New Reinforced Concrete Tie Beams for existing Coloumns

[dhansubba]

In order to give strength to long coloumns, I went down to foundations and constructed new tie beams between existing coloumns. All Reinforced concrete. To not to damage or weaken or disturb existing reinforcement, I made steel cage around the colouns, where from I generated new tie beams. If anyone understood what I mean, please advise me if I did ok. Is there any other way I could have joined new tie beams with existing coloumns ? My house is on bad soil and showing signs of distress. I felt I needed to do above strengthening.

dhan.

 

[RiBeneke]

I think I understand what you did. It sounds an unusual solution to the problem. Without seeing in real life, it is difficult to comment good/bad.

Are you sure your connection is well bonded on the sides between the old and new concrete, so that the old foundations cannot 'push down' through the new foundations that surround them on the sides.

 

[dhansubba]

Dear RiBeneke, thanks for responding. First, I do feel the bond will hold. Second, what was the other way I could have constructed the tie-beam (any advice ?).

Dhan Subba, Sikkim

 

[RiBeneke]

Dhan,

I was not sure what structural issue you are solving with your tie beams.

Was it :
1) Slenderness of the columns ? If so then you have improved the slenderness ratio by increasing the resistance to rotation at the base of the column. If the foundations were small and acting as pinned bottom ends, then you have effectively made fixed bottom ends to the columns.
2) settlement of the foundations ? If so, and if the tie beams are bonded as you say to the old foundations and are bearing on the ground, then you have increased your bearing area.

However, there may be other issues I am not aware of, so it is difficult to give a firm opinion.

Richard Beneke

 

[dhansubba]

Dear Richard, thanks once again (regret, failed to open and read this forum in time). Definitely, I hope to improve bearing and Slenderness Ratio with the tie-beam I have constructed. My question is how much strength gets lost when you join new RCC member with the old one ? I always felt that new and old RCC structures never become homgenious and the bond always remains weak. Because of this reason I did not join two structures, rather I made fresh structure (tie beam) to grip the old structure (Coloumn). Please advise.

Dhan Subba, Sikkim

 

Dhanshuba
You are completely right.

My 1st use of this (exacty like you) was in 80ties. A building w/ 50% of the desired stranght. I create one rectangular RING with steel mesh, plus microsilica grout and by, by.
Design: (mexicans have a very nice work about it) See Mexican National Engineers Association (use Google).
1st you take out the steel recover concrete, and 2nd calculate the strenght of the spiraled NUCLEUS (do not use Ultimate Limit, use te old Yield Strenght, USA have ACI Prof Ferguson concrete book (excelent). 3rd use two stages in concreting the rectangular grouted ring. Make 4 holes in the slab to fill concrete at the top. And by, by.
Congratualations.
Post Scriptum: 3 or 4 weeks ago I made it in a small repair.
Go ahead, you are right.
Lou Bob

40 years in professional batle learn us a bit of experience.

 

[sharky100]

hi dear im eng : ahmed el sharkawi from egypt and i live in kuwait and im 25 years old , well i think that what u have done is ok and it is the best plus i think it is expensive , but i like to say some notes
1- the tie beam should be well reiforced
2- the cage sholud be not directly connected to the coulmns u should leave some space about (5-9) cm so that well contact will be existing between both the beam and the coulmn cover.
3- u should scarch the old searface of coulmn.
4-good knowledge of the distance calculations from the botom of the beam and the coulmn base so that u must minimize the buckjling length .