|Assessment Of Causes Of Building Collapse In Nigeria by Goodboy(m): Thu 04, November, 2021|
Olufemi A. Oyedele, BSc. Estate Management, MSc. International Project Management, MPhil. Construction Management, ANIVS, RSV.AbstractBuilding collapse (BC) in Nigeria is becoming a regular occurrence, each recording great casualties in the number of lives and materials lost. Building collapse is a situation where building which has been completed and occupied, completed but not occupied or under construction, collapses on its own due to action or inaction of man or due to natural event like earthquake, storm, flooding, tsunami or wildfire. It is different from building demolition. There are various causes of building collapse and each case requires expert judgment to decide the cause of its collapse. Rate of building collapse is a reflection of the level of organization and control of building activities and degree of sophistication of the construction professionals in a country. This study explored the use of case study by examining the causes of six (6) collapsed buildings (CB) across Nigeria. Samples of materials from the sites of the collapsed buildings were taken for testing and analysis, while critical observations were made at the sites to note the conditions of the ground (building base). The study found out that majority of the building collapses in Nigeria were due to poor workmanship, sub-standard building materials, followed by bad building base and poor design. The National Building Code 2006 is not effective due to lack of enforcement and the Physical Development Departments of states and Federal Capital Territory are just mere agents of corruption allowing all types of construction without building approvals.Key words: Building collapse, Concrete tests, Differential settlement, Integrity test, Quality control.IntroductionThere were 33 building collapses in Lagos and 22 in Abuja in 2012; 17 buildings collapses in Lagos and 20 in Abuja in 2013 and 13 building collapses in Lagos and 2 in Abuja in 2014. Building collapse is now as constant as northern star in Nigeria due to lack of physical development and building controls. In the first quarter of 2016 alone, the toll in Lagos was 5 collapses. One important issue which is noteworthy about building collapse in Nigeria is that collapses usually occur in buildings with two floors up to five floors.Collapses do not usually occur in bungalows and buildings with more than five floors except where buildings collapse was due to erosion. This is because bungalows are non-load bearing structures requiring simple strip foundation and in some cases like made-up ground, raft or pad foundation. If the floors are more than three in a made-up ground, pile foundation will need to be introduce. Buildings with more than five floors are complex structures requiring professionals with many years of construction experience.“Over the years, Lagosians have witnessed consistent building collapse leading to fatalities, litigations, regulatory actions, pains, injuries, delayed schedules, bad reputations and loss of properties, etc” (Fowode, 2016). Building collapses always bring with them a lot of costs in the form of death, loss of money, loss of time, loss of equipment and wasted building materials. It also affect the reputation of the construction industry of the area where it occurs. The six storey building which collapsed at Synagogue Church of All Nations (SCOAN) in Lagos State recorded 116 lost lives in November 2015.
The one at Lekki Gardens in April 2016 resulted in over 30 casualties. According to Nwannekanma (2016), “tragedy struck yesterday morning when a five-story building collapsed in the Lekki area of Lagos. At least 18 persons died while 12 others were rescued alive from the rubble”. Clients or building construction promoters have three requirements of their buildings. These are : (i) that they are constructed within cost (budget), (ii) that they are constructed within time (schedule) and (iii) that they are constructed to acceptable quality (standard). Corruption and greed are the major debacles of these requirements.Collapsed buildings are those that the qualities have been compromised either due to the materials used, faulty design in place or the ground on which the buildings were erected, were badly made-up. Some projects in Nigeria are planned to fail because the project owners or sponsors refused to employ competent project managers, engineers and builders. It is a known fact that traditionally, projects starts with the client who engages, in most cases, his architect to design the project. He then contracts a project manager to oversee the design and construction. For any project that is more than one floor, structural engineer must be engaged to design and supervise the structures.According to Fowode (2016), “building projects start well before ground is broken”. Failure to recruit the appropriate team for a project is invitation of failure in project delivery. Geological survey needs to be carried out in order to determine the appropriate type and depth of foundation which will carry the superstructure. In most cases, expert judgment is used to determine the type of foundation for buildings, especially in bungalows and buildings up to three floors which are common in Nigeria. Transfer of idea from one site to another may not work because different sites have different geology (sub-soil). This paper will exploit the case study approach by studying the causes of collapse in six (6) buildings in Nigeria to generalize the major causes of collapse in the country.Literature ReviewUnplanned falling of building is usually referred to as building collapse, while planned falling of building is referred to as demolition. Buildings are erected to stand and to be functional for its intended use throughout its lifespan. The ubiquitous building collapse in Nigeria is a cause for concern. According to Oloyede, Omoogun and Akinjare (2010), “in recent times, the incidence of building collapse in the country’s major cities of Lagos, Abuja and Port Harcourt have been alarming”. Building collapse can be partial like the one that occurred at NIDB Building on Broad Street, Lagos State in 2008, or total like the Lekki Garden building collapse.According to Ige (2016), the building collapse in Abeokuta on Friday, May 13, 2016, could have been prevented if due process has been followed by the construction teams. Building construction process involves professionalism in the planning, design, and execution of the project. Engineering consultants must be involved in the design and supervision of construction works. The design structural engineer must visit the site regularly and a sub-soil investigation of the site carried out by a geo-technical professional, followed by a foundation design by an engineer based on the engineer’s knowledge of the terrain and the results of geotechnical survey. A general arrangement of the structural element and production of design calculations, drawings and job scheduling are carried out before signing off for construction.
Construction is not a child’s play. It involves the collaboration of different professionals who have been taught the art and science of the process. The land surveyors determine the shape, geographical orientation and the size of the site. The architects’ duties involve the design of the structure. Structural engineers are in charge of structural design, stating the type and number of reinforcements to be used in slab, lintels and columns and the spacing of stirrups after considering the length of lintel, columns and unsupported span of slab. The town planners must make sure that the building codes stating set-backs, height of buildings, building lines, room sizes, fire exit etc are incorporated in the building.It is the duty of the quantity surveyors to estimate the probable amount that will complete the house and to issue payment certificates at milestones. Quantity surveyors bill of quantities are also good bases for job planning and scheduling. The estate surveyors take control of the building for management after it has been completed. These professionals should ensure that buildings are professionally built and avoid the incessant collapses in Nigeria. In most cases, quacks do take charge of building process and deceive house owners who do not observe due diligence like visiting construction professional bodies (Nigerian Institute of Architects, Nigerian Institute of Building, Nigerian Institute of Civil Engineers etc) in choosing their consultants and contractors.“Before casting concrete, the engineer inspects each element to be cast, issues a written instruction that checked the reinforcement and found same to be in agreement with the structural drawings, and gives the contractor the authority to cast the concrete element in question. This time-tested method is not always followed on many projects, because of our Nigerianess” (Ige, 2016). There is no control on building process in Nigeria. To pass cube test, concrete are re-mixed by most contractors who add more cement to the mixture and dip the cube inside water for some time for adequate curing before taken to the concrete laboratory for analysis.According to Nucera and Pucinotti (2009),”the assessment of in-situ compression strength of a reinforced concrete structure, plays a key role in the evaluation of its safety”. Completed buildings are sometimes subjected to integrity test to determine their strength. Recent innovations provide clear rules for assessing the safety and conduct of static strengthening on existing buildings. Malek and Kaouther (2014) stated that “i t is often necessary to test concrete structures after the concrete has hardened to determine whether the structure is suitable for its designed use”. Concrete has also been tested where there is disagreement on cost between client and contractors.Testing Concrete, Sand, Iron Bars, Water and other construction materials on siteConstruction materials are tested before and during construction as a quality control measure and after construction for integrity test. There are various methods which can be used to test building materials on site. There are many types of construction materials used in Nigeria. These different materials have different strengths and resilience, e.g., reinforcement bars, cement, sand, gravel, particle board, plywood, pine, oriented strand board (OSB), and drywall (gypsum board, SheetRock). The same cross-sectional area of each material must be used as sample in order to make fair comparisons during tests.Some of the methods which are commonly used for quality control of structure will be discussed as follows:
Concrete: Concrete derives strength with increasing age up to 90 days (curing). The compressive strength of typical concrete with 1:2:4 cement: sand: aggregate ratio and good mix of water (0.5 water/cement ratio) is usually 30.5 GPa after 28 days and 32GPa after 90 and 120 days respectively (Malek & Kaouther, 2014). There are two methods of testing concrete; the destructive and non-destructive methods. The destructive tests include cube or cylindrical test (compression test), extraction of cores and the subsequent laboratory test (strength and carbonation test), pull-out test, extraction of rebars, corrosion test, pacometer test, loading test on floor slabs and radar surveys. The non-destructive tests include surface hardness test (Schmidt rebound hammer test), ultrasonic test (Ultrasonic Pulse Velocity System) and combined methods (SONREB method) (Malhotra & Carette, 1991).In destructive method of test, carbonation depth may be used to test the uniformity of concrete test. The depth is usually 10cm in a normal concrete. In lean concrete, it will be more. What influence concrete strength are; the type and dosage of cement, the dimensions and nature of the aggregates, the superficial conditions of the concrete and the humidity and maturity. Concrete is very weak in tensile strength and have weak bending moment, but has high compressive strength. Since iron is very good in tensile strength, it is usually introduce in concrete to improve its bending moment.The parameters which influence the velocity of propagation of ultrasound waves in concrete are: (i) the entity of the load (ii) the age of the concrete (iii) the form and the dimension of the structure (iv) the run length (v) the presence of metallic reinforcements (vi) the water/cement ratio (vii) the state of strength (viii) the temperature (ix) the humidity of the concrete (Pucinotti, 2006).Sand and aggregates: Sieve test is usually done on sand and aggregates to determine the degree of fineness and coarseness of these materials.Water: Drinkable water which is colourless and odourless with Ph7 must be used on site.Iron bars: Bending strength of iron bars determines their strength. There are two types of bars, plain and twisted. There are different thickness and the usage and spacing of bars and stirrups depend on area of building and the span of space in which reinforcement concrete will be used. Addition of adulterated materials may compromise the strength of bars. Density test may be used to test iron rods. Causes of Building CollapseThere are two major causes of building collapse, which are natural and artificial. The natural causes can be due to earthquake, hurricane, tremor, storm, typhoon, flooding, erosion, wildfire etc. The artificial or man-made causes can be due to action or inaction of man leading to tripping (inappropriate slenderness ratio and uneven distribution of load in one part of the structure), shearing due to weak structure (poor materials or bad workmanship), building on weak sub-soil (lack of development and building control), wrong choice of foundation leading to differential settlement of building (lack of professionals on site and lack of development control), bad structural design (lack of professionals on site and lack of control), addition to floor (lack of professionals on site and lack of control), inadequate curing (non-potable water, use of sub-standard sand or cement, inadequate time allowed for curing), etc.
Buildings can also collapse when the building members fail to bond due to stress, strain or shear. In Nigeria, building failure have been attributed to the causes such as design faults (50%), faults on construction site (40%), and product failure (10%) (Oyewande, 1992; Ayininuola & Olalusi, 2004; Ayuba, Olagunju & Akande, 2012). Lack of maintenance and wrong usage of building leading to stress can lead to building collapse. Stress is pressure or tension exerted on a material object. Wind can also cause building collapse due to strain. Strain is a force tending to pull or stretch something to an extreme or damaging degree. Professionals in the built environment have been trained to design and construct structures that have enough strength to withstand extreme stress and strain. Improper distribution of load during and after construction of building like communication mast, antennae, billboard and water reservoir can lead to shearing.Quality Control in Construction WorksQuality control is the part of quality management that ensures products and service comply with requirements and expectations. It is a work method that facilitates the measurement of the quality characteristics of a unit, compares them with the established standards, and analyses the differences between the results obtained and the expected results in order to make decisions which will correct any differences. In construction procurement, the contract will stipulate how the job is to be carried out which will lead to expected standard. Technical specifications define the type of controls that must be carried out to ensure the construction works are carried out correctly. They include not only products materials, but also the process of execution and completion of the works. Technical specification includes the buildings plans, structural plans, mechanical and electrical drawings (services drawings) and the Bill of Quantities.One way of controlling quality is based on the inspection or verification of finished products. Most construction companies have their own Quality Control Department or, at least, Quality Control Officer who is in charge of quality control. The aim is to filter the products before they reach the client, so that products that do not comply with requirements are discarded or repaired. This reception control is usually carried out by people who were not involved in the production activities, which means that costs can be high, and preventative activities and improvement plans may not be effective. It is a final control, located between producer and client, and although it has the advantage of being impartial. Check list is usually handy during quality control of construction works.A construction company must reduce the costs of bad quality jobs as much as possible to maintain a good image, and ensure that the results of its processes comply with the client's requirements. Both internal and external controls can be carried out on quality performance. For example, the inspection of concrete received by the contractor can be carried out by an consultant structural engineer; the execution of steelworks can be controlled by the project manager, or the local council area or state government can establish building control agency for execution of building works.Methodology of research The methodology chosen for this research is the case study. Case study method involves selections of cases to be studied by the researcher. In this case, six collapsed buildings were chosen for study to find out the causes of their collapse. The information collected on these building were generalized as the causes of building collapse in Nigeria. Case studies.
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