Heads up:
There are no amended sections in this chapter.
This chapter provides design requirements for anchors in concrete used to transmit structural loads by means of tension, shear, or a combination of tension and shear between: (a) connected structural elements; or (b) safetyrelated attachments and structural elements. Safety levels specified are intended for inservice conditions, rather than for shortterm handling and construction conditions.
This chapter applies to castin anchors and to postinstalled expansion (torquecontrolled and displacementcontrolled), undercut, and adhesive anchors. Adhesive anchors shall be installed in concrete having a minimum age of 21 days at time of anchor installation. Specialty inserts, throughbolts, multiple anchors connected to a single steel plate at the embedded end of the anchors, grouted anchors, and direct anchors such as powder or pneumatic actuated nails or bolts are not included in the provisions of this chapter. Reinforcement used as part of the embedment shall be designed in accordance with other parts of this Code.
Design provisions are included for the following types of anchors:
(a) Headed studs and headed bolts having a geometry that has been demonstrated to result in a pullout strength in uncracked concrete equal to or exceeding 1.4N_{p}, where N_{p} is given in Eq. (17.4.3.4)
(b) Hooked bolts having a geometry that has been demonstrated to result in a pullout strength without the benefit of friction in uncracked concrete equal to or exceeding 1.4N_{p}, where N_{p} is given in Eq. (17.4.3.5)
(c) Postinstalled expansion and undercut anchors that meet the assessment criteria of ACI 355.2
(d) Adhesive anchors that meet the assessment criteria of ACI 355.4
Anchors and anchor groups shall be designed for critical effects of factored loads as determined by elastic analysis. Plastic analysis approaches are permitted where nominal strength is controlled by ductile steel elements, provided that deformational compatibility is taken into account.
Anchor group effects shall be considered wherever two or more anchors have spacing less than the critical spacing as follows:
Failure mode under investigation  Critical spacing 

Concrete breakout in tension  3h_{ef} 
Bond strength in tension  2c_{Na} 
Concrete breakout in shear  3c_{a}_{1} 
Only those anchors susceptible to the particular failure mode under investigation shall be included in the group.
The design strength of anchors shall equal or exceed the largest required strength calculated from the applicable load combinations in 5.3.
Anchors in structures assigned to Seismic Design Category (SDC) C, D, E, or F shall satisfy the additional requirements of 17.2.3.2 through 17.2.3.7.
Postinstalled anchors shall be qualified for earthquake loading in accordance with ACI 355.2 or ACI 355.4. The pullout strength N_{p} and steel strength in shear V_{sa} of expansion and undercut anchors shall be based on the results of the ACI 355.2 Simulated Seismic Tests. For adhesive anchors, the steel strength in shear, V_{sa}, and the characteristic bond stresses, τ_{uncr} and τ_{cr}, shall be based on results of the ACI 355.4 Simulated Seismic Tests.
Where the tensile component of the strengthlevel earthquake force applied to a single anchor or group of anchors is equal to or less than 20 percent of the total factored anchor tensile force associated with the same load combination, it shall be permitted to design a single anchor or group of anchors to satisfy 17.4 and the tensile strength requirements of 17.3.1.1.
Where the tensile component of the strengthlevel earthquake force applied to anchors exceeds 20 percent of the total factored anchor tensile force associated with the same load combination, anchors and their attachments shall be designed in accordance with 17.2.3.4.3. The anchor design tensile strength shall be determined in accordance with 17.2.3.4.4.
Exception: Anchors designed to resist wall outofplane forces with design strengths equal to or greater than the force determined in accordance with ASCE 7 Equation 12.111 or 12.1410 shall be deemed to satisfy Section 17.2.3.4.3(d).
Anchors and their attachments shall satisfy one of options (a) through (d):
(a) For single anchors, the concretegoverned strength shall be greater than the steel strength of the anchor. For anchor groups, the ratio of the tensile load on the most highly stressed anchor to the steel strength of that anchor shall be equal to or greater than the ratio of the tensile load on tension loaded anchors to the concretegoverned strength of those anchors. In each case:
(i) The steel strength shall be taken as 1.2 times the nominal steel strength of the anchor.
(ii) The concretegoverned strength shall be taken as the nominal strength considering pullout, sideface blowout, concrete breakout, and bond strength as applicable. For consideration of pullout in groups, the ratio shall be calculated for the most highly stressed anchor.
In addition, the following shall be satisfied:
(iii) Anchors shall transmit tensile loads via a ductile steel element with a stretch length of at least eight anchor diameters unless otherwise determined by analysis.
(v) Where connections are threaded and the ductile steel elements are not threaded over their entire length, the ratio of f_{uta}/f_{ya} shall not be less than 1.3 unless the threaded portions are upset. The upset portions shall not be included in the stretch length.
(vi) Deformed reinforcing bars used as ductile steel elements to resist earthquake effects shall be limited to ASTM A615 Grades 40 and 60 satisfying the requirements of 20.2.2.5(b) or ASTM A706 Grade 60.
(b) The anchor or group of anchors shall be designed for the maximum tension that can be transmitted to the anchor or group of anchors based on the development of a ductile yield mechanism in the attachment in tension, flexure, shear, or bearing, or a combination of those conditions, and considering both material overstrength and strain hardening effects for the attachment. The anchor design tensile strength shall be calculated from 17.2.3.4.4.
(c) The anchor or group of anchors shall be designed for the maximum tension that can be transmitted to the anchors by a nonyielding attachment. The anchor design tensile strength shall be calculated from 17.2.3.4.4.
(d) The anchor or group of anchors shall be designed for the maximum tension obtained from design load combinations that include E, with E increased by Ω_{o}. The anchor design tensile strength shall be calculated from 17.2.3.4.4.
The anchor design tensile strength for resisting earthquake forces shall be determined from consideration of (a) through (e) for the failure modes given in Table 17.3.1.1 assuming the concrete is cracked unless it can be demonstrated that the concrete remains uncracked:
(a) ϕN_{sa} for a single anchor, or for the most highly stressed individual anchor in a group of anchors
(b) 0.75ϕN_{cb} or 0.75ϕN_{cbg}, except that N_{cb} or N_{cbg} need not be calculated where anchor reinforcement satisfying 17.4.2.9 is provided
(c) 0.75ϕN_{pn} for a single anchor, or for the most highly stressed individual anchor in a group of anchors
(d) 0.75ϕN_{sb} or 0.75ϕN_{sbg}
(e) 0.75ϕN_{a} or 0.75ϕN_{ag}
where ϕ is in accordance with 17.3.3.
Where anchor reinforcement is provided in accordance with 17.4.2.9, no reduction in design tensile strength beyond that specified in 17.4.2.9 shall be required.
Where the shear component of the strengthlevel earthquake force applied to the anchor or group of anchors is equal to or less than 20 percent of the total factored anchor shear force associated with the same load combination, it shall be permitted to design the anchor or group of anchors to satisfy 17.5 and the shear strength requirements of 17.3.1.1.
Where the shear component of the strengthlevel earthquake force applied to anchors exceeds 20 percent of the total factored anchor shear force associated with the same load combination, anchors and their attachments shall be designed in accordance with 17.2.3.5.3. The anchor design shear strength for resisting earthquake forces shall be determined in accordance with 17.5.

Exceptions:

For the calculation of the inplane shear strength of anchor bolts attaching wood sill plates of bearing or nonbearing walls of lightframe wood structures to foundations or foundation stem walls, the inplane shear strength in accordance with 17.5.2 and 17.5.3 need not be computed and 17.2.3.5.3 shall be deemed to be satisfied provided all of the following are met:
 1.1. The allowable inplane shear strength of the anchor is determined in accordance with ANSI/AWC NDS Table 12E for lateral design values parallel to grain.
 1.2. The maximum anchor nominal diameter is ^{5}/_{8} inch (16 mm).
 1.3. Anchor bolts are embedded into concrete a minimum of 7 inches (178 mm).
 1.4. Anchor bolts are located a minimum of 1^{3}/_{4} inches (45 mm) from the edge of the concrete parallel to the length of the wood sill plate.
 1.5. Anchor bolts are located a minimum of 15 anchor diameters from the edge of the concrete perpendicular to the length of the wood sill plate.
 1.6. The sill plate is 2inch (51 mm) or 3inch (76 mm) nominal thickness.

For the calculation of the inplane shear strength of anchor bolts attaching coldformed steel track of bearing or nonbearing walls of lightframe construction to foundations or foundation stem walls, the inplane shear strength in accordance with 17.5.2 and 17.5.3 need not be computed and 17.2.3.5.3 shall be deemed to be satisfied provided all of the following are met:
 2.1. The maximum anchor nominal diameter is ^{5}/_{8} inch (16 mm).
 2.2. Anchors are embedded into concrete a minimum of 7 inches (178 mm).
 2.3. Anchors are located a minimum of 1^{3}/_{4} inches (45 mm) from the edge of the concrete parallel to the length of the track.
 2.4. Anchors are located a minimum of 15 anchor diameters from the edge of the concrete perpendicular to the length of the track.
 2.5. The track is 33 to 68 mil (0.84 mm to 1.73 mm) designation thickness.
 In lightframe construction bearing or nonbearing walls, shear strength of concrete anchors less than or equal to 1 inch [25 mm] in diameter attaching sill plate or track to foundation or foundation stem wall need not satisfy 17.2.3.5.3(a) through (c) when the design strength of the anchors is determined in accordance with 17.5.2.1(c).

Anchors and their attachments shall be designed using one of options (a) through (c):
(a) The anchor or group of anchors shall be designed for the maximum shear that can be transmitted to the anchor or group of anchors based on the development of a ductile yield mechanism in the attachment in flexure, shear, or bearing, or a combination of those conditions, and considering both material overstrength and strain hardening effects in the attachment.
(b) The anchor or group of anchors shall be designed for the maximum shear that can be transmitted to the anchors by a nonyielding attachment.
(c) The anchor or group of anchors shall be designed for the maximum shear obtained from design load combinations that include E, with the horizontal component of E increased by Ω_{o}. The anchor design shear strength shall satisfy the shear strength requirements of 17.3.1.1.
Where anchor reinforcement is provided in accordance with 17.5.2.9, no reduction in design shear strength beyond that specified in 17.5.2.9 shall be required.
Single anchors or groups of anchors that are subjected to both tension and shear forces shall be designed to satisfy the requirements of 17.6, with the anchor design tensile strength calculated from 17.2.3.4.4.
Anchor reinforcement used in structures assigned to SDC C, D, E, or F shall be deformed reinforcement and shall be limited to ASTM A615 Grades 40 and 60 satisfying the requirements of 20.2.2.5(b) (i) and (ii) or ASTM A706 Grade 60.
Adhesive anchors installed horizontally or upwardly inclined shall be qualified in accordance with ACI 355.4 requirements for sensitivity to installation direction.
For adhesive anchors subjected to sustained tension loading, 17.3.1.2 shall be satisfied. For groups of adhesive anchors, Eq. (17.3.1.2) shall be satisfied for the anchor that resists the highest sustained tension load. Installer certification and inspection requirements for horizontal and upwardly inclined adhesive anchors subjected to sustained tension loading shall be in accordance with 17.8.2.2 through 17.8.2.4.
Modification factor λ_{a} for lightweight concrete shall be taken as:
Castin and undercut anchor concrete failure..........  1.0λ 
Expansion and adhesive anchor concrete failure....  0.8λ 
Adhesive anchor bond failure per Eq. (17.4.5.2).......  0.6λ 
where λ is determined in accordance with 19.2.4. It shall be permitted to use an alternative value of λ_{a} where tests have been performed and evaluated in accordance with ACI 355.2 or ACI 355.4.
The values of f'_{c} used for calculation purposes in this chapter shall not exceed 10,000 psi for castin anchors, and 8000 psi for postinstalled anchors. Testing is required for postinstalled anchors when used in concrete with f'_{c} greater than 8000 psi.
Strength design of anchors shall be based either on computation using design models that satisfy the requirements of 17.3.2, or on test evaluation using the 5 percent fractile of applicable test results for the following:
(c) Pullout strength castin, postinstalled expansion, or undercut anchor in tension (17.4.3)
(e) Bond strength of adhesive anchor in tension (17.4.5)
In addition, anchors shall satisfy the required edge distances, spacings, and thicknesses to preclude splitting failure, as required in 17.7.
The design of anchors shall be in accordance with Table 17.3.1.1. In addition, the design of anchors shall satisfy 17.2.3 for earthquake loading and 17.3.1.2 for adhesive anchors subject to sustained tensile loading.
Failure mode  Single anchor  Anchor group^{[1]}  

Individual anchor in a group  Anchors as a group  
Steel strength in tension (17.4.1)  ϕN_{sa} ≥ N_{ua}  ϕN_{sa} ≥ N_{ua,i}  
Concrete breakout strength in tension (17.4.2)  ϕN_{cb} ≥ N_{ua}  ϕN_{cbg} ≥ N_{ua,g}  
Pullout strength in tension (17.4.3)  ϕN_{pn} ≥ N_{ua}  ϕN_{pn} ≥ N_{ua,i}  
Concrete sideface blowout strength in tension (17.4.4)  ϕN_{sb} ≥ N_{ua}  ϕN_{sbg} ≥ N_{ua,g}  
Bond strength of adhesive anchor in tension (17.4.5)  ϕN_{a} ≥ N_{ua}  ϕN_{ag} ≥ N_{ua,g}  
Steel strength in shear (17.5.1)  ϕV_{sa} ≥ V_{ua}  ϕV_{sa} ≥ V_{ua,i}  
Concrete breakout strength in shear (17.5.2)  ϕV_{cb} ≥ V_{ua}  ϕV_{cbg} ≥ V_{ua,g}  
Concrete pryout strength in shear (17.5.3)  ϕV_{cp} ≥ V_{ua}  ϕV_{cpg} ≥ V_{ua,g} 
^{[1]}Required strengths for steel and pullout failure modes shall be calculated for the most highly stressed anchor in the group.
For the design of adhesive anchors to resist sustained tensions loads, in addition to 17.3.1.1, Eq. (17.3.1.2) shall be satisfied.
0.55ϕN_{ba} ≥ N_{ua,s}  (17.3.1.2) 
where N_{ba} is determined in accordance with 17.4.5.2.
When both N_{ua} and V_{ua} are present, interaction effects shall be considered using an interaction expression that results in computation of strength in substantial agreement with results of comprehensive tests. This requirement shall be considered satisfied by 17.6.
The nominal strength for any anchor or group of anchors shall be based on design models that result in predictions of strength in substantial agreement with results of comprehensive tests. The materials used in the tests shall be compatible with the materials used in the structure. The nominal strength shall be based on the 5 percent fractile of the basic individual anchor strength. For nominal strengths related to concrete strength, modifications for size effects, the number of anchors, the effects of close spacing of anchors, proximity to edges, depth of the concrete member, eccentric loadings of anchor groups, and presence or absence of cracking shall be taken into account. Limits on edge distances and anchor spacing in the design models shall be consistent with the tests that verified the model.
The effect of reinforcement provided to restrain the concrete breakout shall be permitted to be included in the design models used to satisfy 17.3.2. Where anchor reinforcement is provided in accordance with 17.4.2.9 and 17.5.2.9, calculation of the concrete breakout strength in accordance with 17.4.2 and 17.5.2 is not required.
For anchors with diameters not exceeding 4 in., the concrete breakout strength requirements shall be considered satisfied by the design procedure of 17.4.2 and 17.5.2.
For adhesive anchors with embedment depths 4d_{a} ≤ h_{ef} ≤ 20d_{a}, the bond strength requirements shall be considered satisfied by the design procedure of 17.4.5.
Strength reduction factor ϕ for anchors in concrete shall be as follows when the load combinations of 5.3 are used:
(a) Anchor governed by strength of a ductile steel element  
(i) Tension loads..................................................  0.75 
(ii) Shear loads.....................................................  0.65 
(b) Anchor governed by strength of a brittle steel element  
(i) Tension loads..................................................  0.65 
(ii) Shear loads.....................................................  0.60 
(c) Anchor governed by concrete breakout, sideface blowout, bond, pullout, or pryout strength 
Condition A

Condition B


(i) Shear loads................................... 
..........0.75.........

...................0.70 
(ii) Tension loads  
Castin headed studs, headed bolts, or hooked bolts..................................................... 
..........0.75.........

...................0.70 
Postinstalled anchors with category as determined from ACI 355.2 or ACI 355.4  
Category 1.......................................... 
..........0.75.........

...................0.65 
(Low sensitivity to installation and high reliability)  
Category 2........................................... 
..........0.65.........

...................0.55 
(Medium sensitivity to installation and medium reliability)  
Category 3......................................... 
..........0.55.........

...................0.45 
(High sensitivity to installation and lower reliability) 
Condition A applies where supplementary reinforcement is present except for pullout and pryout strengths.
Condition B applies where supplementary reinforcement is not present, and for pullout or pryout strength.
The nominal strength of an anchor in tension as governed by the steel, N_{sa}, shall be evaluated by calculations based on the properties of the anchor material and the physical dimensions of the anchor.
The nominal strength of an anchor in tension, N_{sa}, shall not exceed
N_{sa} = A_{se,N} f_{uta}  (17.4.1.2) 
where A_{se,N} is the effective crosssectional area of an anchor in tension, in.^{2}, and f_{uta} shall not be taken greater than the smaller of 1.9f_{ya} and 125,000 psi.
The nominal concrete breakout strength in tension, N_{cb} of a single anchor or N_{cbg} of a group of anchors, shall not exceed:
(a) For a single anchor
(17.4.2.1a) 
(b) For a group of anchors
(17.4.2.1b) 
Factors ψ_{ec,N}, ψ_{ed,N}, ψ_{c,N}, and ψ_{cp,N} are defined in 17.4.2.4, 17.4.2.5, 17.4.2.6, and 17.4.2.7, respectively. A_{Nc} is the projected concrete failure area of a single anchor or group of anchors that shall be approximated as the base of the rectilinear geometrical figure that results from projecting the failure surface outward 1.5h_{ef} from the centerlines of the anchor, or in the case of a group of anchors, from a line through a row of adjacent anchors. A_{Nc} shall not exceed nA_{Nco}, where n is the number of anchors in the group that resist tension. A_{Nco} is the projected concrete failure area of a single anchor with an edge distance equal to or greater than 1.5h_{ef}
A_{Nco} = 9h_{ef} ^{2}  (17.4.2.1c) 
The basic concrete breakout strength of a single anchor in tension in cracked concrete, N_{b}, shall not exceed
(17.4.2.2a) 
where k_{c} = 24 for castin anchors and 17 for postinstalled anchors.
The value of k_{c} for postinstalled anchors shall be permitted to be increased above 17 based on ACI 355.2 or ACI 355.4 productspecific tests, but shall not exceed 24.
Alternatively, for castin headed studs and headed bolts with 11 in. ≤ h_{ef} ≤ 25 in., N_{b} shall not exceed
(17.4.2.2b) 
Where anchors are located less than 1.5h_{ef} from three or more edges, the value of h_{ef} used for the calculation of A_{Nc} in accordance with 17.4.2.1, as well as for the equations in 17.4.2.1 through 17.4.2.5, shall be the larger of (c_{a,max})/1.5 and s/3, where s is the maximum spacing between anchors within the group.
The modification factor for anchor groups loaded eccentrically in tension, ψ_{ec,N}, shall be calculated as
(17.4.2.4) 
but ψ_{ec,N} shall not be taken greater than 1.0. If the loading on an anchor group is such that only some anchors are in tension, only those anchors that are in tension shall be considered when determining the eccentricity e'_{N} for use in Eq. (17.4.2.4) and for the calculation of N_{cbg} according to Eq. (17.4.2.1b).
In the case where eccentric loading exists about two axes, the modification factor ψ_{ec,N} shall be calculated for each axis individually and the product of these factors used as ψ_{ec,N} in Eq. (17.4.2.1b).
The modification factor for edge effects for single anchors or anchor groups loaded in tension, ψ_{ed,N}, shall be calculated as
If C_{a,min} ≥ 1.5h_{ef}, then ψ_{ed,N} = 1.0  (17.4.2.5a) 
If C_{a,min} < 1.5h_{ef}, then  (17.4.2.5b) 
For anchors located in a region of a concrete member where analysis indicates no cracking at service load levels, the following modification factor shall be permitted:
(a) ψ_{c,N} = 1.25 for castin anchors
(b) ψ_{c,N} = 1.4 for postinstalled anchors, where the value of k_{c} used in Eq. (17.4.2.2a) is 17
Where the value of k_{c} used in Eq. (17.4.2.2a) is taken from the ACI 355.2 or ACI 355.4 product evaluation report for postinstalled anchors qualified for use in both cracked and uncracked concrete, the values of k_{c} and ψ_{c,N} shall be based on the ACI 355.2 or ACI 355.4 product evaluation report.
Where the value of k_{c} used in Eq. (17.4.2.2a) is taken from the ACI 355.2 or ACI 355.4 product evaluation report for postinstalled anchors qualified for use in uncracked concrete, ψ_{c,N} shall be taken as 1.0.
When analysis indicates cracking at service load levels, ψ_{c,N}, shall be taken as 1.0 for both castin anchors and postinstalled anchors. Postinstalled anchors shall be qualified for use in cracked concrete in accordance with ACI 355.2 or ACI 355.4. The cracking in the concrete shall be controlled by flexural reinforcement distributed in accordance with 24.3.2, or equivalent crack control shall be provided by confining reinforcement.
The modification factor for postinstalled anchors designed for uncracked concrete in accordance with 17.4.2.6 without supplementary reinforcement to control splitting, ψ_{cp,N}, shall be calculated as follows using the critical distance c_{ac} as defined in 17.7.6
If C_{a,min} ≥ C_{ac}, then ψ_{cp,N} = 1.0  (17.4.2.7a) 
If C_{a,min} < C_{ac}, then  (17.4.2.7b) 
but ψ_{cp,N} determined from Eq. (17.4.2.7b) shall not be taken less than 1.5h_{ef}/c_{ac}, where the critical distance c_{ac} is defined in 17.7.6.
For all other cases, including castin anchors, ψ_{cp,N} shall be taken as 1.0.
Where an additional plate or washer is added at the head of the anchor, it shall be permitted to calculate the projected area of the failure surface by projecting the failure surface outward 1.5h_{ef} from the effective perimeter of the plate or washer. The effective perimeter shall not exceed the value at a section projected outward more than the thickness of the washer or plate from the outer edge of the head of the anchor.
Where anchor reinforcement is developed in accordance with Chapter 25 on both sides of the breakout surface, the design strength of the anchor reinforcement shall be permitted to be used instead of the concrete breakout strength in determining ϕN_{n}. A strength reduction factor of 0.75 shall be used in the design of the anchor reinforcement.
The nominal pullout strength of a single castin, postinstalled expansion, and postinstalled undercut anchor in tension, N_{pn}, shall not exceed
N_{pn} = ψ_{c,P}N_{p}  (17.4.3.1) 
where ψ_{c,P} is defined in 17.4.3.6.
For postinstalled expansion and undercut anchors, the values of N_{p} shall be based on the 5 percent fractile of results of tests performed and evaluated according to ACI 355.2. It is not permissible to calculate the pullout strength in tension for such anchors.
For single castin headed studs and headed bolts, it shall be permitted to evaluate the pullout strength in tension using 17.4.3.4. For single J or Lbolts, it shall be permitted to evaluate the pullout strength in tension using 17.4.3.5. Alternatively, it shall be permitted to use values of N_{p} based on the 5 percent fractile of tests performed and evaluated in the same manner as the ACI 355.2 procedures but without the benefit of friction.
The pullout strength in tension of a single headed stud or headed bolt, N_{p}, for use in Eq. (17.4.3.1), shall not exceed
N_{p} = 8A_{brg} f'_{c}  (17.4.3.4) 
The pullout strength in tension of a single hooked bolt, N_{p}, for use in Eq. (17.4.3.1) shall not exceed
N_{p} = 0.9f'_{c}e_{h}d_{a}  (17.4.3.5) 
For an anchor located in a region of a concrete member where analysis indicates no cracking at service load levels, the following modification factor shall be permitted
ψ_{c,P} = 1.4
Where analysis indicates cracking at service load levels, ψ_{c,P} shall be taken as 1.0.
For a single headed anchor with deep embedment close to an edge (h_{ef} > 2.5c_{a}_{1}), the nominal sideface blowout strength, N_{sb}, shall not exceed
(17.4.4.1) 
If c_{a}_{2} for the single headed anchor is less than 3c_{a}_{1}, the value of N_{sb} shall be multiplied by the factor (1 + c_{a}_{2}/c_{a}_{1})/4, where 1.0 ≤ c_{a}_{2}/c_{a}_{1} ≤ 3.0.
For multiple headed anchors with deep embedment close to an edge (h_{ef} > 2.5c_{a}_{1}) and anchor spacing less than 6c_{a}_{1}, the nominal strength of those anchors susceptible to a sideface blowout failure N_{sbg} shall not exceed
(17.4.4.2) 
where s is the distance between the outer anchors along the edge, and N_{sb} is obtained from Eq. (17.4.4.1) without modification for a perpendicular edge distance.
The nominal bond strength in tension, N_{a} of a single adhesive anchor or N_{ag} of a group of adhesive anchors, shall not exceed
(a) For a single adhesive anchor:
(17.4.5.1a) 
(b) For a group of adhesive anchors:
(17.4.5.1b) 
Factors ψ_{ec,Na}, ψ_{ed,Na}, and ψ_{cp,Na} are defined in 17.4.5.3, 17.4.5.4, and 17.4.5.5, respectively. A_{Na} is the projected influence area of a single adhesive anchor or group of adhesive anchors that shall be approximated as a rectilinear area that projects outward a distance c_{Na} from the centerline of the adhesive anchor, or in the case of a group of adhesive anchors, from a line through a row of adjacent adhesive anchors. A_{Na} shall not exceed nA_{Nao}, where n is the number of adhesive anchors in the group that resist tension loads. A_{Nao} is the projected influence area of a single adhesive anchor with an edge distance equal to or greater than c_{Na}:
A_{Nao} = (2c_{Na})^{2}  (17.4.5.1c) 
where
(17.4.5.1d) 
and constant 1100 carries the unit of lb/in.^{2}
The basic bond strength of a single adhesive anchor in tension in cracked concrete, N_{ba}, shall not exceed
(17.4.5.2) 
The characteristic bond stress τ_{cr} shall be taken as the 5 percent fractile of results of tests performed and evaluated according to ACI 355.4.
Where analysis indicates cracking at service load levels, adhesive anchors shall be qualified for use in cracked concrete in accordance with ACI 355.4.
For adhesive anchors located in a region of a concrete member where analysis indicates no cracking at service load levels, τ_{uncr} shall be permitted to be used in place of τ_{cr} in Eq. (17.4.5.2) and shall be taken as the 5 percent fractile of results of tests performed and evaluated according to ACI 355.4.
It shall be permitted to use the minimum characteristic bond stress values in Table 17.4.5.2, provided (a) through (e) are satisfied:
(a) Anchors shall meet the requirements of ACI 355.4
(b) Anchors shall be installed in holes drilled with a rotary impact drill or rock drill
Table 17.4.5.2—Minimum characteristic bond stresses^{[1][2]}
Installation and service environment  Moisture content of concrete at time of anchor installation  Peak inservice temperature of concrete, °F  τ_{cr}, psi  τ_{uncr}, psi 

Outdoor  Dry to fully saturated  175  200  650 
Indoor  Dry  110  300  1000 
^{[1]}Where anchor design includes sustained tension loading, multiply values of τ_{cr} and τ_{uncr} by 0.4.
The modification factor for adhesive anchor groups loaded eccentrically in tension, ψ_{ec,Na}, shall be calculated as:
(17.4.5.3) 
but ψ_{ec,Na} shall not be taken greater than 1.0.
If the loading on an adhesive anchor group is such that only some adhesive anchors are in tension, only those adhesive anchors that are in tension shall be considered when determining the eccentricity e'_{N} for use in Eq. (17.4.5.3) and for the calculation of N_{ag} according to Eq. (17.4.5.1b).
In the case where eccentric loading exists about two orthogonal axes, the modification factor ψ_{ec,Na} shall be calculated for each axis individually and the product of these factors used as ψ_{ec,Na} in Eq. (17.4.5.1b).
The modification factor for edge effects for single adhesive anchors or adhesive anchor groups loaded in tension, ψ_{ed,Na}, shall be calculated as
If C_{a,min} ≥ C_{Na}, then ψed,Na = 1.0  (17.4.5.4a) 
If C_{a,min} < C_{Na}, then  (17.4.5.4b) 
The modification factor for adhesive anchors designed for uncracked concrete in accordance with 17.4.5.2 without supplementary reinforcement to control splitting, ψ_{cp,Na}, shall be calculated as:
If C_{a,min} ≥ C_{ac}, then ψcp,Na = 1.0  (17.4.5.5a) 
If C_{a,min} < C_{ac}, then  (17.4.5.5b) 
but ψ_{cp,Na} determined from Eq. (17.4.5.5b) shall not be taken less than c_{Na}/c_{ac}, where the critical edge distance c_{ac} is defined in 17.7.6. For all other cases, ψ_{cp,Na} shall be taken as 1.0.
The nominal strength of an anchor in shear as governed by steel, V_{sa}, shall be evaluated by calculations based on the properties of the anchor material and the physical dimensions of the anchor. Where concrete breakout is a potential failure mode, the required steel shear strength shall be consistent with the assumed breakout surface.
The nominal strength of an anchor in shear, V_{sa}, shall not exceed (a) through (c):
(a) For castin headed stud anchor
V_{sa} = A_{se,V} f_{uta}  (17.5.1.2a) 
where A_{se,V} is the effective crosssectional area of an anchor in shear, in.^{2}, and f_{uta} shall not be taken greater than the smaller of 1.9f_{ya} and 125,000 psi.
(b) For castin headed bolt and hooked bolt anchors and for postinstalled anchors where sleeves do not extend through the shear plane
V_{sa} = 0.6A_{se,V} f_{uta}  (17.5.1.2b) 
where A_{se,V} is the effective crosssectional area of an anchor in shear, in.^{2}, and f_{uta} shall not be taken greater than the smaller of 1.9f_{ya} and 125,000 psi.
(c) For postinstalled anchors where sleeves extend through the shear plane, V_{sa} shall be based on the results of tests performed and evaluated according to ACI 355.2. Alternatively, Eq. (17.5.1.2b) shall be permitted to be used.
Where anchors are used with builtup grout pads, the nominal strengths of 17.5.1.2 shall be multiplied by a factor 0.80.
The nominal concrete breakout strength in shear, V_{cb} of a single anchor or V_{cbg} of a group of anchors, shall not exceed:
(a) For shear force perpendicular to the edge on a single anchor
(17.5.2.1a) 
(b) For shear force perpendicular to the edge on a group of anchors
(17.5.2.1b) 
(c) For shear force parallel to an edge, V_{cb} or V_{cbg} shall be permitted to be twice the value of the shear force determined from Eq. (17.5.2.1a) or (17.5.2.1b), respectively, with the shear force assumed to act perpendicular to the edge and with ψ_{ed,V} taken equal to 1.0.
(d) For anchors located at a corner, the limiting nominal concrete breakout strength shall be determined for each edge, and the minimum value shall be used.
Factors ψ_{ec,V}, ψ_{ed,V}, ψ_{c,V}, and ψ_{h,V} are defined in 17.5.2.5, 17.5.2.6, 17.5.2.7, and 17.5.2.8, respectively. V_{b} is the basic concrete breakout strength value for a single anchor. A_{Vc} is the projected area of the failure surface on the side of the concrete member at its edge for a single anchor or a group of anchors. It shall be permitted to evaluate A_{Vc} as the base of a truncated halfpyramid projected on the side face of the member where the top of the halfpyramid is given by the axis of the anchor row selected as critical. The value of c_{a}_{1} shall be taken as the distance from the edge to this axis. A_{Vc} shall not exceed nA_{Vco}, where n is the number of anchors in the group.
A_{Vco} is the projected area for a single anchor in a deep member with a distance from edges equal or greater than 1.5c_{a}_{1} in the direction perpendicular to the shear force. It shall be permitted to evaluate A_{Vco} as the base of a halfpyramid with a side length parallel to the edge of 3c_{a}_{1} and a depth of 1.5c_{a}_{1}
A_{Vco} = 4.5(c_{a}_{1})^{2}  (17.5.2.1c) 
Where anchors are located at varying distances from the edge and the anchors are welded to the attachment so as to distribute the force to all anchors, it shall be permitted to evaluate the strength based on the distance to the farthest row of anchors from the edge. In this case, it shall be permitted to base the value of c_{a}_{1} on the distance from the edge to the axis of the farthest anchor row that is selected as critical, and all of the shear shall be assumed to be carried by this critical anchor row alone.
The basic concrete breakout strength in shear of a single anchor in cracked concrete, V_{b}, shall be the smaller of (a) and (b):
(a)  (17.5.2.2a) 
ℓ_{e} = h_{ef} for anchors with a constant stiffness over the full length of embedded section, such as headed studs and postinstalled anchors with one tubular shell over full length of the embedment depth;
ℓ_{e} = 2d_{a} for torquecontrolled expansion anchors with a distance sleeve separated from expansion sleeve, and ℓ_{e} ≤ 8d_{a} in all cases.
(b)  (17.5.2.2b) 
For castin headed studs, headed bolts, or hooked bolts that are continuously welded to steel attachments having a minimum thickness equal to the greater of ^{3}/_{8} in. and half of the anchor diameter, the basic concrete breakout strength in shear of a single anchor in cracked concrete, V_{b}, shall be the smaller of Eq. (17.5.2.2b) and Eq. (17.5.2.3)
(17.5.2.3) 
where ℓ_{e} is defined in 17.5.2.2 provided that:
(a) For groups of anchors, the strength is determined based on the strength of the row of anchors farthest from the edge
(c) Reinforcement is provided at the corners if c_{a}_{2} ≤ 1.5h_{ef}
Where anchors are located in narrow sections of limited thickness such that both edge distances c_{a}_{2} and thickness h_{a} are less than 1.5c_{a}_{1}, the value of c_{a}_{1} used for the calculation of A_{Vc} in accordance with 17.5.2.1 as well as for the equations in 17.5.2.1 through 17.5.2.8 shall not exceed the largest of:
(a) c_{a}_{2} /1.5, where c_{a}_{2} is the largest edge distance
(b) h_{a} /1.5
The modification factor for anchor groups loaded eccentrically in shear, ψ_{ec,V}, shall be calculated as
(17.5.2.5) 
but ψ_{ec,V} shall not be taken greater than 1.0.
If the loading on an anchor group is such that only some anchors are loaded in shear in the same direction, only those anchors that are loaded in shear in the same direction shall be considered when determining the eccentricity of e'_{V} for use in Eq. (17.5.2.5) and for the calculation of V_{cbg} according to Eq. (17.5.2.1b).
For anchors located in a region of a concrete member where analysis indicates no cracking at service loads, the following modification factor shall be permitted
ψ_{c,V} = 1.4
For anchors located in a region of a concrete member where analysis indicates cracking at service load levels, the following modification factors shall be permitted:
ψ_{c,V} = 1.0 for anchors in cracked concrete without supplementary reinforcement or with edge reinforcement smaller than a No. 4 bar
ψ_{c,V} = 1.2 for anchors in cracked concrete with reinforcement of a No. 4 bar or greater between the anchor and the edge
ψ_{c,V} = 1.4 for anchors in cracked concrete with reinforcement of a No. 4 bar or greater between the anchor and the edge, and with the reinforcement enclosed within stirrups spaced at not more than 4 in.
Where anchor reinforcement is either developed in accordance with Chapter 25 on both sides of the breakout surface, or encloses the anchor and is developed beyond the breakout surface, the design strength of the anchor reinforcement shall be permitted to be used instead of the concrete breakout strength in determining ϕV_{n}. A strength reduction factor of 0.75 shall be used in the design of the anchor reinforcement.
The nominal pryout strength, V_{cp} for a single anchor or V_{cpg} for a group of anchors, shall not exceed:
(a) For a single anchor
V_{cp} = k_{cp} N_{cp}  (17.5.3.1a) 
For castin, expansion, and undercut anchors, N_{cp} shall be taken as N_{cb} determined from Eq. (17.4.2.1a), and for adhesive anchors, N_{cp} shall be the lesser of N_{a} determined from Eq. (17.4.5.1a) and N_{cb} determined from Eq. (17.4.2.1a).
(b) For a group of anchors
V_{cpg} = k_{cp} N_{cpg}  (17.5.3.1b) 
For castin, expansion, and undercut anchors, N_{cpg} shall be taken as N_{cbg} determined from Eq. (17.4.2.1b), and for adhesive anchors, N_{cpg} shall be the lesser of N_{ag} determined from Eq. (17.4.5.1b) and N_{cbg} determined from Eq. (17.4.2.1b).
In Eq. (17.5.3.1a) and (17.5.3.1b), k_{cp} = 1.0 for h_{ef} < 2.5 in.; and k_{cp} = 2.0 for h_{ef} ≥ 2.5 in.
Unless determined in accordance with 17.3.1.3, anchors or groups of anchors that are subjected to both shear and axial loads shall be designed to satisfy the requirements of 17.6.1 through 17.6.3. The values of ϕN_{n} and ϕV_{n} shall be the required strengths as determined from 17.3.1.1 or from 17.2.3.
If V_{ua}/(ϕV_{n}) ≤ 0.2 for the governing strength in shear, then full strength in tension shall be permitted: ϕN_{n} ≥ N_{ua}.
If N_{ua}/(ϕN_{n}) ≤ 0.2 for the governing strength in tension, then full strength in shear shall be permitted: ϕV_{n} ≥ V_{ua}.
If V_{ua}/(ϕV_{n}) > 0.2 for the governing strength in shear and N_{ua}/(ϕN_{n}) > 0.2 for the governing strength in tension, then
(17.6.3) 
Minimum spacings and edge distances for anchors and minimum thicknesses of members shall conform to 17.7.1 through 17.7.6, unless supplementary reinforcement is provided to control splitting. Lesser values from productspecific tests performed in accordance with ACI 355.2 or ACI 355.4 shall be permitted.
Unless determined in accordance with 17.7.4, minimum edge distances for castin anchors that will not be torqued shall be based on specified cover requirements for reinforcement in 20.6.1. For castin anchors that will be torqued, the minimum edge distances shall be 6d_{a}.
Unless determined in accordance with 17.7.4, minimum edge distances for postinstalled anchors shall be based on the greater of specified cover requirements for reinforcement in 20.6.1, or minimum edge distance requirements for the products as determined by tests in accordance with ACI 355.2 or ACI 355.4, and shall not be less than twice the maximum aggregate size. In the absence of productspecific ACI 355.2 or ACI 355.4 test information, the minimum edge distance shall not be less than:
Adhesive anchors......................................................................  6d_{a} 
Undercut anchorss ..................................................................  6d_{a} 
Torquecontrolled anchors......................................................  8d_{a} 
Displacementcontrolled anchors...........................................  10d_{a} 
For anchors where installation does not produce a splitting force and that will not be torqued, if the edge distance or spacing is less than those specified in 17.7.1 to 17.7.3, calculations shall be performed by substituting for d_{a} a smaller value d'_{a} that meets the requirements of 17.7.1 to 17.7.3. Calculated forces applied to the anchor shall be limited to the values corresponding to an anchor having a diameter of d'_{a}.
Unless determined from tests in accordance with ACI 355.2, the value of h_{ef} for an expansion or undercut postinstalled anchor shall not exceed the greater of ^{2}/_{3} of the member thickness, h_{a}, and the member thickness minus 4 in.
Unless determined from tension tests in accordance with ACI 355.2 or ACI 355.4, the critical edge distance c_{ac} shall not be taken less than:
Adhesive anchors..................................................................  2h_{ef} 
Undercut anchors.................................................................  2.5h_{ef} 
Torquecontrolled expansion anchors...............................  4h_{ef} 
Displacementcontrolled expansion anchors...................  4h_{ef} 
Construction documents shall specify use of anchors with a minimum edge distance as assumed in design.
Anchors shall be installed by qualified personnel in accordance with the construction documents and, where applicable, manufacturer's instructions. The construction documents shall require installation of postinstalled adhesive anchors in accordance with the Manufacturer's Printed Installation Instructions (MPII). Installation of adhesive anchors shall be performed by personnel trained to install adhesive anchors.
Installation of anchors shall be inspected in accordance with 1.9 and the general building code. Adhesive anchors shall be also subject to 17.8.2.1 through 17.8.2.4.
For adhesive anchors, the construction documents shall specify proof loading where required in accordance with ACI 355.4. The construction documents shall also specify all parameters associated with the characteristic bond stress used for the design according to 17.4.5, including minimum age of concrete; concrete temperature range; moisture condition of concrete at time of installation; type of lightweight concrete, if applicable; and requirements for hole drilling and preparation.
Installation of adhesive anchors horizontally or upwardly inclined to support sustained tension loads shall be performed by personnel certified by an applicable certification program. Certification shall include written and performance tests in accordance with the ACI/CRSI Adhesive Anchor Installer Certification program, or equivalent.
The acceptability of certification other than the ACI/CRSI Adhesive Anchor Installer Certification shall be the responsibility of the licensed design professional.
Adhesive anchors installed in horizontal or upwardly inclined orientations to resist sustained tension loads shall be continuously inspected during installation by an inspector specially approved for that purpose by the building official. The special inspector shall furnish a report to the licensed design professional and building official that the work covered by the report has been performed and that the materials used and the installation procedures used conform with the approved construction documents and the Manufacturer's Printed Installation Instructions (MPII).