Carbon Fiber Reinforced Polymer

[khinz]

What is your experience with Carbon Fiber Reinforced Polymer in retrofitting columns for more seismic resistance? What are its pros and cons as far as your personal experience and research with them is concerned? Can it help more in the axial load capacity rather than bending moment capacity and are there bad brands of CFRP or all of them similar?

 

[CANPRO]

I have very limited experience with this...for the one project where this came up we sent column dimension, existing loads and required strength to the CFRP manufacturer and they detailed the repair. Sorry, not much help...but its probably worth calling a supplier and seeing what they have to say.

 

[khinz]

I saw a sample of CFRP, it's just like cloth, the supplier said it only works when the main columns spalls or buckles or the concrete crushes. So I guess it is not for normal column that doesn't have any problem? Does anyone actually put this in perfect column just to survive extreme seismic load?

 

[Robbiee]

We did one project where we reinforced beams not columns. For that we met and consulted a professor who has done extensive research on this subject. Some of the issues you need to be aware of are:
1- The material is not considered a "non-combustible" and when using it in a building with the requirement for non-combustible construction, you could have a battle with the city officials even when spraying over it with the fire resistive material,
2- Need to do strain compatibility analysis. Note, some matrices, ( fibre with cured epoxy), have lower than steel modulus of elasticity,
3- Tension straps need to be anchored properly against delamination,
4- Surface of concrete needs to be tested for bond and it has to meet the minimum required bonding stress,
5-The reinforcing needs to meet the required bonding stress,
6- Carbon fiber reinforcing is not a ductile material and therefore you probably can't meet some of the code's required ductility,
7- suppliers have their own engineers who can help in the design.

 

[Mixtli]

The ACI and the Canadian codes have specific sections for FRP, retrofitting with FRP doesn't comply the steel part of code, specially in regards of ductility, that's why there is a FRP section they deals with this.

Cheers

M