PSI - Issue 70

Anil Pradeep Konda et al. / Procedia Structural Integrity 70 (2025) 153–160

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focuses on identifying, localising, and quantifying the damage by applying an established damage detection method through FE simulations. 2. Background Structural Health Monitoring (SHM) is a proven way to safeguard and extend the service life of civil infrastructure. SHM detects damage early, allowing timely and well-informed repair and rehabilitation decisions for civil infrastructure. Over time, researchers have introduced a range of damage detection techniques that fall within the broader SHM framework. These methods have advanced to the point where they can not only detect and locate damage but also quantify its severity with sufficient accuracy. For flexure-dominant members, a promising damage detection method developed by Le et al., (2019) provides a sound theoretical foundation. It demonstrates applicability across various support conditions for identifying, locating, and quantifying damage. In this context, the damage detection method developed by Le et al., (2019) was adopted for the damage assessment analysis. The method quantifies damage using a damage severity derivative (β), derived from changes in member stiffness (α) in a flexure member, as observed through the deflection change of a damaged beam. For this pu rpose, they applied a unit load at the centre of a determinate beam. They provided the respective coefficients for scenarios with damage located to the left, at the beam's centre, and on the right. To simplify damage quantification, they eliminated the need for a stiffness factor by introducing the Relative Deflection Change (RDC), defined as the ratio of Deflection Change (DC) to the undamaged deflection. Furthermore, since measurement noise is inevitable in practical scenarios, the damage severity consistency (DSC) metric was introduced to address this challenge. The DSC is the ratio of the Relative Deflection Change (RDC) to RDC 50% , where RDC 50% corresponds to the RDC at a 50% reduction in the structural member's stiffness (i.e., when α equals 50%). The damage severity derivative (β) can be calculated by taking the average of the DSC values obtained at each finite element (FE) beam model node. Finally, onc e β is determined, the element damage severity (α) can be quantified using the relationship: α=β/(1+β) . This method demonstrates remarkable versatility, as it quantifies damage using static deflections and can be adapted to various boundary conditions by adjusting the RDC 50% parameter. This adaptability establishes it as one of the most robust and reliable approaches for damage detection. 3. Finite Element Model Validation Due to available resources and specialised equipment constraints, physical testing of castellated girders can be cost prohibitive and logistically challenging. Alternatively, this study employs finite element (FE) simulations, motivated by prior studies in the literature that have consistently shown their agreement with experimental observations. Different modelling strategies were explored in Abaqus/CAE, considering shell, solid, and hybrid approaches for developing the FE model. A pilot study was conducted on a conventional steel plate girder to determine the most suitable model. Figure 1 presents the dimensions of the I-section and its finite element representations using shell, solid, and hybrid modelling approaches.

Fig. 1. (a) Cross Section of I-girder (b) Shell Model (c) Solid Model (d) Hybrid Model