Browsing by Author "Sandjak, Khaled"

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    3D Numerical investigation of asphalt pavements behaviour using infinite elements
    (World Academy of Science, Engineering and Technology (WASET), 2017) Sandjak, Khaled; Tiliouine, Boualem
    This article presents the main results of three-dimensional numerical investigation of asphalt pavement structures behaviour using a coupled Finite Element-Mapped Infinite Element (FE-MIE) model. The validation and numerical performance of this model are assessed by confronting critical pavement responses with Burmister’s solution and FEM simulation results for multi-layered elastic structures. The coupled model is then efficiently utilised to perform (3-D) simulations of a typical asphalt pavement structure in order to investigate the impact of two tire configurations (conventional dual and new generation wide-base tires) on critical pavement response parameters. The numerical results obtained show the effectiveness and the accuracy of the coupled (FE-MIE) model. In addition, the simulation results indicate that, compared with conventional dual tire assembly, single wide base tire caused slightly greater fatigue asphalt cracking and subgrade rutting potentials and can thus be utilised in view of its potential to provide numerous mechanical, economic and environmental benefits
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    Bayesian optimization algorithm based support vector regression analysis for estimation of resilient modulus of crushed rock materials for pavement design
    (EDP Sciences, 2024) Sandjak, Khaled; Mouloud, Ouanani
    The precise determination of the resilient modulus (MR) of the base and sub-base materials is a major preoccupation and a key criterion in the flexible pavement design process. The experimental determination of MR implies a challenging process which requires usually very difficult test procedures and extreme precautions and manpower. This is why soft computing techniques are increasingly popular and of growing importance. Many prediction techniques based primarily on linear and non-linear regression could not provide flexible use and consistent prediction of MR for practical engineering. This article introduces a hybrid of the Bayesian optimization algorithm (BOA) and support vector regression (SVR) as a new modelling tool for the MR prediction of crushed stone materials used as base and sub-base layers for pavement design. For this purpose, an experimental database was utilized to generate the hybrid BOA-SVR model of indirect estimation of the resilient modulus based on material type, basic engineering characteristics and loading conditions. The database consists of 260 experimental datasets obtained from repeated loading triaxial tests performed by the laboratory of the Central Transportation Agency located in Algiers, Algeria. To develop the model, all hyperparameters were optimised using the BOA technique. It was found that the average, median, standard deviation, minimum, maximum and interquartile range of the expected values of the developed hybrid model are very close to the experimental results. Results revealed that the hybrid BOA-SVR model predict the MR of the crushed stone materials with a coefficient of determination of 99.91% and root mean squared error of 3.55. Comparisons with traditional and other Artificial intelligence models showed that BOASVR hybrid model predictions are more accurate and robust than those of other models.
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    Experimental characterisation and numerical modelling of the resilient behaviour of unbound granular materials for roads
    (Université Omar Telidji de Laghouat, 2020) Sandjak, Khaled; Ouanani, Mouloud; Ouanani, Mouloud
    This research paper deals with experimental characterisation and numerical modelling of the resilient behaviour of Unbound Granular Materials (UGMs) usually used in road construction. The first part of thispaper describes the main results of an experimental program that was carried out to assess the mechanical properties of two local Unbound Granular Materials (UGMs) for construction purposes in road pavement. The second part of this paper is devoted to thenumerical modelling of the resilient behaviour of UGMs used in flexible pavements. For this purpose, several nonlinear unbound aggregates constitutive models are implemented within an axi-symmetric finite element code developed to simulate the nonlinear behaviour of pavement structures. In addition, deflection data collected by Falling Weight Deflectometer (FWD) are incorporated into the analysis in order to assess the sensitivity of critical pavement design criteria and pavement design life to the constitutive models. Finally, conclusions of engineering significance are formulated
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    Influence of nonlinear resilient models of unbound aggregates on analysis and performance of road pavements
    (Technical University of Budapest, 2015) Tiliouine, Boualem; Sandjak, Khaled
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    Seismic modification factors for box girder bridges using a proposed pushover technique incorporating torsional vibration modes
    (Croatian Association of Civil Engineers, 2025) Aouiss, Soumia; Aouiss, Soumia; Sandjak, Khaled; Amar, Louzai
    This paper presents the results of numerical investigations on seismic modification factors (R) for algerian box girder bridges (BGBs) with both equal and unequal pier heights, using a proposed pushover technique that incorporates torsional vibration modes. In the first part, the BGB referenced in a project by the Algerian Highway National Agency is selected to evaluate the components of the R-factor in the transverse direction. Conventional pushover analysis (CPA), employing the elastic first mode, uniform, and upper-bound lateral load patterns, as well as the proposed pushover technique, is conducted. The results of CPA and the proposed pushover technique for the reference BGB are examined in terms of R-factor components, including overstrength (Ω) and global ductility (R-µ), and are compared with those obtained using the incremental dynamic analysis (IDA) technique. The findings indicate strong agreement between the proposed pushover technique and the IDA technique
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    Three-dimensional strain analysis of flexible pavement structures using infinite elements
    (Building and Housing Research Center (BHRC), 2015) Sandjak, Khaled; Tiliouine, Boualem