Canals delimited with masonry quay walls are integral elements of many Dutch cities. Historically built to enable the efficient transportation of goods, such infrastructure today also gives these cities their historical and monumental character. In recent years, many quay walls in the city of Amsterdam have shown substantial deformation as well as collapse. These quay walls which are constructed in multi-wythe unreinforced brick masonry and are supported on a system of timber piles, today sustain loads associated with the traffic of a modern city which are far higher than what they were originally designed for. This has given rise to a need for research assessing the safety and reliability of these structures, which are not appropriately covered by any normatives or standardised guidelines. This paper presents the results of a numerical modelling approach to understand the same. In particular, a novel methodology to numerically assess the performance of such quay walls under the effect of dynamic traffic loads is first proposed. A two-step modelling approach is adopted in this methodology. In the first step, a 3D soil-block comprising the carriageway adjacent to quay walls is modelled. The passage of a heavy vehicle over a limited distance on the carriageway is then simulated. From this simulation, recordings are made of : a) the distributions of normal stresses on the quay wall at the instant of occurrence of their maxima and b) the time-histories of the same maxima stresses. In the second step, these recordings are applied in combination to a sequence of sections of the 3D numerical model of the quay wall system. The length of each section in the second step measures the same as the limited distance over which the passage of the vehicle on the soil-block was simulated in the first step. Adopting such a simplified yet conservative approach allows simulation of the passage of vehicles over numerical models of long quay wall systems while avoiding the heavy computational burden associated with the explicit modelling of a soil block. The response of quay walls when subjected to dynamic traffic loads simulated using the proposed methodology is ultimately presented.

The railway transition zone, where the track transitions from a ballasted track to a slab track, is a crucial area that can experience amplified dynamic responses. This work aims to develop a deeper insight into the mechanisms leading to the amplified dynamic response in railway transition zones. The study employs a finite element (FE) model to investigate the amplification of total strain energies due to the phenomena of reflection and redistribution close to the transition interface. The results of the study are obtained for three case studies involving non-reflecting boundaries and homogenous material along the vertical direction of the track, and the conditions are studied for individual and combined effects. The findings of the study show that eliminating these phenomena leads to no amplification of total strain energies in railway transition zones. The conclusion highlights the importance of understanding these mechanisms in order to design an efficient railway transition structure. Keywords: railway transition zones, dynamic response, finite element model, strain energies, reflection, redistribution, ballasted track, slab track.