Replacing RC Beam-Column Joints

[rodsiwa]

Hi, Supposed just for sake of discussion and theoretical understanding, a house with poured reinforced concrete foundation columns and beams are found to have one of the sides trespassing the neighbor due to incorrect land survey before it was constructed. Now the whole say left side of the house will be
removed along with the entire left foundations from column base to beam column joint to girders to the roof girder of the second floor and the entire wall. Now supposed you would put a new steel I-beam as column foundation and new girder and new walls. Can you just cut the reinforced concrete beam near the end and just put it on top of the 6 meter I-beam without support at the middle of the beam? What shearing force would be encountered
when this beam end is in contact with the I-beam by just putting on top of it and maybe adding a steel staple to connect the two. Let’s say the reinforced I-beam is 1 yard in height and 1 foot in thickness with 6 pcs of 20mm Rebar inside arranged 2 at top, 2 at center and 2 at bottom. I read elsewhere that reinforced concrete beam-column joint has opposing shearing forces at top and bottom of it. But when the end is cut and the rebars are not connected
to anything but just imbedded in the beam concrete. And the entire weight of the second floor is supported by the 6 meter beams and the beam ends are cut (removing the original concrete column and joint as described above). Would the end be stable enough to support the weight of the whole concrete and
second floor assuming there was no earthquake. What if there is earthquake and there is lateral movement, would the end of the beam just give way? Anyway. How do you attached the cut end of the 6 meter beam to a new column I-beam at the sides to give
strength not far from original without having put support to the 6 meter beam halfway?
Thanks.

 

[hokie66]

This doesn't sound hypothetical. I suggest that you need to retain the services of a structural engineer to determine whether this disaster can be saved.

 

[rodsiwa]

Hi, Last year I already sold the house. But now after
hearing of the Turkey quake and plan to buy a new
house. I just want to understand this particular
details about shear forces acting on a RC beam that
is attached to a steel i-beam out of pure curiosity.
Since the rebars are not connected directly to the
column but hang free and the attachment is to be
via drilled hole and the RC beam stapled to the new
i-beam. Would be be stable against seismic loads?
Or is this a hopeless action? Why?

 

[rodsiwa]

Actually my neighbor bought my house because he wanted
it for commercial expansion. Anyway. I guess my question
should be simplified to:

What are the vertical and horizontal shearing forces
acting on an open ended RC beam when it is put on an
I-beam in seismic lateral movement? We mostly heard
of seismic actions on RC beam-column joint or pure
steel beam-column but not on RC beam and steel I-beam.

 

[dik]

Your question is too difficult for a general question... as Hokie noted, you should seek the services of a structural engineer. He will be able to provide you with some guidance.

Dik

 

[concretemasonry]

Sounds like a typical "midnight construction project" initially that built very quickly on disputed land and left to be resolved later to get titles. - Could it be in Istanbul?

All of the loads and forces must be determined by an engineer. There are many good engineers in Turkey. I spent about a week or 10 days there there to give daily reinforced masonry classes to 17 engineers of a construction firm. It was a real challenge since they had all the basics and just needed refinement, which made it enjoyable in a great city (despite the traffic and only 2 bridges over the Bosporus).

Just look to the professionals.

Dick

Engineer and international traveler interested in construction techniques, problems and proper design.

 

[rodsiwa]

No, the house was already demolished last year when neighbhor
bought it. It was part of a duplex.. that is two houses mirror-like or the same with a common foundation. I wonder if you
guys have heard of duplex house before. Is there none like it
in the United States?

Now supposed a person bought the other side and want to
build larger building. He owns half the foundation. In my
case. It's worse. He owns the entire foundation because
of survey mistakes.

After checking out new buildings for sale. I remembered
my situation with the past. So I wonder what would happen
if an R.C. beam and joint are not connected in original
pouring but just put on top of each other. Whether
seismic situations can topple or make the sides slide.

Since you guys are experts and this is a unique question.
Then I thought I would ask it. But don't worry. I won't
apply it on any existing house because my house was
already demolished last year.

 

[hokie66]

Each situation would have to be resolved on its own merits. It is impossible to answer your question other than to say that a modification of that type would likely compromise the integrity of the structure unless other strengthening was done.

"Duplex" is a common term in most countries for two residences which share a wall, normally referred to as a "party wall". The legal resolution of boundary disputes caused by survey mistakes varies from country to country.

 

[rodsiwa]

I've been researching a lot about designs of beam-column joint connections especially how the rebars should be connected
because I've been deciding whether to buy a condo in a
40 storey high skyscraper.. also in case I wanna have
a new house constructed that will be ultimate earthquake
resistant. Next year in 2012. There would be major
earthquakes the world over with average of Intensity 9.0.
Now what beam-column joint design is the best that can
withstand such earth shake. Can you recommond any books
about this or web site of new designs? I heard many
structural engineers just use the average or standard design.

 

[hokie66]

You can't get an earthquake engineering education by asking questions on the internet.