Hi Grant,
Hilti is often asked to provide guidance regarding the retrofitting of cast-in-place light pole anchors with post-installed adhesive anchors. Post-installed anchor design in accordance with the American Concrete Institute Building Code Requirements for Structural Concrete (ACI 318-14) is complex and requires checking multiple potential failure modes. The edge distance from the center of the anchor to the edge of the foundation, spacing between anchors, concrete thickness, and embedment depth are often limiting factors when determining anchor capacity. Furthermore, many light pole bases are typically round in shape, and ACI 318 anchor design is based on orthogonal structures, such as a square shape.
The required embedment depth for a post-installed anchor is typically greater than the depth required for a cast-in-place anchor. Since Hilti cannot provide engineering design services, we suggest that you consider consulting an engineer to evaluate anchor capacity. Many design engineers will consider using Hilti’s HIT-RE 500 V3 or HIT-HY 200 V3 (-A/-R) adhesive anchor to post-install new anchor bolts. To assist with referencing technical documents for the adhesive and threaded rods, please click on the links below:
- HIT-RE 500 V3 Technical Data with threaded rod
- HIT-HY 200 V3 Technical Data with threaded rod
Engineers typically consider utilizing a conservative approach to evaluate a round concrete structure by modeling anchor capacity based on the size of a square shape that will fit within the outside diameter. Additionally, engineers will also consider using rebar development theory as an alternate design method to evaluate potential post-installed anchor solutions.
Final selection of a post-installed anchor system will be the decision of the design engineer, who may use anchor design software, simplified design tables, hand calculations, and engineering judgment. Typically, engineers will utilize Hilti’s PROFIS Engineering software to perform calculations based on the specific conditions of the project. Please click here to access PROFIS Engineering from Hilti’s website.
Regards,
Ashley