The key parameters governing collision energy calculation are the velocity of the vessel, its mass, and the angle of approach. The conventional method outlined in the Recommendations of the Committee for Waterfront Structures Harbours and Waterways (EAU, 2012), which was specifically developed for berthing ships, relies on an overly simplistic model that fails to capture the dynamics of ship­to­guiding structure collisions. Nevertheless, in the Netherlands, the Guidelines for Civil Engineering Structures (Richtlijnen Ontwerp Kunstwerken, ROK) suggest that the EAU 2012 method be applied unmodified for guiding structures. This report introduces a methodological approach aimed at refining the calculation of collision energy by addressing specific deficiencies in the existing framework, particularly regarding its application to guiding structures.

The kinetic energy approach used in the EAU 2012 method requires, as inputs, the mass of the ship, its velocity vector normal to the structure, a virtual mass coefficient accounting for water mass moving with the ship, and an eccentricity coefficient accounting for energy loss due to rotation when the ship does not approach the structure parallel.

The literature review identifies critical gaps in the EAU 2012 approach to calculating collision energy for guiding structures. An unsuitable application of the eccentricity coefficient and assumptions about the velocity vector direction, which do not align with actual conditions in ship­to­guiding structure colli­ sions, are discovered. Moreover, the review reveals that the framework does not differentiate between berthing and guiding approaches, resulting in a one­size­fits­all approach that fails to account for the unique characteristics and requirements of guiding structures. The framework only partially includes the ship’s angle of approach to the structure in the kinetic energy calculation. Although the recommen­ dation is to calculate the kinetic energy using the normal ship speed to the structure—thus indirectly accounting for the approach angle—when it comes to the eccentricity coefficient, which relies on ap­ proach geometry, the recommendation is to consider the total velocity vector. This practice results in exaggerated collision energy when a ship maintains forward speed near guiding structures while passing through the lock.

The theoretical refinement proposed in this thesis focuses on the scenario where the ship approaches a guiding structure with purely longitudinal speed. Specifically, a new definition for the angle variable in the eccentricity coefficient expression is proposed, which directly reflects the effect of the approach angle of the ship linked to the contributing velocity vector and not only laterally through the magnitude of the contributing vector. This proposed change is validated through comparative analysis.

The comparative analysis is performed using historical data cases from model research published by Ri­ jkswaterstaat (Ministry of Infrastructure and Water Management). The data consist of experiments with ship approaches to structures that have characteristics fitting guiding structure approaches. The ships are of lengths commonly found in lock passages, maintain forward speed, and approach structures similar to those at lock entrances. The historical data provide the maximum force exerted on the tested structure and the resulting deflection. This information is used to derive the energy absorbed by the structure. The published reports valuable to this research resulted in the Virtual Water Mass method. This method is reproduced to provide benchmark values for the kinetic energy absorbed, which are compared to both the EAU 2012 collision energy calculation and the proposed refined calculation for the historical data cases.

The findings of the comparative analysis suggest that the proposed refined calculation provides results closer to the benchmark values than the EAU 2012 calculation. However, a consistent improvement was not discovered. Although the refined calculation is significantly closer to the benchmark value in every case compared to the EAU 2012 calculation, this improvement cannot be quantified as a universal percentage, as it varied for each case. Despite this, the comparative analysis still supports the main objective of demonstrating the exaggeration in the EAU 2012 collision energy calculation.

A case study, as part of this research, explores the potential effect of the refined calculation on an actual structure design. In the case study, the design vessel, velocity, and angle of approach are sourced from the Waterway Guidelines (2011, 2020) and ROK 2.0 (all documents published by Rijkswaterstaat). After calculating the impact energy using the two methods compared in this research, the design of the mono­ pile follows the Blum method. The structure is modeled as a series of piles connected by a main girder, with the girder having the same diameter as the piles to ensure uniformity and strength.

The case of the Volkerak locks is chosen, and calculations using both the standard EAU 2012 method and the proposed refined one are executed. Two designs are produced and compared. With the refined calculation, a design with a smaller pile diameter of 1,620 mm and a longer in­between pile distance of 6.5 m is achieved, compared to the EAU 2012 design, where the pile diameter is 2,020 mm and the distance between piles is 3 m. These results demonstrate the potential for material savings if the refined calculation is adopted.

The study concludes that a refined approach is indeed necessary and that focus should be placed on specific definitions and descriptions in the guidelines. Ambiguity in such definitions leaves decision­ making subject to individual interpretations, creating inconsistency among the designs of structures with the same purpose. Although this inconsistency may not be inherently dangerous, as it usually results in an overly conservative design, it contributes to excess material usage and resource waste.