Building Collapse: Error leads to terror


Buildings, like all structures, are designed to support certain loads without deforming excessively. The loads are the weights of people and objects, the weight of rain and snow and the pressure of wind--called live loads--and the dead load of the building itself. With buildings of a few floors, strength generally accompanies sufficient rigidity, and the design is mainly that of a roof that will keep the weather out while spanning large open spaces. With tall buildings of many floors, the roof is a minor matter, and the support of the weight of the building itself is the main consideration. Like long bridges, tall buildings are subject to catastrophic collapse.
The causes of building collapse can be classified under general headings to facilitate analysis. These headings are:
  • Bad Design
  • Faulty Construction
  • Foundation Failure
  • Extraordinary Loads
  • Unexpected Failure Modes
  • Combination of Causes
Bad design does not mean only errors of computation, but a failure to take into account the loads the structure will be called upon to carry, erroneous theories, reliance on inaccurate data, ignorance of the effects of repeated or impulsive stresses, and improper choice of materials or misunderstanding of their properties. The engineer is responsible for these failures, which are created at the drawing board.
Faulty construction has been the most important cause of structural failure. The engineer is also at fault here, if inspection has been lax. This includes the use of salty sand to make concrete, the substitution of inferior steel for that specified, bad riveting or even improper tightening torque of nuts, excessive use of the drift pin to make holes line up, bad welds, and other practices well known to the construction worker.

Even an excellently designed and constructed structure will not stand on a bad foundation. Although the structure will carry its loads, the earth beneath it may not. The Leaning Tower of Pisa is a famous example of bad foundations, but there are many others. The old armory in St. Paul, Minnesota, sank 20 feet or more into soft clay, but did not collapse. The displacements due to bad foundations may alter the stress distribution significantly. This was such a problem with railway bridges in America that statically-determinate trusses were greatly preferred, since they were not subject to this danger.

Unexpected failure modes are the most complex of the reasons for collapse, and we have recently had a good example. Any new type of structure is subject to unexpected failure, until its properties are well understood. Suspension bridges seemed the answer to bridging large gaps. Everything was supported by a strong cable in tension, a reliable and understood member. However, sad experience showed that the bridge deck was capable of galloping and twisting without restraint from the supporting cables. Ellet's bridge at Wheeling collapsed in the 1840's, and the Tacoma Narrows bridge in the 1940's, from this cause.

The conservative, strong statically-determinate trusses were designed with pin-connected eyebars to be as strong and safe as possible. Sad experience brought the realization of stress concentration at the holes pierced in the eyebars. From earliest times, it has been recognized that tension members have no surprises. They fail by pulling apart when the tension in them becomes too high. If you know the tension, then proportioning a member is easy. A compression member, a column, is different. If it is short and squat, it bears its load until it crushes. But if you try to support a load with a 12-foot column that will just support the load with a 1-foot column, you are in for a surprise. The column bends outward, or buckles, and the load crashes to earth.

Suppose you have a beam supported at the ends, with a load in the center. You know the beam will bend, and if the load is too great, it may break apart at the bottom, or crush at the top, under the load. This you expect. However, the beam may fail by splitting into two beams longitudinally, or shearing, or by the top of the beam deflecting to one side or the other, also called buckling. In fact, a beam will usually fail by shearing or buckling before breaking.

A hollow tube makes a very efficient column or beam. If you think about it, it is the material on the surface that most resists buckling and bending. A column that is modified from a compact cross-section, like a cylinder, to an extended cross-section, like a pipe, can still support the same load per unit area, but with much greater resistance to buckling. As a beam, one side is in compression and the other in tension, while the pipe cannot buckle to one side or the other. When you do bend a pipe, notice that it crushes inward reducing the cross-section to a line, which bends easily. Tubes need to be supported against buckling. Such a tube has a very high ratio of strength to weight, and hence strength to cost.

Tall buildings have generally been made with a rigid steel skeleton, sheathed in the lightest materials to keep out the weather. Alternatively, reinforced concrete, where the compression-resisting and protecting concrete surrounds the tough, tension-resisting steel, integrated into a single body, has been used. Such structures have never failed (when properly built on good foundations), and stoutly resist demolition. When the lower supports of a steel skeleton are destroyed, the weight of the building seems to crush the lower parts and the upper parts descend slowly into the pile of debris. Monolithic reinforced-concrete buildings are diffcult to demolish in any fashion.

The World Trade Center towers used neither a steel skeleton nor reinforced concrete. They were designed as square tubes made of heavy, hollow welded sections, braced against buckling by the building floors. Massive foundations descended to bedrock, since the towers had to be safe against winds and other lateral forces tending to overturn them. All this was taken into consideration in the design and construction, which seems to have been first-rate. An attempt to damage the buildings by a bomb at the base had negligible effect. The strong base and foundation would repel any such assault with ease, as it indeed did. The impact of aircraft on the upper stories had only a local effect, and did not impair the integrity of the buildings, which remained solid. The fires caused weakening of the steel, and some of the floors suddenly received a load for which they were not designed.

What happened next was unexpected and catastrophic. The slumped floors pushed the steel modules outwards, separating them from the floor beams. The next floor then collapsed on the one below, pushing out the steel walls, and this continued, in the same way that a house of cards collapses. The debris of concrete facing and steel modules fell in shower while the main structure collapsed at almost the same rate. In 15 seconds or so, 110 stories were reduced to a pile 9 stories high, mainly of steel wall modules and whatever was around them. The south tower collapsed 47 minutes after impact, the north tower 1 hour 44 minutes after impact. The elapsed times show that the impacts were not the proximate cause of collapse; the strong building easily withstood them. When even one corner of a floor was weakened and fell, the collapse would soon propagate around the circumference, and the building would be lost.
It is clear that buildings built in this manner have a catastrophic mode of failure ("house of cards") that should rule out their future construction. It is triggered when there is a partial collapse at any level that breaks the continuity of the tube, which then rolls up quickly, from top to bottom. The collapse has a means of propagation that soon involves the whole structure, bypassing its major strengths and impossible to interrupt. There is no need for an airliner; a simple explosion would do the job. There were central tubes in the towers, for elevators and services, but they appeared to play no substantial role in the collapse, and were not evident in the pictures or wreckage.

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Having a building come up from scratch to the top and to that dream home is not a one day work. Achieving your goal of a lovely building depends largely on the foundation. In turn, the foundation is not laid out the moment you get to the site. In fact, it boils down to a perfect plan drawn by a world-class architect. This is very important because right on the paper you should see the detailed and perfect blueprint of that your house. Yes, you need to understand every bit of it from the scratch. Here all that you require should be captured; also the implications of each feature therein to the overall structure and beauty needs to be thoroughly understood. 


It is the job of the architect to make you see all the facets of the building on paper. Sadly, most architects find it difficult to go the extra-mile to explain these to their clients. Furthermore, some clients never could determine how additional features to their house  could affect their cost. So they just begin like that and find out along the line that the building would swallow more money than determined. This leads to abandonment of project on the way.


It is not enough to desire a particular design in your building, the architect needs to explain to you the cost implication and the general look of it when it is completed. You need to know the current building designs to adopt and not the type that friends will always make negative comments about the old-fashioned design you chose as a result of ignorance. You don’t want to feel sad in the end, do you?

A costly, and perhaps avoidable mistakes clients make is that as the project progresses they keep making alterations to it all the way. This is a waste of time, resources and energy. In most cases this happens when the client does not seek the services of a qualified architect before commencing the building project.


SUMMARY

1.       You need Property PRO’s  world-class architect

2.       Get a building plan that reflects the perfect designs you want

3.       Don’t try  to minimize cost by using quacks, otherwise, in the end you spend more.

4.       Know how much it will cost you for additional beauty enhancing designs

5.       Match your project with  your pocket to avoid leaving the building half-way

6.       Get all the information you need before you begin the project
 

HOW NIGERIANS ABROAD ARE EXPLOITED BY BELOVED FRIENDS AND FAMILY MEMBERS IN PROPERTY MATTERS


MANY Nigerians leave the shores of the country to improve their lot in life and that of their family members. They spend enormously to secure visa and other traveling expenses, which sometimes runs into a million. On getting to their destination they set audacious goal of  sending money back home to build or purchase a property. Family members expect you to do this since most people have done likewise. After settling for a while, they begin making arrangement for this purpose. To this end, most take up as many jobs as possible and often running shifts from one job to the other. They work so hard that there is little time for rest, relaxation and recreation. Then money start coming in gradually.

Some choose to send money to their brother in Nigeria to start up the building project. First, he will have to buy a suitable land. Sadly, when the money gets to the hand of the brother it is a completely different issue. The money is been diverted and used for different other purposes never before arranged. He begins to live a different lifestyle with your hard-earned money. He goes to clubs, having fun with different girls who are ever ready to yield upon the scent of money. He changes his ward-drop and begin leaving big. As you keep sending money down, he further expands his taste. He buys a car, drives around the community to the admiration and cheers of friends. They hail him. They bow in his approach in attempt to get him to drop some money for them. Of course, he wont disappoint them. Some purchase their own property and start developing it gradually, spending the leftover own your project.  All these happen over the course of time.

"The hen that lays the golden egg suffers great pain in the process, but the consumer eats the egg with pleasure"....Rutherford Chidi
 
All along you receive reassurance that the building project is moving on smoothly. At a point you develop some doubt and want to see the stage your building has reached. So you request a photo shot of the project. The so-called brother, having known that the truth is about to come to light, runs around and gets a photographer to snap somebody else’s building. This he sends across to you. Upon receiving it you are very happy. 
It is now time to come to the country to greet your loved ones and friends and most importantly  to see the house they built for you. Guess what happens!. You are taken to a building they claim is yours which is far from complete. From your calculation, you know that the money you have sent over the years is enough to erect a befitting structure. Now filled with disappointment, anger and  betrayer you vow never to come back to the country and never to send any money back home for whatever purposes.

The situation described above is all too common. Worst still it takes the cooperation of other family members for you to be carried away by such lies. Even some parents find it difficult to tell you the exact situation at home.

WHAT SHOULD YOU DO TO AVOID THIS SITUATION

1.       Know your family very well. Can you trust them with such project? Analyse them very well. In money matters a lot of honorable people have abandoned their morals for quick financial gain.
2.       Have other information gathering source to monitor the project
3.       Give the project to a trusted, reliable contractor(click here to know more about the activities of some contractors) with a track record of good job.
4.        Leave nothing to chance. Do your best to know the level of work been carried  out.
5.       Contact us for more information about how to secure your building project.07031384722

EXPOSED: 8 TERRIBLE TRICKS OF SOME GREEDY BUILDING CONTRACTORS AND 6 TERRIFIC SOLUTIONS.


All the shame and sham of some greedy contractors is hereby unveiled. I feel particularly compelled to write this article because, among others, there  is a wave of confusion among our esteemed clients and high-level of distrust. They have lost all trust for   contractors even though there may still be those who are genuine and does not exploit their clients. Following are the different techniques counterfeit contractors employ to dupe their clients:

1.       Deliberate increase of cost of materials: when they observe that you have little knowledge of the prevalent price of materials in the market place, then they are set to put a big hole in your pocket and just put a bowl beneath it so that it pours into it. About four months ago a friend of mine related to me how a London based Nigerian citizen, precisely a lady in her mid-sixties who have spent well over twenty years in London, came back to her beloved country Nigeria to erect some structures. She contacted her lawyer and informed him of her plans. Thus the lawyer contacted a seemingly  honest but wolf –in- sheep- clothing friend to handle the contract. Having realized that the client was well loaded with cash coupled with the fact that the client lacked the Nigerian blood flowing through her veins (she had complete trust on the contractor ) the so-called contractor swung into action. A bag of cement that cost about 1800 naira became 20,000 naira and he bought plenty bags at this rate. Worst still the client fell for it and kept bringing out more money. Later on the son of the client came around to see how the project was going and was horrified to see the mind-blowing charges. He screamed. Immediately the contractor and lawyer were arrested and the case was about to be charged to court. Even in this situation the advanced lady felt pity for the contractor on the reason that he might have been very poor to act in such dubious ways. In the end, they were let off the hook but with the innocent lawyer’s image badly damaged.

2.       Purchase of substandard materials so as to realize high profit margin. Hmm, this is a crazily popular trend. Substandard materials are flowing everywhere. These contractors know just where to buy them and go for them. In fact, every building material  has a fake counterpart. Indeed, there are fake cement, fake rods, fake pipes and every goddamn thing used in building. They simply purchase large quantities of these and build your desired home with them. Then give your building a very beautiful painting, thereby heavily concealing the imperfect material used. In the long run, you see cracks on the wall. Worse, this situation is largely responsible for the widespread report of collapsed building with lives lost. You don’t want to risk your life and that of your family members, do you? The Bible says: “you will know the truth and the truth will set you free”

3.       Closely related to the  practice above is the habit of buying cement whose quantity has been deliberately reduced. Some cement dealers greedily take some quantity from different bags of cement to form another bag and then carefully seal it back. Some contractors patronize them, and still buy the cement at the same prevailing rate or price. The result: the same bag of cement but with a reduced quantity now also required to give the same number of blocks per bag. Step on the block and it destroys, rain also washes it away.

4.       Recruiting low paid workers or quacks to do the job and maximize profit. The cost of hiring real experts is usually higher because of their level of experience. To avoid this situation, they simply opt for quacks who accept lower pay. Now think of this: have you ever passed through a building whose seeming lifespan is far into the future but which has visible cracks on the wall? Have you wondered what caused this? Well, when quacks handle a building projects there are cracks later.

5.       Stealing materials. This ugly practice is common among the greedy class of contractors. Right now I look back at the experience I had many years ago. I visited a particular  work site to participate on a building project. But behold! The contractor in charge was seen making space in a heap of sand where he could carefully conceal a bag of cement. The truth is when left unmonitored, many items are diverted for personal use. In the case of cement, when some bags are missing they still try to produce the same quantity of blocks expected from a standard filled bag. But this time with a higher quantity of sand and reduced quantity of cement. Thus making the resulting blocks less strong. And could easily be washed away by rain.

6.       Outright lies and deception. Assuming a tipper is to supply ten-tipper load of sand, the greedy contractor connives with the driver to only supply eight or nine. With the effect that the remaining money for the unsupplied sand is put in his pocket.

7.       Poor monitoring of projects because of too many engagements. In fact, even veteran contractors commit this crime. They handle many building projects at the same thereby reducing the quality and quantity of monitoring attention. You see them running like a headless chicken from one project to the other. Sometimes before they come back to inspect the project the damage is already done, necessitating adjustments. This situation also leads to a shabby execution of projects.

8.       Conniving with workers to misrepresent facts. These greedy contractors appear smart and knowing very well that property owners will sometimes seek confirmation of facts from the workers, they proactively intimate the workers in this regard and tell them what they have to say when the situation arrives. The building owner is completely DECEIVED.

TERRIFIC SOLUTIONS

1.       Get informed. Always survey the market to know the current price of building materials.
2.       Consult other experts in the field to confirm the originality or quality of materials.
3.       Frequent the site to know when projects are not handled properly.
4.       Only patronize contractors (as we are) that have track records of honesty and quality delivery.
5.       Dig deeper into facts, go extra miles in ascertaining the truth.
6.       Keep records of materials bought.
REMEMBER: HE WHO TELLS YOU THE TRUTH IS YOUR FRIEND.
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