hollow block resistance

[jasem81]

when we calculate the hollow block resistance, for the stress shall we consider the whole area of the block or we have to deduct the hole areas from the block surface area
R=P/A
A: with holes area or without?

 

[KootK]

You consider just the solid area of the block which would include the grout in any grouted cells.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[concretemasonry]

jasem81 -

I would suggest you get a copy of ACI 530. It is the standard for masonry design and specifications.

The basic item used is the "masonry strength", f'm. All building codes use the same concepts because it is based on decades of testing. The f'm is a 2 block hollow concrete masonry prism to create a measure of the masonry strength and CMUs can be made with unit net compressive strengths of up to 8000 psi, but for practical purposes lower strength are used because the ultra high strengths are just for testing purposes.

The reason for testing of a block and mortar sample is more realistic since mortar strength does not really affect the f'm. An an example a f'm strength of prism can be 4500 psi using 2200 psi - all stresses are based on face shell bedding.

Trying to dissect a masonry wall into individual materials is a misleading folly.

Enforcement based on individual site samples cannot even done because there is no ASTM method for testing site sampled mortar.

Dick

Engineer and international traveler interested in construction techniques, problems and proper design.