Preventing transfer of uplift

[InEngCAN]

I have a steel beam that I want to transfer gravity loads to an existing clay brick parapet and wall. I plan on preventing the transfer of shear by using slotted connections. How can I prevent the uplift from being transferred to the brick if I am connecting my anchors from the top. The brick and mortar are terrible in tension so I need to find a way transfer most of the uplift load to the other support. Can I use a rubber washer to give the connection the degree of freedom in the vertical direction?

-Andrew

http://www.INengineering.ca

 

[jayrod12]

Why use bolts at all then?

You're going to need to provide a sketch to get some real pertinent answers, but where are you expecting the uplift to go then?

 

[dhengr]

InEngCAN:
Without much more detailed design info. and some sketches, dimensions, loads, etc. it is tough to know what you are really doing, or what you want and need. I assume that your main objective is that you do not want to induce tension into the brickwork, from whatever the loadings, but that you can tolerate more compression. One way to do this would be to prestress the hold down bolts/rods below the stl. beam to counteract any uplift loads. That is, run stl. rods down into the wall far enough so that the wall DL, plus some FoS on the DL, will be greater than the load it is counteracting. Then there will never be tension in the wall from this loading, but some greater compression in the wall below the beam, when this load is not present. The rods terminate at a large flat washer in a brick joint, or in a bond beam (bond block) which is integrated into the wall, maybe in a footing. Slotted holes can’t be relied upon to prevent some lateral load transfer, you need another means of doing that.

 

[InEngCAN]

Here was my original idea:

The design is for a steel platform to go on a roof a building and tie into the existing steel columns. I wanted to decrease the load on the existing footings for the column so my plan was to distribute the load between the column line and the brick wall. The brick wall can't handle the shear and uplift from the platform so that's why I was trying to figure out a way to transfer only gravity loads. The steel column can take the loads.

dhengr
It's a clay brick wall so there are no voids to run a tie rod down, it's also 4 four storeys up.

However, last night before falling asleep I came up with a way better plan! Thanks for the help.

-Andrew

http://www.INengineering.ca

 

[kmart30]

Curious to see what solution you came up with....I had a similar situation with some old brick.

 

[InEngCAN]

There may be a beam running below the roof between the column and brick wall that I am going to tie into. If there isn't a beam then I will put one in.

-Andrew

http://www.INengineering.ca

 

[Whoopdedo_LSU]

Why not make the support a gravity connection only? Are you resisting shear at the connection? If you put bolts there, I'd say it will take uplift loading no matter what you put between the base plate and the wall.

 

[InEngCAN]

That was my original idea. But to accomplish that you would just have the beam resting on the parapet. I feel like at a minimum it should be bolted.

Do you have any experience with having a beam bearing on a wall with no connection?

-Andrew

http://www.INengineering.ca

 

[jayrod12]

As long as it was restrained from lateral movement elsewhere in the system yes