Cracks in Structural Slabs and Walls 2

[StrucConsultant]

Hi everyone!
I'm looking to find good references, books or articles on the subject of 'Cracks in structural slabs and walls' and in particular on the subject of 'normallity of having some cracks'.
We all know that a cetain amount of cracks is normal in concrete poured on site. But when it comes to convincing non engineer or non tech people (like building managers in condominium towers with one, two, or three underground levels for parkings) in that the cracks they have in their structural slabs or walls is - to a certain extend - normal, it is quite difficult.
Anyone can help?
Thanks

 

[TXStructural]

I recommend quickly evaluating the members and identifying the nature of the cracks (shrinkage/restraint, flexural, shear).

The International Concrete Repair Institute has a publication titled "Causes, Evaluation and Repair of Cracks in Concrete Structures" available at icri.org

 

[Ron]

I agree with TX...learn what caused the cracks and you can better explain such to a non-engineer. Most cracks are caused by drying shrinkage. They have certain characteristics. Others may be caused by stresses induced by settlement...they also have certain characteristics. Others may be caused by structural overstress of another source...again, certain characteristics.

ASCE has a publication on the structural inspection of structures. You might want to get that in addition to the one noted by TX. Further, ACI has some good publications on the subject.

 

[slickdeals]

ASCE has a publication on the structural inspection of structures. You might want to get that in addition to the one noted by TX. Further, ACI has some good publications on the subject.

I have always been interested in knowing the characteristics of cracks induced by certain modes. Ron, would you be able to point out the references that you mentioned?

Engineers always get asked why concrete cracked and a non-engineer usually thinks it is a big deal (an eyesore more than anything else) and it would be good to know what causes cracks of a certain kind and be able to explain in lay man terms.

 

[rscassar]

This is something that was given to me along the way:

 

[StrucConsultant]

Thank you all.
I'll look at all your suggestions and references.
That is all very interesting.
kikflip, your document is quite interesting and summarizes it all.

In my case, I know that all the cracks I've seen were caused by shrinkage. I've designed tens of buildings with underground parking levels and there are always a few cracks. The thing is to convince non engineers that it is quite normal and it is not dangerous. That's why I'm looking for an independent source to reassure them. Some condo owners get scare so easily or they want to create trouble.
I’ll try and find all your references.
If you have any other ideas, there are all welcome.
Thank you.

 

[msquared48]

Don't have any good books, but did nrun into a classic example of diagnol tension failure some years past.

Had a 12 foot high retaining wall... (gee you think) ... with two 90 degree return walls at the ends, serving as the back wall of a commercial structure. Well, you can probably imagine the rest - two perfect 45 degree cracks from the ends of the wall to the foundation - absolutely perfect, like it was planned, from overcompacting a green wall!

So denied the contractor as he removed the wall.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[Ron]

Mike...interesting consistency among contractors, even diagonally across the country!!

 

[JoshPlumSE]

I did some post Northridge damage assessment work back in the 90's. There were some papers that were used as the basis for assessing damage.

1) Robert Hanson, "Evaluation of Reinforced Concrete Members Damaged by Earthquakes". I believe this was published in "Earthquake Spetra Volumn 12, No3 in August of 1996.

2) Hasan Sassi, Richard Ranous, "The Effect of Yielding in Reinforcing Steel on Concrete Shear Capacity". Published by OES...the Office of Emergency Services (california's equivalent of FEMA)

3) Hassan Sassi, "Shear Failure in Reinforced Concrete Walls". Also published by OES

4) ACI 224.1R-93 (reaffirmed in 1998): Causes, Evaluation and Repair of Cracks in Concrete Structures.

5) ACI 224R-90 Control of Cracking in Concrete Structures.

In my opinion, references 2 and 3 were not very rigorously derived and were too simplified to be of much use for a true engineering report. Though, it was a simplified enough procedure that just about anyone could do it.... easy to show to a client or building owner.