Browsing by Author "Abdullahi, M."

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Assessment of Safety Provisions on Building Construction Sites in Abuja, Nigeria: Professionals and Workers Perspectives
(Proceedings of the 2nd International Engineering Conference, Federal University of Technology Minna, Nigeria., 2017-01-02) Kolo, D. N.; Yitmen, I.; Tsado, T. Y.; Abdullahi, M.; Yakubu, D. M.
Despite the growth of the building construction sector in Nigeria, the provision of the basic safety materials and facilities to workers remains a challenge. The construction industry is believed to be a pillar of domestic economy in most nations; it is believed to contribute about 2.08% to the GDP of Nigeria. Yet, the rate of non-fatal, fatal injuries and illnesses exceeds that of many other industries, the construction industry has the most fatality rate when compared to other industry sectors. This paper examines the level of provision of the basic safety materials and facilities to workers by contractors in the Nigerian construction industry, the study employed the work study and field survey research method. Structured questionnaire were administered to the Architects, Engineers, Project managers and Contractors as well as the workers engaged in construction. The research exposed the neglect in the provision of safety materials and facilities on the part of the contractors. Scaffolds and shovels where the materials readily provided by the contractors from the list of safety materials provided as recommended by the regulatory authorities. The Institute of safety professionals of Nigeria, Council of registered builders of Nigeria and other statutory government agencies should be more diligent to effectively monitor the activities of building construction contractors in Abuja, Nigeria.
Empirical Relationship between Compressive, Flexural and Splitting Tensile Strengths of Concrete Containing Kuta Gravel as Coarse Aggregate
(Journal of Engineering Research and Reports, 2025-02-02) Abubakar, J.; Abdullahi, M.; Aguwa, J. I.; Abbas, B. A.; Kolo, D. N.
Flexural and tensile strengths of concrete are of great importance in structural engineering. Understanding the flexural strength of concrete helps designers prevent and control development of cracks in concrete elements, ensuring durability. In addition to serviceability, shear, bond failure and flexural capacity in concrete members are directly linked to the tensile strength of the concrete. When compared to flexural and tensile strengths, determination of the compressive strength of concrete is easier to carry out in the field. It is therefore, customary to determine the compressive strength and correlate it to other strength properties. In this study, empirical relationships have been developed to relate the compressive strength to the flexural and splitting tensile strengths of concrete using Kuta river gravel as coarse aggregate. Using varying total aggregate to cement, coarse aggregate to total aggregate and water to cement ratios, 20 mixes were generated using Central Composite Design (CCD) in Minitab 21. The compressive, flexural and splitting tensile strengths of concrete samples from these mixes were determined at 28 days of age. From the strength data obtained, regression equations were developed that relate the strength properties with the aid of regression analysis tool in Microsoft Excel. The empirical models developed to predict the flexural and splitting tensile strengths of concrete from the compressive strength recorded R2 values of 1 for both models, P-values of 5.23 × 10−29 and 4.47 × 10−30, and standard errors of 0.21 and 0.06 respectively. Furthermore, residuals from the values of predicted strength properties show that there is very slight deviation between the experimental and predicted values. It was concluded that the empirical equations developed are significant, have high predictive capabilities and can be used in predicting the flexural and splitting tensile strengths of concrete.
Investigation into the Mechanical properties of concrete using Pebbles from Bida Environ as coarse aggregate in concrete production
(Polish Journal of Science, 2024-01-02) Abbas, B. A.; Abdullahi, M.; Sadiku S.; Aguwa J.I.; Abubakar J.; Kolo, D. N.
Strength performance remains the most important property of structural concrete, from engineering point of view. This paper investigates the mechanical properties of concrete made from Bida natural stones, extensive experimental work was conducted using 1,600 specimens for compressive strength, flexural strength, splitting tensile strength and elastic modulus (four hundred specimens for each property). Central composite design was used for the factor setting with the following range of values; W/C= 0.4, 0.5, 0.6, CA/TA= 0.55, 0.615, 0.68, TA/C= 3.0, 4.5 and 6.0. The specimens were produced and cured for 7, 14, 21 and 28days. The highest strength was achieved using low W/C, low TA/C and high level of CA/TA corresponding to 0.4, 3.0 and 0.68 respectively
Modelling the Slump, Compressive Strength and Density of Concrete Containing Coconut Shell as Partial Replacement for Crushed Granite
(USEP: Journal of Research Information in Civil Engineering, 2017) Abdullahi, M.; Aminulai, H. O.; Alhaji, B.; Abubakar, Mahmud
In this research, crushed coconut shell was used to partially replace crushed granite as coarse aggregate in the production of concrete. Tests were conducted on the physical properties of crushed coconut shell and crushed granite. Thirty one random mixes were generated using Mini Tab 14 statistical software package. A total of 108 cubes were cast and cured for 28 days and then crushed to determine their compressive strength. The results were used to develop empirical models for the slump, compressive strength and density of the concrete. The concrete developed in this work has slump ranging from 0 – 135 mm, compressive strength ranging from 8.94 N/mm2 – 27.11 N/mm2 and density ranging from 1757.04 kg/m3 to 2198.52 kg/m3 respectively. This implies that concrete made using coconut shell as partial replacement for crushed granite can be used for structural application such as in the construction of reinforced concrete slabs, beams, columns and foundations. Polynomial model was developed with the capability of explaining the under-laying relationship of 93.8%, 83.6% and 72.3% for slump, compressive strength and density respectively.
Reliability studies on reinforced concrete beam subjected to bending forces with natural stone as coarse aggregate
(Asian Journal of Civil Engineering, 2020-01-12) Kolo, D. N.; Aguwa, J. I.; Tsado, T. Y.; Abdullahi, M.; Yusuf, A.; Oritola, S. F.
This paper presents the results of structural reliability analysis of a structural element (beam) in building using First-order reliability method (FORM) to ascertain the level of safety. The natural stone (NS) which is the by-product of Precambrian deposits of the Bida trough was used as coarse aggregate: unwashed and washed aggregates were used. A total of 80 concrete cubes of 150 mm × 150 mm × 150 mm were cast and used for this study, sensitivity analysis was conducted by varying the span, depth, effective depth, area of shear reinforcement and dead load of the beam in bending. The result of the sensitivity analysis revealed that the beam utilising unwashed and washed NS are both structurally safe at a span of 3000 mm with probabilities of failure of 9.20 × 10–5 and 2.06 × 10–8 and both safe at a depth of 600 mm with probabilities of failure of 4.19 × 10–4 and 2.602 × 10–4, respectively, in bending.
Reliability-Based Code Calibration in Civil Engineering: A Critical Review
(USEP: Journal of Science and Engineering Production, 2021) Abubakar, Mahmud; Aguwa, J. I.; Abdullahi, M.; Sadiku, S.
The use of new materials and the complexities in modern civil engineering infrastructures call for a systematic attempt to find accurate design solutions. It is clear that deterministic values are not reliable and that their use in the design of civil engineering structures can lead to instant failures. Thus, the use of the probability theory to determine the most reliable value of a parameter for the design of civil engineering structures is very relevant. This work is intended to review the literature on the application of probability theory in the calibration of civil engineering design codes. Consequently, to better evaluate designs and design details, it is important to understand the techniques as highlighted herein.
Top Cited Articles on Structural Engineering Reliability by the Nigerian Authors
(USEP: Journal of Research Information in Civil Engineering, 2020) Abubakar, Mahmud; Aguwa, J. I.; Abdullahi, M.; Sadiku, S.; Oritola, S. F.
This study analyses the characteristics of top-cited articles on structural reliability with at least one author affiliated to Nigeria. A search in the Google Scholar database for articles published between 2010 and 2020 was carried out. From the top-cited articles, variables related to the journal, article, and authors, such as journal ranking from SCImago Journals & Country Rank (SJR), H-index, author affiliations, international research collaboration, and source of funding were collected and descriptively analysed. A sample of 25 original reports was identified from the search. The average citations per year ranged between 0.10 and 6.1. The articles were published in 20 different journals (36% found in only four journals) with five of them based in Nigeria. It was observed, that international collaboration on reliability-based researches was present in 4% of the articles, and funding was reported in just 1 article. Articles having Nigerians as first authors were reported in 100% of the articles. Articles with authors affiliated to ABU, Zaria were more frequent in the sample. A list of top-cited articles is thus, presented to provide an overview of the top-cited articles. This study could aid in supporting further analyses regarding publication, citation behaviours, research funding and international collaboration of structural reliability based researches in Nigeria.