CONCRETE-FILLED CIRCULAR TUBE

[OnePowers]

Salutes to all of you engineers!!

I am working with a concrete-filled circular tube. I am checking the transfer of forces beetween steel and concrete.

It's difficult for constructor put shear connectors inside the tube then i was looking for another mechanism, i found one that is called Direct Flattening, which says (AISC 360 I6):

Note: An example of force transfer via an internal bearing mechanism is the use of internal steel plates within the filled composite member.

My request is: Can anyone can explain to me how the plates have to be located inside the steel member?

Thanks and very sorry for my english!!

 

[centondollar]

Is this a column? If it is, then shear connectors are not necessary. Surrounding a circular concrete column with a steel CHS profile is done to increase concrete confinement, flexural capacity (M-N diagrams are used for composite columns) and stiffness of the member - there is no shear transfer check involved. Furthermore, shear connectors are usually studs (similar in shape to bolt shafts, but without threading), not plates.

If this is a beam that is primarily meant to act in flexure, you can find materials describing shear transfer from the ESDEP site (

http://fgg-web.fgg.uni-lj.si/~/pmoze/esdep/master/wg10/toc.htm

, "SHEAR CONNECTION I" --> "SHEAR CONNECTION III"). The basic principle is to provide enough shear studs (which must resist shear and bending effects) per unit length of the beam to carry all (preferably, if a zero-slip, maximum strength connection is required) longitudinal shear flow (V = S*Q/I); the studs should also be ductile.

 

[OnePowers]

Thanks for your answer CENTONDOLLAR. I really appreciate your reply.

I have an column. It's a circular tube column filled in concrete without steel reinforcement. I designed this type of columns for an 8 story structure and some engineers are asking me to check shear transfer between steel and concrete.

I am surprising i dont have to check shear transfer. Maybe Yes, i dont know!! In fact, that text i put there i got it from AISC.

But where in AISC says what you're saying?

Thanks

 

[dik]

See CIDECT Design Guide 5, and attached from STI

[URL unfurl="true"]https://res.cloudinary.com/engineering-com/image/upload/v1642294908/tips/HSS_Article_Composite_Concrete_Filled_HSS_1116_060120_ojorc2.pdf[/url].

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[OnePowers]

Thanks DiK again!!

Can anyone else give me another oppinion? I would be very grateful!!

 

[dik]

There's another opinion?

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[Agent666]

I've seen a number of ways this transfer of forces is achieved in practice (in no particular order):-

1) Vertical plates extending through the column in a slot in the column wall, bearing checked on underside of the plate, plate checked for bending/shear as a simply supported beam. Often this would simply be an extension of a shear tab just carrying all the way through the column. Can get complicated if you have two-way arrangement of beams, in this case if a column goes several storeys usually it will be spliced at each level of connecting beams and all the plates welded to one another inside the column before welding the column sections together. Also, can get in the way of reinforcement, as reinforcement needs to be built into the column, no dropping them in after.

2) Weld larger diameter reinforcement bars through the column, drill holes each face, feed through bar, weld via fillet weld on outer face. Can be added after reinforcement cage which facilitates placing any reinforcement cages you may have. Design reinforcement utilising shear friction provisions.

3) Reliance on the natural friction/mechanical/chemical bond between concrete and steel materials. Usually only good for smaller loads being introduced to the face of column. Usually not great if reliant on the column being unprotected for fire, as you'll lose this mechanism once the steel expands under fire.

4) Detailing of connections to beams to ensure any beams bear into the core of the concrete. In practice this could mean a fabricated column head that bears on the concrete but allows the reinforcement through.

5) welding of shear studs internally to steel column, usually only possible in larger diameter columns where there is sufficient access for welding.

https://engineervsheep.com

 

[OnePowers]

Thanks Agent666. Your reply helped me a lot!! Constructor/builder liked option 2 more than others: through bars

In really, everyone with his replies helped me a lot!! Thanks to everyone!!

I already know that must do in this case!!

Thanks again!!