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M. B. Anoop - One of the best experts on this subject based on the ideXlab platform.

  • durability based Service Life Design of rc structures chloride induced corrosion
    2020
    Co-Authors: N. J. Yogalakshmi, Balaji K Rao, M. B. Anoop
    Abstract:

    In this present study, chloride ion diffusion into cover concrete is modelled as a sub-diffusion process. A time-fractional partial differential equation is used to describe the sub-diffusion process and the numerical solution of this equation is obtained using explicit finite difference scheme. The parameters \(C_{\text{s}}\), \(\alpha\) and \(D_{\alpha }\) involved in the solution are estimated by data fitting performed using genetic algorithm-based optimization technique in MATLAB. This study is carried out for predicting the chloride profiles of OPC concrete that are available in the literature, exposed to marine environment for a long time. The collected profiles correspond to both laboratory samples exposed to field exposure and sample drawn from a real existing structure. The initiation time of corrosion is then determined numerically by finding the time at which chloride concentration at rebar reaches the critical chloride concentration. The results of the sub-diffusion model are also compared with fib model, whose parameters are also fitted using optimization technique. Based on field observations reported in the literature, it is found that the initiation times of corrosion predicted by sub-diffusion model are less conservative and more realistic compared to the predictions of fib model.

  • Durability-Based Service Life Design of RC Structures—Chloride-Induced Corrosion
    Reliability Safety and Hazard Assessment for Risk-Based Technologies, 2019
    Co-Authors: N. J. Yogalakshmi, K. Balaji Rao, M. B. Anoop
    Abstract:

    In this present study, chloride ion diffusion into cover concrete is modelled as a sub-diffusion process. A time-fractional partial differential equation is used to describe the sub-diffusion process and the numerical solution of this equation is obtained using explicit finite difference scheme. The parameters \(C_{\text{s}}\), \(\alpha\) and \(D_{\alpha }\) involved in the solution are estimated by data fitting performed using genetic algorithm-based optimization technique in MATLAB. This study is carried out for predicting the chloride profiles of OPC concrete that are available in the literature, exposed to marine environment for a long time. The collected profiles correspond to both laboratory samples exposed to field exposure and sample drawn from a real existing structure. The initiation time of corrosion is then determined numerically by finding the time at which chloride concentration at rebar reaches the critical chloride concentration. The results of the sub-diffusion model are also compared with fib model, whose parameters are also fitted using optimization technique. Based on field observations reported in the literature, it is found that the initiation times of corrosion predicted by sub-diffusion model are less conservative and more realistic compared to the predictions of fib model.

  • Stochastic Analysis of Flexural Strength of RC Beams Subjected to Chloride Induced Corrosion
    Materials Research, 2015
    Co-Authors: Parammal Vatteri Ahsana, Kanchi Balaji Rao, M. B. Anoop
    Abstract:

    Importance of consideration of chloride induced corrosion in Service Life Design of reinforced concrete (RC) structures situated in marine environment is well known. This paper attempts to provide, within the framework of Monte Carlo Simulation, methodologies for durability based Service Life Design of RC members. A methodology using fragility curves is proposed to assist in the Service Life Design of freely degrading RC flexural beams. For maintained RC beams, a methodology is developed, that incorporates the concepts of virtual aging, failure rate approach and time-variant reliability analysis. By addressing maintenance at the Design stage itself, the methodology developed would help in sustainability based Service Life Design. The use of both the methodologies is demonstrated by considering an example of T-beam. From the results of the example problem considered, it has been found that corrosion initiation time would govern the Service Life. 30% replacement of cement with pulverized fuel ash is considered as a sustainable alternative for construction of durable structures satisfying the Service Life performance targets with lesser number of repairs.

  • A Refined Methodology for Durability‐Based Service Life Estimation of Reinforced Concrete Structural Elements Considering Fuzzy and Random Uncertainties
    Computer-Aided Civil and Infrastructure Engineering, 2011
    Co-Authors: M. B. Anoop, B. K. Raghuprasad, K. Balaji Rao
    Abstract:

    A reliable method for Service Life estimation of the structural element is a prerequisite for Service Life Design. A new methodology for durability-based Service Life estimation of reinforced concrete flexural elements with respect to chloride-induced corrosion of reinforcement is proposed. The methodology takes into consideration the fuzzy and random uncertainties associated with the variables involved in Service Life estimation by using a hybrid method combining the vertex method of fuzzy set theory with Monte Carlo simulation technique. It is also shown how to determine the bounds for characteristic value of failure probability from the resulting fuzzy set for failure probability with minimal computational effort. Using the methodology, the bounds for the characteristic value of failure probability for a reinforced concrete T-beam bridge girder has been determined. The Service Life of the structural element is determined by comparing the upper bound of characteristic value of failure probability with the target failure probability. The methodology will be useful for durability-based Service Life Design and also for making decisions regarding in-Service inspections.

  • A METHODOLOGY FOR DURABILITY-BASED Service Life Design OF REINFORCED CONCRETE FLEXURAL MEMBERS
    Magazine of Concrete Research, 2003
    Co-Authors: M. B. Anoop, K. Balaji Rao, T. V. S. R. Appa Rao
    Abstract:

    This paper proposes a methodology for durability-based Service Life Design of reinforced concrete (RC) flexural members that ensures acceptable performance under Service loads. The performance measures considered are safety (or collapse) and Serviceability (or cracking) of the RC member with respect to chloride-induced corrosion of reinforcement. In the proposed methodology, the uncertainties arising due to the use of linguistic terms for describing the exposure conditions and quality of construction are taken into account by considering the time for corrosion initiation and the variables affecting the rate of corrosion as fuzzy variables. The efficacy of the proposed methodology in predicting the corrosion damage to the structural members is demonstrated through a practical case study. An example is provided to illustrate usefulness of the proposed methodology in making Design decisions.

Arul Arulrajah - One of the best experts on this subject based on the ideXlab platform.

  • Durability against Wetting–Drying Cycles of Water Treatment Sludge–Fly Ash Geopolymer and Water Treatment Sludge–Cement and Silty Clay–Cement Systems
    Journal of Materials in Civil Engineering, 2016
    Co-Authors: Suksun Horpibulsuk, Wisanukhorn Samingthong, Runglawan Rachan, Cherdsak Suksiripattanapong, Arul Arulrajah
    Abstract:

    AbstractThe viability of using two waste materials, water treatment sludge (WTS) and fly ash (FA), for developing sustainable masonry units has been previously investigated in terms of strength but the important aspect of durability against wetting–drying (w–d) cycles has yet to be studied. A study on durability against w–d cycles, an important parameter for Service Life Design of the sustainable masonry units, is investigated in this paper. The liquid alkaline activator (L) was a mixture of sodium silicate (Na2SiO3) and sodium hydroxide (NaOH), and a high calcium fly ash (FA) was used as a precursor. The results of cyclic w–d test indicate that the WTS–FA geopolymer manufactured with an optimum ingredient (L:FA=1.6, Na2SiO3:NaOH=90∶10) and at an optimum heat condition of 85°C for 72 h can be used as durable bearing masonry units; i.e., the compressive strength is greater than 12 MPa after 12 w–d cycles. For this optimum ingredient, the w–d cycle strength, qu(w−d) at heat temperatures between 65 and 95°C ...

  • Durability against wetting-drying cycles of sustainable Lightweight Cellular Cemented construction material comprising clay and fly ash wastes
    Construction and Building Materials, 2015
    Co-Authors: Anek Neramitkornburi, Suksun Horpibulsuk, Arul Arulrajah, Shui-long Shen, Avirut Chinkulkijniwat, M. Disfani
    Abstract:

    The viability of using waste materials such as clay and fly ash (FA) for developing a sustainable Lightweight Cellular Cemented (LCC) construction material is investigated in this paper. LCC clay has a wide range of applications in infrastructure rehabilitation as well as in the construction of new facilities. The durability against wetting–drying (w–d) cycles is an important parameter for Service Life Design of LCC clay; however, studies on this aspect to date are very limited. The role of cemented soil structure (fabric and cementation bond) on w–d cycle strength of LCC clay are investigated, analyzed and presented in this paper. The strength reduction with increasing number of w–d is attributed to degradation of the cemented structure. The degradation index, qualifying the rate of degradation with number of w–d cycles, is proposed in term of initial soaked strength (without w–d cycle). Using the degradation index, the predictive w–d cycle strength equation at different number of w–d cycles is furthermore proposed. The applicability of the proposed equation is validated using a separate test data. This approach of predicting w–d cycle strength is beneficial from both engineering and economic points of view.

Suksun Horpibulsuk - One of the best experts on this subject based on the ideXlab platform.

  • Durability against Wetting–Drying Cycles of Water Treatment Sludge–Fly Ash Geopolymer and Water Treatment Sludge–Cement and Silty Clay–Cement Systems
    Journal of Materials in Civil Engineering, 2016
    Co-Authors: Suksun Horpibulsuk, Wisanukhorn Samingthong, Runglawan Rachan, Cherdsak Suksiripattanapong, Arul Arulrajah
    Abstract:

    AbstractThe viability of using two waste materials, water treatment sludge (WTS) and fly ash (FA), for developing sustainable masonry units has been previously investigated in terms of strength but the important aspect of durability against wetting–drying (w–d) cycles has yet to be studied. A study on durability against w–d cycles, an important parameter for Service Life Design of the sustainable masonry units, is investigated in this paper. The liquid alkaline activator (L) was a mixture of sodium silicate (Na2SiO3) and sodium hydroxide (NaOH), and a high calcium fly ash (FA) was used as a precursor. The results of cyclic w–d test indicate that the WTS–FA geopolymer manufactured with an optimum ingredient (L:FA=1.6, Na2SiO3:NaOH=90∶10) and at an optimum heat condition of 85°C for 72 h can be used as durable bearing masonry units; i.e., the compressive strength is greater than 12 MPa after 12 w–d cycles. For this optimum ingredient, the w–d cycle strength, qu(w−d) at heat temperatures between 65 and 95°C ...

  • Durability against wetting-drying cycles of sustainable Lightweight Cellular Cemented construction material comprising clay and fly ash wastes
    Construction and Building Materials, 2015
    Co-Authors: Anek Neramitkornburi, Suksun Horpibulsuk, Arul Arulrajah, Shui-long Shen, Avirut Chinkulkijniwat, M. Disfani
    Abstract:

    The viability of using waste materials such as clay and fly ash (FA) for developing a sustainable Lightweight Cellular Cemented (LCC) construction material is investigated in this paper. LCC clay has a wide range of applications in infrastructure rehabilitation as well as in the construction of new facilities. The durability against wetting–drying (w–d) cycles is an important parameter for Service Life Design of LCC clay; however, studies on this aspect to date are very limited. The role of cemented soil structure (fabric and cementation bond) on w–d cycle strength of LCC clay are investigated, analyzed and presented in this paper. The strength reduction with increasing number of w–d is attributed to degradation of the cemented structure. The degradation index, qualifying the rate of degradation with number of w–d cycles, is proposed in term of initial soaked strength (without w–d cycle). Using the degradation index, the predictive w–d cycle strength equation at different number of w–d cycles is furthermore proposed. The applicability of the proposed equation is validated using a separate test data. This approach of predicting w–d cycle strength is beneficial from both engineering and economic points of view.

K. Balaji Rao - One of the best experts on this subject based on the ideXlab platform.

  • Durability-Based Service Life Design of RC Structures—Chloride-Induced Corrosion
    Reliability Safety and Hazard Assessment for Risk-Based Technologies, 2019
    Co-Authors: N. J. Yogalakshmi, K. Balaji Rao, M. B. Anoop
    Abstract:

    In this present study, chloride ion diffusion into cover concrete is modelled as a sub-diffusion process. A time-fractional partial differential equation is used to describe the sub-diffusion process and the numerical solution of this equation is obtained using explicit finite difference scheme. The parameters \(C_{\text{s}}\), \(\alpha\) and \(D_{\alpha }\) involved in the solution are estimated by data fitting performed using genetic algorithm-based optimization technique in MATLAB. This study is carried out for predicting the chloride profiles of OPC concrete that are available in the literature, exposed to marine environment for a long time. The collected profiles correspond to both laboratory samples exposed to field exposure and sample drawn from a real existing structure. The initiation time of corrosion is then determined numerically by finding the time at which chloride concentration at rebar reaches the critical chloride concentration. The results of the sub-diffusion model are also compared with fib model, whose parameters are also fitted using optimization technique. Based on field observations reported in the literature, it is found that the initiation times of corrosion predicted by sub-diffusion model are less conservative and more realistic compared to the predictions of fib model.

  • A Refined Methodology for Durability‐Based Service Life Estimation of Reinforced Concrete Structural Elements Considering Fuzzy and Random Uncertainties
    Computer-Aided Civil and Infrastructure Engineering, 2011
    Co-Authors: M. B. Anoop, B. K. Raghuprasad, K. Balaji Rao
    Abstract:

    A reliable method for Service Life estimation of the structural element is a prerequisite for Service Life Design. A new methodology for durability-based Service Life estimation of reinforced concrete flexural elements with respect to chloride-induced corrosion of reinforcement is proposed. The methodology takes into consideration the fuzzy and random uncertainties associated with the variables involved in Service Life estimation by using a hybrid method combining the vertex method of fuzzy set theory with Monte Carlo simulation technique. It is also shown how to determine the bounds for characteristic value of failure probability from the resulting fuzzy set for failure probability with minimal computational effort. Using the methodology, the bounds for the characteristic value of failure probability for a reinforced concrete T-beam bridge girder has been determined. The Service Life of the structural element is determined by comparing the upper bound of characteristic value of failure probability with the target failure probability. The methodology will be useful for durability-based Service Life Design and also for making decisions regarding in-Service inspections.

  • A METHODOLOGY FOR DURABILITY-BASED Service Life Design OF REINFORCED CONCRETE FLEXURAL MEMBERS
    Magazine of Concrete Research, 2003
    Co-Authors: M. B. Anoop, K. Balaji Rao, T. V. S. R. Appa Rao
    Abstract:

    This paper proposes a methodology for durability-based Service Life Design of reinforced concrete (RC) flexural members that ensures acceptable performance under Service loads. The performance measures considered are safety (or collapse) and Serviceability (or cracking) of the RC member with respect to chloride-induced corrosion of reinforcement. In the proposed methodology, the uncertainties arising due to the use of linguistic terms for describing the exposure conditions and quality of construction are taken into account by considering the time for corrosion initiation and the variables affecting the rate of corrosion as fuzzy variables. The efficacy of the proposed methodology in predicting the corrosion damage to the structural members is demonstrated through a practical case study. An example is provided to illustrate usefulness of the proposed methodology in making Design decisions.

M. Disfani - One of the best experts on this subject based on the ideXlab platform.

  • Durability against wetting-drying cycles of sustainable Lightweight Cellular Cemented construction material comprising clay and fly ash wastes
    Construction and Building Materials, 2015
    Co-Authors: Anek Neramitkornburi, Suksun Horpibulsuk, Arul Arulrajah, Shui-long Shen, Avirut Chinkulkijniwat, M. Disfani
    Abstract:

    The viability of using waste materials such as clay and fly ash (FA) for developing a sustainable Lightweight Cellular Cemented (LCC) construction material is investigated in this paper. LCC clay has a wide range of applications in infrastructure rehabilitation as well as in the construction of new facilities. The durability against wetting–drying (w–d) cycles is an important parameter for Service Life Design of LCC clay; however, studies on this aspect to date are very limited. The role of cemented soil structure (fabric and cementation bond) on w–d cycle strength of LCC clay are investigated, analyzed and presented in this paper. The strength reduction with increasing number of w–d is attributed to degradation of the cemented structure. The degradation index, qualifying the rate of degradation with number of w–d cycles, is proposed in term of initial soaked strength (without w–d cycle). Using the degradation index, the predictive w–d cycle strength equation at different number of w–d cycles is furthermore proposed. The applicability of the proposed equation is validated using a separate test data. This approach of predicting w–d cycle strength is beneficial from both engineering and economic points of view.