Anchor Fastening Technical Guide , Edition 22
for a single anchor . This is the capacity of a single anchor with no edge distance or concrete thickness influences and is based on the assumptions outlined in the footnotes below each table .
Reduction factor tables are created by comparing the single anchor capacity to the capacity that includes the influence of a specific edge distance , spacing , or concrete thickness , using the equations of ACI 318 Chapter 17 .
Determination of bolt bending — Strength Design
3.1.7 CSA A23.3 ANNEX D LIMIT STATE DESIGN
Limit State Design of anchors is referenced in the provisions of CSA A23.3 Annex D , which cover headed studs and bolts , hooked bolts and post-installed anchors that meet the assessment of ACI 355.2 and ACI 355.4 . Furthermore , the suitability of post-installed anchors for use in concrete must be demonstrated by the ACI 355.2 and ACI 355.4 prequalification tests .
LOAD DISTRIBUTION
The provisions of CSA A23.3 Annex D and ACI 318 Chapter 17 are based on identical assumptions . Refer to Section 3.1.6.2 for more details .
3.1.8 HILTI SIMPLIFIED DESIGN TABLES
The Hilti Simplified Design Tables is not a new “ method ” of designing an anchor that is different than the provisions of ACI 318 Chapter 17 or CSA A23.3 Annex D . Rather , it is a series of pre-calculated tables and reduction factors meant to help the designer create a quick calculation of the capacity of the Hilti anchor system , and still be compliant with the codes and criteria of ACI and CSA .
The Hilti Simplified Design Tables are formatted similar to the Allowable Stress Design ( ASD ) tables and reduction factors which was a standard of practice for design of post-installed anchors .
The Hilti Simplified Design Tables combine the simplicity of performing a calculation according to the ASD method with the code-required testing , evaluation criteria and technical data in ACI 318 Chapter 17 and CSA Annex D .
SIMPLIFIED TABLES DATA DEVELOPMENT
The Simplified Tables have two table types . The single anchor capacity table and the reduction factor table .
Single anchor capacity tables show the design strength ( for ACI ) or factored resistance ( for CSA ) in tension and shear
HILTI MECHANICAL ANCHORS OR HILTI HIT-Z ( -R ) ANCHOR RODS
The single anchor tension capacity is based on the lesser of concrete breakout strength or pullout strength :
ACI / AC308 : |
ФN n
= min | ФN cb ; ФN pn
|
|
CSA : |
N r
= min | N cbr ; N cpr
|
|
|
ФN n
= N r
|
The shear value is based on the pryout strength .
ACI / AC308 : CSA :
ФV n
= ФV cp
V r
= V cpr
ФV n
= V r
Concrete breakout and pryout are calculated according to ACI 318 Chapter 17 and CSA A23.3 Annex D using the variables from product specific ICC-ES Evaluation Service Reports ( ESR ' s ). These values are equivalent .
Pullout for torque controlled adhesive anchors is not recognized in ACI or CSA , so this is determined from AC308 Section 3.3 and the value of N p , uncr or N p , cr from ESR-4868 . This is a similar approach to mechanical anchor pullout strength . ACI and CSA values are equivalent .
HILTI ADHESIVE ANCHORS WITH STANDARD THREADED RODS , REBAR , AND HILTI HIS- ( R ) N INTERNALLY THREADED INSERTS
The single anchor tension capacity is based on the lesser of concrete breakout strength or bond strength :
ACI : |
ФN n
= min | ФN cb ; ФN a
|
|
CSA / ACI : |
N r
= min | N cbr ; N a
|
|
|
ФN n
= N r
|
The shear value is based on the pryout strength .
ACI : CSA / ACI :
ФV n
= ФV cp
V r
= V cpr
ФV n
= V r
Concrete breakout , bond , and pryout are calculated according to ACI 318 Chapter 17 and CSA A23.3 Annex D using the variables from product specific ICC-ES Evaluation Service Reports ( ESR ' s ). These values are equivalent , however , the values will be calculated based on standard concrete compressive strengths specified in the US or Canada .
Anchor Fastening Technical Guide Edition 22 | 3.0 ANCHORING SYSTEMS | 3.1 ANCHOR PRINCIPLES AND DESIGN Hilti , Inc . 1-800-879-8000 | en español 1-800-879-5000 | www . hilti . com | Hilti ( Canada ) Corporation | www . hilti . ca | 1-800-363-4458
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