Reliability studies of the frame of the C1 shipping opening

This article presents a comprehensive computational study of the metal frame of the caisson gate of the C1 shipping opening, part of the St. Petersburg flood protection system. The relevance of this study stems from the need to ensure the strength, stability, and safe operation of this unique 120-meter-long structure, which supports the segmental caisson gate during its movement from the dry dock to the structure's span. The frame is distinguished by its cantilever structure of variable thickness and reinforced with stiffeners. The aim of the study was to develop an adequate spatial computational model of the frame and caisson gate and analyze their stress-strain state for a stationary position in a dry dock. The study was conducted using the finite element method, taking into account constant static loads, including the structures' own weight and hydrostatic pressure. The paper presents the developed spatial finite element model and describes the adopted boundary conditions and loads. Permissible stresses and deflections are determined. The calculations yielded stress and displacement fields. It was determined that the maximum equivalent stresses in the frame do not exceed permissible values. The maximum frame deflection is also within acceptable limits. An analysis of the dynamic characteristics of the structure was conducted. The natural frequencies of vibration were determined for the caisson gate. A stability analysis was performed, showing that the safety factor for the first positive buckling mode exceeds the minimum required. Based on the obtained results, a conclusion was reached that the calculated stresses and deformations comply with regulatory requirements and provide the necessary safety and stability margins. To monitor the condition of the structure during operation, it is recommended to install vibration sensors at critical points, as well as conduct further research.