Maduka Nweke
Several factors have been listed as major causes of housing collapse including the inability of developers to abide by the template drafted prior to the commencement of the project construction. It is on record that most developers add more storeys when in the middle of the construction they found their pockets still heavy. The added floors come to the detriment of the foundation weight allowed.
A building collapse occur when the load is beyond the strength of the foundation. It is equal to asking a baby to carry a heavy box when you know the baby will not be able to withhold the strain. Even if the foundations and the materials are strong enough for what they were originally built for, that purpose may change. If a building was designed to be a home and is then turned into a library where boxes and boxes of books are piled up, the building may strain under the weight and this is capable of pulling it down.
Recall a recent upmarket apartment block which had more storeys than planned collapsed in Lagos, killing 34 people. That came two years after a church accommodation for the famous preacher TB Joshua collapsed. The authorities said, it collapsed because it had more floors than the foundation could hold. In that case more than 100 people lost their lives.
It is important that at all points of construction the strength of the building should be tested. You have to be strict about policing building. The law says you must test. It is the enforcement of the law which is the problem because often times, the authorities pervert the rule of engagement just for a token. Many a time a kobo mistake results in millions expenses yet most builders who want to maximize space refuse to take correction. The ploy to change the structural designs is a big problem and it mostly happens when at every stage of construction there is someone with a strong motivation to save money or take money. There are many physical reasons a building can collapse and in all, only one driving motivation for that to happen and that is money. That is the real reason buildings collapse – corruption.
Another problem that can result in building collapse is when the building materials are not strong enough to carry the structure whether a bungalow or storey building. Materials that are not strong enough to withhold the load when used are likely to make the structure to shrink. The above is according to African Organization for Standardisation, whose organisation met recently in Nairobi to discuss why so many African buildings collapse. The Organisation observed and noted that there is a market for counterfeit materials – going as far as to say that sometimes scrap metal is used instead of steel.
When a six-storey building in Uganda’s capital Kampala collapsed recently, the director of the city authority suggested it had been constructed with counterfeit materials. There are even cases of counterfeiters faking authentification certificates. This at times suggests that contractors also knowingly use the incorrect materials to cut costs. So they may use concrete intended to bear the load of a one-storey building in a four-storey building. Structural failure can also occur from many types of problems, most of which are unique to different industries and structural types. However, most can be traced to one of five main causes.
It could be that the structure is not strong and tough enough to support the load, due to either its size, shape, or choice of material. If the structure or component is not strong enough, catastrophic failure can occur when the structure is stressed beyond its critical stress level. The failure could also be from fatigue or corrosion, caused by instability in the structure’s geometry, design or material properties. These failures usually begin when cracks form at stress points, such as squared corners or bolt holes too close to the material’s edge. These cracks grow as the material is repeatedly stressed and unloaded (cyclic loading), eventually reaching a critical length and causing the structure to suddenly fail under normal loading conditions.
Also the structural failure could be caused by manufacturing errors, including improper selection of materials, incorrect sizing, improper heat treating, failing to adhere to the design, or shoddy workmanship. This type of failure can occur at any time and is usually unpredictable. Defective materials could be the reason. This type of failure is also unpredictable, since the material may have been improperly manufactured or damaged from prior use. The other cause of failure could be from lack of consideration of unexpected problems. This type of failure can be caused by events such as vandalism, sabotage, or natural disasters. It can also occur if those who use and maintain the construction are not properly trained and therefore overstress the structure.
Aside the noticeable failures mentioned above, other problems that can make buildings fail could be as a result of employment of unskilled workmen and use of poor building materials without any proper structural design that ultimately lead to the collapse of the buildings. Such accidents often involve buildings in low-income, semi-formal and informal housing sectors. There are indeed gaps in the system that lead to poor construction which need to be addressed at various levels. Most of the illegally constructed buildings are more often than not, likely to be substandard and dangerous. The buildings which are constructed without professional engineering protocols and usually with untrained construction workers are most vulnerable.
Another major reason for building collapse is that the owners of buildings are irresponsible and have no concern for the condition of their buildings. The old buildings are left in dilapidated conditions and are never repaired. Even when structural cracks begin to appear, no actions are taken, resulting in eventual collapse, as happened in Lagos in 2015. Even before the building collapsed, portions of inner slabs had begun collapsing. But the owners apparently did not make any effort at getting them repaired. The buildings and their foundations are usually designed to carry dead loads, live loads and sometimes even resist horizontal forces due to wind or earthquakes.