huangyhg

bolt anhor in old brick
an 8 inch 1906 brick wall is proped as an anchor for a seismic reinforcement.needed is a rational idea on determing the probable capacity of a half inch anchor bolt set in epoxy. but what kind of capacity can be expected from that bolt in good but old brick? using an instrument in the brick pattern is not desireable because ultimatly that wall will be exposed and the pattern important.
i consulted with hilti on a similar age of construction. i think you want to use a hybrid chemical (like hy20) instead of just epoxy. i don't think you will find data for that old of brick, but i have been told by anchoring companies that brick strengthens with age.
i would definitely suggest talking to hilti or another brick anchor mfr. for the closest load tables you can use for a comparison. i think most of the data was set up for use in cavity walls instead of thick solid brick (is this what you have?), but they may give you a conservative value to use, i believe this is what they did for me last time when i had a old & thick solid brick wall.
it might be useful if you check cintec anchors. they have been used in the uk on historic masonry buildings and bridges, and i have used them on several occasions. good points about them is that they do not put any additional load into the brick (unlike expansion anchors), the grout they used is cementitious and they can manufacture the anchor to your specs.
i don't think you would ever come close to developing the strength of a post-installed anchor. the controlling factor will be the brick/mortar strength which can be assessed through shearjack tests (for shear) and flatjack tests (for compression).
the brick manufactured at the turn of the last century is going to have much much lower strength characteristics tha today's bricks. and i would hesitate to assume that its strength has increased over the years. the last city that i was employed in had numerous buildings built at the same time period as the one you are working with and they were literally falling apart from weathering. brick manufactured today is fired in kilns that reach much higher temperatures than brick kilns of 100 years ago. the higher temperatures in the firing process result in stronger bricks. i have seen bricks where they are so "soft" the sand is literally being washed out of them due to the weathering over time; same for their mortar.
this doesn't tell you what you asked for but you should be very careful when trying to use old brick for anchorage. are you intending to only use the deadweight of the brick and structure over your anchor or are you wanting to develop tensile and/or moment resistance? be very careful in evaluating what path the loads/reactions will take as well as the substrate to which you want to embed your anchor(s).
to those who commented on my question about mounting a bolt in old brick---thank you very much. i have not heard of cintec anchors. never to old to learn.
this is an old solid brick wall. looks just fine!!
revank-
i have several comments but its unclear from your post exactly what you are trying to do. is the seismic retrofit intent to bind together two existing wythes that are presently not bonded? is there much of a gap between the wythes? is one of the wythes on an exterior wall? is the wall a bearing wall?
if you are trying to tie together two existing wythes, there are several options. a helical anchor like helifix might be appropriate (they are on the web.) if the wall is built solid with no cavity between the wythes, consider using through bolts in oversize holes, with washers, to tie the wythes together.
tms 402 can provide some guidance about spacing and diameter of the anchors, depending on what you are trying to accomplish.
i agree with pmkpe that the older brick will not be as strong as newer brick, especially if the brick or joints have been exposed to weather. even masonry has a design life.
if you are going to use the existing wall as a shear wall to resist seismic forces, thats a whole different ball of wax. old unreinforced clay masonry walls by themselves have almost no ductility and are generally unsuited to carry seismic loads unless the forces are extremely small. in this situation you might consider a reinforced shotcrete overlay on one face of the wall.
hope this helps.
i have seen crappy old brick before also that was flaking apart, but it sounded like in your first post the brick was in good shape and has not had severe exposure. have you poked at the wall with a pick or anything?
i have a paper that might be of some help, "a historical survey and analysis of the compressive strength of brick masonry", i can email it to you if you want. it lists info from tests about 100 years ago up to about 1960. they did use some pretty strong brick in the tests.`
also, the strength of the wall will also be a function of the mortar used and not the brick alone. this can be the controlling factor and not the brick itself.(i don't know what else you plan on using this wall for besides installing anchors).
also, if you put too much new force into that old wall, you may be required to bring it up to current code. this may include looking at the seimic or wind loads perpendicular and parallel to the wall and determining if it should be theoretically standing or not.
is it possible to through-bolt the masonry wall with a large "washer" on each side. you can get decorative "washers" or use 4"x4" or 6"x6" plates 1/4" or 3/8" thick to engage more brick, depending on the loading.
haynewp could you e-mail the paper "a historical survey and analysis of the compressive strength of brick masonry" to me at
good examples of the "earthquake bolts", that jheidt2543 mentioned, are seen all over charleston, sc. the washers are probably about 12" to 18" in diameter. here is a link to a brief, typical story of one building:

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