flexural strength of reinforced masonry column

[jgeng]

In analyzing/verifying compatibility with current code requirements a coastal residential structure sitting on exposed 12" CMU masonry piers with rc footers. With the only reinforcement specified in the original plan (recent design) for the piers is (2) #5 rebar, the placement of which in the column is ill-defined. On some of the columns the rebar is shown to be placed in in one in one axis direction and on others in the other axis direction. I am assuming I should look at this as a fixed condition at bottom and pin condition at top and analyze the columns for combined compression and flexure. However only say 1/2 of the columns for any given axis direction have any resisting flexural capacity because of the reinforcment arrangement. How do I look it this as far as proportioning the loads to the resisting columns and what is the proper check for the compression and flexural strenght of the pier? and is this design (reinforcement arrangement) even code compliant per IBC & BCRMS? There are no ties specified for the longitudanal steel either, I know this desirable for buckling and shear concerns, but it is it a requirement. And the original design called for the cells to be filled with concrete, shouldn't that be grout? Thanks for any advice!

 

[ishvaaag]

Judgement of compliance with any current code is difficult to attest without correct knowledge of the actual disposition of the structural and non-structural elements; it used not to be exigible just for that. The trend, coming mainly from substitution os obsolete mechanical services is reaching by now to entire buildings and structures. The codes are there but the info on the state many times not, and without the necessary works, won't; so a kind of stalemate. And there's much to know of a building to assert compliance.

Now, as long as it is acceptable by the standing code, anything that resolves in a satisfactory structure may be thought as the structural system. In the USA you use to think much more than in Europe in teerms of a vertical system as separate from a lateral resisting system; this can be useful in your case ... but is it acceptable? And so on, one likely soon will find some items made in accord to past practice that is not in accord with present ones; no one knows the future. So it is a matter of your intent to expreess in what extent your building you know complies with a current code. Some may have even rules for that, even maybe institutional rules for building revisions, so look if there is such a thing there.