Language: English
Strengthening of RC Slabs with Openings
Carbon Fiber Plate
The strengthening solution uses carbon fiber reinforced polymer (CFRP) plates bonded to the slab soffit in two perpendicular directions, with additional plates reinforced along the opening perimeter.
Project Overview
This project involves the structural strengthening of a reinforced concrete floor slab at a hospital building in Peru.
Some rectangular openings were required to accommodate upgraded MEP services for the hospital's medical equipment expansion. The existing slab reinforcement was cut during opening creation, requiring flexural capacity restoration in both directions.
The strengthening solution uses carbon fiber reinforced polymer (CFRP) plates bonded to the slab soffit in two perpendicular directions, with additional plates reinforced along the opening perimeter.
Code Reference
Design follows ACI 440.2R-17 Guide for the Design and Construction of Externally Bonded FRP Systems for Strengthening Concrete Structures.
The floor slab is reinforced at the bottom with carbon fiber plates to simulate the original two-way reinforcing steel system, compensating for the loss of flexural capacity caused by the cut-off steel bars.
Strengthened carbon fiber plate hoops are installed around the openings: carbon fiber plates are added around the openings to restrain the edges, address stress concentration, and compensate for the weakening of the cross-section caused by the openings.
The carbon fiber plates extend to the support (beam/wall) area to ensure sufficient anchorage length and prevent FRP-concrete interface delamination failure.
Material Profile: HM‑1.4T CFRP Plate
HM‑1.4T is pultruded unidirectional carbon‑fiber‑reinforced polymer laminate for structural retrofitting, thickness 1.4 mm, applied together with HM‑120CP epoxy adhesive.
Key mechanical properties (ASTM D3039)
| Item | Value |
|---|---|
| Thickness | 1.4 mm |
| Characteristic tensile strength | 2600 MPa |
| Tensile modulus | 160 000 MPa |
| Elongation at break | ≥1.7 % |
| Standard width | 50 mm, 100 mm |
Pultruded manufacturing guarantees straight carbon‑fiber alignment and excellent flatness, helping full contact between plate and concrete substrate.
Ultra‑thin 1.4 mm thickness brings negligible added weight and no loss of ceiling height.
Good chemical resistance and long‑term durability, suitable for humid ambient conditions in South America.
Higher stiffness compared with CFRP fabric, delivering better deflection control for cut‑out slab.
