₦airaland Forum

Rubbiish:
@bold isn't true. Depth of foundation works greatly with height, reason why pile is recommended for high rise buildings.

He is right. The depth of foundation doesn't actually depend on how tall the building is but the location of suitable soil strata with the right properties that can carry the anticipated load of the structures, and the loading intensity of the structure.

take a look at this simple Rankin's equation for calculating the minimum depth of a shallow foundation
Dmin = (q/g) * [(1 – sinØ) / (1 + sinØ)]2
here, we have q = floor loading intensity
g = unit weight of soil that the foundation is resting on and
Ø = repose angle of the soil
floor loading intensity is a load of a structure over the area that the structure is resting on, in simple terms, it is all the load coming through the columns or walls divided by the floor area of the ground floor

unit weight is the dry density of the soil multiply by the acceleration due to gravity

the angle of repose is also a soil property

In conclusion, the depth of foundation depends on how high the floor loading intensity or the safe bearing capacity of the soil, how closely packed the soil particle is and the position of the water level

akinolaolujide:
i dont intend to Argue with you on this i will simply give 2 clear analogies and corroborate with what you said.
1 if your assertion are correct that why arn't tall building done in the fashion because they want a strictly framed building.
2 i dont know your profession but i know for a fact that the use of block wall allows flexibility to the quantity and dimension of steel in design, whereas all this does not arise wit framed structures.
lastly read my post clearly never said it was not effective but its definitely not the best like agreed form work makes the dimension of the beams and columns much more precise and accurate.i know good structural and builders will never joke with dimensions of Structural elements.
i will also like more enlightened contributions. We are all still learning.

The analogy you gave is spot on. Both of them are frame building both the one where all the formwork are done according to size, the concrete is cast and properly cure to attain the required strength is better and more economical when one is building more than two suspended floor.

You have already enumerated the advantages of this type of construction earlier, which include not limited to;
It enables the dimension of the beam and columns to be accurate since a form will be created for them instead of using the block partitions
It enables proper vibration of the structural members (especially the columns)
It enables proper detailing schedule of reinforcing steel
It enables proper curing of the structural members ( wetting of members especially columns is better using this method)

The disadvantages include the following, as related to Nigeria construction environment;
Lack of proper bonding between the partition walls and the structural members ( especially columns, so many building have this horizontal cracks between the point where the partition block work join the columns and beams
It requires more formwork and brazing of formwork when it is not properly brazed it can collapse under the weight of fresh concrete or vibration of the concrete poker machine

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EgunMogaji:
I know how you feel but I tell you it's much cheaper to stop now and take stock. No need to rush ahead.

You should at least get a second opinion from professional builders before you proceed.

Even if the decision is to introduce columns it can still be done now with few destructions.

This is a very good advice. That building shouldn't have been built that way.

If I am been honest I will advise he get an engineer that can do a simple structural design, then introduce the columns specified by the engineer now before, filling and German floor.

At this stage, the cost will be minimal and all the future problem can now be avoided

asids55:
this is my first time building,the money ain't an issue,I would not even be aware of this if not for mr saydfact who I give daily pictorial updates of the progress of the work..he made the issue aware to me and when I confronted the engineer,he said they usually put mats for waterlogged lands etc.

If I may ask sir, how do your builder knows that the soil is very strong and doesn't require a mat/pad footing or the foundation footing generally?
Did the building pass through the developmental units of your city or state because if it does it will surely have a structural design which will specify the size, depth and the number of footings to be used to carry the columns?

Am asking these questions to be sure of my replies. From your explanation above, there is no way the builder will be able to ascertain the strength of the land without carrying out a detailed soil test. If the soil test is carried out and the soil is deemed to be of good properties in relation to what you are planning to build on it (if the bearing capacity is good enough and if the settlement is minimal) then you will still have to do a mat/footing for your columns.

From your picture and explanation above I can deduce that you didn't carry out a structural design and that the builder is only working with the architectural working drawings. It is wrong to build hollow block without frames because the ground blocks will carry the weight of the slab, upper floor blocks, and the roof load, this blocks may not have the properties (strength) to withstand these loads coming in from above

twinskenny:
borehole that i dug with my own money?? how do the do this thingss

But look at it from a different perspective, the water you are tapping from below the ground is a natural resources that belongs to the state.

Your drilling activity can cause long term problem such as earth movement etc. In reality, you actually using up a very scarce resources called underground water which the government have the right to tax you.

OtunbaLeXuS:
Sir,

Can you please assist in costing the materials needed and labour cost for casting a column of 225 by 225mm from foundation (3) to roof level (12) = 15 courses.?

Thanks.

1. 2 bags of cement. some sand. some gravel. 4 number of 1 x 12 soft timber. 1 bar of main reinforcement ( Y12 bar for a bungalow), 1 bar of Y10 or Y8 for the ring.

Labor cost: carpenter 3k, mason 3k, iron bender 3k

krak101:
Good day great minds. I just bought a piece of land around Kpaduma area of Guzape. What steps do i now take to get the necessary documents? Thanks all for your anticipated assistance

I think you need to go to developmental control to get all the needed information.

ceelog:
Engr's and Builders
Please is it wrong to cast a pillar (or column) seperately from the lintel or roof beam? I think I see this being done with the frame structure build and not block build? In other words is it a must to cast column and lintel at the same time in a non frame build?

The best practice is to cast the column (vertical structural member) separately, and then cast the lintel and head course separately( horizontal member), this will allow each of them to be properly vibrated and all voids removed.

It is not a must to cast column and lintel at the same time, it is better to cast them separately than to cast them together

Naaseer01:
lies lies lies

Dan fodio fought Hausa rulers only when they attack him first (for self defence)in order to stop him from preaching the true teaching of Islam which was diluted at that time by the Hausa King with Idol worshiping like tsumburbura and barbushe idols in kano. and that's is what Dan fodio fought against. he was attacked, his students killed, their wealth burnt down by those rulers just because he preachea against mixing Islam with idol worshiping. and that is when he took the action of self defence.

he did not fight to rule totally but to ensure the true teaching of Islam and fought against those tyrant rulers of that time who are dictators and oppressors of their subject. that is even why he get support of local Hausa people there.

Note : any other reason you would get is fabricated by the enemies of Islam. if you want to know shehu Dan fodio , go and read his book and what he teach. and you will know the true reason why he fought those rulers. and yes the entire Nigerian Muslims are happy he did because if not we would not find a true Islam as we did today

Look at your logic, we must read his book to know. The entire Nigeria Muslim are not happy about his actions. Intelligent Muslim know that Usman Dan fodio jihad was a political tool used to conquered Northern Nigeria for himself and family.

Islam has been part of different part of Nigeria before Usman was born. This is the story you Fulani elite and their accomplice tell uneducated masses to continue to use their head.

Qc1:
Are you busy? E be like say another job don land ooo...!

I dey o my oga...when make I come sir ?

Rubbiish:
Sir is this 0.2L like a constant when designing a cantilevered slab?

From a structural engineering perspective, that formulae will give an optimal cantilever length that will reduce slab span moment

Flaghouse1:
Eku Laakai Sir,

Well dissected , my question on this cantilever discourse to you sir are.

1.what is the relationship between the quantity of iron rods used in cantilever and decking in terms of sizes of iron rod.

2.-What is the ideal length of a cantilever shoot out from the decking in terms of feels or metres

Thank you

Nice question sir

1. There is no relationship between the quantity of reinforcement used in a cantilever and the that used on the adjoining slab (the decking). What we have is the percentage lapping length of the cantilever slab reinforcement ( mostly top bar extended into the adjoining slab). this lap length are taking to be 1.5L ( where L is the width of the cantilever).

There is no ideal length of a cantilever because in structural engineering you only provide a solution to the problem posed by the architect. The architect will make the design based on the need of the client, for example, some cantilever is to serve aesthetics function like long balconies while some serve functionality purpose, like extension out to add extra space to the living area. experience has shown that for a continuous slab construction with an overhanging slab (cantilever slab), optimal design moment is achieved at 0.2L ( where L is the length of the slab adjoining the cantilever. so, for a slab of 6m, the width of the cantilever adjoining it will be 0.2 x 6000 = 1200mm ( 1.2m)

Androidking:
Let me come here so let's say a building has a cantilever . now that cantilever has a beam .
Now the column on d which d cantilever is on, is may be 525 x 225 mm .

Even if the cantilever is long . must d column project out ?? As in, part it in d wall part of it kicking out?? For d longer side

D reason for this is places like Aba and Onitsha they always do that no matter what d architect design dey keep pushing columns out and tell u, its for it to carry the cantilever . even if its 6 floors,
can't a structural ENGR design a building without those columns shouting of the wall .?

Pls am just a beginner and I hate it when engrs change my elevations .




Look at pix below u will see d columns projecting even d beams . does it mean its cheaper that way or dey are afraid to power a cantilever without those columns kicking out..

Or will it more expensive to do so??


Even in Two storey they still do it . as far as its blocks of flats u will it at Aba and Onitsha .

Pls no mind my repetition of sentences. I just want to learn

Like it when everything if flushing smoothly

I think the problem is most of these building don't have structural design and if they do, the designs are not properly done.
Before I can answer your question, I will like to define and differentiate some terms that are interchangeably used from a structuring engineering point
cantilever slab: when the slab of a building or other structural member shootout from a beam perpendicular to the length width of the adjacent beam (a layman definition)
Overhanging slab: when a part of the slab is hanging out from an inner slab, where the two slab share the same beam at a point
cantilever beam: look up to the cantilevered slab above
Overhanging beam: look up to the overhanging slab above.

the major reasons while most of the building cantilever or overhung have such load is the presence of loaded slab at the edge which exacts too much point load, thereby increasing the moment and share at such end. The better arrangement is to have the slab cantilevered out without a column on top, where the slab will carry only the wall load of one floor.
If there is a need to have a wider slab, The slab can be accompanied by a beam which can be concealed ( raft or waffle slab) or shoot out below.
From experience, the best approach is to have an overhanging beam that extended into the slab thereby neutralizing the effect bending moment on the beams and columns

More updates

Kimiwa:
Well done for the good work. Please Sir I've sent you a private mail asking for advice. I'd appreciate your early response. Thanks for your selfless giving of professional tips.

You can check your mail for my reply

Completed

KolaShangOne:
For discuss sake, sometimes last week, i was just moving around my site and came across this site..

Pic attached.

Clearly, the Engineer was filling this swamp land with laterite prior to Foundation. The foundation will be built on this filled 'imported' sand.

The problem with this is that:

-Vegetation was not removed

-Under this vegetation we have about 400-600mm depth of black muddy soil which should also have been removed.

I asked the Engineer If he could do remove the top soil (in a friendly way) but he said there's no need as time will be wasted, labour fees will also be increased and this is how they do it in Ajah where he comes from.

Engineers and Enthusiasts, What do you think? Have you adopted this method of filling and building on the sand?

I think it is wrong to fill or build on vegetable top soil of pit.

For every construction, the vegetable top soil need to be removed before any work can be done.

After the soil test has been carried out and well known that a shollow foundation in the form of surface raft can sit confortably on either the existing ground level or fill, the best thing to do is to clear the grasses, removed the vegetation and possible pit and other weak top soil before anything can be done. It is either the foundation is found on the existing soil, if it will be economical tp do that ( when depth of natural ground level is not much lower than the height of the road level or the site is filled with improved soil (preferably non cohessive soil) and properly compacted either mechanically or by natural process ( consolidation over a long period of time), even when compacted with a roller is still good to allow the soil conslidate for a minimum of 6 months before the surface raft can be done.

spyder880:
Thank you for this, I have also seen designs for buildings with 4 suspended floors where the lower floors does not have columns designed to shoot out. The column design was still rectangular, 450x225 with Y20 x 6 rods as reinforcement but designed to flush on the walls without coming out. I think it was designed that way because the building has no cantilevers.

I think the problem we have here is we don't do proper analysis and most of the designers don't understand the theories behind most of our design softwares.

It is possiblle to have such scenario but in most cases a rectangular section pf 400x225 with any number of reinforcement can only be sufficient for cases where the load and bending is predominant along one axix, In this case the axis where the load/moment is more will have the bigger section. But in most cases it as be shown that for such high rise building, the bending will come from the both axis, the solution will either to use a column that will fit into the walls or to use a pylogon column . A sketch below will through more light on my point.

Below we have a simple floor system for a proposed four storey open floor office complex, along axix x-x the grids are spaced at 20' (6000mm) at regular intervals while along the y-y axis the spacing is 10'(3000mm). The columns are polygons and their dimensions is as follows, edge and side column is a polygon 450 x 450 x 225 x 225 and center column is 600 x 600 x 225 x225

KolaShangOne:
For discuss sake, sometimes last week, i was just moving around my site and came across this site..

Pic attached.

Clearly, the Engineer was filling this swamp land with laterite prior to Foundation. The foundation will be built on this filled 'imported' sand.

The problem with this is that:

-Vegetation was not removed

-Under this vegetation we have about 400-600mm depth of black muddy soil which should also have been removed.

I asked the Engineer If he could do remove the top soil (in a friendly way) but he said there's no need as time will be wasted, labour fees will also be increased and this is how they do it in Ajah where he comes from.

Engineers and Enthusiasts, What do you think? Have you adopted this method of filling and building on the sand?

Make I come learn boss

Androidking:
Guys I have serious question Or let me say important question
We all know that most people that design three to 4 storey building usually use kick out columns
Even when der is cantilever or not
Pls I want to ask is it actually necessary or it old style of building
What if u buried d pillar for it to flush with d wall is der any structural implication in it ??


Because I building of 3 deck and d structural ENGR buried d columns inside d walls and it was stamped and approved by LGA .


Now I saw an ENGR who is building 4 deck and he kicked out his columns but in d architectural design of the same house . d architect (me) designed it in a away all column must be buried .

Does it mean our engrs cant do wonders with structures any more. .must I kick out my columns pls I need answers and ideas. Thanks

I will start by pointing out some simple term use by you that is a bit confusing
When you say, buried columns do you mean that the column section is of the same dimension with the wall? In this case, our normal walls are 225mm thick ( 9" walls) which means the wall will also have a section of 225 x 225mm.

To the best of my understanding, the section of a column ( the size which is the width and length of the column) is governed by the magnitude of the load that the column will carry, minimum cover size ( the gap between the reinforcement and the outer surface of the column, this cover size which also depend on how long you want the column to withstand fire in the case of outbreak and also natural condition like moisture) and to some extent the hight of the column.

For a building with four suspended floors, It will be normal for the upper column to be flushed with the building because it carries a smaller load, but as the column comes down the section of the column increases where the column will need to shoot out of the walls for it to be adequate, reason why we normally have shoot columns for high rise building.

KolaShangOne:
Well done!

Thank boss

More updates

More updates from the pop work

Baaballiyo:
Nigeria was indeed respected by them a lot in those days, I heard it on good authority they even had an official mourning for the demise of Sardauna in the 60's and that of Murtala Ramat in late 70's. And there was a time when Nigeria used give some financial assistance to the Saudi Government.

There's one Dr. in Bayero University Kano Dr. Ahmad, he was originally a Ghanian, he studied in Saudi btw the 50's and 60's he said after their graduation their University in Saudia offered to retain them and they also got offer from Bayero University, and the salary page in Nigeria was two folds morethan that of the Saudi at that time, hence they decided to accept that of Bayero University.

Me too would love to have those good old days back. It's unfortunate how things fell apart for us. But I still believe that some day we would make it back, though not soon but eventually we'll.

Saudi Arabia was a poor country before the oil boom of the seventies and eighties that may explain the reasons for the respect they have for Nigerians those days.

EgunMogaji:
How did I miss this build?

Very very nice job Sir.

This is my style of architecture, perfectly executed.

You are welcome sir

ayoxelee:
Are you from Ilorin or d u have a very close person from Ilorin

My wife is from Ilorin and have relative from there

ayoxelee:
Exactly, But those pure Yorubas are minority in Ilorin, majority of people in Ilorin have either Fulani, Hausa or Nupe lineage.

How can pure Yoruba be few in Ilorin when Ilorin was originally a pure Yoruba village?
Majority of Ilorin indigene are pure Yoruba while majority of her elite are hybrid Yoruba-Nupe-fulani-hausa.

In terms or heritage, Tue largest group are Yoruba, followed by Nupe, then borqu people of kebbi, then Fulani, then very small Hausa.

Looking at the location of Ilorin you will know that it will be easier for immigration from Yoruba heartland than immigration from far away kano, sokoto etc. The Oyo's are a majority in Ilorin

Efewestern:
It's a known fact, for example the culture of the ilajes are similar to that of bini, not only ilaje almost all yoruboid group in Ondo and also itsekiri.

Those areas were at some time controlled by the binis, thou they still retain their original Yoruba language.

I am from ondo state, the northern part that share boundary with Edo (akoko Edo) state, we were never under the control of the benis in our history. We have interaction with eghira and Nupe but can't remember any written history about beni influence

adeyanwale5:
suleja

I am in suleja presently, we can set up a meeting to meet up and see the land

IamBlanco:
most of you have failed to identify the bane of this senseless domination, its ISLAM. Islam is not a religion, its a political ideology. deep yourself into the history of Islam, ull find out that where ever Muslims are minority, dy aim for political dominance cux dats d only way to spread d ideology. have u ever heard of Christian republic of, Hindu republic of, Baha'i replublic of? even in Japan that is majority Shinto don't call themselves Shinto republic of. Islam is a tyrant ideology that it takes total control of the life of its follower. such as culture which encompasses eating, meals, dressing, language, beliefs, etc. Islam is the sole reason y fulanis are still on top up until now because their subordinates first identify themselves as Muslims before there respective ethnicities. they don't integrate into your society, dy don't accept your culture, dy allow their sons to marry your daughters but forbid their daughters to marry your sons. incase of future uprising, dy will inter-marry with the kafirs & ppl of other ethnicity so as to prevent it. that's y Yorubas are confused, you're a Christian but your uncle 1 is a Muslim & uncle 2 is a pagan. be wise... I'll never practice a religion/ideology that was passed on to my forefathers through war, coercion & deceit.

Stop spreading hate speech and trying to caused confusion among yorubas. Yorubas are not confused, they are smart enough to know that religion is personal. Else don't have identity crises we are just more liberal and more bonded by our ethnicity than any other ideology

Konquest:
^^^^^^^^
This is NOT correct.
Islam was already in Hausaland, Kanuriland
and Yorubaland before Uthman Dan Fodio
or even his grandparents were born.

The history books have this information.
Oyo Empire was very powerful from trading as far as Timbuktu in Mali, Ghana, Northern Nigeria,
and with the Europeans, so the Malian Muslim
clerics came to Iwo and you will see the FIRST
mosque in Yorubaland there... Over 500 years
old. Dan Fodios so-called jihad started in 1803!

All those Social Studies books don't capture
advanced Nigerian histories. They are just meant
for simplistic Primary School education.

I have been trying to educate some of my northern friend about this. The Yorubas got their Islam through interaction with Malian traders and returnees from Brazil. The usman danfodio jiad never gain any foothold in Yoruba land.