tension & Shear + CSA A23.3-04 Code

N_u= 89 kN ( Tension ) V_u = 111.2 kN

Concrete f_c’= 27.6 MPa Rebar f_y= 414 MPa

Pedestal size 406mm x 406mm

Anchor stud AWS D1.1 Grade B 1.0” dia h_ef= 1397mm h_a =1524mm

Seismic design I_EF_aS_a(0.2) >= 0.35

Anchor reinforcement Tension à 8-25M ver. bar

Shear à 2-layer, 4-leg 15M hor. bar

No built-up grout pad for embedded plate.

Note: The stud length used in this example may not be commercially available and it’s for illustration purpose only.

Deep anchor stud embedment h_ef is required for anchor reinforcement to develop resistance on both sides of the

failure plane.

Example 23: Welded Stud + Anchor Reinft + Tension Shear & Moment + ACI 318-08 Code

M_u = 35 kip-ft N_u= 10 kips (Compression) V_u = 25 kips

Concrete f_c’= 4 ksi Rebar f_y= 60 ksi

Pedestal size 26” x 26”

Anchor stud AWS D1.1 Grade B 1.0” dia h_ef= 55” h_a =60”

Seismic design category < C

Anchor reinforcement Tension à 2-No 8 ver. bar

Shear à 2-layer, 2-leg No 4 hor. bar

No built-up grout pad for embedded plate.

Note: The stud length used in this example may not be commercially available and it’s for illustration purpose only.

Deep anchor stud embedment h_ef is required for anchor reinforcement to develop resistance on both sides of the

failure plane.

Example 24: Welded Stud + Anchor Reinft + Tension Shear & Moment + CSA A23.3-04 Code

M_u = 47.4 kNm N_u= 44.5 kN (Compression) V_u = 111.2 kN

Concrete f_c’= 27.6 MPa Rebar f_y= 414 MPa

Pedestal size 660mm x 660mm

Anchor stud AWS D1.1 Grade B 1.0” dia h_ef= 1397mm h_a =1524mm

Seismic design I_EF_aS_a(0.2) < 0.35

Anchor reinforcement Tension à 2-25M ver. bar

Shear à 2-layer, 2-leg 15M hor. bar

No built-up grout pad for embedded plate.

Note: The stud length used in this example may not be commercially available and it’s for illustration purpose only.

Deep anchor stud embedment h_ef is required for anchor reinforcement to develop resistance on both sides of the

failure plane.

Example 31: Welded Stud + No Anchor Reinft + Tension & Shear + ACI 318-08 Code

N_u= 20 kips (Tension) V_u = 10 kips

Concrete f_c’= 4.5 ksi

Anchor stud AWS D1.1 Grade B 1.0” dia h_ef= 12” h_a =15”

Seismic design category < C

Supplementary reinforcement Tension à Condition A

Shear à Condition A Y_c,V = 1.2

No built-up grout pad for embedded plate.

Note: The stud length used in this example may not be commercially available and it’s for illustration purpose only.

Example 32: Welded Stud + No Anchor Reinft + Tension & Shear + CSA A23.3-04 Code

N_u= 89 kN (Tension) V_u = 44.5 kN

Concrete f_c’= 31 MPa

Anchor stud AWS D1.1 Grade B 1.0” dia h_ef= 305mm h_a =381mm

Seismic design I_EF_aS_a(0.2) < 0.35

Supplementary reinforcement Tension à Condition A

Shear à Condition A Y_c,V = 1.2

No built-up grout pad for embedded plate.

Note: The stud length used in this example may not be commercially available and it’s for illustration purpose only.

Example 33: Welded Stud + No Anchor Reinft + Tension Shear & Moment + ACI 318-08 Code

This example taken from Example 10 on page 82 of ACI 355.3R-11 Guide for Design of Anchorage to Concrete: Examples Using ACI 318 Appendix D

M_u = 30 kip-ft N_u = 0 kips, V_u=20 kips, f_c’ = 4.5 ksi

Anchor stud d_a=7/8 in h_ef =9 in h_a=18 in

Supplementary reinforcement Tension à Condition B Shear à Condition A Y_c,V =1.2

Provide built-up grout pad Seismic is not a consideration

Field welded plate washers to base plate at each anchor

Notes:

There are two locations in this calculation which are different from calculation in ACI 355.3R-11 Example 10

1. Concrete tension breakout A_Nc = 1215 in², different from A_Nc = 1519 in² , value in ACI 355.3R-11 page 86.

We assume the moment may apply in both directions. When moment causes tensile anchors being close to the edge

side, the A_Nc value is consequently reduced.

2. Concrete shear breakout c_a1 reduction from 27” to 12” in ACI 355.3R-11 page 90 is not correct. It doesn't comply with both edge distances c_a2,1<1.5c_a1 and c_a2,2<1.5c_a1 . Refer to ACI 318-11 Fig. RD.6.2.4 for more details.

Example 34: Welded Stud + No Anchor Reinft + Tension Shear & Moment + CSA A23.3-04 Code

This example taken from Example 10 on page 82 of ACI 355.3R-11 Guide for Design of Anchorage to Concrete: Examples Using ACI 318 Appendix D

M_u = 40.7 kNm N_u = 0 kN, V_u=89 kN, f_c’ = 31 MPa

Anchor stud d_a=7/8 in h_ef =229mm h_a=457mm

Supplementary reinforcement Tension à Condition B Shear à Condition A Y_c,V =1.2

Provide built-up grout pad Seismic is not a consideration

Field welded plate washers to base plate at each anchor

Notes:

There are two locations in this calculation which are different from calculation in ACI 355.3R-11 Example 10

1. Concrete tension breakout A_Nc = 1215 in², different from A_Nc = 1519 in² , value in ACI 355.3R-11 page 86.

We assume the moment may apply in both directions. When moment causes tensile anchors being close to the edge

side, the A_Nc value is consequently reduced.

Example 41: Shear Lug Design ACI 349-06 Code

Example 42: Shear Lug Design ACI 349M-06 Code

Example 51: Base Plate (LRFD) & Anchor Bolt (ACI 318-08) Design With Anchor Reinforcement

Example 52: Base Plate (S16-09) & Anchor Bolt (CSA A23.3-04) Design With Anchor Reinforcement

3.0 REFERENCES

1. ACI 318-08 Building Code Requirements for Structural Concrete and Commentary

2. ACI 318M-08 Metric Building Code Requirements for Structural Concrete and Commentary

3. ACI 349-06 Code Requirements for Nuclear Safety-Related Concrete Structures & Commentary

4. ACI 349.2R-07 Guide to the Concrete Capacity Design (CCD) Method - Embedment Design Examples

5. ACI 355.3R-11 Guide for Design of Anchorage to Concrete: Examples Using ACI 318 Appendix D

6. Design of Anchor Reinforcement in Concrete Pedestals by Widianto, Chandu Patel, and Jerry Owen

7. CSA A23.3-04 (R2010) - Design of Concrete Structures

8. AISC Design Guide 1: Base Plate and Anchor Rod Design 2nd Edition

9. PIP STE05121 Anchor Bolt Design Guide-2006

Anchor Bolt Anchor Reinforcement Supplementary Reinforcement ACI 318-08 ACI318-08 Appendix D ACI 349-06 CSA-A23.3-04 CSA-A23.3-04 Annex D CSA-A23.3-04 (R2010) ACI 349.2R-07 ACI 355.3R-11 ACI318-08 D.5.2.9 ACI318-08 RD.5.2.9 ACI318-08 D.6.2.9 ACI318-08 RD.6.2.9 Anchor Bolt Blowout Anchor Bolt Breakout Anchor Bolt Pryout Anchor Bolt Pullout Anchor Bolt Shear Anchor Bolt Moment Anchor Bolt Tension Anchor Bolt Tensile

Concrete Anchorage Anchor Rod Anchor Bolt Ductility Anchor Bolt Ductile Anchor Bolt Seismic Anchor Bolt Condition A Anchor Bolt Condition B Base Plate Base Plate Large Moment Base Plate Small Moment Base Plate Tensile

Base Plate Compression AISC Design Guide 1 Base Plate and Anchor Rod Design Anchor Bolt CCD Anchor Bolt Sleeve Anchor Stud Hairpin Anchor Ductile Grout Pad Ductile Steel Anchor Bolt Strut-and-Tie Anchor Bolt Concrete

Anchor Bolt Concrete Anchorage Anchor Bolt Embedment Anchor Bolt Pretension Anchor Bolt Edge Distance Anchor Bolt Three Edges Anchor Bolt Hairpin Anchor Bolt Design Anchor Bolt Design Software Anchor Bolt Design Spreadsheet