Monitoring and reliability assessment of a Caisson gate frame in operational conditions

The article explores the comprehensive stress-strain state, reliability assessment, and monitoring of the caisson frame of the S-1 Ship Passage Structure, part of the St. Petersburg Flood Protection Complex. The relevance of this study lies in the uniqueness of the structure, which is unique in the country in terms of its length, as well as the complex and dynamic operating conditions in the Neva Bay. The structure is subject to a variety of factors, including variable hydrostatic pressure, ice loads, and temperature deformations, which shape the stress and strain patterns in the load-bearing elements. Particular attention is paid to the presence of initial residual deformations in the frame, recorded during in-kind inspection, which impact the performance of the structure. The study methodology is based on the finite element method. A detailed finite element model was developed that takes into account the actual geometry of the structure, the physical and mechanical properties of the materials, and the actual initial deformations. A series of calculations was conducted for a set of key operational scenarios: the caisson gate in wet and dry dock, initial moment of movement, and various temperature conditions. For each case, stresses, displacements, and reactions in the support hinge were analyzed. The calculation results showed that local and overall stresses in the frame do not exceed permissible values. Similarly, forces in the support hinge remain below the ultimate load-bearing capacity. However, deformation analysis revealed large deflections, which may be due to installation errors. Large deflections are observed in areas 45-95 meters from the support hinge. Based on the analysis of stress and deformation fields, critical areas of the structure most susceptible to loads and deformations were identified. Recommendations for the placement of vibration, deformation, and strain gauge sensors within the monitoring system were developed for these areas.