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Dr Naftary Gathimba

Department of Civil, Construction and Environmental Engineering - Jomo Kenyatta University of Agriculture and Technology

n_gathimba@jkuat.ac.ke

Civil Engineering

Brief Information

Dr Naftary Gathimba (PhD) is a Civil/Structural Engineer/academician/researcher. Research interests: Steel structures; Concrete structures; Composite construction; Corrosion Engineering; Sustainable construction materials and technologies.

Research Projects

  • Performance of UPVC Pipe Confined Concrete Columns in Compression

    • Project   Jun 2021

    Composite columns have been used in the construction industry with great efficiency for a number of years. This is because composite column offers a superior column system as compared to the conventional column systems such as Reinforced concrete (RC), steel or timber columns. The reason is that the composite column utilizes the combined properties of different individual materials. Steel and fibre-reinforced polymer tubes have been the commonly used confining media in concrete-encased column construction. However, steel is faced with the problem of corrosion especially when used in a corrosive environment while the manufacture of fibre-reinforced polymer involves rather expensive technology. This research proposed a novel-type concrete-filled composite column where unplasticized polyvinylchloride (UPVC) plastic tube was used to confine concrete. Concrete of varying class strengths namely; C30, C25, and C20 were used to fill UPVC tubes. The tubes had outer diameters of 55 mm, 83 mm and 110 mm and thicknesses of 2.5 mm, 3.0 mm and 2.5 mm respectively. The composite columns had slenderness ratios of 2, 3 and 4. The columns were then tested on a universal testing machine (UTM) to determine their behaviour under compressive load. Applied loads, deformation and strains on the specimen were monitored through in-built load cells, Linear Variable Displacement Transducers (LVDTs) and strain gauges respectively. Results showed that UPVC pipes are effective in confining concrete, since in all cases f' cc /f' >1. Confined strength values increased between 1.18 to 3.65 times the unconfined strength values. Columns filled with low strength concrete tended to be more ductile since they underwent large deformations under load before failure. This great ductility implied more energy absorption capacity suggesting a potentially earthquake resistant composite column system. There is enormous potential for UPVC tubes for use in composite systems as illustrated by this research. The resultant is a cheap, more economical type of column for lightweight construction. The principal target audience for this project is individuals involved in the application of building materials within the construction industry. Since the use of uPVC in confining column is a relatively new area of research, limited literature was available. Long term performance of these columns was also not studied

    Dr Naftary Gathimba , Prof. W. Oyawa; Prof. G. Mang'uriu, Dr. N. Gathimba

    Department of Civil, Construction and Environmental Engineering - Jomo Kenyatta University of Agriculture and Technology



    This project is licensed under: Attribution-NonCommercial-NoDerivs licence
       
  • Static ductility of structural steel with corrosion roughness

    • Project   Jun 2021

    Corrosion is known to cause a reduction in thickness and a change in surface geometry due to differential corrosion rates on the surface of a steel member. The effects of thickness reduction on the ultimate strength of corroded steel plate members have been investigated intensively. However, until recently the effect of surface configuration on the strength and deformation capacity of the corroded members has received limited attention. Due to surface unevenness, as a result of corrosion, high-stress concentration is anticipated during load application. In evaluating the ultimate limit state of corroded steel structures, it is important to understand the post-yielding behavior of such members. One way of studying the post-yielding behavior is by evaluating the ductility. Ductility provides a measure of deformation capacity and energy dissipation from the point of yielding until the ultimate failure occurs. A number of past researches have reported a significant effect of corrosion on the ductility of corroded members. Nevertheless, an in-depth literature review shows that there is a lack of detailed research on the ductility performance of corroded steel members with regard to corrosion surface morphology. In fact, a concise model relating ductility to corrosion surface roughness is not yet available. Therefore, this study was conducted with the objective of clarifying the effect of surface configuration on the ductility of corroded steel plate members.

    Dr Naftary Gathimba ,

    Department of Civil, Construction and Environmental Engineering - Jomo Kenyatta University of Agriculture and Technology



    This project is licensed under: All rights reserved licence
       

Publications

  • Compressive strength characteristics of concrete-filled plastic tubes short columns

    • Publication   Sep 2014


    Dr Naftary Gathimba , Walter O. Oyawa, Geoffrey N. Mang'uriu

    Department of Civil, Construction and Environmental Engineering - Jomo Kenyatta University of Agriculture and Technology



    This publication is licensed under: All rights reserved licence
       
  • Innovative composite concrete-filled plastic tubes in compression

    • Publication   Aug 2015


    Dr Naftary Gathimba , Walter O. Oyawa, Geoffrey N. Mang'uriu

    Department of Civil, Construction and Environmental Engineering - Jomo Kenyatta University of Agriculture and Technology



    This publication is licensed under: All rights reserved licence
       
  • Structural response of composite concrete-filled plastic tubes in compression

    • Publication   Jun 2016


    Dr Naftary Gathimba , Walter O. Oyawa, Geoffrey N. Mang'uriu

    Department of Civil, Construction and Environmental Engineering - Jomo Kenyatta University of Agriculture and Technology



    This publication is licensed under: All rights reserved licence
       
  • Static ductility evaluation of corroded steel plates considering surface roughness characteristics

    • Publication   Aug 2018


    Dr Naftary Gathimba , Yasuo Kitane

    Department of Civil, Construction and Environmental Engineering - Jomo Kenyatta University of Agriculture and Technology



    This publication is licensed under: All rights reserved licence
       
  • Characterization of surface topography for corroded steel members exposed to marine environments

    • Publication   Nov 2018


    Dr Naftary Gathimba , Yasuo Kitane

    Department of Civil, Construction and Environmental Engineering - Jomo Kenyatta University of Agriculture and Technology



    This publication is licensed under: Attribution-NonCommercial-NoDerivs licence
       
  • Influence of surface roughness on the ductility of corroded steel: an experimental study

    • Publication   Dec 2018


    Dr Naftary Gathimba , Yasuo Kitane

    Department of Civil, Construction and Environmental Engineering - Jomo Kenyatta University of Agriculture and Technology



    This publication is licensed under: Attribution-NonCommercial-NoDerivs licence
       
  • Numerical investigation on the effect of surface roughness on the ductility of steel plates corroded in marine environments subjected to tensile loading

    • Publication   Mar 2019


    Dr Naftary Gathimba , Yasuo Kitane

    Department of Civil, Construction and Environmental Engineering - Jomo Kenyatta University of Agriculture and Technology



    This publication is licensed under: Attribution-NonCommercial-NoDerivs licence
       
  • Surface roughness characteristics of corroded steel pipe piles exposed to the marine environment

    • Publication   Apr 2019


    Dr Naftary Gathimba , Yasuo Kitane, Takeshi Yoshida, Yoshito Itoh

    Department of Civil, Construction and Environmental Engineering - Jomo Kenyatta University of Agriculture and Technology



    This publication is licensed under: All rights reserved licence
       
  • Time-dependent corrosion degradation and surface roughness characteristics and their effect on the mechanical property of structural steel

    • Publication   Nov 2019


    Dr Naftary Gathimba , Yasuo Kitane

    Department of Civil, Construction and Environmental Engineering - Jomo Kenyatta University of Agriculture and Technology



    This publication is licensed under: All rights reserved licence
       
  • Estimating remaining ductility of corroded steel based on surface roughness characteristics

    • Publication   Dec 2019


    Dr Naftary Gathimba , Yasuo Kitane

    Department of Civil, Construction and Environmental Engineering - Jomo Kenyatta University of Agriculture and Technology



    This publication is licensed under: All rights reserved licence
       
  • Effect of surface roughness on tensile ductility of artificially corroded steel plates

    • Publication   Jan 2021


    Dr Naftary Gathimba , Yasuo Kitane

    Department of Civil, Construction and Environmental Engineering - Jomo Kenyatta University of Agriculture and Technology



    This publication is licensed under: All rights reserved licence
       
  • Estimating Remaining Ductility of Corroded Steel by Using Surface Roughness Characteristics Based on Tensile Coupon Test Results

    • Publication   Jan 2021


    Dr Naftary Gathimba , Yasuo Kitane

    Department of Civil, Construction and Environmental Engineering - Jomo Kenyatta University of Agriculture and Technology



    This publication is licensed under: All rights reserved licence
       

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