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Structural strengthening design for PT and RC slabs and beams
When an existing slab or beam has to carry more, lose some of its section to a new opening, or make up for a deficiency, our team assesses it and designs the strengthening. We design; the strengthening works are carried out by the specialist contractor appointed for the project.
When strengthening design is needed.
Existing post-tensioned and reinforced concrete floors are changed more often than people expect. A tenant needs a new stair or shaft, a floor changes use from office to storage or plant, a site test shows low concrete strength, or a review finds a deficiency in the original design. Each case starts the same way: an assessment of what the existing structure can carry, then a strengthening scheme designed to close the gap.
- New openings and coring in PT slabs: locating tendons from the as-built drawings and a scan, then checking the slab with tendons cut or re-routed. See our guide to openings and coring in PT slabs.
- Load increase and change of use: checking flexure, shear, punching and deflection under the new loads.
- Deficiency remediation: low concrete strength, missing reinforcement, tendon damage or a design shortfall found in review.
- Punching shear strengthening at slab-column connections.
Strengthening methods we design.
The method is chosen to suit the structure, the access and the programme.
| Method | Typical use |
|---|---|
| CFRP / FRP strengthening (laminates, sheets, near-surface mounted bars) | Flexural and shear strengthening of slabs and beams, around new openings and for load increase. Designed to ACI 440.2R or the specified guideline. |
| External post-tensioning | Adding prestress to beams and transfer members to restore or increase capacity and reduce deflection. |
| Steel plate bonding and steel framing | Trimming new openings, local flexural strengthening and supports where FRP is not suitable. |
| Section enlargement (concrete jacketing, overlays, new drop panels) | Increasing depth or section where loads rise significantly. |
| Punching shear strengthening (post-installed shear bolts or studs, collars, drop panels) | Increasing punching resistance at columns. |
What you receive.
- Assessment report of the existing structure, with the assumptions and any testing relied on.
- Strengthening calculations, clause-referenced to ACI 318, ACI 440.2R, PTI guidance or the governing code.
- Strengthening drawings and method notes for the specialist contractor, including sequencing and temporary propping where needed.
- Responses to authority or consultant comments, and site inspection of the installed strengthening by arrangement.
We provide design and engineering only; strengthening materials and installation are by the specialist contractor appointed for the project. Related services: PT design review and site supervision.
Questions we are asked about this.
Can you design strengthening for a post-tensioned slab?
Yes. PT slabs need extra care because cutting or debonding a tendon affects the slab beyond the opening. We assess the tendon layout and design the strengthening around it.
Which strengthening method is best?
It depends on the deficiency, access, fire and durability requirements and programme. CFRP is light and quick, external post-tensioning suits beams, and steel or section enlargement suit larger load increases.
Do you install the CFRP or steelwork?
No. We design the strengthening and can inspect it on site. Materials and installation are by the specialist contractor appointed for the project.
What do you need to start?
As-built structural drawings, the PT shop drawings if available, the proposed change, and any test or scan results.
Related services and guides.
Most projects touch more than one of these. The Iron Axis home page has the full overview.
Openings and coring in PT slabs
Cutting tendons safely.
Read more →
PT design review
A thorough check of a post-tension design before it is approved or built.
Read more →
PT transfer slabs & beams
Heavy-load members.
Read more →
PT site supervision
Pre-pour inspections of profiles, anchorages and coordination.
Read more →Send the drawings. Get an answer from our engineers.
WhatsApp or email the architectural or structural set, the location and what you need. The reply comes from the engineers who will do the work, with a proposed scope and programme.
- +971 52 118 2569
- Telephone
- +971 52 118 2569
- Office
- Al Warqa 1, Dubai, UAE
- Hours
- Sunday – Thursday, 09:00 – 18:00 GST