point load on rc wall

[monchie]

Hello,

Is it possible to have point load on top of an rc wall at a certain distance?If yes, How?

Regards,

 

[PSEPK]

IMO, yes.

You may create a point at top of the rc wall, at desired location, by meshing of wall and apply point load to it.



A good structural engineer is often a blessing for others.

 

[monchie]

Thanks PSEPK for you reply, my only concern is if you have a couple of point loads on top of the wall, does it mean that you're going to mesh with irregular interval? but how will you do that in ETABS?

Is it possible also to create a "dummy" beam instead?

 

[PSEPK]

Yes. You might need some irregular meshing, but not to a large extent. One way of doing this in ETABs, is that at first mesh the wall to some suitable uniform spacing. And, after that, depending upon location of the point loads,use a finer mesh only in those elements (located at top level) of the wall, where point loads are to be applied.

Is it possible also to create a "dummy" beam instead?

Yes. But IMO it would be better if you create 'dummy' beams only in smaller element portions, containing point load locations, instead of a single beam for the whole wall length.

HTH.

A good structural engineer is often a blessing for others.

 

[monchie]

Thanks again PSEPK!

 

[monchie]

"Yes. But IMO it would be better if you create 'dummy' beams only in smaller element portions, containing point load locations, instead of a single beam for the whole wall length."

Personally, I would like to create a dummy beam,ie,.01x.01 rc beam, for the whole length of the wall(on top of an rc wall),because it is very easy to have multiple point loads with varying distance. Is there any disadvantages in using this?

Also, another option you mentioned, is that I need to create a mesh matching the point load's distance;

1. if you create a regular meshed on the wall, how can you meshed again at a certain location to match a certain distance of a point load,by the way, can you measure distance on "elevation view", i've tried measuring the meshed but it always goes back to "plan view" to reflect the dimension.


Any comments will be greatly appreciated.

 

[PSEPK]

Personally, I would like to create a dummy beam,ie,.01x.01 rc beam, for the whole length of the wall(on top of an rc wall),because it is very easy to have multiple point loads with varying distance. Is there any disadvantages in using this?

There may or may not be any disadvantage. You may check it.

if you create a regular meshed on the wall, how can you meshed again at a certain location to match a certain distance of a point load,by the way, can you measure distance on "elevation view", i've tried measuring the meshed but it always goes back to "plan view" to reflect the dimension.

Let me explain this using numbers. I assume that wall under consideration is 12 ft long & 15 ft high. Moreover, you have two point loads of 3 kip & 5 kip acting at distances of 4.75 ft and 7.25 ft from start joint of wall. You may mesh the wall into 4 horizontal by 5 vertical elements, each element being 3 ft wide as well as 3 ft high. This is the regular spacing meshing referred my previous post. of course, you will do it in vertical plan.

Now looking at top level meshed elements, 1st point load will fall within 2nd element from starting point of wall, because its location point (4.75 ft from start of wall), as 1st element ends at 3 ft from start of wall, from where 2nd element starts. Similarly, 2nd point load will lie in 3rd element, starting from 6 ft and ending at 9 ft from start of wall.

In order to apply 1st point load (which is 4.75-3.00=1.75 ft into 2nd element) exactly on top of a joint, you will need to mesh 2nd element into .25 ft wide finer elements, say 12x1 elements. Using this fine mesh, you may now locate a joint, located at exact distance of 4.75 ft from start of wall, for applying 1st point. For applying 2nd point load, you will need to further mesh 3rd element in a similar way.

Hopefully, this explanation clarifies the procedure, I had suggested.


A good structural engineer is often a blessing for others.