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.
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Bolt Anhor in old brick 2
- Thread starter revank
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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.
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.
SimpleStructures
Structural
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).
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).
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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 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).
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.
jheidt2543
Civil/Environmental
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 jheidt2543@aol.com ? Thanks
haynewp could you e-mail the paper "A Historical Survey and Analysis of the Compressive Strength of Brick Masonry" to me at jheidt2543@aol.com ? Thanks
SlideRuleEra
Structural
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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- #12
You people have certainly been a gold mine of thoughts about bolting into an old brick wall with solid 1906 mortar, whatever that seems to be. Thank you very much. To get us all in sync here, is what I am trying to do.
It is a 1906 three story frame guarded with fine old South Columns in the front. A local landmark. It is all frame except when the walls sink into the bawement which is underatanble. But those walls are brick for the first top five feet and then become concrete. They are not available from their exterior but the interior is laced with fine ald cast sewer pipes collecting and distributing stuff.
The Sill Plate at the botom of the exterior frame wall consists of a 2 1/2" by 5 1/2" hunk of wood. And the best part is that the studs coming down on that plate are 1 bys that rest on that sill without the confusion of any nails. They just sit there. And just above them is the very fine stiff first floor that distributes all interior loads to those exterior walls sitting on that 5 x1 1/2" 1906 sill. It is not a thrilling contemplation. The seismic loads are determined by loading each floor by the horizonal seismic load and putting that on the top of the partitions below proportioned according to their length, since they are all the same. And when NEHRP suggest that a reasonable horizonal shear capacity for that partition may be 200 pounds per foot, that is the number we compare our own horizontal shear with. And surprisingly on this house that comparison is favorable but in this system all that load ultimately collects on the first floor which in turn is very stiff and hands that to the basement well.
The basement walls can buckle and probably will, so an attempt to reinforce it against buckling seems reasonable. So a vertical brace might do the trick. So a vertical ST 2x4 seems hopeful. So with that pinned by a bolt to the top brick portion and the bottom pinned into the concrete a reinforcing beam might help a lot.And to augment the probable help the old sill is not loaded by the horizontally loaded studs because they are not sitting on a nailed intersection. So a possibility is to run an ST 2- 1/2 x 5 1/2" tube horizontally against the bottom of the studs. (The outside of those studs is available if the bick facing is removed which is not an easy task).
Hence my interst in grabbing that wall. The exterior is against the basement dirt, so I thought about creating a couple with a beam that is resisting the shear of the outer wall as a horizontal load pushing on that lever, with the upper anchor fastened to the brick wall as being available, and the lower anchor in the concrete at the bottom of the wall.
So there it is. There is much to thinking about more how's
but this is about where I am now. And haynewp I would also appreciate a copy of your paper. My number is revank@tplaza.org.
Thanks for your help.The ideas are very informative.
It is a 1906 three story frame guarded with fine old South Columns in the front. A local landmark. It is all frame except when the walls sink into the bawement which is underatanble. But those walls are brick for the first top five feet and then become concrete. They are not available from their exterior but the interior is laced with fine ald cast sewer pipes collecting and distributing stuff.
The Sill Plate at the botom of the exterior frame wall consists of a 2 1/2" by 5 1/2" hunk of wood. And the best part is that the studs coming down on that plate are 1 bys that rest on that sill without the confusion of any nails. They just sit there. And just above them is the very fine stiff first floor that distributes all interior loads to those exterior walls sitting on that 5 x1 1/2" 1906 sill. It is not a thrilling contemplation. The seismic loads are determined by loading each floor by the horizonal seismic load and putting that on the top of the partitions below proportioned according to their length, since they are all the same. And when NEHRP suggest that a reasonable horizonal shear capacity for that partition may be 200 pounds per foot, that is the number we compare our own horizontal shear with. And surprisingly on this house that comparison is favorable but in this system all that load ultimately collects on the first floor which in turn is very stiff and hands that to the basement well.
The basement walls can buckle and probably will, so an attempt to reinforce it against buckling seems reasonable. So a vertical brace might do the trick. So a vertical ST 2x4 seems hopeful. So with that pinned by a bolt to the top brick portion and the bottom pinned into the concrete a reinforcing beam might help a lot.And to augment the probable help the old sill is not loaded by the horizontally loaded studs because they are not sitting on a nailed intersection. So a possibility is to run an ST 2- 1/2 x 5 1/2" tube horizontally against the bottom of the studs. (The outside of those studs is available if the bick facing is removed which is not an easy task).
Hence my interst in grabbing that wall. The exterior is against the basement dirt, so I thought about creating a couple with a beam that is resisting the shear of the outer wall as a horizontal load pushing on that lever, with the upper anchor fastened to the brick wall as being available, and the lower anchor in the concrete at the bottom of the wall.
So there it is. There is much to thinking about more how's
but this is about where I am now. And haynewp I would also appreciate a copy of your paper. My number is revank@tplaza.org.
Thanks for your help.The ideas are very informative.
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