Browsing by Author "Auta, S. M."

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    Effect Of Water Cement Ratio On The Compressive Strength Of Revibrated Concrete
    (Environmental Technology and Science Journal, 2015) Auta, S. M.; Abubakar, Mahmud; Yusuf, A.
    Effect of water cement-ratio on compressive strength of re-vibrated concrete is presented. The mix proportion of 1:2:4 aggregates were considered to cast 39 cubes each as laboratory specimen with 0.65, 0.70 and 0.75 water-cement ratios. Each of these categories were revibrated at time lag intervals of 10minutes for 120 minutes period of revibration process and cured for 7, 21 and 28 days. When tested for their respective compressive strength, the result obtained shows that there is a gradual increase in compressive strength of the concrete specimen with increase in time and in water-cement ratio. The maximum compressive strength at 120th minute for ages of 28 days are 25.42, 26.67 and 40.44N/mm2 for concrete with water-cement ratio of 0.65, 0.70 and 0.75 respectively. The maximum attained compressive strength for 28 days curing is 40.44N/mm2 (for 0.75w/c) appears to be higher than 25.42N/mm2 (for 0.65 w/c). Water-cement ratio has adversely enhanced the compressive strength of concrete when re-vibrated.
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    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.