₦airaland Forum

Casting of ground beams.

The position of columns are determined by the structural engineer from the architectural drawings. They are placed in such a way that they do not obstruct circulation while ensuring that the stability and design of the structure is not compromised.

In this picture, we can not but assume that this column is placed outside the wall because that's where the structural engineer deem it should be from the drawing available to him.

Such columns are referred to as unbraced..

Akerewe:
Good evening engineers in the house. Pls what type of pillar is this and why are they outside and not inside as usual

It's a good option but costlier..but how about the finishing. You can't plaster over it .

diordaves:
What about instead introduce a Rolling Steel Joist (RSJ) beam underneath the bow? What is your take? This will save a lot of cracking and cranking the already compromised beam.

This could be a better option. Highly effective and save buying props, cracking, time and all that manual labour of trying to straighten the beam.

What do you think?

Thanks

There specifications depends on the span but for this warehouse
Columns: 254x146x31
Tie beams: 203x13

dangoteinlaw:
Nice work Engineer. So beautiful to see women doing well in structural engineering unlike some I know that resorted to selling to selling teddy bears and make up kits.
Quick question, those UBs(rafters) and UCs what are their specifications.

More picture update

Sorry but I don't understand what your engineer said he's going to do so I can't comment on it.

I believe you are building terrace apartments and would love that they have the same features. Since your engineer has confirmed that the problem isn't structural, here's what I'll do.

I will break off the circled portion completely, straighten the rebars and put the formwork back with an additional stiffener at Y. Make sure the props are sufficient enough to support the load then recast.

3strikes:
@aforxzy and Diordaves, I also dont think this is structural related....What is the way forward based on his explanation? What are your thoughts on the solution @hajivince suggested?

Formwork.

We are using the marine boards for the formwork because we intend to reuse them and also to have a smooth finish for the structural members.

You should have corrected it the next day before the concrete gain much strength.
With the buckling of the beam, the rebars have been affected too.



[quote author=Hajivince post=117400617][/quote]

The first picture is not clear enough but it looks like the beam has buckled.

If you are sure that the beam buckled due to inadequate support then all you need do is to break off the affected panel(s) , provide adequate support( (props) and recast.

However, this seems more like a structural issue than propping because inadequate props would have caused the whole panel to collapse during or immediately after casting cos of the weight of the concrete.

From the picture, there are blocks already laid on the slab and the supporting props have been removed so it couldn't have been the support that caused it.

More like poor design caused the bending under load.
I'll suggest your break the affected part and redesign the beams before you go ahead with the casting again.

can u post a clearer pix of the slab and beam?

3strikes:
Good Morning all,

This is not a bashing post!!!

I have been advised to seek professional opinions on this.
Please I will need experts and professionals in the house to please advise on best approach on how to tackle this.

Quick summary:
During casting these areas were not well supported and almost gave way. From the look of things, beam seems to be affected.

@hajivince could you please explain the solutions you have proffered so far. I want the professionals in the house to weigh in on this to see if any of these approaches will work.



How can we correct this at this point?

Here is the link to the thread https://www.nairaland.com/7015272/nigerian-house-plan-construction-4-units

More pictures of the ground reinforcements

Raft beam rebars.

The raft beams are 230x 1500-1650mm. We have the, columms, shear wall and lift reinforcement starter bars inplace.

The columns are 350x 500mm.

This building is heavily reinforced because of its intended use. We have various diameters of rebars: 10mm, 12mm, 16mm, 20mm and 25mm

The Kitchenette

Contact us for your building projects

Blinding

Beautiful couple spreading the gospel. If only people are trully touched by what they hear, Nigeria would have been a better place to live in.

Happy Birthday Sir.

Excavation of trenches for ground beams and lift pit

Yes, it is good and better you continue the columns with 16mm bars.

Please don't ignore the structural drawings unless the building drawings has been completely altered.

Akerewe:
It's a storey building on 30feets W by 60feets L
Hmm, what if 12mm is already in the ground foundation of like 3 coaches foundation, is it possible to continue the remaining long pillars with 16mm?

structural design is at the back of the building plan but I think it's bn ignored because am not on ground physically but everybody checking it said the buildings ok so far but I still want to b on more saver side

How many floors does your building has?

For your ground to first floor columns ( pillars) please use 16mm bars.

Beam reinforcements are determined by the load it will be subjected to and the length/span of the beam. This will be calculated/ designed by the structural engineer. So I can't tell you the rebars to use on your beams.


However for the slab, Y12mm is very appropriate but the spacing depends on the load and span..

Do you have a structural drawing for your building?

Akerewe:
Thanks for the Swift respond!
Is it possible to use 12mm for the pillars and also the beams including the slabs(decking)?

16mm for all the columns(pillars) or beams?

Since he did the crime let him just do the time.
Now he will reason well before he acts.

For this reinforced concrete roof slab and beams, we used a total of about one ton of steel ( Y10&Y12 for the slab and beams, while Y16m bars for the beams).

Akerewe:
Pls like how many tons of steel for this decking?

We are constructing a mixed development for our client in Lagos.
The building consists of a church auditorium, offices and residential apartments. The cark park is on the ground floor.

The buidling has three floors and a pent with two open well staircases, lift shaft and shear walls. The structureis framed in reinforced concrete slab with beams around the perimeter and within the slab to stiffened the panels as well as transfer loads through the columns and the shear walls to the foundation. The roof beams support the steel trusses.

The foundation type is raft beam and slab.

How did we get here

Aluminum partitioning continues

Male rest room

Freeze criticism is to gain access to these men of God and collect his own share from the tithe and offering.

Thanks.

Abudu2000:
great job here on the rebars arrangements I already got tired of seeing quack jobs on this forum. Kudos ma

I don't think there is any specific duration for a sand filled site to settle before u can build on it, if the sandfilling process is properly done and a good soil bearing capacity is achieved.


Sandfilling is expected to be done in layers and each layer compacted with an appropriate compactor to achieve a soil bearing capacity that can conveniently support the intended load or building. It is advisable to employ the services of geotechnical consultant during the sandfilling process especially for large builds. The soil bearing capacity should be confirmed by geotechnical investigation or testing of the site before building on it.

In addition to compacting in layers, it is better to soak the sand with water to removes the pores or voids within it. Personally, I always recommend that the sandfilled site goes through series of heavy rainfall as well.

So whatever duration it takes you to get all these done is good enough in my opinion.

dominic17:
Dear professionals in the house,
Please how long should a sand filled land be allowed to fully settle before building on it?

More pictures : Rest room

Those are honeycombs on the raft beams.
Some of the pictures are blurry but they appear quite much and can affect the strength and porosity of the concrete.

Honeycombs can occur if the coarse aggregates size is bigger than the space from the rebars, poor mix ratio, openings on the formwork and poor vibration of the concrete.

I suggest he chisel those portions and recast them while ensuring that there are little or no opening on the formwork. Also the size of your coarse aggregates should be reduced, the concrete should be workable, and also vibrate the concrete from outside the formworks (due of the number of the top rebars there is little space for the porker vibrator) to prevent a reoccurrence.

conceptbiz:
Hello my people.

Please, how do you rectify a raft foundation with minor defects like the ones in the picture 1 and 2? The third picture is perfect from what I can see but I will let the house talk about it.

My friend is going crazy about this because of the amount of money spent on the raft foundation alone at sangotedo Lekki. They completed the works only three days ago.

He’s also afraid his two-storey building will fall down in the future because of these defects that appear in two places.

90% of works done are perfect, just the one in the last picture.

Thanks

Aji

Na houseboy be that, no be husband hanti

Atleast he should calm down while the other guy explain to him. The gra gra ko necessary.