Avoiding Overfitting in Inverse Modeling of Chloride Migration in Concrete

Sreejith Nanukuttan, Neven Ukrainczyk, Desmond Robinson, Eduardus Koenders

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Abstract

Inverse analysis for reactive transport of chlorides through concrete in the presence of electric field is presented. The model is solved using MATLAB’s built-in solvers “pdepe.m” and “ode15s.m”. The results from the model are compared with experimental measurements from accelerated migration test and a function representing the lack of fit is formed. This function is optimised with respect to varying amount of key parameters defining the model. Levenberg-Marquardt trust-region optimisation approach is employed. The paper presents a method by which the degree of inter-dependency between parameters and sensitivity (significance) of each parameter towards model predictions can be studied on models with or without clearly defined governing equations. Eigen value analysis of the Hessian matrix was employed to investigate and avoid over-parametrisation in inverse analysis. We investigated simultaneous fitting of parameters for diffusivity, chloride binding as defined by Freundlich isotherm (thermodynamic) and binding rate (kinetic parameter). Fitting of more than 2 parameters, simultaneously, demonstrates a high degree of parameter inter-dependency. This finding is significant as mathematical models for representing chloride transport rely on several parameters for each mode of transport (i.e., diffusivity, binding, etc.), which combined may lead to unreliable simultaneous estimation of parameters.
Original languageEnglish
Title of host publicationProceedings of the International RILEM Conference on Materials, Systems and Structures in Civil Engineering 2016
Pages599-608
Number of pages10
Publication statusPublished - 22 Aug 2016
EventRilem International Conference 2016: Materials, Systems and Structures in Civil Engineering - Technical University Denmark, Lyngby, Denmark
Duration: 15 Aug 201619 Aug 2016
https://files.conferencemanager.dk/medialibrary/2A179311-431D-479F-9B86-AC05B769477E/images/Service_Life_1_conf_proceedings.pdf

Conference

ConferenceRilem International Conference 2016
Abbreviated titleMSSCE 2016
CountryDenmark
CityLyngby
Period15/08/201619/08/2016
Internet address

Keywords

  • concrete
  • Modelling
  • principal component analysis
  • Chloride transport

ASJC Scopus subject areas

  • Civil and Structural Engineering

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    Nanukuttan, S., Ukrainczyk, N., Robinson, D., & Koenders, E. (2016). Avoiding Overfitting in Inverse Modeling of Chloride Migration in Concrete. In Proceedings of the International RILEM Conference on Materials, Systems and Structures in Civil Engineering 2016 (pp. 599-608)