Shear Crack in Concrete Beams

[aguynamedbryan]

Hi All,

I was hoping to gain some insight on visible shear cracks in concrete beams. At what point does a visible shear crack become a concern? I've attached a picture of a crack in a parking structure beam; is this something to be concerned about?

Thanks for your input.

Bryan

 

[rapt]

Kootk,

While most engineers in the world have at least some capacity to understand English, that makes it a logical language to use. Even in Asian countries, a lot of engineering education is at least partly in English. Most Asians and Europeans have English as a 2nd or 3rd language.

On the other hand, most do not use ACI codes. Maybe we could make the assumption that it is ACI code users who ask most of the questions but that could be taken as being offensive by ACI code users!

I was not having a go at you. It is about time that people asking questions on this site, nominally engineers with an understanding of the information needed to make engineering decisions, started providing sufficient information for people to comment logically. Sometimes it takes several posts to get someone to give the information that is pertinent. If they do not know what information is required in the first place, that is a problem in itself as an engineer working in an area should at least know what information is pertinent to the question.

Re shear cracks in PT members, a principal tensile shear crack would not extend to the tension face, as a flexure-shear crack would. Principal tensile shear cracks happen in low flexural stress zones (normally fully compressive near points of contra-flexure or at free ends) where there will not be a flexural crack at all. That is why knowing if it is PT would be helpful.

However, the crack does appear to extend to the tension face in this case, though it does get thinner there. This would be expected if sufficient flexural reinforcement has been supplied. The flexure crack might initiate the shear crack, but the flexural reinforcement is sufficient to keep that part of the crack contained while there may be insufficient shear reinforcement to contain the shear part of the crack.