Browsing by Author "MacLeod, Ethan"

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    Dynamic bridge weigh in motion using hybrid sensor data
    (University of New Brunswick, 2023-05) MacLeod, Ethan; Arjomandi, Kaveh
    Bridge Weigh In Motion (BWIM) methods estimate the weights of vehicles at full highway speeds by using an instrumented bridge as a scale. In this thesis, current deficiencies of traditional BWIM methods are addressed with a novel BWIM approach that considers the dynamic response of the bridge through the inclusion of hybrid sensor data consisting of acceleration and strain into both the vehicle identification and weighing algorithms. The details of the development and implementation of the experimental long-term monitoring of the case study bridge is presented which covers the selection and preliminary analysis of the structure, instrumentation system design, system installation, as well as programing and data management. Current vehicle identification methods are limited to short-span bridges. To address this a novel acceleration-based vehicle identification method is employed within a hybrid bridge-weight-in-motion (BWIM) system in which the traditional strain based BWIM system is augmented with an array of accelerometers. The accuracy of the proposed vehicle identification method was studied in detail using an extensive set of field study data. From this study, it was found that the proposed hybrid system resulted in more accurate velocity estimation, axle identification, and ultimately better GVW estimation. Previous research shows the accurate simulation of vehicle-bridge systems is not feasible using beam models due to oversimplistic assumptions while complex closed-form analytical solutions and FE models can prove impractical being computationally expensive and cumbersome to develop. To address these limitations, a novel analytical vehicle-bridge simulation method is developed which utilizes the experimentally estimated modal parameters of a bridge structure that is valid for any generalized structural system and boundary conditions. Dynamic vehicle bridge interaction is the largest source of error in current commonly employed static BWIM methods. To address these errors, the proposed vehicle bridge simulation method is extended to a novel dynamic parametric BWIM method that utilizes the experimentally estimated modal parameters of the structure to simulate the response of a three-dimensional bridge structure to a moving load. The implementation of these proposed methods are discussed and validated through a full-scale case study of an arterial highway bridge in the province of New Brunswick, Canada.
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    Enhanced methods of operational modal analysis
    (University of New Brunswick, 2018) MacLeod, Ethan; Arjomandi, Kaveh
    In this thesis practical considerations for Operational Modal Analysis (OMA) are discussed and two new methods of analysis are proposed. First, it is shown that although natural frequencies may be accurately estimated, the estimated mode shapes when the input excitation is other than Gaussian white noise contain significant errors, and in most cases, accurate estimation is not feasible. A modal filter system is proposed which implements a nonlinear optimization algorithm to perform OMA on a system subjected to input excitations other than Gaussian white noise. The proposed method is validated using numerical parametric studies on a 4 DOF analytical system subjected to a generalized broadband excitation. Lastly, the application of automated OMA as a solution for practical Structural Health Monitoring is discussed and a novel scale space based frequency domain automated OMA method is proposed. The method is successfully validated with a 4 DOF analytical system and a comparative study is performed using vibration test data from a scale cable stayed bridge model.