Beam taking action of Column

[Muhammad Hashmi]

Assalam O Alykum

I am badly stuck in one critical beam (Cantilever) that is carrying the auditorium column of load of 530 Kilo-Newton. The beam is taking the action of column itself. I am hereby attaching bending moment diagram extracted from Etabs model ( Beam at bottom level ). Can any body help in this regard.

Column bending moment M2 is 1226 Kilo-Newton meter however beam bending moment is also same in M3 direction 1226 Kilo-Newton meter.

Column axial force 530 Kilo-Newton and Beam Axial force is also 530 Kilo-Newton.

 

[Ayesha]

Did you do a breakdown to see which load case is causing this?

Normally I check the the governing load combination, then run each load case separately of the governing load combination to see what is contributing the most. If you have already done it, can you tell us which load case is causing this big axial load and then after identifying the problem we can suggest a solution. 

Is this structure steel or concrete?

[Muhammad Hashmi]

Assalam O Alykum

Bending moment diagram for the beam for every load combination is like a moment shape of column regardless whatever the value is, May be it is due to a Cantilever that is supporting planted column.

Whenever I release the moment value of column from the bottom side it will take proper action of beam.

May be program is reading as a frame action?

See the attached negative moment through out 

[Ayesha]

First, I need to understand your question.

Is this the cantilever beam that you are talkin about. See snapshot below and confirm.

What does this statement mean - "Whenever I release the moment value of column from the bottom side it will take proper action of beam." What is proper action of beam? Does this statement mean your axial load goes away? That is why I am emphasizing that you figure out the "load case" not "load combination" which is causing this trouble and also why releasing moment is removing axial load, doesn't make sense.

Where is the axial load diagrams? Can your first please explain in detail.

 

[Muhammad Hashmi]

Assalam o alykum 

Yes this is cantilever beam. 

No axial load doesnot goes away but reduced to 335 Kilo-Newton after release. Earlier I was 530 Kilo-newton load combination Dead+ Live for example.

Can see Bending moment diagram of both cases posted yesterday. 

 

[Muhammad Hashmi]

First figure is the bending moment diagram before release shape looks behave like a col. Axial load D+L = 530 Kn.

2nd figure is the bending moment diagram after release column from bottom. Axial load D+L = 335 Kn.

I don't know it's clear for team or no? 

[Nustian371]

On 9/7/2021 at 2:20 AM, Muhammad Hashmi said:

Assalam O Alykum

I am badly stuck in one critical beam (Cantilever) that is carrying the auditorium column of load of 530 Kilo-Newton. The beam is taking the action of column itself. I am hereby attaching bending moment diagram extracted from Etabs model ( Beam at bottom level ). Can any body help in this regard.

Column bending moment M2 is 1226 Kilo-Newton meter however beam bending moment is also same in M3 direction 1226 Kilo-Newton meter.

Column axial force 530 Kilo-Newton and Beam Axial force is also 530 Kilo-Newton.

 

Hi What are your expectations, if the column have the load which needs to be transferred through the cantilever beam than what other load path would you expect?

[Muhammad Hashmi]

Assalam O Alykum 

Muhammad you could not get the question. 

Planted column resting on the cantilever beam having load 530 Kn, but the cantilever beam shows the moment diagram like a column.

[Nustian371]

On 9/10/2021 at 5:05 PM, Muhammad Hashmi said:

Assalam O Alykum 

Muhammad you could not get the question. 

Planted column resting on the cantilever beam having load 530 Kn, but the cantilever beam shows the moment diagram like a column.

so what are you expecting, in this case? the moment on the cantilever beam and column would be same. 

[Badar (BAZ)]

Let me break down the BM diagrams for you.

The first case: High point load  accompanied by a negligible bending moment transferred to the edge of the cantilever beam from the planted column. If we neglect the contribution of bending moment, we will get the following distribution of bending moment in each member.

If the planted column transfers huge bending moment ( and negligible point load) at the edge of the cantilever beam, following distribution will result

 

You are saying the you have assigned the hinge at the lower end of column, the end where it connects to the cantilever beam. If that's the case, you should get the BMD shown in the first figure. 

[Badar (BAZ)]

If there is no error in the model, then the planted column is not the major source of design forces for the cantilever. Check which load case is responsible for the transfer of sagging moment at the end of cantilever beam.

[Muhammad Hashmi]

Problem solve Mr. Nustian. Thank you very much.

[Muhammad Hashmi]

Dear Eng. Badar,

Thank you for your support. I will get back to you personally in case any clarification required.

I am personally request to you and Eng.Umar to spend their quality time at least once in a week to help others.

Thank you 

M.Omair Hashmi