BA, the structural engineer told me he will only authorize any replacement of the epoxy after he sees the stress-strain curve because he believes that something with compressive strength of 11,000 psi should have large modulus and said the concrete relationship E=57,000 (sqrt(fc)) may hold for...
BA or others,
The book says steel tensile strength peak can go up to 0.008. But it also said that "If the small knee prior to yielding of the steel is disregarded, i.e., if the steel is assume to be sharp-yielding, the strain at which it yields is
strain(y)=fy/Es=60,000/29,000,000=0.00207"...
Ron, I'm not limiting it to 0.0005 in/in of strain in epoxy. The reason I use 0.0005 is it's the elastic limit of concrete. Above 0.0005. Concrete is no longer elastic but plastic (permanent deformation). I'm assuming uniform strain for a cylinder with say half of concrete and half of epoxy...
http://imageshack.us/photo/my-images/46/stressstraincurve.jpg/
Hokie, I've been concerned about the greater epoxy creep than concrete (details below). I'm still looking for the repair company that can do the job while trying to think how to introduce all this strain compatibility thing to my...
Ba wrote:
I wonder or curious how you could come out with such an idea of epoxy layer sandwidth between concrete spaces. Unless the advantage is more than the disadvantage. The advantage would be no eccentricity (at least internally as there is always external eccentricity), the disadvantage...
I got the figure from the following page:
http://www.epcserver.com/Structural/analysis/concrete/info_concrete_repair.asp
The illustration above about form extended above void was what my contractor told me how they would proceed if I demand it replacing it including the whole section removed...
BA, you said the centroid of section shifts to the right so the eccentricity is to the left of the new centroid, but you said the section "deflection will be to the right". Did you mean the column will bend to the left or right? If to the right, then you are saying the midspan will sway to the...
Both the contractor and structural engineer don't understand and refuse to analyze this epoxy load reduction stuff. They told me they build 20 storey buildings and use epoxy as repair all the time and it is standard as there is no other more effective repair replacements. That's right. In the...
rowingengineer, in my country we don't have fire rating in columns... our ready mix concrete are only one kind. The column with hole filled with structural epoxy is 1 foot below the ground floor level slabs with tie beams connecting to it. In other word, it is a joint but the tie beams are not...
http://imageshack.us/photo/my-images/843/stressanalysis.jpg/
BA, you brought up a point about transformed section that makes it worse and the calculations may not be valid. In the illustration above, the centroid of the above section goes to the right side. Now do you think the concrete in the...
TXStructural. It could have been easier if the void is still not filled. But two weeks ago. The contractor told the epoxy company to check and the epoxy engineer said they can cover it up with epoxy and it's stronger than concrete. And the structural engineer complied...
BA wrote:
Yes. I thought of this yesterday while driving and imagining the stress distribution from the top to the bottom of the column... above the hole, it is 3625 Kn. In the hole filled with epoxy capacity of both concrete and epoxy is just 2566 Kn. So I wonder how that section could take...
The shear bond strength is on the surfaces of old concrete and new concrete or mateial. It has to reach 5000 psi too. If not. He said to imagine a big stone and a tiny stone. You put the big stone on top of small stone, the small stone has tendency to break, the small concrete he refers to the...
Compressive strength tests of their products in the form of epoxy cubes are done and strength can reach up to 8,000 psi. But for a cylinder the height of 8 inches or 200mm. A strain of 0.0005 would be only 0.1mm and we don't have the machine to measure that micro strain versus stress in that...
BA, according to many engineers locally, the reason they avoid it is the connections between the concrete inserted to the column would have minimal shear bond strength. Whereas they said if one puts epoxy, the shear bond strength is around 3000 to 5000 psi. They reason that if the new concrete...
