STRENGTH DESIGN OVERVIEW
Advanced anchor design superseding Allowable Stress Design
Strength design of anchors is based on an assessment of the load conditions for an anchorage and the
calculated anchor capacities corresponding to possible failure modes. North America currently uses
strength design (SD) and limit states design (LSD) methods for cast-in-place and post-installed anchor
design in concrete.
Strength Design: The Strength Design Method has been included as the basis for anchor design in the
International Building Code (IBC) and the American Concrete Institute Building Code Requirements for
Structural Concrete (ACI 318). The method assigns specific strength reduction factors corresponding to
possible failure modes, provides predictions for the strength associated with a failure mode and compares
the calculated strength for each failure mode to a factored load. The Strength Design Method is
considered state-of-the-art with respect to anchor design in concrete and has superseded the Allowable
Stress Design method in the United States. Strength design qualification for post-installed mechanical
anchors is conducted in accordance with the ICC-ES acceptance criteria (AC193) and the ACI test
standard (ACI 355.2). Strength design qualification for post-installed adhesive anchors is conducted in
accordance with the ICC-ES acceptance criteria (AC308) and the ACI test standard (ACI 355.4). Hilti
post-installed mechanical anchors and adhesive anchors are qualified via AC193/ACI 355.2 and
AC308/ACI 355.4, respectively, for use with the anchoring-to-concrete provisions of the IBC and ACI 318.
Limit States Design: The Limit States Design Method for anchor design is described and included in the
anchorage provisions of CSA A23.3 Annex D. In principle, the method follows the strength design
concept by assigning specific reduction factors corresponding to possible failure modes, providing
predictions for the resistance associated with a failure mode and comparing the calculated resistance for
each failure mode to a factored load. The Limit States Design Method has begun to supersede Allowable
Stress Design in Canada.
For a detailed breakdown of these design methods including design examples, please reference the Hilti
Product Technical Guide Volume 2: Anchor Fastening for the US and Canada.
Hilti offers best in-class design software, PROFIS Anchor, to assist you when designing with the anchoring
provisions of ACI 318 and CSA A23.3. The software is a comprehensive and intuitive tool that performs
calculations per the anchoring provisions of ACI 318-08 and ACI 318-11 Appendix D, ACI 318-14 Chapter
17, ACI 349-01 Appendix B, and CSA A23.3-14 Annex D and produces a design report with the
calculations and 3D schematic of the anchor design.
Included within PROFIS Anchor software are a number of powerful features, exclusive to Hilti, that greatly
enhance the user's choice and efficiency. Users can design with Hilti mechanical and adhesive anchor
systems as well as cast-in-place headed studs and headed bolts. Tutorials explain step-by-step how to
navigate within the software and the searchable Design Guide is an innovative, interactive tool that
explains ACI 318 strength design calculations and PROFIS Anchor “black box” design assumptions.
Give your next project the power of strength design or limit states design calculations and Hilti codecompliant anchors by adding our complimentary PROFIS Anchor software to your toolbox.
US download
Canada download