Structural Strengthening using CFRP
Carbon fibre reinforced polymer (CFRP) composites consist of a resin (usually epoxy) which transfers the stress between the fibres and protects them. CFRP strengthening can be applied to beams, slabs and columns to increase structural capacity in flexure, shear or both as well as to serve as confinement for ductility improvement.
We provide a design and installation service for FRP composite strengthening using pultruded plates and wrap systems.
Application #1: Bridge Pier Strengthening using CFRP Wrap
CFRP enhances the inside-core compressive strength of the column (fc') by increasing confinement stress (fl), i.e.
fcc' = fc' + k*fl (AASHTO, ACI 440.2-23, simplified)
k = constant i.e. k = 2.0 (AASHTO)
fl = confining stress
*FRP wrapping is a common method to improve the axial strength of a column. When combined with concrete jacketing technique, the column-PMM strength envelope can be significantly improved.
Photo: Repair and Strengthening of Airport Rail Link Pier by CFRP wrapping (Posteck Prestressing, 2023)
Application #2: Beam Strengthening
In this project, we apply CFRP strips at the top and bottom layers to strengthen a two-span continuous beam supporting a swimming pool structure. The objective is to compensate for the deteriorated rebar due to Chloride attack.
Moreover, shear strength is enhanced by using U- wrap technique. The design agrees with ACI 440.2 requirements.
Photo : (Top) Flexural strengthening of beam with CFRP plates.
(Bottom) Shear strengthening using U wrap (Posteck Prestressing, 2025)
Software Tools for CFRP Strengthening Design
FLEX-S (2019), COLUMN-S (2019):
Strengthening design based on ACI 440.2 demands analysis of the existing and design of the strengthened section. To handle such a process, we have developed a few application tools to simplify the strengthening design of both prestressed and non-prestressed flexural members. Our state-of-the-art tools enhance the speed and accuracy of the strengthening design significantly.
FLEX-S is used for flexural strengthening design of beam and slab while COLUMN-S is for column strengthening design that supports rebar jacketing and CFRP wrapping.
