Building Maintenance and Rehabilitation

[deadlord]

Dear members,

In the case that a footing is overloaded just like in the situation that new stories are added to an existing building,to account for the Soil's bearing capacity properties the area of the footing is increased by casting the required additional contact area so that the bearing Capacity will check.

Ok,now that we enlarged the contact area,dowels should be provided between the old and new parts of the footing to make sure they Two parts work together.
Can anyone please tell me how can I calculate/assign these dowels?what are the criteria to meet?

Regards,
Husam.

[kmmh76]

For these dowels, the criteria to meet should be the shear reinforcement requirement at that section.

[deadlord]

Dear Kmmh,
So I just find the shear value at that surface and find the adequate
Area of steel that could take this shear on it's section?
Any remarks,notes or rules on the layout and distribution of the dowels?

[ravisbassi]

It appears that additional stories are being added to the originally constructed building. There are two scenarios.

One: The building is originally planned for the additional stories. In this case, the footings will be designed for the ultimate loading, and sized accordingly. So no change in footing should be required.

Second: The additional loading was not planned in the original design. This is very tricky. Now the whole original and new building configuration needs to be looked at in detail - the columns, connection design for different building response etc. As far as footings are concerned, you also now need to look at building construction. Were the original footings on undisturbed soil, or compacted soil. How much, and what type of disturbance was caused during original construction. etc.

Also, what type of underpinning will be needed during footing resizing. This is not a simple structural issue. Do get in touch with an experienced geotech engineer for advice.

[deadlord]

Dear ravisbassi ,
The issue is that I don't have a real life problem,I'm taking this building maintenance and rehabilitation course in college and the Professor said nothing about the computation and layout of the dowels,so I'm concerned in this case only,what you've said resembles The real life problem solving procedure ,but for me now I just need conformation on the method of computing the area of the dowels And the layout .

[ravisbassi]

I am wondering as I write.

Some of the recent postings have been obviously from engineers-to-be. Should we have a separate section, under whatever heading we call it, to provide input to them.

This is an apt case. My reply above was akin to killing a mosquito with a tank. I am responding with my 30 plus years experience to a student problem, without knowing that the question was a classroom problem.

Maybe we should have a college student Q/A subpage, to which the experienced members can visit as and when they have time. In my position, such questions would have been addressed by people much lower in organizational heirarchy (staff engineer - project engineer - senior engineer).

Since the poster's age is not known, it is difficult to assess where the question is coming from. But recent experience seems to indicate that a lot of questions are student related.

Should we fine tune these type of querries? It will save time for me.

[ravisbassi]

Here is a response that I received from deadlord on my PM. I am reproducing in full, except the editing, where I crossed out his name (for his confidentiality) and put XXXX.

Dear ravisbassi ,
All efforts in answering any question are highly appreciated,it's an honor that a 30 years experienced engineer answers my questions.You cannot go furious on someone asking to learn student or not,it's all learning,excuse me sir and I'm sorry to say,but if u read my reply to Kmmh and knew what I was asking about specifically this wouldn't have happened,and a "classroom" problem is an engineering problem whether it is in the classroom or in real life.We should answer the exact question then go around and explain other things attached to the same subject.

By the way,sir don't you think this great forum serves students a lot more than engineers?
Regards,
XXXXXX

Dear XXX,

We are in complete agreement.

In reverse to your question, I agree it is a great forum. Otherwise why would we waste time over this.

I strongly believe that it is the duty of people who share knowledge. Otherwise it becomes a case of accumulating it in your mind, and then one fine day it is pooof, kick the bucket, meet your maker, or whatever one calls it.

Now, coming to the first part of your message, it was not meant at you. Read my wording carefully. I started the third para with the sentence "This is an apt case." It was only an example. No offense meant, or implied.

What I meant was, that there probably is a need to have a student question type of thread. I do not know. That is why my querry "Some of the recent postings have been obviously from engineers-to-be. Should we have a separate section, under whatever heading we call it, to provide input to them."

Dear XXX - your reply is appreciated and treasured. You do remind me of the halycon days of my own youth.

To all the Folks, I request that we carefully read, absorb, reflect, and then maybe respond.

[deadlord]

Well I tried to keep my personal replies off the public so I won't take much space in a/any subject without any benefit to users who want to learn.

Sir the Irony in the way you talk isn't nice at all but I can't say anything further because of the age difference :).

Please do not write anything off the subject.
So sir,do you know anything about the layout of dowels between the newly cast part of the footing and the old one?

[ravisbassi]

Touche.

As a hypothetical scenario, If it is symetrical from axial loading, spread them symetrically into existing footing. Make sure you give more than 3 inch cover on the side dowels into existing footing side,and avoid existing reinforcement.

Also you need to clean the exposed concrete on the sides where the new concrete will be cast against, and coat it with a binder.

Now comes the trick part. What will you do about bending reinforcement? Hence back to my basic question. This is a classroom discussion.