Fully grouted masonry in ETABS

[nicaeng]

Hi everyone, i was working on modeling a masonry structure in ETABS 2015 and i wondered if ETABS always considers the wall to be fully grouted?. If a partially grouted wall be needed, what would be the best way to model it?.

Thanks in advance.

 

[EZBuilding]

To the best of my knowledge the wall properties for masonry walls in ETABs 2015 always considers the wall to be fully grouted. In the past I have accounted for the change in weight/mass/and stiffness by creating different wall types which have property modifiers.

 

[nicaeng]

Thank you.

Instead of modifying the properties, could it be the same if we use different wall thicknesses?, i.e. the Masonry design code for Dominican Republic includes a table where they give you "equivalent" wall thicknesses according to the spacing of the rebar (assuming only the rebar cells are grouted).

 

[Pcacciat]

In our office we model the equivalent thickness of the wall based on the grouting pattern as you suggest. The Reinforced Masonry Engineering Handbook has some useful tables for checking equivalent thicknesses based on net area calculations. I also use this simple chart from a CMU manufacturers website:

http://www.angelusblock.com/products/technical_articles_wall_weights.cfm

This method is effective for modeling in-plane stiffness of shear walls. If you are counting on any out-of-plane stiffness from your walls contributing to the lateral system (which I would not recommend for CMU) then I would use property modifiers instead and reduce the membrane stiffnesses of the wall (f11, f22, f12).