Concrete Beam Strengthening
Concrete Beam Strengthening
(OP)
We have a sitution where 60 ft span beam have to carry more live load and reinforcement becomes less than the required. I need to provide deficient reinforcement with steel plates anchored to soffit of the beam. How can i design the anchors? Beam is 24"x48" in X-sec.






RE: Concrete Beam Strengthening
RE: Concrete Beam Strengthening
RE: Concrete Beam Strengthening
RE: Concrete Beam Strengthening
One option may be to verify the actual strength of the concrete in the beam. Quite often, the actual strength is more than the design strength. You may opt to have some cores taken to verify this.
If the higher strength does not give your beam sufficient capacity, you may try external post tensioning.
Sometimes, if possible, adding an extra beam (secondary) line on the side of the existing beam may help.
RE: Concrete Beam Strengthening
RE: Concrete Beam Strengthening
RE: Concrete Beam Strengthening
I understand the beam is already loaded and we are fixing that plate to account for additional live loads. How can i determine force in anchor which might be longitudinal shear force in the beam for additional moments. As in some cases we cannot guarantee the hole size in plate exactly same as anchor so anchor looks like only holding the plate to concrete face.
(Beam is not going to be overreinforced and there is no deflection problem as such now).
RE: Concrete Beam Strengthening
RE: Concrete Beam Strengthening
Check quakewrap.com for more information.
RE: Concrete Beam Strengthening
RE: Concrete Beam Strengthening
A steel channel either side may do the trick(expensive, but probably cheaper than carbon fibers). Yuo need to look at strain compatability though.
RE: Concrete Beam Strengthening
RE: Concrete Beam Strengthening
RE: Concrete Beam Strengthening
Can you suggest a standard or code to use for justifying the steel to concrete bond through the epoxy adhesive? What adhesive would you use? What are the creep characteristics of the adhesive? What shear stress would be used? Is a clamping force necessary? What about the fire rating of the beam? There may be answers for all this, but the justification is not well enough formulated for my liking.
I agree with others that external posttensioning is the way to go.
RE: Concrete Beam Strengthening
RE: Concrete Beam Strengthening
RE: Concrete Beam Strengthening
RE: Concrete Beam Strengthening
RE: Concrete Beam Strengthening
"Design manual for roads and bridges. Vol. 3: Highway structures: inspection and maintenance. Section 3: Repair and strengthening. Part 1: Strengthening of concrete highway structures using externally bonded plates.
Corporate Author: Great Britain Department of Transport
Publisher: HMSO
DTp (now the Highways Agency) publication no. BA 30/94. Dated February 1994. "
RE: Concrete Beam Strengthening
RE: Concrete Beam Strengthening
I'm in Canada, not able to reach the british standards.
Better refer something to Canadian Standards or US.
RE: Concrete Beam Strengthening
RE: Concrete Beam Strengthening
RE: Concrete Beam Strengthening
RE: Concrete Beam Strengthening
RE: Concrete Beam Strengthening
RE: Concrete Beam Strengthening
I mean fibrewrap type of retrofit (passive) http://www.geosyseng.com/0301fibrewrap.html, not external prestressing.
RE: Concrete Beam Strengthening
RE: Concrete Beam Strengthening
Retrofit is about lots of money for just a little bit of capacity. Fibrewrap application becomes more popular since it improves bending and shear capacity as well. Call to the local representatives they will be happy to quote.