Supplementary reinforcement is additional steel reinforcement placed at specific locations in a concrete structure to resist local stress concentrations. These are reinforcement bars added alongside the regular main and distribution reinforcement at points where extra tensile forces or cracking risks occur.
When is supplementary reinforcement needed?
- Openings and voids — around holes in slabs or walls (for services, stairs, lift shafts) stress concentrations require extra steel
- Corners and re-entrant angles — at corners in walls or slabs additional forces arise
- Bearing points — where a beam or slab rests on a support, extra shear reinforcement is needed
- Fixed supports — at fixed-end connections, additional bars are needed for the hogging moment
- Crack control — at locations with a heightened risk of cracking, supplementary bars are placed
Practical workflow
- Calculation — the structural engineer determines where supplementary reinforcement is required
- Drawing — the additional bars are shown as separate positions on the reinforcement drawing
- Fixing — the steel fixer places the supplementary bars at the indicated locations
- Inspection — before pouring, all supplementary reinforcement is checked for correct placement
Related terms
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