adding a fence on high thin RC wall
adding a fence on high thin RC wall
(OP)
Im adding a glass fence on existing RC wall. Wall is thin (150 mm wide and 1580 mm high). Reinforcement in wall is fi8/20 cm. Since Im adding a fence on top, wall will be exposed to additional load from wind forces. So I have to check existing reinforcement (larger moments at the base of the wall).
My question is:
Can i consider a fence as an extension of existing wall when making a model (model A in the picture – cantilever with height of 2,58 m = 1,58 m wall + 1m fence)
Or should I model wall and fence seperatelly (model B) and then add reaction from fence on the top of a wall where fence will be fixed.
Im asking this because I dont know how to take into account tension forces (F1 and F2) from bending moment of a fence (detail 1). Does this mean that actual force on top of a wall is more like VB + F1?
If I fix fence on top of a wall as shown in detail 2 i dont have this problem?
Im confused since I get different results in both cases. In model B existing reinforcement is not sufficient but in model A it is.



My question is:
Can i consider a fence as an extension of existing wall when making a model (model A in the picture – cantilever with height of 2,58 m = 1,58 m wall + 1m fence)
Or should I model wall and fence seperatelly (model B) and then add reaction from fence on the top of a wall where fence will be fixed.
Im asking this because I dont know how to take into account tension forces (F1 and F2) from bending moment of a fence (detail 1). Does this mean that actual force on top of a wall is more like VB + F1?
If I fix fence on top of a wall as shown in detail 2 i dont have this problem?
Im confused since I get different results in both cases. In model B existing reinforcement is not sufficient but in model A it is.









RE: adding a fence on high thin RC wall
In your sketch A, I think analysis is straight forward.
In your sketch B, total moment will be equal to the moment from the wind against the wall + the horizontal reaction * the height of the wall + the moment at the base of the glass. Did you miss one of these components?
F1 & F2 in your final sketch are the forces in the bolts that need to be considered to design that connection, but I wouldn't utilize them to determine wall design forces.
RE: adding a fence on high thin RC wall
RE: adding a fence on high thin RC wall
RE: adding a fence on high thin RC wall
Attachment 1 and 2:
Likely attachment 1 is easiest to develop forces, but, is more difficult to install. Attachment 2 is easier, but it may be more difficult to anchor, given edge distances, etc.
Dik
RE: adding a fence on high thin RC wall
From your question, I think it's possible that you're adding the bolt tension force to the shear and this is what's causing your model B to have a different base moment than model A. The bolt tension shouldn't be added to the overall model; it's an internal force that is necessary for the elements of your structure to act with continuity.
RE: adding a fence on high thin RC wall
I dont think thats the right approach since you ll be getting much bigger moments at the base of the wall that way and they are no way the same when using model A. Bending moments at the base of the wall should NOT be in correlation with how fence is fixed in a parapet in my opinion. right engineers?
If you choose model B, i dont know how you ll be taking MB - moment at the base of the fence acting on top of a parapet into account to get bending moment at the base of the wall. Someone shall explain that to you.
RE: adding a fence on high thin RC wall
h = a + b
Model A,
Ma = wh2/2
Model B,
Ma = wa2/2 +wab +wb2/2
= (w/2)(a2 + 2ab + b2)
= wh2/2
Same result for Models A and B
BA
RE: adding a fence on high thin RC wall
RE: adding a fence on high thin RC wall
I need to determine effective width of a RC wall at the base (beff). I need this so I can control if existing reinforcement at the base is sufficient. What should be taken for ALPHA? I was thinking about 30o
RE: adding a fence on high thin RC wall
Dik