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Item Structural Assessment of a Lattice Tower in Federal Capital Territory, Abuja(Nigeria Journal of Engineering and Applied Sciences (NJEAS), 2022-01-02) Auta, S. M.; Okunyomi, O. O.; Kolo, D. N.Since the licensing of GSM operators in Nigeria from 2001, there was an astronomical increase in construction and maintenance towers. In a bid to reduce maintenance cost, tower sharing was adopted by some telecommunication providers. The Nigerian Communications Commission guidelines for installation of masts and towers stipulates that all lattice towers should be checked for their structural health status every five years. This requirement has promoted this research work. The objective of the study includes selection of a lattice with weakest parameters, determine the tower’s structural stability and its utilization percentage. A 45m tower with 3-legs erected over 8 years and shared by three telecommunication operators in the Federal Capital Territory (FCT) was selected. Audit was conducted on the tower and its foundation. There were no warped member and no visible crack on the tower foundation. The average compressive strength of the stub columns determined using the digital Schmidt hammer were 25.1, 25.9 and 25.9 N/mm2 for legs A, B and C. From the structural analysis using the EPA model, the tower utilization percentage was found to be at 59.4% after optimization. The STAAD pro. V8i analysis showed that the utilization ratio of the tower members is ≤ 1. Furthermore, design properties for the tower members are less than the properties of the actual tower members used and there was no failed member identified after the structural analysis. In conclusion, the lattice tower can be said to be stable and fit for continuous use.Item Partial Replacement of Fine Aggregate with waste Glass in Concrete made from Bida Natural Aggregate(. Proceedings of the 3rd International Engineering Conference, Federal University of Technology Minna, Nigeria, 2019-02-05) Alhaji, B.; Kolo, D. N.; Abubakar M.; Yusuf A.; Abdullahi, A.; Shehu, M.This study reports the experimental investigation on the suitability of waste glass as partial replacement for fine aggregate in concrete made using Bida natural aggregates (BNA). Glass is widely used in our daily lives through manufactured products such as sheet glass, bottles, glassware, and vacuum tubing. It is an ideal material for recycling. The increasing awareness of glass recycling speeds up inspections on the use of waste glass with different forms in various fields. Mix ratio of 1:2:4 batched by weight with water cement ratio of 0.55 was used. The percentage replacement varied from 0% to 40% at 5% intervals. Slump test was conducted to assess the workability of the fresh concrete. The compressive strengths and densities of cured concrete cubes of sizes 150mm x 150mm x 150mm were evaluated at 7, 21 and 28days. A total of 81 concrete cubes were cast and tested. It was observed that an increase in the percentage replacement of fine aggregate with waste glass reduces workability, density and compressive strength. The compressive strength and density vary with days of curing. The findings of this study indicated that the optimum replacement percentage of waste glass with conventional fine aggregate was 20%. However waste glass can effectively be used as fine aggregate replacement (up to 40%) without substantial change in concrete strength.Item 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.Item Structural Reliability Studies on Pulverized Glass Powder Concrete Subjected to Bending Forces with Natural Aggregate(Ethiopian International Journal of Engineering and Technology (EIJET), 2024-02-01) Kolo, D. N.; Aguwa, J. I.; Hadi, A. M.; Shehu, M.; Ashraf, M.L.M.The shortage of housing and basic infrastructure in Nigeria is increasing with a continuous rise in the price of construction materials. Cement is a major component in concrete production. Its production, however, is accompanied by huge carbon dioxide emissions. This research presents the results of structural reliability analysis conducted on reinforced concrete beam produced with pulverized glass powder as partial replacement for cement with Natural aggregate (NA) as coarse aggregate by subjecting it to bending forces. First order reliability method (FORM) was employed to determine the level of safety of the beam. The result of the sensitivity analysis showed that the pulverized glass powder beam with NA as coarse aggregate is structurally safe at a span of 3000 mm and depth of 600 mm with probabilities of failure of 1.00 × 10-3 and 1.04 × 10-3 respectively.Item Reliability Assessment of Natural Aggregate Pulverized Glass Powder Concrete Beam Subjected to Shearing Forces(Journal of Computational Engineering and Physical Modeling, 2023-01-02) Kolo, D. N.; Kolo, S. S.; Abdulazeez, M. H.Cement is the most expensive ingredient in the process of making concrete. Reducing the quantity of cement used in the production of concrete with Pulverized glass powder (PGP) will reduce the cost of concrete production and help tackle environmental, disposal and CO2 emission challenges. The results of structural reliability assessment performed on Pulverized glass powder concrete produced using locally sourced Natural aggregate (NA) as coarse aggregate. Concrete cubes measuring 150 × 150 ×150 mm were cast, cured for 28 days and tested using the universal compressive testing machine. First order reliability method (FORM) was employed to determine the level of safety of the reinforced concrete beam. Result of sensitivity analysis under shearing forces shows the beam is structurally safe at a span of 3250 mm with Probability of failure (Pf) of 1.14 × 10-3 , Effective depth of 459 mm and corresponding Probability of failure (Pf) of 5.77 × 10-8 and an Area of Shear reinforcement (Asv) of 201 mm2 with Probability of failure (Pf) of 5.01 × 10-5 .Item Probability-Based Calibration of Load Duration Modification Factors for the Nigerian Grown Timber(2023-01-02) Aguwa, J. I.; Sadiku, S.; Afolayan, J. O.; Aliyu, A.; Abubakar, M.; Kolo, D. N.All along, load duration modification factors used in Nigeria for design of timber structures were based on BS 5268 of 2002 and this is not a good engineering practice since the strength of timber depends so much on the soil as well as on the environment. There is the need to localize the modification factors based on our environment since Nigerian grown timber is generally used for all timber structures designed and built in Nigeria. Probability-based calibration of load duration modification factors for the Nigerian grown timber was successfully carried out. The results showed significant difference between the calibrated factors and those from BS 5268 of 2002. The calibrated modification factors are; 1.25 for long-term, 1.35 for medium-term, 1.70 for short term, and 2.0 for very short-term duration. This paper recommends the use of these calibrated load duration factors based on Nigerian grown environment.Item A Comparative Analysis of Grillage method and Beam line analysis of a reinforced concrete waffle bridge deck(Nigeria Journal of Engineering and Applied Sciences (NJEAS), 2022-01-12) 8. Adamu, H. N.; Abbass, B. A.; Abubakar, M.; Yusuf, A.; Kolo, D. N.; Shehu, M.The analysis of reinforced concrete waffle bridge deck using chanchaga bridge as a case study was carried out with the aid of computer program written in MATLAB. The bridge deck which is a beam bridge was idealized to be a waffle slab. A mathematical model of the bridge was developed using the method of grillages because very complex shapes of problem domain with prescribed conditions can be handled easily using the method. The bridge deck was modelled as interconnection of grid elements. The analysis was carried out using direct stiffness matrix method. The nodal displacements and the resulting static internal forces; shear forces, bending moments and twisting moments of each grid element were determined using the matrix. The results obtained using the method of grillages were then compared with beam line analysis and the former method gave a 10% decrease in forces which will result in the reduction of overall design and materials by 10%.Item Development of Statistical Models to predict the compressive strength of concrete produced using Quarry dust as partial replacement of fine aggregate(LAUTECH Journal of Civil and Environmental Studies, 2022-01-12) Kolo, D. N.; Enwongulu, J. O.Concrete is an assemblage of Cement, aggregates and water. The most frequently used fine aggregate for concrete production is sand sourced from river banks. The continuous use of this river sand as a result of rapid infrastructural development has resulted in its scarcity and often high cost. This paper examines the suitability of using quarry dust (QD) as partial replacement for fine aggregate in concrete production. Preliminary test (specific gravity) was conducted on the aggregates to determine their suitability for concrete production. Concrete with 5, 10, 15, 20 and 25% QD – Fine aggregate content was cast with a mix ratio of 1:2:4. The freshly prepared Quarry Dust Concrete (QDC) was cast in moulds measuring 150 x 150 x 150mm and cured using ponding method. The Compressive strength result shows that replacement of fine aggregate with QD leads to a general increase in compressive strength of concrete. Statistical package for the Social Sciences (SPSS) version 21 was utilised to develop the linear regression models for the 7 and 28 days compressive strength of the QDC. The developed models were found to be sufficient in predicting the 7 and 28 days compressive strengths with R2 values of 98.9% and 95.2 % respectively.Item Durability Characteristics of Lateritic Subgrade Treated with Iron Ore Tailings and Lime Exposed to Moisture Fluctuations(. Nigeria Journal of Engineering and Applied Sciences (NJEAS), 2018-02-11) Mohammed, A. M.; Amadi, A. A.; Aguwa, J. I.; Kolo, D. N.This research evaluated the durability of lateritic subgrade treated with Iron Ore Tailings (IOT) and lime exposed to moisture variations. Representative sample of the subgrade was treated with 0, 5, 10, 15, and 20% IOT and optimal lime percent (6.2%) determined through Eades and Grim pH test. Preliminary tests such as particles size distribution, Atterberg limits and compaction were conducted to characterize the mixtures while Unconfined Compressive Strength (UCS) and CBR-swell tests were carried out to access durability of the soil mixtures. Addition of lime to the soil increased the liquid limit to 45% from 36% obtained in natural soil. Similarly, the plastic limit of the lime-treated sample increased from 16 to 26% with reduced plasticity index. While the natural soil exhibited CBR of 3 and 75% for soaked and unsoaked specimens respectively, the value increased and peaked at 11 and 118% with addition of lime and 15% IOT. Durability of the soil improved with addition of IOT and lime. 15% IOT and lime treated soil recorded the best results with UCS of 240 kN/m2 and 200% Relative Volumetric Stability (RVS), which is a measure of strength loss of a soil. Similarly, swell value of 0% was recorded when the lime-IOT samples were subjected to CBR-Swell test. This shows that the lime-IOT treated samples are less vulnerable to moisture condition normally prevalent in the pavement subgrades.Item Development of Sensitivity based Model for Flexural Failure of Singly Reinforced Concrete Slabs Based on BS 8110: 1997(. Nigeria Journal of Engineering and Applied Sciences (NJEAS), 2017-03-22) Tsado, T.Y.,; Sadiku, S.,; Iorkar, A.; Kolo, D. N.This research presents mathematical models for checking the effect of variation in key designed parameters on the structural collapse of singly reinforced concrete solid slabs in buildings due to flexural failure based on British Standard (BS) 8110, 1997. The increasing complexity of construction process requires very high level of engineering and management skills to combat the structural collapses widely experienced globally. Most of the collapses were adjudged to be due to improper management arising from variations in structural key design parameters during construction, and this call for mathematical models to check the effect of variation in key design parameters on the structural collapse. The key design parameters considered in this research are; characteristic strength of reinforcement, grade of concrete, diameter and spacing of tension reinforcement, effective depth of tension reinforcement, applied moment. Sensitivity analysis was applied to study the effect of variation in the key parameters on the moment capacity. The results of sensitivity analysis were utilized in regression analysis to develop simplified equations for estimating the moment capacity of the slab. Computer programme was developed based on BS 8110, 1997 standard using Java to verify the model. Flexure safety factor was also checked based on BS 8110, 1997 requirements. Forty five numerical examples were taken to validate the model with the developed computer programme at 5% significance level using Chi-squared as an instrument for sensitivity-based model for flexural failure of singly reinforced concrete slab. The results show that the model is adequate at 5% significance level for checking flexural failure of singly reinforced concrete slab at construction stage based on BS 8110, 1997. It was recommended that the construction practitioners should consider the diverse effect of change in key deigned parameters during construction, otherwise the developed model should be strictly considered for quick safety check especially deflection safety of a solid slab during construction.