ACI App Appen endix dix D – Upd Update ates s for ACI 318 318-11 -11 By Mark Bartlett, PE RLG Consulting Engineers
SE University, January, January, 2013
www.LearnWithSEU.com www.LearnWithSEU.co m
Topics to be covered
Review of Appendix D (ACI 318-02, 05, 08)
Very brief review
Major 2011 Updates to Appendix D
es ve nc ors Seismic Revisions Installation and Inspection of Anchors
What does IBC 2009 say about anchors?
How to correctly specify post-installed anchors 2
ACI Appendi Appendix x D – Updates for ACI ACI 318-11 318-11
REVIEW OF APPENDIX D (ACI 318-02, 05, 08) 3
Appendix D – D.2.2
Strength design method for anchorage to concrete
Headed bolts, Hooked bolts, Headed studs,
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Appendix D – D.2.2
Post-installed anchors
Undercut anchors, Expansion anchors (Sleeve anchors and Wedge anchors) and Post-installed Anchors must undergo prequalification testing ACI 355.2 for mechanical anchors ACI 355. 355.44 for adh adhesi esive ve anchors anchors
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Appendix D – D.2.2
Anchors not covered Specialty inserts Through-bolts crew- ype anc ors Multiple anchors connected to a single plate at the embedded end of the anchors Grouted anchors (not the same as adhesive anchors) Powder or pneumatic actuated nails
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ACI ACI 31 3188 - Appe Append ndix ix D Strength Strength design method for anchorage anchorage to concrete concrete (i.e. Nu ≤ ΦNn or Vu ≤ ΦVn)
Nu & Vu – Ultimate capacities determined from Nn & Vn – Nominal capacities determined from equations Φ – Strength Strength reduction reduction factor based on factors factors such such as failure mode, supplemental reinforcement and anchor category 7
Appendix D Design Equations & Failure Modes
Design equations check multiple failure modes
Steel capacity (Tension and Shear)
Shear) Pullout/Pull-through capacity (Tension) Pullout/Pull-through Concrete Pryout (Shear) Concrete side-face blowout (Tension for CIP anchors only) Bond Strength (Tension for Adhesive Anchors only) 8
Tension Equations
Steel (D.5.1)
Concrete Breakout (D.5.2)
Nsa = nAse,N f uta N
= A /A
Ψ
,
Ψ
,
Ψ, Ψ
,
N
Pullout/Pull-through (D.5.3)
Concrete Side-face Blowout (D.5.4)
Bond Strength (D.5.5)
Npn = Ψc,P Np
Nsb = (160ca1√Abrg)λ√f’c
Nag = ANa/ANao Ψec,Na Ψed,Na Ψcp,Na Nba 9
Shear Equations
Steel (D.6.1)
Vsa = n 0.6 Ase,V f uta
oncre e rea ou
. .
Vcbg = AVc/AVco (Ψec,V Ψed,V Ψc,V Ψh,V Vb)
Conc Concre rete te Pryo Pryout ut (D.6 (D.6.3 .3)) Vcpg = kcp Ncb
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Effects of Reinforcement
Anchor Reinforcement (D.4.2.1)
Where anchor reinforcement is provided in accordance with D.5.2.9 and D.6.2.9, calculation of
D.5.2 and D.6.2 is not required. Refer to sections D.5.2.9, RD.5.2.9, D.6.2.9 and RD.6.2.9 for specific requirements requirements
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Effects of Reinforcement
Supplemental Reinforcement (D.4.2.1) Configuration and placement similar to anchor reinforcement o spec ca y es gne o rans er e u es gn load from the anchors into the structural st ructural member (ex. stirrups for shear reinforcement) r einforcement)
Condition Condition A – with supplemen supplemental tal reinforc reinforcement ement Condition Condition B – without without supplemental supplemental reinforcement reinforcement
Explicit design of supplemen s upplemental tal reinforcement is not required (RD.4.3) 12
Phi Phi (Φ) (Φ) fa fact ctor orss- Secti Section on D.4. D.4.33 Ф Factor
Failure Mode
Anchor Property
Steel
Ductile Brittle
Side Face Blowout
CIP
0.75
0.75
0.70
0.70
CIP Cat. 1 Cat. 2 Cat. 3 CIP Cat. 1 Cat. 2 Cat. 3 CIP Cat. 1 Cat. 2 Cat. 3
0.75 0.75 0.65 0.55
0.75 0.75 0.75 0.75
0.70 0.65 0.55 0.45 0.70 0.65 0.55 0.45 0.70 0.65 0.55 0.45
0.70 0.70 0.70 0.70 0.70 0.70 0.70 0.70 0.70 0.70 0.70 0.70
Breakout
Pullout
Pryout
What about Bond Failure?
Condition A Tension Shear Use Condition B
Use Condition B
Use Condition B
Condition B Tension Shear 0.75 0.65 0.65 0.60
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Post-Installed Anchor Category
Category 1
Category 2
Medium sensitivity to installation and medium reliability
Category 3
Low sensitivity to installation and high reliability
High sensitivity to installation and lower reliability
Determined from testing per ACI 355.2
Mechanical anchors only
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Interac Int eractio tionn of Tensio Tensionn and Shear Shear - Sectio Sectionn D.7
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Interac Int eractio tionn of Tensio Tensionn and Shear Shear - Sectio Sectionn D.7
If Vua ≤ 0.2ΦVn full tension allowed ua
.
n
Otherwise Nua Vua < 1.2 + ΦNn ΦVn 16
ACI Appendi Appendix x D – Updates for ACI ACI 318-11 318-11
MAJOR 2011 UPDATES ADHESIVE ANCHOR ADDITION 17
Adhesives in Appendix D
Biggest Change to Appendix D
Like mechanical anchors, you still need input
More than just design equations Assumptions regarding installation conditions Installation by trained personnel
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Adhesives in Appendix D
Section D.2.2
Minimum concrete age of 21 days at the time of anchor installation Moisture issue, not strength Cover this information in your general notes and specs Common that anchors are installed prior to 21 days
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Adhesives in Appendix D
Section D.3.5
Horizontal or upwardly inclined installations and anchors anchors sub ected to sustaine sustainedd tension tension loading must satisfy D.4.1.2 (45% capacity reduction)
Satisfy Installer certification and inspection requireme requirements nts per D.9.2.2 D.9.2.2 – D.9.2.4 D.9.2.4
These installations will be more expensive 20
Adhesives in Appendix D
Section D.3.6
40% reduction in lightweight concrete (20% for expansion and 0% for CIP and undercut)
Section D.3.7 f’c < 10,000 psi for CIP f’c < 8,000 psi for Post-installed
Difficulty of expanding wedge type anchors in very high strength concrete (VHSC) Adhesive bond strength negatively affected in VHSC
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Adhesive in Appendix Appendix D
Section D.4.1.2
Adhesive anchors resisting sustained tension loads > , N ba : Basic bond strength in tension per D.5.5.2 N ua,s: Factored sustained tension load
Sustained tension loads (hanging loads) are especially critical 22
Adhesives in Appendix D
Section D.5.5: Bond strength of adhesive anchor in tension a
=
Na
Na o
ed,Na
cp,Na
ba
-
Single Anchor
Nag = ANa/ANao Ψec,Na Ψed,Na Ψcp,Na Nba (D-19)
Group of anchors
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Adhesives in Appendix D Nag = ANa/ANao Ψec,Na Ψed,Na Ψcp,Na Nba ANa: Influence area for a group of adhesive anchors ANao: Influence area for a single anchor
ANao= (2cNa)2 c Na = 10da√(τuncr /1100) d = anchor diameter a τ uncr : bond stress (per testing / manuf.)
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Adhesives in Appendix D Nag = ANa/ANao Ψec,Na Ψed,Na Ψcp,Na Nba
Ψec,Na : Modification for eccentric loading
Ψed,Na : Modification for edge effects
Ψcp,Na : Modification for adhesive anchors designed for uncracked concrete without supplementary reinforcement to control splitting 25
Adhesives in Appendix D Nag = ANa/ANao Ψec,Na Ψed,Na Ψcp,Na Nba
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Manufacturer’s Info Permitted Embedment Depth Range
Minimum Anchor Spacing
Critical and Minimum Edge Distance
Minimum Concrete Thickness
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Manufacturer’s Info Steel Strength in Tension
Concrete Breakout Strength in Tension 28
Temperature Range during service life (interior or exterior conditions)
Continuous or Periodic Inspection Dry or Water-saturated Concrete
Strength reduction factor factorss (Φ factor factor)) 29
Software
Use it Simpson Hilti
Free downloads
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ACI Appendi Appendix x D – Updates for ACI ACI 318-11 318-11
MAJOR 2011 UPDATES SEISMIC REVISIONS 31
Appendix D Seismic
Section D.3.3.1
Additional requirements if Seismic Design Category is C, D, E or F
. . .
Appendix D does not apply for anchors located in a plastic hinge
Section D.3.3.3
Post-installed anchor must pass simulated seismic testing 32
Appendix D Seismic
Section D.3.3.4.1
If seismic forces are less than 20% of total tensile force, the extra requirements of section D.3.3.4.3 are not necessar
Section D.3.3.4.2
If seismic forces are more than 20% of total tensile force, the extra requirements of section D.3.3 D.3.3.4 .4.3 .3 are are ne neces cessar saryy 33
Appendix D Seismic
Section D.3.3.4.3 Without reading the commentary, this section is hard to follow Anchors and their attachments must satisfy one of options (a) through (d) This section is trying to prevent brittle failures from occurring during a seismic event
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Appendix D Seismic
Section D.3.3.4.3 (a)
Transmit tensile loads via a ductile steel element. Threads
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Appendix D Seismic
Section D.3.3.4.3 (b)
Section D.3.3.4.3 (c)
Ductile yielding of the t he attachment Anchor capacity limited by a non-yielding attachment like a wood sill plate
Section D.3.3.4.3 (d)
Anchors designed for maximum tension obtained from design load combinations that include E with E increased by Ωo 36
Appendix D Seismic
Section D.3.3.4.4
25% reduction to anchor tensile strength for all failure
in table D.4.1.1 Assume concrete is cracked unless demonstrated that it remains uncracked
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Appendix D Seismic
Section D.3.3.4.5 When anchor reinforcement is provided, no redu reduct ctio ionn in in anch anchor or ten tensi sile le str stren en th is is required D.5.2.9 requires a 25% reduction in the design of the anchor reinforcement
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Appendix D Seismic
Section D.3.3.5.1
If seismic forces are less than 20% of total shear force, the extra requirements of section D.3.3.5.3 are not necessar
Section D.3.3.5.2
If seismic forces are more than 20% of total shear force, the extra requirements of section D.3.3 D.3.3.5 .5.3 .3 are are ne neces cessar saryy 39
Appendix D Seismic
Section D.3.3.5.3 Shear “ductile” requirements similar to the t he ones for tension loads uc e y e mec an sm sm n e a ac men a (b) anchors designed for the maximum shear that can be transmitted to the anchors by a non-yielding attachment (c) Anchors designed for maximum shear obtained from design load combinations that include E with E increased by Ωo
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Appendix D Seismic
Section D.3.3.5.4
Section D.3.3.6
When anchor reinforcement is provided, no reduction in shear strength is required r equired Anchors subject to both tension and shear shall be designed to satisfy D.7 (interaction equation) with tensile strength calculated from D.3.3.4.4 (25% reduction)
Section D.3.3.7
Anchor reinforcement must be ASTM A615 Grades 40 and 60 or ASTM A706 Grade 60
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Appendix D Seismic
Section D.3.4
Adhesive anchors installed horizontally or upwardly inclined shall be tested per ASTM 355.4 for sensitivity
Section D.3.5 For adhesive anchors subjected to sustained tension t ension loading, D.4.1.2 (45% reduction) shall be satisfied s atisfied Installer certification and inspection requirements shall be in accordance with D.9.2.2 through D.9.2.4
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Appendix D Seismic
Section D.3.6
Modification factor for lightweight concrete
CIP and undercut undercut anchor concrete failure failure – 1.0λ xpans on an a es ve anc or concre e a ure - . Adhesive Adhesive anchor bond failure failure – 0.6λ
Section D.3.7
f’c max is 10,000 psi for CIP and 8,000psi for PI
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ACI Appendi Appendix x D – Updates for ACI ACI 318-11 318-11
MAJOR 2011 UPDATES INSTALLATION AND INSPECTION OF ANCHORS 44
Appendix D Section D.9
Section D.9.1 Anchors shall be installed by qualified personnel in accordance with the . contract docum documents ents shall shall require require The contract installation of post-installed 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.
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Appendix D Section D.9
Section D.9.2 Installation of anchors shall be inspected in acco ac cord rdan ance ce with ith se sect ctio ionn 1. 1.33 In Inss ec ectitioon an andd the general building code. Adhesive anchors shall be subject to the following additional requirements (sections D.9.2.1 through D.9.2.4)
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Appendix D Section D.9
Section D.9.2.1 The contract contract docume documents nts shall shall specify proof proof loading loading where required in accordance with ACI 355.4. e con rac ocumen s s a a so spec y a parameters associated with the characteristic bond stress used for the design including:
minimum age of concrete concrete temperature range moisture condition of concrete at time of installation type of lightweight concrete (if applicable) requirements for hole drilling and preparation 47
Appendix D Section D.9
Section D.9.2.2
For horizontal and upwardly inclined adhesive installations, the installer shall be certified by an Program or equivalent.
Section D.9.2.3
Acceptability of other certifications is the responsibility of the licensed design professional.
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Appendix D Section D.9
Section D.9.2.4 Horizontal and upwardly inclined installations re uire continuous s ecial ins ection Inspector shall be specially approved for that purpose by the building official
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ACI Appendi Appendix x D – Updates for ACI ACI 318-11 318-11
IBC 2009 SECTION 1912
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IBC 2009 Section 1912
Anchorag Anchoragee to Concre Concrete te – Strengt Strengthh Design Design CIP anchors, expansion anchors and unde un derc rcut ut an anch chor orss “sha “shallll be des desii ne nedd in in accordance with Appendix D of ACI 318” “The strength design of anchors that are not within the scope of Appendix D of ACI 318…shall be in accordance with an approved procedure.”
Concrete screws, specialty inserts, etc. 51
Poll Question Where do you currently specify the requirements for post-installed concrete anchors? . B. General Notes only C. Details only D. Specs and Details E. General Notes and Details F. Specs, General Notes and Details 52
ACI Appendi Appendix x D – Updates for ACI ACI 318-11 318-11
HOW TO PROPERLY SPECIFY CONCRETE ANCHORS 53
Specifying Concrete Anchors
Specifications
Add a dedicated section for concrete anchors Sample specs can be downloaded from either Simpson or Hilti
Download both and use the best parts of each one
Useful for legal reasons, but how practical is the information? 54
Specifying Concrete Anchors
General Notes
Add a dedicated section for concrete anchors Sample general notes can be downloaded from either Simpson or Hilti
These will probably not include the requirements called out in Appendix D section D.9.2.1
minimum age of concrete, concrete temperature range, moisture condition of concrete at time of installation, etc. 55
Specifying Concrete Anchors
Details If possible, stay generic; If not, be very s ecific fic about th the anch choor Refer back to the general notes or specifications for additional information Create a standard “anchor detail” and refer to it when possible
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Specifying Concrete Anchors Good Term
Torque-Controlled Torque-Controlled Anchor
Refer to General Notes for ASTM designation
Not all adhesives are epoxies; not all epoxies are structural
Epoxy Grout or Grout
Too generic
Epoxy Anchor
Threaded rod separate
Threaded Rod
Expansion Anchor / Exp. Bolt
Referenced in App. D; includes rod and adhesive
Structural Adhesive
A little wordy, but accurate
Adhesive Anchor
Bad Term
Grouted anchors are different
Bolt
Too generic; bolts are not fully threaded 57
Specifying Concrete Anchors
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Specifying Concrete Anchors
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Specifying Concrete Anchors
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Specifying Concrete Anchors
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Specifying Concrete Anchors
Type of threaded rod is not called out
determine the “Or Equal” alternative
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Specifying Concrete Anchors
“Drill & Epoxy Grout” is too open ended Older adhesives have not been tested per ACI 355.4 and are not a owe
Simpson SET and AT Hilti HY 150 and RE 500 Powers Power-Fast
Acceptable versions
Simpson SET-XP & AT-XP Hilti HY150 MAX-SD & RE500-SD Powers PE1000+ and AC100+ Gold 63
Specifying Concrete Anchors
8” embed. is too deep “Exp. Bolt” is too t oo generic Older “Exp. Bolts” not tested per ACI 355.2 and are not allowed per code
Simpson Wedge-All Hilti Kwik Bolt 3 Powers Power-Stud
Acceptable versions
Simpson Strong-Bolt 2 Hilti Kwik Bolt TZ Powers Power-Stud+ SD1 64
Specifying Concrete Anchors
“Exp. Bolt” again
”
Not a big deal here
. ≈ 5,000 lbs. tension ≈ 18,000 lbs. shear
Overkill
½” anchor acceptable
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Summary Adhesive Anchors added to Appendix D Seismic provisions re-written
requirements Proper anchor anchor specifying is critical Fix that stair stringer detail detail 66
Questions
67
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By Mark Bartlett, PE RLG Consulting Engineers
SE University, January, January, 2013
www.LearnWithSEU.com
