Moving load on guide works during a brush collision with a vessel

Abstract

In the vicinity of locks and bridge piers, guide works are placed in order to steer inland navigation vessels through a narrowed passage. The design of these structures is generally done in a static way, thus without consideration of time-dependent phenomena. By treating the contact force during a brush collision as a static force, several phenomena are overlooked. First of all, it is possible that, in case of a brush collision, a second impact occurs due to the yawing motion of the vessel that is generated during the first impact. Considering the time domain in the analysis of brush collisions also enables the investigation of the length that is required for a guide work to fulfill its function. Within this thesis the time aspect is considered for brush collisions between inland navigation vessels and guide works with steel hollow tubular cross-sections.Objective of this research is to quantify the second impact and to provide a recommendation for the length of guide works, in order to answer the question: “In what ways is the design of guide works affected by taking into account the time domain?. A parametric tool that simulates brush collisions is created in Python. By variation of one parameter at a time, the influence of this parameter on the magnitude of the second impact and the required length for a guide work is visualised. 
Eventually, the model created in Python is translated to SCIA Engineer. By using the automatic post-processing environment of the Finite Element Software, this translation can be used to speed up the design guide works in future projects. On top of that, the influence of torsion on the mechanical behaviour of the structure is taken into account. For the investigated parameters a second impact always occurs within the 90 seconds of performed analysis, except for vessels with a large mass or length, or a small initial velocity. On top of that, the contact force during the second impact generally appears to be 30 to 40 percent larger than the first impact, while guide works are commonly designed for the first impact. Only for initial contact angles larger than 13 degrees or vessels with draught of more than 7 meters, the first impact is governing. The required length of a guide work to facilitate a brush collision itself is very well obtainable by using the created model. Nonetheless, due to the spread of the location of the first contact, a large uncertainty still remains in determining the total length of a guide work. For the translation to SCIA Engineer it holds that it is possible translate the Python model into a model involving SCIA Engineer. The long computation time of this translation, however, make this tool rather impractical.