TY - JOUR
T1 - A Bayesian methodology for detection of railway ballast damage using the modified Ludwik nonlinear model
AU - Adeagbo, Mujib Olamide
AU - Lam, Heung Fai
AU - Ni, Yi Qing
N1 - Funding Information:
The major components of the ballasted track may be sub-divided into two: the superstructure consisting of the rails, rail-pads, rail fastenings, and sleeper/tie; and the substructure consisting of the ballast, sub-ballast, and subgrade. Vehicle loads are directly transferred from the rails to the sleepers, which are supported by the sub-structure. For ballasted tracks built on reinforced concrete structures (like the track considered in this study), the substructure is essentially the ballast situated on a rigid support.
Publisher Copyright:
© 2021 Elsevier Ltd
PY - 2021/6/1
Y1 - 2021/6/1
N2 - In this paper, an improved nonlinear model of railway ballast is proposed based on the modified Ludwik model. The accuracy of model-based structural damage detection relies on the correct representation of the mechanical behavior of the system, hence the need for incorporating nonlinearity into track models. The modified form of the Ludwik model is proposed for describing the stress–strain relationship of the ballast layer during its loading and unloading. In this study, a section of ballasted track across a single sleeper is modeled using the beam on elastic foundation theory. In the finite element model of the track system, the concrete sleeper and the underlaying ballast are modeled by Timoshenko beam elements and a series of nonlinear springs, respectively. The elastoplasticity of these springs during the vertical vibration of the track system can be effectively captured using the proposed model, which can be easily integrated into the Bayesian statistical framework. For correct identification of the scaling factors of the system properties, as well as quantification of the inherent uncertainties, a time-domain Markov chain Monte Carlo-based Bayesian model updating method with a novel stopping criteria is developed. The efficacy of the proposed methodology is demonstrated using in-situ measurements obtained during impact hammer tests on an indoor full-scale track segment under laboratory conditions, with artificially simulated ballast damage. A series of impact hammer tests are carried out to study the effects of impact locations and sensor sparsity on the performance of the proposed methodology. The methodology exhibits very high accuracy in identifying the simulated ballast damage under the target sleeper, even with different impact and sensor configurations.
AB - In this paper, an improved nonlinear model of railway ballast is proposed based on the modified Ludwik model. The accuracy of model-based structural damage detection relies on the correct representation of the mechanical behavior of the system, hence the need for incorporating nonlinearity into track models. The modified form of the Ludwik model is proposed for describing the stress–strain relationship of the ballast layer during its loading and unloading. In this study, a section of ballasted track across a single sleeper is modeled using the beam on elastic foundation theory. In the finite element model of the track system, the concrete sleeper and the underlaying ballast are modeled by Timoshenko beam elements and a series of nonlinear springs, respectively. The elastoplasticity of these springs during the vertical vibration of the track system can be effectively captured using the proposed model, which can be easily integrated into the Bayesian statistical framework. For correct identification of the scaling factors of the system properties, as well as quantification of the inherent uncertainties, a time-domain Markov chain Monte Carlo-based Bayesian model updating method with a novel stopping criteria is developed. The efficacy of the proposed methodology is demonstrated using in-situ measurements obtained during impact hammer tests on an indoor full-scale track segment under laboratory conditions, with artificially simulated ballast damage. A series of impact hammer tests are carried out to study the effects of impact locations and sensor sparsity on the performance of the proposed methodology. The methodology exhibits very high accuracy in identifying the simulated ballast damage under the target sleeper, even with different impact and sensor configurations.
KW - Damage detection
KW - Markov chain Monte Carlo
KW - Nonlinear vibration
KW - Railway ballast
KW - Time domain
UR - http://www.scopus.com/inward/record.url?scp=85106326400&partnerID=8YFLogxK
U2 - 10.1016/j.engstruct.2021.112047
DO - 10.1016/j.engstruct.2021.112047
M3 - Journal article
AN - SCOPUS:85106326400
VL - 236
JO - Structural Engineering Review
JF - Structural Engineering Review
SN - 0141-0296
M1 - 112047
ER -