Through bolts in CMU

[ARKeng]

Does anyone have any source or a good methodology for the capacity of a threaded rod (or bolt) placed through a masonry wall with a washer or plate on each side?

I'd be interested in it for both grouted and ungrouted CMU (and with Appendix D creating issues in concrete the way it is, it seems like we could use it in concrete also). We typically just use epoxy or expansion anchors for grouted.

The ungrouted situation happens frequently in existing buildings where it's a guessing game as to whether or a not there's a horizontal bond beam at the height we need and it's usually not for a large load. I just can't find anything on this issue on the net or in my own library. It seems like there should be an approach that considers the dowel bearing strength for shear and a bearing and possibly a punching shear type of failure for tension, but I'd feel a lot better with some written source backup.

This had to happen all the time before wedge and epoxy anchors became available, no?

 

[ishvaaag]

As you say, mandatory aspects apart, insets always may be evaluated on the principles of structural design. So you really can take bearing for shear and punch action from a plate with maybe even some interaction of the small shear coming from lever action from the other side and so on, to be used against some fragile failure criteria, or just fixity action on one face; for all cases that the fastener is hold in bearing will be the hypothesis. On this basis you can say what the safety factor is going to be.

 

[ron9876]

I assume about 1" bearing, check bearing stresses and check bending in the bolt.

 

[haynewp]

I couldn't find anything in ACI to back this up but have wanted to use this application before also. The closest I found is in ACI 530 that gives EMBEDED plate/nut anchor values in section 2.1.4.2., but there doesn't appear to be any increase in shear cone that can be considered when using a large plate anchor. They still limit you as a function of the bolt length.

It would seem like you would just easily take a punching shear cone radiating from the edges of a large plate like you would with concrete and use this cone area in ACI 530 equation 2-1, but I can't find such a technique explicitly mentioned in the code. You would also check bearing under the plate on the face shell.