Product Technical Guides : US-EN Anchor Fastening - August 2021 | Page 24

The following is a general summary of the accuracy of the simplified tables :
• Single anchor tables have values equivalent to a calculation according to ACI or CSA .
• Since the table values , including load adjustment factors , are calculated using equations that are not linear , linear interpolation is not permitted . Use the smaller of the two table values listed . This provides a conservative value if the application falls between concrete compressive strengths , embedment depths , or spacing , edge distance , and concrete thickness .
• For one anchor near one edge , applying the edge distance factor typically provides accurate values provided the failure mode of the table values is the same . If the failure mode is not the same , the values are conservative .
• For two to four anchors in tension with no edge reductions , applying the spacing factors provides a value that is equivalent to the ACI and CSA calculated values , provided the controlling failure modes of the table values are the same . If the failure mode is not the same , the values are conservative .
• The spacing factor in shear is conservative when compared to two anchors with no edge distance considerations . This factor is based on spacing near an edge and can be conservative for installations away from the edge of the concrete member . Note : for less conservative results , it is possible to use the spacing factor in tension for this application if there is no edge distance to consider .
• The concrete thickness factor in shear is conservative when compared to an anchor with no edge influences . This factor is based on applications near an edge . In the middle of a concrete member this is conservative . Note : for less conservative results , this factor can be ignored if the application is not near an edge .
LIMITATIONS USING SIMPLIFIED TABLES
There are additional limitations that the Simplified Tables do not consider :
• Load Combinations : Table values are meant to be used with the load combinations of ACI 318 Section 5.3 and CSA A23.3 Chapter 8 . Other load combinations from other code sections are not considered .
• Supplementary Reinforcement : Table values , including reduction factors , are based on Condition B which does not consider the effects of supplementary reinforcement , nor is there an influence factor that can be applied to account for supplementary reinforcement .
• Eccentric loading : Currently , there is not a method for applying a factor to the tables to account for eccentric loading .
• Moments or Torsion : While a designer can apply a moment or torsion to the anchor system and obtain a specific load per anchor , the tables themselves do not have specific factors to account for moments or torsion applied to the anchor system .
• Standoff : Standoff is not considered in the steel design tables .
• Anchor layout : The Simplified Tables assume an orthogonal layout with no more than 2 nearby edges .
As stated above , while the Simplified Tables are limited in application , the designer can use the PROFIS Engineering which does account for the conditions noted above .
There may be additional applications not noted above . Contact Hilti with any questions for specific applications .
IMPORTANT NOTE :
For applications such as a four bolt or six bolt anchor pattern in a corner in a thin slab , the calculation can be up to 80 % conservative when compared to a calculation according to ACI or CSA , and when using the PROFIS Engineering . It is always suggested to use the PROFIS Engineering or perform a calculation by hand using the provisions of ACI and CSA to optimize the design . This is especially true when the Simplified Table calculation does not provide a value that satisfies the design requirements . The fact that a Simplified Table calculation does not exceed a design load does not mean the Hilti anchor system will not fulfill the design requirements . Additional assistance can be given by your local Hilti representative .
20 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