Since the purpose for any structure of a building is to satisfy some human needs, there is need for the design of such structure to be at par with the functional objectives of safety, serviceability, and economy.This article delves into the menace of structural failures in Nigeria
The tools to enable an engineer realise the functional objectives of safety, serviceability, and economy in building construction are his knowledge of structural mechanics, available research materials, government regulations, codes, his experience, and professional knowledge. The structure must be safe under the worst system of loads.
Under extreme loadings, damage to the structure can be localized and possible loss of lives reduced, but progressive and catastrophic collapses must not occur. Under the working load, the deformation of the structure must not impair the appearance, durability, and performance of the structure.
A structure is assumed to have failed when it can no longer serve the purpose for which it was built. Failures may occur during construction or later in the course of the design life of the structure. Irrespective of the type of failure or the period in the lifetime of the structure that the failure occurs, the effects are always devastating.
The possible causes of failure can be traced to the activities that take place in the following stages of a building process: conception-design stage, construction-supervision stage, and post construction-service stage. For the realisation of quality jobs in any of these stages of the building process, a high level of skill and professionalism is needed.
Design stage is the planning and feasibility studies stage in which some professionals may assist the owner to evaluate the technical and economical options available and then realize the design. The design consists of the creation of the architectural form, identification of the loads, selection of materials, and proportioning of the sections.
During this stage, the basic requirements of safety, aesthetic, economy, and constructability must be considered, irrespective of the client’s brief . The structure produced from this design is strictly for the loads considered. Should there be need to subject the structure to loads greater than the design loads, it will be essential for a certified engineer to redesign the structure for the new loads and make adequate strengthening on the structure where necessary.
The construction stage is the physical realization and over-seeing of the structure designed in the previous stage. During this implementation stage, every effort is made to ensure compliance with the design and specifications. The activities that take place within this stage are so numerous, and often conflicting with each other.
The management of scheduling, materials, human and technical resources is often enormous such that only trained professionals can handle them. Certified engineers, architects, builders, and skilled artisans all have their respective roles in this phase so as to enforce the quality assurance specifications.
During the service stage, the constructed facility serves the purpose for which it was built. It is expected to serve effectively the purpose for which it was built without causing any form of discomfort to the user. For a good usage of any built structures, a management and monitoring team must always be at hand to continuously assess the true state of the structure and make recommendations for maintenance.
Visual inspection may be combined with non-destructive testing techniques to assess internal defects and make maintenance meaningful. Failure to execute appropriate maintenance may pose a great danger to the structure and the users.
Structural failures occur all over the world. The rate of occurrence and the intensity of damage are low in the advanced nations where strict controls, enforcement of the codes and high ethics of professionalism are obtainable.
Even under severe natural hazards such as earthquakes, catastrophic destruction is often curtained because of the ductility inherent in the structures. For example, the extensive collapse and casualties verified in the 2010 earthquake in Haiti is related to the absence of ductility in most of their buildings, including the presidential palace. A later earthquake in Italy of comparable magnitude produced far less damages when compared to the Haitian seismic event.
On a regular basis, just a one-day non-stop rain fall is enough to hold the whole Lagos State to a standstill as failed drainages and flooded-potholed roads make it impossible for most people to go about their activities. Look at what is happening in Lagos Island for instance. Lagos Island has parts like Lekki and Banana Island as places with the highest real estate valuation in Lagos state and probably Nigeria at large, albeit water is no respecter of place. The flood that bedevils that area belittles the huge money people spend to live and work on the Island.
One of the most pathetic issues concerning building collapse is that not all the cases are brought to the knowledge of the public. When they occur in remote areas or in exclusive private environments, the news is not made public.
Another issue is the quality of information that comes from the journalists after each collapse. Since most of them have no technical idea of structures, they release news that is not compatible with the causes of the collapse. Without any idea of building technicalities, passersby pronounce the causes of the collapse. Conclusions are made before any serious investigation takes place. Only accurate forensic analysis is needed to ascertain the true cause of most structural collapses.
The causes of these failures in the Nigerian built environment can be traced to abnormal factors not obtainable in most nations. Worldwide, the generally known causes of structural collapse are design flaws, aging, material fatigue, extreme operational and environmental conditions, accidents, terrorist attacks, and natural hazards.
But in Nigeria, the principal causes of collapse are non-adherence to the building codes, use of unskilled artisans, poor supervision, inferior materials, ignorance, lack of maintenance, misuse of structures, conflicts among professionals and corruption.
Hence, the Nigerian building industry needs to be completely overhauled.