Due to increasingly efficient engineering of the last decades, the design process for civil structures is heading in the direction of optimal solutions. Among other things, the reduction in self-weight enhances the susceptibility to dynamic loads. As the process for the determination of realistic modal parameters from a digital model often diverges from the reality, the uncertainties should be investigated. This research aims to gain knowledge on the accuracy and stability of such modal parameter estimates. A case study is investigated to determine modal parameters for a realized tied-arch railway bridge. The desired modal properties include the natural frequencies, mode shapes and damping parameters. The frequency domain decomposition (FDD) method is applied on a set of accelerational measurements to determine the modal parameters. Four dominant frequencies are identified and investigated, from which the most dominant operational deflection shapes are extracted. The overall response of the structure shows great similarities with the expected mode shapes for similar bridge types. The computed modes show signs of complex behaviour, due to the characteristics of the load or the structure. An effective method to reduce uncorrelated noise is the application of an autocorrelation function (ACF) to the time domain signals, before execution of the FDD. Prior to the computation of the final results related to the case study, a simplified test case is considered to validate correctness of the FDD implementation.

Compressive membrane action is a phenomenon commonly found in reinforced concrete structures after significant cracking and deformation have taken place. In this thesis report, the potential benefit of CMA in immersed tubes subjected to fires is quantified through a finite element study. Furthermore, sensitivity studies are conducted in order to determine the boundary conditions necessary in immersed tubes to induce CMA.

Port of Rotterdam has the ambition to reduce the footprint for building new quay walls, this is in line with their ambition to reduce the footprint and with national goals to limit global warming. The aim is to use less materials and/or use different design solutions. These reinforced structures are designed in a conventional way and the internal forces are determined by performing a Linear Elastic Analysis. The reinforcement is calculated using the internal forces and is based on the Eurocode 1992 -1-1. The conventional approach includes various assumptions that affect the amount of concrete and steel used, which influences the CO2 footprint, structure reliability, and costs. In order to know the effects of these assumptions, advanced nonlinear calculations are carried out using volume elements