Why buildings collapse
In the light of the incident at the Synagogue Church of all Nations, the incidence of building collapse in Lagos state is now growing at an alarming rate, seemingly uncontrollable or beyond easy control and this should be a source of serious concern to all stake holders – the professionals in building industry, government, private developers, clients and users, as well as neighbourhood residents. The effects of building collapse could be quite devastating and should be avoided using all necessary precautions and machineries possible.
Ultimately, the effect of collapse of building structures is colossal. A building, once properly constructed is expected to be in use for a very long time. 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 the pressure of wind and most recently the joke called infrasonic radiation as claimed by ‘SCOAN’
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 factors responsible for the collapse of hitherto pompous buildings are; bad design, faulty construction, foundation failure, extraordinary loads, unexpected failure modes and combination of causes. We will be taking a quick look at all the factors aforementioned;
• 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. The final object of structural analysis is to enable the Engineering design and construct a building structure, which is satisfactory in service, and that such design must be approved by the approving body. This means that it must not collapse when loads area applied and the deformation must not be excessive. However, in Nigeria, in order to try and save cost, a lot of people patronize quacks to do designs for them and such designs are grossly inadequate and usually result in building failure.
• 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 funny looking storey buildings in Onitsha are typical examples of bad foundations, but there are many others. In August, 1977, a residential building in Bamawa housing Estate, Kaduna collapsed killing 27 people. On May 1986, a mosque in Oshogbo also collapsed killing two people, both catastrophe due to faulty designs. Lagos has also had its fair share of disasters due to faulty design as was evident in the 6 –storey hotel collapse that occurred at Mende village in October 1989.
• Extraordinary loads are often natural, such as repeated heavy rainfall or thunderstorm, or the shaking of an earthquake, or the winds of a hurricane. A building that is intended to stand for some years should be able to meet these challenges. A flimsy flexible structure may avoid destruction in an earthquake, while a solid masonry building would be destroyed. Earthquakes may cause foundation problems when moist filled land liquefies.
• 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, the historic collapse of the U.S State of Washington, Tacoma Narrows Bridge caught on tape in the 1940 is a typical example of collapse due to unexpected failure
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 difficult to demolish in any fashion
Albeit, to effectively curb the incidences of building collapse in Nigeria;
1. All clients or building developers should be compelled to comply with approved building regulations before the construction and demolition of their buildings and that all building construction works should be well designed and supervised by a registered member of Architects’ Registration Council of Nigeria (ARCON), Council for the Regulation of Engineering in Nigeria (COREN) and Council of Registered Builders of Nigeria (CORBON). Only competent registered contractors should be employed to execute construction works or projects.
2. The professional bodies should hold regular workshops and Continuous Professional Development Programmes (CPDP) in order to improve the professional competence of members.
3. There should be a law in every state in Nigeria, providing heavy penalties for contractors who fail to have registered professionals in supervisory capacity in major building projects. Systematic inspection of building works should be enforced at the Local Government level and penalties for failure to comply with the building standard regulation should be provided for.
4. All building construction materials like sand, cement, aggregates, reinforcement bars and particularly foundation soil should be tested before commencement of any construction. The mineralogy and alkalinity tests of coarse aggregates should be done to know whether the material contains some percentage of impurities, which deleterious and injurious to cement and reinforcement rods.
5. Government should quickly promulgate a National Building Regulation for the elimination or considerable reduction of the incessant collapse of buildings in Nigeria and quick response committee for investigating incidents of building collapse should be formed.
6. The law governing all approved structural details of buildings, materials and effective supervision by the local Town Planning Authorities should be enforced and not compromised. Section 30(1) of the Nigerian Urban and Regional Planning Decree 88 of 1992, which demands that no building or structure or any part thereof should be erected , converted, altered or enlarged unless a development permit has been obtained by the owner or his agent from the ministry should be enforced. The Government should fund this board established through the decree so as to ensure adequate monitoring of the building approval and construction in our society.
7. Government should exercise leadership in protecting and enhancing the quality of all the buildings by encouraging and enforcing regular maintenance so as to protect human life and properties.
8. All Government functionaries and building developers should be properly trained and encouraged to always give construction of large scale buildings to competent and registered contractors who will also be supervised by a registered Structural Engineering consultant and Architect who preferably have designed such projects
It is only when the rules and regulations of development control are implemented that building collapse, resulting from structural failure can be averted.
