Detailers must exercise caution when working with bolts and edge distances, as these are common areas for errors in structural detailing. In this blog, I’ll share my experience with a bolt edge distance issue and how it was resolved.
The Scenario
In a recent project, the design required a UB (Universal Beam) to sit on a 200mm-thick concrete wall, secured with M20 chemset bolts.
Upon review, it became clear this setup wasn’t feasible:
- Anchor Distance: M20 bolts require a minimum anchor distance of 120mm.
- Edge Distance: A minimum edge distance of 80mm is necessary.
Additionally, the beam wasn’t centered on the wall, further complicating the bolt placement.
The Proposed Solution
To address the issue, I proposed welding plates to the bottom of the beam. This adjustment allowed the beam to be bolted to the side of the wall rather than its top.
The Engineer’s Feedback
After reviewing the proposal, the engineer suggested a simpler solution: using a single row of bolts instead of two. This change eliminated the edge distance problem.Engineer mentioned that one row of bolt is enough for this beam.
In this project, the engineer did not accept our proposal, as they determined that the beam does not require that level of support. However, as detailers, it is our responsibility to highlight the issue and propose suitable solutions.
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