Australian FRP Strengthening

[Trenno]

Hi all,

I would like to get familiar with external FRP strengthening techniques for RC structures, as opposed to traditional methods (additional steel beams etc).

Can anybody share some good links to information regarding the design of these systems, with possibly an Australian flavour?

Who are the major suppliers of FRP wrap in Australia? Is it really that cost effective?

Would be good to hear your thoughts of FRP in general...

Thanks

 

[EngineeringEric]

in the US. we have ACI 440. it is a good tool. may be useful for you for some preliminary info. probably will find published presentations and so far with a few searches

 

[rowingengineer]

I would start with the sika Carbodur product as they have some very helpful reps that will at least get you on the path to a solution. They also have testing ect, and can point you in the direction of the right standards.

http://www.nceng.com.au/

"Programming today is a race between software engineers striving to build bigger and better idiot-proof programs, and the Universe trying to produce bigger and better idiots. So far, the Universe is winning."

 

[Trenno]

Awesome, thanks RE.

Have you used Sika before?

 

[Ingenuity]

I have designed and installed SIKA, BASF and FYFE Co. FRP systems, and all three have very similar wet-layup systems and pultruded systems too. Similar products as far as site applications (saturators, resins, primers etc), and similar materials props (tensile strength, and modulus). Some manufacturer's have some 'boutique' weaves (carbon/Aramid, +/-45, double density etc).

Pultruded sytems are quick to install, but higher cost of materials, and obviously only work for planar-type surfaces.

With wet-layup systems you typically wish to avoid full surface coverage as it can lead to moisture-vapor transmission - wait a few hours and watch the FRP 'bubble and bllister' right in front of your eyes as it cures and 'out gasses'. Not a pretty sight!

Probably the most significant difference between the manufacturers is how to design for fire under the strengthened/repaired state given that the glass transition temperature for the resin typically used is less than 180F (83C). Some manufacturer's go the UL-tested route and provide fire protection for say 2 upto 4 hr endurance (Fyfe Co, for example) validated by lab fire tests, whilst in contrast, BASF state "that it will not take long for an externally bonded FRP material to this glass transition temperature, and common means of fire protection, such as intumescent coatings, sprayed mineral fibers, or gypsum board, do not provide sufficient insulation to keep the temperature of the FRP below the glass transition temperature. It is, therefore, recommended to completely neglect the fire endurance of these materials. It is instead necessary to rely on the existing (unstrengthened) structure for fire endurance. (This is actually necessary for any reinforcement that relies on epoxy adhesives for bond, such as external steel plate bonding.) Although the temperature resistance of the FRP material itself is relatively low, it is still possible for an FRP strengthened structure to attain required fire endurance levels [Bisby et al. 2005]. It is suggested to evaluate the fire endurance of the existing structure using a performance-based approach as detailed in ACI 216R. In this approach, the temperature distribution throughout a section is found for a given fire endurance requirement (e.g.,2 hours). For this particular temperature distribution, the strength of the concrete and steel is reduced due to the elevated temperature (e.g., the yield strength of the steel is reduced to fyθ)."

You also have to probably satisfy Flame Spread and Smoke Generation index too - usually achieved via a roll-on coating tested to satisfy.

We always provide a coating of some description to finished FRP - if no fire conditions are required (exterior application, for example) we still apply a UV protection coating, usually color-matched to the existing finish.