This thesis presents a prestressed and modular design for relieving platforms in deep-sea
quay walls that reduces concrete usage, thereby lowering carbon emissions, and enabling
future upgrades.

About 37% of the world’s CO2 emissions come from the built environment, making it
a significant contributor. To address these issues the Port of Rotterdam has set sustainability
goals, which include becoming climate neutral by the year 2050 and reducing CO2
emissions from material consumption by 25% by the year 2030. This thesis has contributed
to these goals by designing and optimizing a modular prestressed relieving platform for
deep-sea quay walls, that has reduced material usage and carbon emissions. The focus
lied on the relieving platform floor, creating a flexible and upgradable quay wall structure.
The application of post-tensioning has been investigated in the design of the relieving
platform. Several different prestressing variants have been designed, parameterized and
later optimized. In addition a parametric cross-section optimization has been performed
by creating an opening around the neutral axis, that further reduced the concrete usage
in the floor. A final design of the relieving platform floor using a total prestressing tendon
area of 4.500 mm2 per meter resulted in a minimum cross-section height of 890 mm and
an embodied carbon reduction of 20%.

A prefabricated, modular solution has been designed that enables the upgrade of a
quay wall structure by allowing for the relieving platform floor to be added at a later
stage. The building sequence has been designed with a focus on efficiency. The modular
design benefited from the weight reduction of 50% that resulted from the application of
prestressing. Three main connections have been designed, for which several solutions have
been proposed, namely: the module-to-module connection, the module-to-wall connection
and the module-to-foundation pile connection. Particular attention is given to the placement
of the prestressing anchor on the water side of the relieving platform, for which two
alternative solutions have been proposed.

The findings of this thesis show that prestressing can play an important role in creating
lightweight, lower-carbon and modular relieving platforms for deep-sea quay walls. It has
allowed for a significant material reduction, crack control and weight reduction, facilitating
the prefabrication of the floor. This design offers a flexible, upgradeable and lightweight
alternative to traditional the relieving platform design.

Increased traffic loads and ageing of concrete bridges and overpasses in the Netherlands make it necessary to reassess these existing structures. Consequently, the current condition and capacity of many concrete structures need to be evaluated. Residual capacity could be discovered during reassessments of concrete slabs due to a phenomenon called compressive membrane action (CMA). CMA is the formation of internal compressive arches caused by the lateral restraint. As a result, the load is not only transferred by bending action but also by arching action. Research has shown that the ultimate capacity can be significantly increased due to the occurrence of CMA. The goal of this study is to examine the influence of geometrical nonlinearity on this increase in capacity. Also, accurate quantification of the capacity enhancement for a variety of concrete slab variants can be scientifically useful and increases the knowledge on CMA. The study is confined to one way reinforced and restrained concrete slabs.

A new analytical model is presented to quantify the capacity enhancement due to CMA and the geometrical nonlinear (GNL) effect on the capacity. Calibration of the analytical model is performed with a finite element model in DIANA FEA. Also, the finite element model validates the analytical results and is used to study the failure mode of a restrained concrete slab in detail.

The enhancement factor – defined as the enhanced capacity divided by the conventional capacity – turned out to be varying between 1.35 and 4.7 for a large variety of restrained concrete slabs. Thus, the ultimate capacity of restrained one way slabs is significantly increased due to CMA. However, the capacity enhancement would have been even greater if geometrical nonlinearity was not accounted for. Geometrical nonlinearity reduces the increase in capacity because the formed compressive arches will tilt as a result of deflections, therefore leading to a relative decrease of the resisting arching moments. This GNL reduction effect varies between 3% and 37% according to the finite element model. The calibrated analytical model sufficiently estimates this effect with a maximum deviation of about 12%. An important finding was that the enhancement factor is larger for deep slabs than for slender slabs, while the reduction of the ultimate load due to geometrical nonlinearity is larger for slender slabs than for deep slabs.

The Submerged Floating Tunnel (SFT), also called an Archimedes Bridge, is a state of the art solution for crossing deep and large waters. The concept of a SFT has been around for many decades. However, none has still been build up till today. A general literature study showed a number of ‘blank spots’ which still need to be researched before building the first ever “test” SFT. This Thesis discusses the shore connection of the flexible SFT to the fixed land tunnel and several parameters which influence the design of the End Joint.