A two-stage method to estimate the embedded length of foundation piles using FRF-based model updating

Ioakim, A.; Prendergast, L. J.

Abstract

Dynamic soil-structure interaction (SSI) is an important field in civil engineering with applications in earthquake engineering, structural dynamics, and structural health monitoring (SHM). There is an ongoing need for the development of numerical methods that can accurately estimate SSI parameters to model these systems. In this paper, a Frequency Response Function (FRF)-based model updating method is developed that can estimate the embedded length of foundation piles, in addition to the mobilized soil mass and stiffness, when a lateral impact load is applied. Knowledge of the embedded length of piles is very important for modelling foundation behaviour, and may not be readily available from as-built construction information. For example, if developing reference damage models or digital twins of foundation structures, full knowledge of the pile geometry is required. The work in this paper develops a two-stage iterative model updating method, which utilizes FRF data obtained at the pile's head as a result of an applied lateral impact load. The method uses information from the 1st mode of vibration to estimate the mobilised soil mass and stiffness, and subsequently uses information from the 2nd mode of vibration to estimate the embedded length. To appraise the approach, impact tests are numerically simulated on a number of 'piles' (numerical spring-beam systems) with varying length/diameter (L/D) ratios to derive FRFs, whereby the models have known length and dynamic properties. These FRFs are then used as targets in the model updating approach, which iteratively varies the properties of a numerical model of a pile to obtain a match in the FRF data, and subsequently estimates the mobilised stiffness, mass, and embedded length. The results of the analyses illustrate that by minimising the difference in the first and second FRF peaks between the target and estimated FRFs, the method can accurately estimate the mass, stiffness and embedded length properties of the test 'piles'. The performance of the approach against numerical case applications is assessed in this paper, as the properties of these systems are known in advance, facilitating quantification of the errors and performance. The developed method requires further validation through full-scale testing to confirm its effectiveness in real-world scenarios.

Citation

Ioakim, A., & Prendergast, L. J. (2024). A two-stage method to estimate the embedded length of foundation piles using FRF-based model updating. Mechanical Systems and Signal Processing, 219, Article 111603. https://doi.org/10.1016/j.ymssp.2024.111603

• Journal Article Type: Article
• Acceptance Date: Jun 3, 2024
• Online Publication Date: Jun 8, 2024
• Publication Date: Oct 1, 2024
• Deposit Date: Jun 8, 2024
• Publicly Available Date: Jun 10, 2024
• Journal: Mechanical Systems and Signal Processing
• Print ISSN: 0888-3270
• Electronic ISSN: 1096-1216
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 219
• Article Number: 111603
• DOI: https://doi.org/10.1016/j.ymssp.2024.111603
• Keywords: Soil Stiffness; Model-Updating; Dynamics; Winkler; Soil-Structure Interaction; Parameter Estimation
• Public URL: https://nottingham-repository.worktribe.com/output/35803965
• Publisher URL: https://www.sciencedirect.com/science/article/pii/S0888327024005016?via%3Dihub
• Additional Information: This article is maintained by: Elsevier; Article Title: A two-stage method to estimate the embedded length of foundation piles using FRF-based model updating; Journal Title: Mechanical Systems and Signal Processing; CrossRef DOI link to publisher maintained version: https://doi.org/10.1016/j.ymssp.2024.111603; Content Type: article; Copyright: © 2024 The Author(s). Published by Elsevier Ltd.