PSI - Issue 81

Ahsan Anugrah Elbar et al. / Procedia Structural Integrity 81 (2026) 3–10

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maintain reservoir functionality (Kurniawan et al., 2022). These removal operations rely on a ramp plate, which serves as the trash box's bottom structural surface on the boat, providing crucial support for the movement and transfer of wet biomass. However, continuous exposure to water and repeated heavy loading accelerate corrosion of the ramp plate, resulting in thickness reduction, lower structural strength, and increased susceptibility to deformation (Melchers and Jeffrey, 2008). As the material weakens, even moderate operational loads can cause excessive deflection, local stress concentration, and damage, thereby interrupting harvesting activities and increasing maintenance costs. To address these issues, this study combines analytical calculations based on classical plate theory with finite element simulations (Prabowo et al., 2023; Naufal et al., 2024; Saputra et al., 2025) to evaluate how the ramp plate responds to real loading and corrosion conditions at Cengklik Reservoir, providing insights for improving its durability and reliability in the field. 2. Analytical Calculation Before performing numerical simulation, an analytical formulation was first established to describe the plate deflection and stress behavior under uniform and triangular pressure loadings. This formulation validates the finite element results (Fuadi et al., 2024; Wiranto et al., 2024; Fitri et al., 2025; Malsyage et al., 2025) and provides a theoretical reference for evaluating deflection and stress distribution on the bottom plate of the structure. The deflection of a fully clamped square plate under uniform pressure loading can be expressed using the plate theory (Timoshenko and Woinowsky-Krieger, 1959), as shown in Eq. (1) = 4 (1) where is the maximum deflection in meter, is the applied pressure in N/m², is the plate side length (m), is the plate flexural rigidity (N·m), and is a dimensionless coefficient that depends on the boundary conditions and plate aspect ratio. The flexural rigidity of the plate represents the resistance of the material to bending deformation and is determined using Eq. (2) (Ugural, 2010). = 3 12(1− 2 ) (2) where is the elastic modulus of the plate material, is its thickness, and is Poisson’s ratio. The uniform pressure acting on the plate surface is calculated as the total applied load divided by the surface area, as defined in Eq. (3). = (3) where is the total resultant force acting normally on the plate surface, and is the total loaded area. Under certain loading conditions, the pressure distribution is non-uniform and can be modeled as a triangular load. The maximum pressure at the plate edge is determined using Eq. (4) (Timoshenko and Woinowsky-Krieger, 1959). = 2 (4) To assess the accuracy of the finite element simulation, the percentage error between analytical and numerical deflection is calculated using Eq. (5) (Prabowo et al., 2024; 2025; Mohammed et al., 2018). (%) = | − | | | ×100% (5) 3. Material and Method 3.1. Geometry model and material properties The ramp plate geometry is shown in Fig. 1a, with dimensions of 2095 mm × 960 mm and a thickness of 2.5 mm. The plate is made of galvanized steel, selected for its strength and corrosion resistance. The material properties adopted from Kamal et al. (2013) are summarized in Table 1. The nonlinear stress – strain curve used in the simulation, shown in Fig. 1(b), follows the data of Wang and Shao (2023) and represents the elastic, yielding, and strain-hardening behavior of galvanized steel.