Akeee
Structural
- Nov 14, 2013
- 78
Hello my fellow engineers,
I need some guidance in this matter: I am trying to find the best solution (safe and not too expensive ) to detach the masonry wall from RC beam and column elements. I have a structure with a high probability to develope soft story at the first or second level, thing that is higly not recommanded in a seismice zone because of high rotation demand in columns. So to be sure that not happen i have to detach the wall from the frame and add a layer of soft material like polystyren 3 or 5cm thick between concrete and masonry. But now my biggest problem is that i have to make sure that this wall dont fall down from perpendicular action (its worst the soft story).
So far i've got this:
1. If the masonry and concrete elements are built at the same time things are not that hard:
a) within the columns i install 2 rebars of 6mm diameter for every 2 bricks on the story height, these rebars will go on the left 60cm in the wall (bricks joints) then go trough the column and the same 60cm on the other side in the mansonry wall.
b) to be extra safe from the beam above the wall i install at half meter steps rebars 8 or 10mm diameter that go in the hearth of the beam (the rebars are vertical) and in the fist vertical joint of the bricks. If the bricks are with holes i can go with the rebar ever more deep roung 2 layer height of the wall.
Now with this solutions i will have a simple support wall (like a simple supported slab) that i have to check for bending at the half. If it's not holding the i can add 4mm steel net on them to take the tension from bending (now i am getting to "too expensive part", it is a lot of steel consumtion if i add 4mm net on the both side of the masonry walls).
2. If the masonry and concrete elements are NOT built at the same time (now the things are getting hard):
a) in the columns they drill a 3-5cm deep hole and install a rebar 6 or 8 mm diameter that will go in the bricks about 60cm, same as above every 2 bricks on the story height. The problem is that most of my clients dont afford/want to buy chemical anchors for this bars and so they set them without any bound and they will work only with dowel effect to take the shear from the overturning moment of the wall (i am not so sure if it is so ok, my fear is that the rebar will bend and will be pulled out from the column hole...)
b) i cant add bars from the beams
So the only thing that ensure stability of the wall are that rebars with no anchor mounted in the columns.. i dont like this solution that is why i am asking you for suggestions.
For the walls that are not in a frame, from slab to slab, i can on the end of the wall (the bottom of the above slab) on the left and right of the wall within 1cm add steel angles that ensure the wall will never fall over. The solution is expensive and not so 100% safe because if a high earthquake comes and the slab moves in the perpendicular direction of the wall its the risck that angles itsfel push the wall until break (with the rebars it was a semi rigid connecion they can bend before the wall collaps but with the angles not so).
Any suggestions please? Thank you.
I need some guidance in this matter: I am trying to find the best solution (safe and not too expensive ) to detach the masonry wall from RC beam and column elements. I have a structure with a high probability to develope soft story at the first or second level, thing that is higly not recommanded in a seismice zone because of high rotation demand in columns. So to be sure that not happen i have to detach the wall from the frame and add a layer of soft material like polystyren 3 or 5cm thick between concrete and masonry. But now my biggest problem is that i have to make sure that this wall dont fall down from perpendicular action (its worst the soft story).
So far i've got this:
1. If the masonry and concrete elements are built at the same time things are not that hard:
a) within the columns i install 2 rebars of 6mm diameter for every 2 bricks on the story height, these rebars will go on the left 60cm in the wall (bricks joints) then go trough the column and the same 60cm on the other side in the mansonry wall.
b) to be extra safe from the beam above the wall i install at half meter steps rebars 8 or 10mm diameter that go in the hearth of the beam (the rebars are vertical) and in the fist vertical joint of the bricks. If the bricks are with holes i can go with the rebar ever more deep roung 2 layer height of the wall.
Now with this solutions i will have a simple support wall (like a simple supported slab) that i have to check for bending at the half. If it's not holding the i can add 4mm steel net on them to take the tension from bending (now i am getting to "too expensive part", it is a lot of steel consumtion if i add 4mm net on the both side of the masonry walls).
2. If the masonry and concrete elements are NOT built at the same time (now the things are getting hard):
a) in the columns they drill a 3-5cm deep hole and install a rebar 6 or 8 mm diameter that will go in the bricks about 60cm, same as above every 2 bricks on the story height. The problem is that most of my clients dont afford/want to buy chemical anchors for this bars and so they set them without any bound and they will work only with dowel effect to take the shear from the overturning moment of the wall (i am not so sure if it is so ok, my fear is that the rebar will bend and will be pulled out from the column hole...)
b) i cant add bars from the beams
So the only thing that ensure stability of the wall are that rebars with no anchor mounted in the columns.. i dont like this solution that is why i am asking you for suggestions.
For the walls that are not in a frame, from slab to slab, i can on the end of the wall (the bottom of the above slab) on the left and right of the wall within 1cm add steel angles that ensure the wall will never fall over. The solution is expensive and not so 100% safe because if a high earthquake comes and the slab moves in the perpendicular direction of the wall its the risck that angles itsfel push the wall until break (with the rebars it was a semi rigid connecion they can bend before the wall collaps but with the angles not so).
Any suggestions please? Thank you.
